Page 1
FDC37N869
100 Pin TQFP Package
5V and 3.3V Super I/O Controller with Infrared Support for
Portable Applications
FEATURES
§ PC 99 Compliant
§ 5 Volt and 3.3 Volt Operation
§ Intelligent Auto Power Management
§ 16 Bit Address Qualification
§ 2.88MB Super I/O Floppy Disk Controller
- Licensed CMOS 765B Floppy Disk Controller
- Software and Register Compatible with
SMSC’s Proprietary 82077AA Compatible
Core
- Supports One Floppy Drive Directly
- Configurable Open Drain/Push-Pull Output
Drivers
- Supports Vertical Recording Format
- 16 Byte Data FIFO
- 100% IBM Compatibility
- Detects All Overrun and Underrun Conditions
- Sophisticated Power Control Circuitry (PCC)
Including Multiple Power-Down Modes for
Reduced Power Consumption
- DMA Enable Logic
- Data Rate and Drive Control Registers
- Swap Drives A and B
- Non-Burst Mode DMA Option
- 48 Base I/O Address, 15 IRQ and 4 DMA
Options
- Forceable Write Protect and Disk Change
Controls
§ Floppy Disk Available on Parallel Port Pins
ACPI Compliant
§ Enhanced Digital Data Separator
- 2Mbps, 1 Mbps, 500 Kbps, 300 Kbps,
250 Kbps Data Rates
- Programmable Precompensation Modes
§ Serial Ports
- Two High Speed NS16C550 Compatible
UARTs with Send/Receive 16 Byte FIFOs
- Supports 230k and 460k Baud
- Programmable Baud Rate Generator
- Modem Control Circuitry
§ Infrared Communications Controller
- IrDA v1.1 (4Mbps), HPSIR, ASKIR, Consumer
IR Support
- 2 IR Ports
- 96 Base I/O Address, 15 IRQ Options and 4
DMA Options
§ Multi-Mode Parallel Port with ChiProtect
- Standard Mode
- IBM PC/XT, PC/AT, and PS/2 Compatible Bidirectional Parallel Port
- Enhanced Parallel Port (EPP) Compatible
- EPP 1.7 and EPP 1.9 (IEEE 1284 Compliant)
- Enhanced Capabilities Port (ECP)
Compatible (IEEE 1284 Compliant)
- Incorporates ChiProtect Circuitry for Protection
Against Damage Due to Printer Power-On
- 192 Base I/O Address, 15 IRQ and 4 DMA
Options
§ Game Port Select Logic
- 48 Base I/O Addresses
§ General Purpose Address Decoder
- 16-Byte Block Decode
SMSC DS – FDC37N869 11/09/2000
ORDERING INFORMATION
Order Number: FDC37N869TQFP
Page 2
© 2000 STANDARD MICROSYSTEMS CORPORATION (SMSC)
80 Arkay Drive
Hauppauge, NY 11788
(631) 435-6000
FAX (631) 273-3123
Standard Microsystems is a registered trademark of Standard Microsystems Corporation, and SMSC, ChiProtect, SuperCell and Multi-Mode are
trademarks of Standard Microsystems Corporation. Product names and company names are the trademarks of their respective holders. Circuit
diagrams utilizing SMSC products are included as a means of illustrating typical applications; consequently complete information sufficient for
construction purposes is not necessarily given. Although the information has been checked and is believed to be accurate, no responsibility is
assumed for inaccuracies. SMSC reserves the right to make changes to specifications and product descriptions at any time without notice. Contact
your local SMSC sales office to obtain the latest specifications before placing your product order. The provision of this information does not convey
to the purchaser of the semiconductor devices described any licenses under the patent rights of SMSC or others. All sales are expressly conditional
on your agreement to the terms and conditions of the most recently dated version of SMSC's standard Terms of Sale Agreement dated before the
date of your order (the "Terms of Sale Agreement"). The product may contain design defects or errors known as anomalies which may cause the
product's functions to deviate from published specifications. Anomaly sheets are available upon request. SMSC products are not designed,
intended, authorized or warranted for use in any life support or other application where product failure could cause or contribute to personal injury or
severe property damage. Any and all such uses without prior written approval of an Officer of SMSC and further testing and/or modification will be
fully at the risk of the customer. Copies of this document or other SMSC literature, as well as the Terms of Sale Agreement, may be obtained by
visiting SMSC’s website at http://www.smsc.com.
SMSC DISCLAIMS AND EXCLUDES ANY AND ALL WARRANTIES, INCLUDING WITHOUT LIMITATION ANY AND ALL IMPLIED WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE, AND AGAINST INFRINGEMENT, AND ANY AND ALL WARRANTIES
ARISING FROM ANY COURSE OF DEALING OR USAGE OF TRADE.
IN NO EVENT SHALL SMSC BE LIABLE FOR ANY DIRECT, INCIDENTAL, INDIRECT, SPECIAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES;
OR FOR LOST DATA, PROFITS, SAVINGS OR REVENUES OF ANY KIND; REGARDLESS OF THE FORM OF ACTION, WHETHER BASED ON
CONTRACT; TORT; NEGLIGENCE OF SMSC OR OTHERS; STRICT LIABILITY; BREACH OF WARRANTY; OR OTHERWISE; WHETHER OR NOT
ANY REMEDY IS HELD TO HAVE FAILED OF ITS ESSENTIAL PURPOSE, AND WHETHER OR NOT SMSC HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
SMSC DS – FDC37N869 Page 2 Rev. 11/09/2000
Page 3
GENERAL DESCRIPTION
The SMSC FDC37N869 is a 5v/3.3v PC 99-compliant Super I/O Controller with Infrared support. The FDC37N869
utilizes SMSC’s proven SuperCell technology and is optimized for motherboard applications. The FDC37N869
incorporates SMSC’s true CMOS 765B floppy disk controller, advanced digital data separator, 16-byte data FIFO,
two 16C550 compatible UARTs, one Multi-Mode parallel port with ChiProtect circuitry plus EPP and ECP support,
game port chip select logic and one floppy direct drive support. The FDC37N869 does not require any external
filter components, is easy to use and offers lower system cost and reduced board area. The FDC37N869 is
software and register compatible with SMSC’s proprietary 82077AA core.
The true CMOS 765B core provides 100% compatibility with IBM PC/XT and PC/AT architectures and provides data
overflow and underflow protection. The SMSC advanced digital data separator incorporates SMSC’s patented data
separator technology allowing for ease of testing and use. The FDC37N869 supports both 1Mbps and 2Mbps data
rates and vertical recording operation at 1Mbps Data Rate.
The FDC37N869 also features a full 16-bit internally decoded address bus, a Serial IRQinterface with PCI
nCLKRUN support, relocatable configuration ports and four DMA channel options.
Both on-chip UARTs are compatible with the NS16C550. One UART includes additional support for a Serial
Infrared Interface that complies with IrDA v1.2 (Fast IR), HPSIR, and ASKIR formats (used by Sharp, Apple Newton,
and other PDAs), as well as Consumer IR.
The parallel port and the game port select logic are compatible with IBM PC/AT architectures. The parallel port
ChiProtect circuitry prevents damage caused by an attached powered printer when the FDC37N869 is not
powered.
The FDC37N869 incorporates sophisticated power control circuitry (PCC). The PCC supports multiple low power
down modes. The FDC37N869 also features Software Configurable Logic (SCL) for ease of use. SCL allows
programmable system configuration of key functions such as the FDC, parallel port, and UARTs.
SMSC DS – FDC37N869 Page 3 Rev. 11/09/2000
Page 4
TABLE OF CONTENTS
GENERAL DESCRIPTION ...................................................................................................................3
PIN CONFIGURATION........................................................................................................................8
PIN DESCRIPTION.............................................................................................................................9
BUFFER TYPE PER PIN ..................................................................................................................9
BUFFER TYPE SUMMARY .................................................................................................................... 15
OUTPUT DRIVERS.............................................................................................................................. 15
FUNCTIONAL DESCRIPTION ............................................................................................................17
HOST PROCESSOR INTERFACE............................................................................................................. 17
FLOPPY DISK CONTROLLER ...........................................................................................................17
MODES OF OPERATION...................................................................................................................... 17
Floppy Modes........................................................................................................................... 17
Interface Modes......................................................................................................................... 18
FLOPPY DISK CONTROLLER INTERNAL REGISTERS .................................................................................... 18
STATUS REGISTER A (SRA)..................................................................................................... 18
STATUS REGISTER B (SRB)..................................................................................................... 21
DIGITAL OUTPUT REGISTER (DOR)........................................................................................... 23
TAPE DRIVE REGISTER (TDR) .................................................................................................. 24
MAIN STATUS REGISTER (MSR).............................................................................................. 25
DATA RATE SELECT REGISTER (DSR) .................................................................................... 26
DATA REGISTER (FIFO) ............................................................................................................29
DIGITAL INPUT REGISTER (DIR)................................................................................................ 29
CONFIGURATION CONTROL REGISTER (CCR).......................................................................... 31
STATUS REGISTER ENCODING.............................................................................................................. 32
RESET............................................................................................................................................ 33
RESET Pin (Hardware Reset)..................................................................................................... 34
DOR Reset vs. DSR Reset (Software Reset)................................................................................. 34
DMA TRANSFERS............................................................................................................................. 34
CONTROLLER PHASES ....................................................................................................................... 34
Command Phase........................................................................................................................ 34
Execution Phase ....................................................................................................................... 34
Result Phase ............................................................................................................................. 35
COMMAND SET/DESCRIPTIONS ............................................................................................................. 36
INSTRUCTION SET.............................................................................................................................. 38
DATA TRANSFER COMMANDS.............................................................................................................. 46
Read Data ................................................................................................................................. 46
Read Deleted Data .....................................................................................................................48
Read A Track............................................................................................................................ 48
Write Data .................................................................................................................................49
Write Deleted Data .................................................................................................................... 50
Verify......................................................................................................................................... 50
Format A Track .........................................................................................................................51
CONTROL COMMANDS ....................................................................................................................... 52
Read ID .....................................................................................................................................52
Recalibrate................................................................................................................................ 52
Seek ......................................................................................................................................... 53
Sense Interrupt Status ................................................................................................................ 53
Sense Drive Status ....................................................................................................................54
Specify ..................................................................................................................................... 54
SMSC DS – FDC37N869 Page 4 Rev. 11/09/2000
Page 5
Configure.................................................................................................................................. 54
Version..................................................................................................................................... 55
Relative Seek............................................................................................................................. 55
Perpendicular Mode.................................................................................................................. 56
LOCK........................................................................................................................................ 57
ENHANCED DUMPREG............................................................................................................. 57
COMPATIBILITY ............................................................................................................................ 57
PARALLEL PORT FLOPPY DISK CONTROLLER.......................................................................................... 57
SERIAL PORT (UART)...................................................................................................................... 59
REGISTER DESCRIPTION...................................................................................................................... 59
RECEIVE BUFFER REGISTER (RB)............................................................................................ 59
TRANSMIT BUFFER REGISTER (TB)......................................................................................... 59
INTERRUPT ENABLE REGISTER (IER)....................................................................................... 59
INTERRUPT IDENTIFICATION REGISTER (IIR) ............................................................................ 60
FIFO CONTROL REGISTER (FCR) ..............................................................................................62
LINE CONTROL REGISTER (LCR) ..............................................................................................63
MODEM CONTROL REGISTER (MCR)....................................................................................... 64
LINE STATUS REGISTER (LSR) ................................................................................................ 65
MODEM STATUS REGISTER (MSR).......................................................................................... 66
SCRATCHPAD REGISTER (SCR)............................................................................................... 67
PROGRAMMABLE BAUD RATE GENERATOR DIVISOR LATCHES ........................................... 67
The Affects of RESET on the UART Registers............................................................................ 68
FIFO INTERRUPT MODE OPERATION...................................................................................................... 68
FIFO POLLED MODE OPERATION......................................................................................................... 69
NOTES ON SERIAL PORT FIFO MODE OPERATION................................................................................... 70
GENERAL................................................................................................................................. 70
TX AND RX FIFO OPERATION ...................................................................................................71
INFRARED INTERFACE .................................................................................................................... 71
IRDA SIR/FIR AND ASKIR................................................................................................................ 71
CONSUMER IR.................................................................................................................................. 72
HARDWARE INTERFACE...................................................................................................................... 72
IR HALF DUPLEX TURNAROUND DELAY TIME........................................................................................... 72
PARALLEL PORT............................................................................................................................. 74
IBM XT/AT COMPATIBLE, BI-DIRECTIONAL AND EPP MODES ........................................................75
DATA PORT ..............................................................................................................................75
STATUS PORT ..........................................................................................................................75
CONTROL PORT ....................................................................................................................... 76
EPP ADDRESS PORT ................................................................................................................77
EPP DATA PORT 0.................................................................................................................... 77
EPP DATA PORT 1.................................................................................................................... 77
EPP DATA PORT 2.................................................................................................................... 77
EPP DATA PORT 3.................................................................................................................... 77
EPP 1.9 OPERATION .................................................................................................................... 77
Software Constraints .................................................................................................................78
EPP 1.9 Write ............................................................................................................................78
EPP 1.9 Read ............................................................................................................................ 78
EPP 1.7 OPERATION .................................................................................................................... 79
Software Constraints .................................................................................................................79
EPP 1.7 Write ............................................................................................................................79
EPP 1.7 Read ............................................................................................................................ 79
EXTENDED CAPABILITIES PARALLEL PORT.................................................................................. 81
Vocabulary ............................................................................................................................... 81
ISA IMPLEMENTATION STANDARD.......................................................................................... 82
SMSC DS – FDC37N869 Page 5 Rev. 11/09/2000
Page 6
Description ............................................................................................................................... 82
Register Definitions................................................................................................................... 83
OPERATION.............................................................................................................................. 89
AUTO POWER MANAGEMENT ......................................................................................................... 93
FDC POWER MANAGEMENT ............................................................................................................... 93
DSR From Powerdown ..............................................................................................................93
Wake Up From Auto Powerdown.............................................................................................. 93
Register Behavior...................................................................................................................... 94
Pin Behavior............................................................................................................................. 94
UART POWER MANAGEMENT ............................................................................................................. 96
PARALLEL PORT.............................................................................................................................. 96
SERIAL IRQ .................................................................................................................................. 96
Introduction.............................................................................................................................. 96
IRQSER Cycle Modes................................................................................................................ 97
IRQSER IRQ/Data Frames.......................................................................................................... 98
Stop Cycle Control.................................................................................................................... 99
Latency..................................................................................................................................... 99
EOI/ISR Read Latency ............................................................................................................... 99
AC/DC Specification Issue .........................................................................................................99
Reset and Initialization ................................................................................................................99
ADD PCI NCLKRUN SUPPORT ....................................................................................................100
Overview.................................................................................................................................100
Using nCLKRUN ......................................................................................................................100
CONFIGURATION...........................................................................................................................101
CONFIGURATION ACCESS PORTS........................................................................................................101
CONFIGURATION STATE ....................................................................................................................102
Entering the Configuration State .............................................................................................102
Configuration Register Programming ......................................................................................102
Exiting the Configuration State...............................................................................................102
Programming Example ...........................................................................................................102
Configuration Select Register (CSR) ........................................................................................103
CONFIGURATION REGISTERS DESCRIPTION ............................................................................................103
CR00.......................................................................................................................................104
CR01.......................................................................................................................................104
CR02.......................................................................................................................................106
CR03.......................................................................................................................................106
CR04.......................................................................................................................................107
CR05.......................................................................................................................................108
CR06.......................................................................................................................................108
CR07.......................................................................................................................................109
CR08.......................................................................................................................................109
CR09.......................................................................................................................................109
CR0A ......................................................................................................................................110
CR0B ......................................................................................................................................110
CR0C ......................................................................................................................................111
CR0D ......................................................................................................................................111
CR0E ......................................................................................................................................111
CR0F.......................................................................................................................................111
CR10.......................................................................................................................................112
CR11.......................................................................................................................................112
CR12 - CR13 ............................................................................................................................112
CR14.......................................................................................................................................113
CR15.......................................................................................................................................113
CR16.......................................................................................................................................113
SMSC DS – FDC37N869 Page 6 Rev. 11/09/2000
Page 7
CR17.......................................................................................................................................113
CR18 - CR1D ...........................................................................................................................114
CR1E ......................................................................................................................................114
CR1F.......................................................................................................................................114
CR20.......................................................................................................................................115
CR21.......................................................................................................................................115
CR23.......................................................................................................................................115
CR24.......................................................................................................................................116
CR25.......................................................................................................................................116
CR26.......................................................................................................................................116
CR27.......................................................................................................................................117
CR28.......................................................................................................................................117
CR29.......................................................................................................................................118
CR2A ......................................................................................................................................118
CR2B ......................................................................................................................................118
CR2C ......................................................................................................................................118
CR2D ......................................................................................................................................119
CR2E ......................................................................................................................................119
CR2F.......................................................................................................................................119
OPERATIONAL DESCRIPTION .......................................................................................................120
MAXIMUM GUARANTEED RATINGS .............................................................................................120
DC ELECTRICAL CHARACTERISTICS ...........................................................................................120
AC TIMING.....................................................................................................................................126
HOST TIMING..................................................................................................................................126
FDD TIMING ..................................................................................................................................130
SERIAL PORT TIMING .......................................................................................................................131
PARALLEL PORT TIMING...................................................................................................................136
Parallel Port EPP Timing .........................................................................................................137
Parallel Port ECP Timing.........................................................................................................142
PACKAGE OUTLINES ..................................................................................................................... 146
FDC37N869 REVISIONS .................................................................................................................147
SMSC DS – FDC37N869 Page 7 Rev. 11/09/2000
Page 8
IRMODE/IRRX3
RXD1
TXD1
nDSR1
nRTS1
nCTS1
nDTR1
nRI1
nDCD1
nRI2
nDCD2
RXD2
TXD2
nDSR2
nRTS2
nCTS2
nDTR2
nADRX/nCLKRUN
VSS
nDACK_C
A10
IRQIN
DRQ_C
IOCHRDY
DRVDEN0
nMTR0
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
nSTROBE
nAUTOFD
nERROR
75
74
73
PIN CONFIGURATION
nINIT
nSLCT
VCC
PD0
PD1
PD2
PD3
VSS
PD4
PD5
PD6
PD7
nACK
BUSYPESLCT
72
71
70
69
68
67
66
65
64
63
62
61
60
59
58
57
FDC37N869
100 PIN TQFP
PWRGD
RESET_DRV
D7D6D5
56
55
54
53
52
D4
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
DRQ_B
D3
D2
D1
D0
VSS
AEN
nIOW
nIOR
A9
A8
A7
CLK33
SIRQ
A12
A11
nDACK_B
TC
A6
A5
A4
A3
A2
A1
A0
1 2 3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
A13
A14
nDS0
VSS
nDIR
nSTEP
nWDATA
nHDSEL
nWGATE
nTRK0
nINDEX
VCC
nRDATA
nWRTPRT
DRQ_D
DRVDEN1
nDSKCHG
CLK14
FIGURE 1 - FDC37N869 PIN CONFIGURATION
19
20
DRQ_A
nDACK_A
21
22 2324
nDACK_D
IRTX2
IRRX2
25
A15
SMSC DS – FDC37N869 Page 8 Rev. 11/09/2000
Page 9
PIN DESCRIPTION
BUFFER TYPE PER PIN
Table 1 - DESCRIPTION OF PIN FUNCTIONS
TQFP
PIN # NAME SYMBOL
46-49
Data Bus 0-7D0-D7 IO12 The data bus connection used by the host
51-54
42 nI/O Read nIOR IS This active low signal is issued by the host
43 nI/O Write nIOW IS This active low signal is issued by the host
44 Address
AEN IS Active high Address Enable indicates DMA
Enable
26-32
39-41,
Address
Bus
A0-A15 I These host address bits determine the I/O
95,35,
36,1,
3,25
19,50,
97,17
DMA
Request
A, B, C, D
DRQ_A
DRQ_B
DRQ_C
DRQ_D
20,34,
94,22
nDMA
Acknowledge
A, B, C, D
33 Terminal
nDACK_A
nDACK_B
nDACK_C
nDACK_D
TC IS This signal indicates that DMA data transfer is
Count
37 Serial IRQ SIRQ IO12 Serial IRQ pin used with the CLK33 pin to
38 PCI Clock CLK33 ICLK 33MHz PCI clock input, used with the SIRQ and
55 Reset RESET_
DRV
98 I/O Channel
IOCHRDY OD12 This pin is pulled low to extend the read/write
Ready
(Note4)
14 nRead Disk
nRDATA IS Raw serial bit stream from the disk drive, low
Data
BUFFER
6
MODE
DESCRIPTION
HOST PROCESSOR INTERFACE
microprocessor to transmit data to and from the
chip. These pins are in a high-impedance state
when not in the output mode.
microprocessor to indicate an I/O read
operation.
microprocessor to indicate an I/O write
operation.
operations on the host data bus. Used internally
to qualify appropriate address decodes.
address to be accessed during nIOR and nIOW
cycles. These bits are latched internally by the
leading edge of nIOR and nIOW. All internal
address decodes use the full A0 to A15 address
bits.
O12 These active high outputs are the DMA request
for byte trans fers of data between the host and
the chip. These signals are cleared on the last
byte of the data transfer by the nDACK signal
going low (or by nIOR going low if nDACK was
already low as in demand mode).
IS These are active low inputs acknowledging the
request for a DMA transfer of data between the
host and the chip. These inputs enable the DMA
read or write internally.
complete. TC is only accepted when nDACK_x
is low. In AT and PS/2 model 30 modes, TC is
active high and in PS/2 mode, TC is active low.
transfer FDC37N869 interrupts to the host.
the nCLKRUN pins to serially transfer
FDC37N869 interrupts to the host.
IS This active high signal resets the chip and must
be valid for 500ns minimum. The effect on the
internal registers is described in the appropriate
section. The configuration registers are not
affected by this reset.
command. IOCHRDY can used by the IRCC and
by the Parallel Port in EPP mode.
FLOPPY DISK INTERFACE
active. Each falling edge represents a flux
transition of the encoded data.
SMSC DS – FDC37N869 Page 9 Rev. 11/09/2000
Page 10
TQFP
PIN # NAME SYMBOL
8 nWrite
nWGATE (O12/
Gate
BUFFER
MODE
OD12)
6
DESCRIPTION
This active low high current driver allows current
to flow through the write head. It becomes active
just prior to writing to the diskette.
7 nWrite
Data
nWDATA (O12/
OD12)
This active low high current driver provides the
encoded data to the disk drive. Each falling
edge causes a flux transition on the media.
9 nHead
Select
nHDSEL (O12/
OD12)
This high current output selects the floppy disk
side for reading or writing. A logic “1” on this pin
means side 0 will be accessed, while a logic “0”
means side 1 will be accessed.
5 Direction
Control
nDIR (O12/
OD12)
This high current low active output determines
the direction of the head movement. A logic “1”
on this pin means outward motion, while a logic
“0” means inward motion.
6 nStep Pulse nSTEP (O12/
OD12)
This active low high current driver issues a low
pulse for each track-to-track movement of the
head.
15 Disk
Change
nDSKCHG IS This input senses that the drive door is open or
that the diskette has possibly been changed
since the last drive selection. This input is
inverted and read via bit 7 of I/O address 3F7H.
The nDSKCHG bit also depends upon the state
of the Force Disk Change bits in the Force FDD
Status Change configuration register (see
section CR17 on page 109).
2 nDrive
Select 0
100 nMotor On 0 nMTR0 (O12/
nDS0 (O12/
OD12)
Active low output selects drive 0.
These active low output selects motor drive 0.
OD12)
99 Drive
Density 0
12 nWrite
Protected
DRVDEN0 (O12/
OD12)
Indicates the drive and media selected. Refer to
configuration registers CR03, CR0B, CR1F.
nWRTPRT IS This active low Schmitt Trigger input senses
from the disk drive that a disk is write protected.
Any write command is ignored. The nWRPRT bit
also depends upon the state of the Force Write
Protect bit in the Force FDD Status Change
configuration register (see section CR17 on
page 109).
11 wTrack 00 nTRK0 IS This active low Schmitt Trigger input senses
from the disk drive that the head is positioned
over the outermost track.
10 nIndex nINDEX IS This active low Schmitt Trigger input senses
from the disk drive that the head is positioned
over the beginning of a track, as marked by an
index hole.
16 Drive
Density 1
DRVDEN 1 (O12/
OD12)
Indicates the drive and media selected. Refer to
configuration registers CR03, CR0B, CR1F.
SERIAL PORTS INTERFACE
86 Receive
Data 2
87 Transmit
Data 2
RXD2 IS Receiver serial data input for port 2. IR Receive
Data
TXD2 O12PD Transmit serial data output for port 2. IR
transmit data.
(Note5)
76 Receive
RXD1 I Receiver serial data input for port 1.
Data 1
SMSC DS – FDC37N869 Page 10 Rev. 11/09/2000
Page 11
TQFP
PIN # NAME SYMBOL
77 Transmit
TXD1 O12 Transmit serial data output for port 1.
Data 1
79,89 nRequest to
nRTS1
Send
nRTS2
(System
(SYSOPT)
Option)
81,91 nData
nDTR1
Terminal
Ready
80,90 nClear to
nDTR2
nCTS1
Send
nCTS2
78,88 nData Set
nDSR1
Ready
nDSR2
83,85 nData
nDCD1
Carrier
Detect
nDCD2
BUFFER
6
MODE
DESCRIPTION
O6 Active low Request to Send outputs for the Serial
Port. Handshake output signal notifies modem
that the UART is ready to transmit data. This
signal can be programmed by writing to bit 1 of
the Modem Control Register (MCR). The
hardware reset will reset the nRTS signal to
inactive mode (high). nRTS is forced inactive
during loop mode operation.
At the trailing edge of hardware reset the nRTS2
inputs is latched to determine the configuration
base address: 0 = INDEX Base I/O Address 3F0
Hex; 1 = INDEX Base I/O Address 370 Hex.
O6 Active low Data Terminal Ready outputs for the
serial port. Handshake output signal notifies
modem that the UART is ready to establish data
communication link. This signal can be
programmed by writing to bit 0 of Modem Control
Register (MCR). The hardware reset will reset
the nDTR signal to inactive mode (high). nDTR
is forced inactive during loop mode operation.
I Active low Clear to Send inputs for the serial port.
Handshake signal which notifies the UART that
the modem is ready to receive data. The CPU
can monitor the status of nCTS signal by reading
bit 4 of Modem Status Register (MSR). A nCTS
signal state change from low to high after the
last MSR read will set MSR bit 0 to a 1. If bit 3 of
the Interrupt Enable Register is set, the interrupt
is generated when nCTS changes state. The
nCTS signal has no effect on the transmitter.
Note: Bit 4 of MSR is the complement of nCTS.
I Active low Data Set Ready inputs for the serial
port. Handshake signal which notifies the UART
that the modem is ready to establish the
communication link. The CPU can monitor the
status of nDSR signal by reading bit 5 of Modem
Status Register (MSR). A nDSR signal state
change from low to high after the last MSR read
will set MSR bit 1 to a 1. If bit 3 of Interrupt
Enable Register is set, the interrupt is generated
when nDSR changes state. Note: Bit 5 of MSR
is the complement of nDSR.
I Active low Data Carrier Detect inputs for the
serial port. Handshake signal which notifies the
UART that carrier signal is detected by the
modem. The CPU can monitor the status of
nDCD signal by reading bit 7 of Modem Status
Register (MSR). A nDCD signal state change
from low to high after the last MSR read will set
MSR bit 3 to a 1. If bit 3 of Interrupt Enable
Register is set, the interrupt is generated when
nDCD changes state. Note: Bit 7 of MSR is the
complement of nDCD.
SMSC DS – FDC37N869 Page 11 Rev. 11/09/2000
Page 12
TQFP
PIN # NAME SYMBOL
82,84 nRing
nRI1
Indicator
nRI2
BUFFER
MODE
I
(Note1)
6
DESCRIPTION
Active low Ring Indicator inputs for the serial
port. Handshake signal which notifies the UART
that the telephone ring signal is detected by the
modem. The CPU can monitor the status of nRI
signal by reading bit 6 of Modem Status Register
(MSR). A nRI signal state change from low to
high after the last MSR read will set MSR bit 2 to
a 1. If bit 3 of Interrupt Enable Register is set,
the interrupt is generated when nRI changes
state. Note: Bit 6 of MSR is the complement of
nRI.
TQFP
PIN # NAME SYMBOL
71 nPrinter
nSLCT
Select
Input/FDC
nStep
Pulse
(Note3)
72 nInitiate
nSTEP
nINIT
Output/
FDC
nDirection
Control
(Note3)
74 nAutofeed
nDIR
nAUTOFD
Output/
FDC
nDensity
Select
(Note3)
nDENSEL
75 nStrobe
nSTROBE
Output/
FDC
nDrive
Select 0
(Note3)
nDS0
59 Busy/
BUSY
FDC
nMotor On
1
nMTR1
BUFFER
6
MODE
DESCRIPTION
PARALLEL PORT INTERFACE (NOTE 2)
(OD14/OP14)/OD12 This active low output selects the printer.
This is the complement of bit 3 of the
Printer Control Register.
Refer to Parallel Port description for use
of this pin in ECP and EPP mode.
See FDC Pin definition.
(OD14/OP14)/OD12 This output is bit 2 of the printer control
register. This is used to initiate the printer
when low.
Refer to Parallel Port description for use
of this pin in ECP and EPP mode.
See FDC Pin definition.
(OD14/OP14)/OD12 This output goes low to cause the printer
to automatically feed one line after each
line is printed. The nAUTOFD output is
the complement of bit 1 of the Printer
Control Register.
Refer to Parallel Port description for use
of this pin in ECP and EPP mode.
See FDC Pin definition.
(OD14/OP14)/OD12 An active low pulse on this output is used
to strobe the printer data into the printer.
The nSTROBE output is the complement
of bit 0 of the Printer Control Register.
Refer to Parallel Port description for use
of this pin in ECP and EPP mode.
See FDC Pin definition.
I/OD12 This is a status output from the printer, a
high indicating that the printer is not ready
to receive new data. Bit 7 of the Printer
Status Register is the complement of the
BUSY input. Refer to Parallel Port
description for use of this pin in ECP and
EPP mode.
See FDC Pin definition.
SMSC DS – FDC37N869 Page 12 Rev. 11/09/2000
Page 13
TQFP
PIN # NAME SYMBOL
60 nAcknowl-
nACK
edge/FDC
nDrive
Select 1
BUFFER
6
MODE
I/OD12 A low active output from the printer
indicating that it has received the data and
is ready to accept new data. Bit 6 of the
Printer Status Register reads the nACK
input. Refer to Parallel Port description for
nDS1
use of this pin in ECP and EPP mode.
See FDC Pin definition.
58 Paper End/
FDC
nWrite
Data
PE
I/OD12 Another status output from the printer, a
high indicating that the printer is out of
paper. Bit 5 of the Printer Status Register
reads the PE input. Refer to Parallel Port
description for use of this pin in ECP and
nWRDATA
EPP mode.
See FDC Pin definition.
57 Printer
Selected
Status/
FDC
nWrite
Gate
73 nError/FDC
nHead
Select
SLCT
nWGATE
nERROR
I/OD12 This high active output from the printer
indicates that it has power on. Bit 4 of the
Printer Status Register reads the SLCT
input. Refer to Parallel Port description for
use of this pin in ECP and EPP mode.
See FDC Pin definition.
I/OD12 A low on this input from the printer
indicates that there is a error condition at
the printer. Bit 3 of the Printer Status
register reads the nERR input. Refer to
Parallel Port description for use of this pin
nHDSEL
in ECP and EPP mode.
See FDC Pin definition.
69 Port Data
PD0
IOP14/IS Port Data 0
0/FDC
nIndex
68 Port Data
nINDEX
PD1
See FDC Pin definition.
IOP14/IS Port Data 1
1/FDC
nTrack 0
67 Port Data
nTRK0
PD2
See FDC Pin definition.
IOP14/IS Port Data 2
2/FDC
nWrite
nWRTPRT
See FDC Pin definition.
Protected
66 Port Data
PD3
IOP14/IS Port Data 3
3/FDC
nRead
nRDATA
See FDC Pin definition.
Disk Data
64 Port Data
PD4
IOP14/IS Port Data 4
4/FDC
nDisk
nDSKCHG
See FDC Pin definition.
Change
63 Port Data 5 PD5 IOP14 Port Data 5
62 Port Data
PD6
IOP14/ OD12 Port Data 6
6/FDC
nMotor On
nMTR0
See FDC Pin definition.
0
61 Port Data 7 PD7 IOP14 Port Data 7
DESCRIPTION
SMSC DS – FDC37N869 Page 13 Rev. 11/09/2000
Page 14
TQFP
STBY
PIN # NAME SYMBOL
BUFFER
MODE
6
ALTERNATE IR PINS/MISC
18 14.318 MHz
Input Clock
CLK14 ICLK The external connection to a single source 14.318
MHz clock.
23 IR Receive 2 IRRX2 IS IR Receive input
DESCRIPTION
24 IR Transmit 2
IRTX2 O12PD IR transmit output
(Note5)
92 Address X/
PCI Clock
Controller
nADRX/
nCLKRU
N
OD12/
IOD12
The active-low address decoder output nADRX can
be asserted on 1, 8, or 16-byte address
boundaries (an external pull-up is required). Refer
to configuration registers CR03, CR08, and CR09
for more information. nCLKRUN is used to
indicate the PCI clock status and to request that a
stopped clock be started.
21 IR Mode/ IR
Receive 3
IRMODE/
IRRX3
O6/IS IR mode
IR Receive 3
56 Power Good/
nGame Port
Chip Select
PWRGD
I/O4 This active high input indicates that the power
(VCC) is valid. For device operation PWRGD must
be active. When PWRGD is inactive, all inputs are
disconnected and put into a low power mode; all
outputs are put into high impedance. The contents
of all registers are preserved as long as VCC is
valid. The output driver current drain when
PWRGD is inactive mode drops to I
current.
nGAMEC
S
This is the Game Port Chip Select output - active
low. It will go active when the I/O address, qualified
by AEN, matches that selected in Configuration
register CR1E.
96 External
Interrupt
IRQIN IS This pin is used to steer an interrupt signal from
an external device onto one of 15 IRQs.
Input
POWER INTERFACE
13,70 Power VCC Positive Supply Voltage. (5V or 3.3V)
4,45,
Ground VSS Ground Supply.
65,93
- standby
Note 1: nRI and the UART interrupts are active when PWRGD is active and the UARTS are either fully powered
or in AUTOPOWER DOWN mode.
Note 2: The FDD output pins multiplexed in the PARALLEL PORT INTERFACE are OD drivers only and are not
affected by the FDD Output Driver Controls (see section CR05 on page 108).
Note 3: Active (push-pull) output drivers are required on these pins in the enhanced parallel port
modes.
Note 4: An external pull-up must be provided for IOCHRDY.
Note 5: The pull-down on this pin is always active including when the output driver is tristated and regardless of
the state of PWRGD.
Note 6: Buffer Modes describe the pad driver properties per function. Buffer Modes on multiplexed pins are
separated by a slash “/”. For example, the Buffer Modes for a multiplexed pin with two functions where
the primary function is an input and the secondary function is an 8mA bidirectional driver is “I/IO8”.
Buffer Modes in parenthesis represent multiple Buffer Modes for a single pin function.
SMSC DS – FDC37N869 Page 14 Rev. 11/09/2000
Page 15
Buffer Type Summary
Table 2 below describes the buffer types shown in Table 1. All values are specified at V
= +3.3v, ±10%
cc
Table 2 - FDC37N869 Buffer Type Summary (See Note)
BUFFER TYPE DESCRIPTION
IO12 Input/Output. 12mA sink; 6mA source
O12 Output. 12mA sink; 6mA source
O12PD Output. 12mA sink; 6mA source with 30µa pull-down
OD12 Open Drain. 12mA sink
O6 Output. 6mA sink; 3mA source
OD14 Open Drain. 14mA sink
OP14 Output. 14mA sink; 14mA source. Backdrive Protected
IOP14 Input/Output. 14mA sink; 14mA source. Backdrive Protected
O4 Output. 4mA sink; 2mA source
ICLK Input to Crystal Oscillator Circuit (TTL levels)
I Input TTL Compatible
IS Input with Schmitt Trigger
IOD12 Input/Open Drain Output. 12mA sink
Note: These are minimum ratings guaranteed at 5V and 3.3V.
Output Drivers
Active output drivers in the FDC37N869 will always achieve the minimum specified DC Electrical Characteristics
shown in Table 120.
Note: If there is a pull-up on an external node driven by an active output driver the FDC37N869 may sink current
from the pull-up through the low impedance source.
SMSC DS – FDC37N869 Page 15 Rev. 11/09/2000
Page 16
TXD1, nCTS1, nRTS1,
nWGATE
nCS
nIOR
nIOW
AEN
A0-A15
D0-D7
DRQ_A-D
nDACK_A-D
SIRQ
CLK33
nADRX/nCLKRUN
RESET
IRQIN
IOCHRDY
TC
HOST
CPU
INTERFACE
Vcc (2)
14.318
CLOCK
Vss (4)
CLOCK
GEN
PWRGD/nGAMECS
POWER
MANAGEMENT
ADDRESS BUS
SMSC
PROPRIETARY
82077
COMPATIBLE
VERTICAL
FLOPPYDISK
CONTROLLER
CORE
nINDEX
nDIR
nTRK0
nSTEP
nDSKCHG
DRVDEN0
nWRPRT
DRVDEN1
DATA BUS
CONFIGURATION
REGISTERS
CONTROL BUS
WDATA
WCLOCK
RCLOCK
RDATA
nDS0
nMTR0
nHDSEL
nWDATA
DIGITAL
DATA
SEPARATOR
WITH WRITE
PRECOM-
PENSATION
nRDATA
MULTI-MODE
PARALLEL
PORT/FDC
MUX
16C550
COMPATIBLE
SERIAL
PORT 1
16C550
COMPATIBLE
SERIAL
PORT 2 WITH
INFRARED
IR
GAME
PORT
DECODER
nSLCTIN/nSTEP,nINI
T/nDIR, nAUTOFD/
nDENSEL,
nSTROBE/nDS0,
BUSY/nMTR1,
nACK/nDS1,
PE/nWRDATA,nERR
OR/nHDSEL,
PD0/nINDEX,
PD1/nTRK0,
PD2/nWRTPRT,
PD3/nRDATA,
PD4/nDSKCHG,
PD6/nMTR,
PD5/
PD7
RXD1
nDSR1, nDCD1, nRI,
nDTR1
IR Mode/IRR3
TXD2/IRTX,nCTS2,
nRTS2
RXD2/IRRX
nDSR2,nDCD2,
nRI2,nDTR2
IRRX2, IRTX2
See Power Mgt
FIGURE 2 - FDC37N869 BLOCK DIAGRAM
SMSC DS – FDC37N869 Page 16 Rev. 11/09/2000
Page 17
FUNCTIONAL DESCRIPTION
Super I/O Registers
Table 3 shows the addresses of the various device blocks of the Super I/O immediately after power up. The base
addresses must be set in the configuration registers before accessing these devices. The base addresses of the
FDC, Serial and Parallel Ports can be moved via the configuration registers.
Host Processor Interface
The host processor communicates with the FDC37N869 using the Super I/O registers. Register access is
accomplished through programmed I/O or DMA transfers. All registers are 8 bits wide. All host interface output
buffers are capable of sinking a minimum of 12 mA.
Table 3 - FDC37N869 Block Addresses
ADDRESS BLOCK NAME NOTES
3F0, 3F1 or 370, 371 Configuration Write only; Note 1
Base +[0:7] Floppy Disk Disabled at power up; Note 2
Base +[0:7] Serial Port Com 1 Disabled at power up; Note 2
Base1 +[0:7]
Base2 +[0:7]
Base +[0:3] all modes
Base +[4:7] for EPP
Base +[400:403] for ECP
Serial Port Com 2
Parallel Port Disabled at power up; Note 2
Disabled at power up; Note 2
Note 1: Configuration registers can only be modified in the configuration state, refer to section CONFIGURATION
on page 101 for more information. All logical blocks in the FDC37N869 can operate normally in the Configuration
State.
Note 2: The base addresses must be set in the configuration registers before accessing the logical device
blocks.
FLOPPY DISK CONTROLLER
The Floppy Disk Controller (FDC) provides the interface between a host microprocessor and the floppy disk drives.
The FDC integrates the functions of the Formatter/Controller, Digital Data Separator, Write Precompensation and
Data Rate Selection logic for an IBM XT/AT compatible FDC. The true CMOS 765B core guarantees 100% IBM PC
XT/AT compatibility in addition to providing data overflow and underflow protection.
The FDC37N869 is compatible with the 82077AA using SMSC’s proprietary floppy disk controller core. For
information about the floppy disk on the Parallel Port pins refer to section Parallel Port Floppy Disk Controller on
page 57.
Modes Of Operation
The FDC37N869 Floppy Disk Controller has two Floppy modes and three Interface modes. Each of the three
Interface modes are available in each of the two Floppy modes.
Floppy Modes
The Floppy modes are used to select alternate configurations for the Tape Drive register. The active Floppy mode
is determined by the Enhanced Floppy Mode 2 bit in Configuration Register 3 (see section CR03 on page 106).
When the Enhanced Floppy Mode 2 bit is 0 Normal Floppy mode is selected, otherwise Enhanced Floppy Mode 2
(OS/2 mode) is selected. See section TAPE DRIVE REGISTER (TDR) on page 24 for the affects of the Enhanced
Floppy Mode 2 bit on the Tape Drive register.
SMSC DS – FDC37N869 Page 17 Rev. 11/09/2000
Page 18
Interface Modes
The Interface modes are determined by the MFM and IDENT configuration bits in Configuration Register 3 (see
section CR03 on page 106).
PC/AT Interface Mode
When both IDENT and MFM are high the PC/AT register set is enabled, the DMA enable bit of the Digital Output
Register becomes valid, FINTR and DRQ can be hi-Z, and TC and DENSEL become active high.
PS/2 Interface Mode
When IDENT is low and MFM is high PS/2 Interface mode is selected. This mode supports the PS/2 models
50/60/80 configuration and register set. The DMA bit of the Digital Output Register becomes a “don’t care,” FINTR
and DRQ are always valid, TC and DENSEL become active low.
Model 30 Interface Mode
When both IDENT and MFM are low Model 30 Interface Mode is selected. This mode supports PS/2 Model 30
configuration and register set. The DMA enable bit of the Digital Output Register becomes valid, FINTR and DRQ
can be hi-Z, TC is active high and DENSEL is active low.
Floppy Disk Controller Internal Registers
The Floppy Disk Controller contains eight internal registers that provide the interface between the host
microprocessor and the floppy disk drives. Table 4 shows the addresses required to access these registers.
Registers other than the ones shown are not supported.
Table 4 - Status, Data and Control Registers
BASE I/O
ADDRESS REGISTER
+0
+1
+2
+3
+4
+4
+5
+6
+7
+7
R
R
R/W
R/W
R
W
R/W
R
W
Status Register A
Status Register B
Digital Output Register
Tape Drive Register
Main Status Register
Data Rate Select Register
Data (FIFO)
Reserved
Digital Input Register
Configuration Control Register
SRA
SRB
DOR
TDR
MSR
DSR
FIFO
DIR
CCR
STATUS REGISTER A (SRA)
Status Register A (Base Address + 0) monitors the state of the FINTR pin and several disk interface pins in PS/2
interface mode (Table 5) and Model 30 interface mode (Table 6). SRA is read-only and can be accessed at any
time when in these modes. During a read in the PC/AT interface mode the data bus pins D0 - D7 are held in a
high impedance state.
SMSC DS – FDC37N869 Page 18 Rev. 11/09/2000
Page 19
PS/2 Interface Mode
Table 5 - SRA PS/2 Mode
7 6 5 4 3 2 1 0
INT
nDRV2 STEP nTRK0 HDSEL nINDX nWP DIR
PENDING
RESET
0 1 0 N/A 0 N/A N/A 0
CONDITION
Direction, Bit 0
Active high status indicating the direction of head movement. A logic “1” indicating inward direction, a logic “0”
outward.
nWRITE PROTECT, Bit 1
Active low status of the WRITE PROTECT disk interface input. A logic “0” indicating that the disk is write protected.
The nWRITE PROTECT bit also depends upon the state of the Force Write Protect bits in the Force FDD Status
Change configuration register (see section CR17 on page 109).
nINDEX, Bit 2
Active low status of the INDEX disk interface input.
Head Select, Bit 3
Active high status of the HDSEL disk interface input. A logic “1” selects side 1 and a logic “0” selects side 0.
nTRACK 0, Bit 4
Active low status of the TRK0 disk interface input.
Step, Bit 5
Active high status of the STEP output disk interface output pin.
nDRV2, Bit 6
The nDRV2 bit is always “1”.
Interrupt Pending, Bit 7
Active high bit indicating the state of the Floppy Disk Interrupt output.
SMSC DS – FDC37N869 Page 19 Rev. 11/09/2000
Page 20
PS/2 Model 30 Interface Mode
Table 6 - SRA PS/2 Model 30 Mode
7 6 5 4 3 2 1 0
INT
DRQ STEP F/F TRK0 nHDSEL INDX WP nDIR
PENDING
RESET
0 0 0 N/A 1 N/A N/A 1
CONDITION
nDIRECTION, Bit 0
Active low status indicating the direction of head movement. A logic “0” indicating inward direction a logic “1”
outward.
Write Protect, Bit 1
Active high status of the WRITE PROTECT disk interface input. A logic “1” indicating that the disk is write protected.
The nWRITE PROTECT bit also depends upon the state of the Force Write Protect bits in the Force FDD Status
Change configuration register (see section CR17 on page 109).
Index, Bit 2
Active high status of the INDEX disk interface input.
nHEAD SELECT, Bit 3
Active low status of the HDSEL disk interface input. A logic “0” selects side 1 and a logic “1” selects side 0.
Track, Bit 4
Active high status of the TRK0 disk interface input.
Step, Bit 5
Active high status of the latched STEP disk interface output pin. This bit is latched with the STEP output going
active, and is cleared with a read from the DIR register, or with a hardware or software reset.
DMA Request, Bit 6
Active high status of the DRQ output pin. Interrupt Pending, Bit 7 Active high bit indicating the state of the Floppy
Disk Interrupt output.
SMSC DS – FDC37N869 Page 20 Rev. 11/09/2000
Page 21
STATUS REGISTER B (SRB)
Status Register B (Base Address + 1) is read-only and monitors the state of several disk interface pins in PS/2
interface mode (Table 7) and Model 30 interface mode (Table 8). SRB can be accessed at any time when in these
modes. During a read in PC/AT interface mode the data bus pins D0 - D7 are held in a high impedance state.
PS/2 Interface Mode
Table 7 - SRB PS/2 Mode
7 6 5 4 3 2 1 0
RESET
1 1 DRIVE
SEL0
1 1 0 0 0 0 0 0
WDATA
TOGGLE
RDATA
TOGGLE
WGATE MOT EN1 MOT EN0
CONDITION
Motor Enable 0, Bit 0
Active high status of the MTR0 disk interface output pin. This bit is low after a hardware reset and unaffected by a
software reset.
Motor Enable 1, Bit 1
Active high status of the MTR1 disk interface output pin. This bit is low after a hardware reset and unaffected by a
software reset.
Write Gate, Bit 2
Active high status of the WGATE disk interface output.
Read Data Toggle, Bit 3
Every inactive edge of the RDATA input causes this bit to change state.
Write Data Toggle, Bit 4
Every inactive edge of the WDATA input causes this bit to change state.
Drive Select 0, Bit 5
Reflects the status of the Drive Select 0 bit of the DOR (address 3F2 bit 0). This bit is cleared after a hardware
reset, it is unaffected by a software reset.
Reserved, Bits 6 - 7
Always read as a logic “1”.
SMSC DS – FDC37N869 Page 21 Rev. 11/09/2000
Page 22
PS/2 Model 30 Interface Mode
Table 8 - SRB PS/2 Model 30 Mode
7 6 5 4 3 2 1 0
nDRV2 nDS1 nDS0 WDATA F/F RDATA F/F WGATE
nDS3 nDS2
F/F
RESET
N/A 1 1 0 0 0 1 1
CONDITION
nDRIVE SELECT 2, Bit 0
Active low status of the DS2 disk interface output.
nDRIVE SELECT 3, Bit 1
Active low status of the DS3 disk interface output.
Write Gate, Bit 2
Active high status of the latched WGATE output signal. This bit is latched by the active going edge of WGATE and is
cleared by the read of the DIR register.
Read Data, Bit 3
Active high status of the latched RDATA output signal. This bit is latched by the inactive going edge of RDATA and
is cleared by the read of the DIR register.
Write Data, Bit 4
Active high status of the latched WDATA output signal. This bit is latched by the inactive going edge of WDATA and
is cleared by the read of the DIR register. This bit is not gated with WGATE.
nDRIVE SELECT 0, Bit 5
Active low status of the DS0 disk interface output.
nDRIVE SELECT 1, Bit 6
Active low status of the DS1 disk interface output.
nDRV2, Bit 7
The nDRV2 bit is always “1”.
SMSC DS – FDC37N869 Page 22 Rev. 11/09/2000
Page 23
DIGITAL OUTPUT REGISTER (DOR)
The Digital Output register (Base Address + 2) controls the drive select and motor enables of the disk interface
outputs (Table 9 and Table 10). The DOR also contains the DMA logic enable and a software reset bit. The DOR
is read/write and unaffected by a software reset.
Table 9 - Digital Output Register
7 6 5 4 3 2 1 0
RESET
MOT EN3 MOT EN2 MOT EN1 MOT EN0 DMAEN nRESET DRIVE
SEL1
0 0 0 0 0 0 0 0
DRIVE
SEL0
CONDITION
DOR Bit Descriptions
DRIVE SELECT, Bits 0 - 1
These two bits are binary encoded for the four drive selects DS0-DS3, there by allowing only one drive to be
selected at one time.
nRESET, Bit 2
A logic “0” written to this bit resets the Floppy disk controller. This reset will remain active until a logic “1” is written
to this bit. This software reset does not affect the DSR and CCR registers, nor does it affect the other bits of the
DOR register. The minimum reset duration required is 100ns, therefore toggling this bit by consecutive writes to
this register is a valid method of issuing a software reset.
DMAEN, Bit 3
PC/AT and Model 30 Interface Mode
In PC/AT and Model 30 mode writing this bit to logic “1” will enable the DRQ, nDACK, TC and FINTR outputs. This
bit being a logic “0” will disable the nDACK and TC inputs, and hold the DRQ and FINTR outputs in a high
impedance state. In PC/AT and Model 30 mode the DMAEN bit is a logic “0” after a reset.
PS/2 Interface Mode
In PS/2 mode the DRQ, nDACK, TC and FINTR pins are always enabled. During a reset the DRQ, nDACK, TC, and
FINTR pins will remain enabled, but the DMAEN bit will be cleared to a logic “0”.
MOTOR ENABLE 0, Bit 4
This bit controls the MTR0 disk interface output. A logic “1” in this bit will cause the output pin to go active.
MOTOR ENABLE 1, Bit 5
This bit controls the MTR1 disk interface output. A logic “1” in this bit will cause the output pin to go active.
MOTOR ENABLE 2, Bit 6
The MOTOR ENABLE 2 bit controls the MTR2 disk interface output. A logic “1” in this bit will cause the output pin to
go active.
MOTOR ENABLE 3, Bit 7
The MOTOR ENABLE 3 bit controls the MTR3 disk interface output. A logic “1” in this bit causes the output to go
active.
SMSC DS – FDC37N869 Page 23 Rev. 11/09/2000
Page 24
Table 10 - Drive Activation Values
DRIVE DOR VALUE
0 1CH
1 2DH
2 4EH
3 8FH
Table 11 - Internal 2 Drive Decode: Drives 0 and 1
DIGITAL OUTPUT REGISTER
DRIVE SELECT OUTPUTS
(ACTIVE LOW)
MOTOR ON OUTPUTS
(ACTIVE LOW)
Bit 7 Bit 6 Bit 5 Bit 4 Bit1 Bit 0 nDS1 nDS0 nMTR1 nMTR0
X X X 1 0 0 1 0 nBIT 5 nBIT 4
X X 1 X 0 1 0 1 nBIT 5 nBIT 4
X 1 X X 1 0 1 1 nBIT 5 nBIT 4
1 X X X 1 1 1 1 nBIT 5 nBIT 4
0 0 0 0 X X 1 1 nBIT 5 nBIT 4
TAPE DRIVE REGISTER (TDR)
The Tape Drive register (Base Address + 3) is included for 82077 software compatibility and allows the user to
assign tape support to a particular drive during initialization. Any future reference to that drive automatically invokes
tape support. The Tape Select bits TDR.[1:0] determine the tape drive number. Table 12 illustrates the Tape Select
bit encoding. Note that drive 0 is the boot device and cannot be assigned tape support.
The encoding of the TDR depends on the Floppy mode (see section Floppy Modes on page 17). The TDR is
unaffected by a software reset.
Table 12 - Tape Select Bits
TAPE SEL1
(TDR.1)
TAPE SEL0
(TDR.0)
DRIVE
SELECTED
0 0 NONE
0 1 1
1 0 2
1 1 3
Normal Floppy Mode
In Normal mode the TDR contains only bits 0 and 1 (Table 13). During a read in Normal mode TDR bits 2 - 7 are
high impedance. The Tape Select Bits are Read/Write.
Table 13 - TDR Normal Floppy Mode
DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
TDR Tri-state Tri-state Tri-state Tri-state Tri-state Tri-state Tape
Sel1
Tape
Sel0
SMSC DS – FDC37N869 Page 24 Rev. 11/09/2000
Page 25
Enhanced Floppy Mode 2 (OS2)
The configuration of the TDR in the Enhanced Floppy Mode 2 (OS/2 mode) is shown in Table 14.
Table 14 - TDR Enhanced Floppy Mode 2
DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
TDR Reserved Drive Type ID
Floppy Boot Drive Tape
Sel1
Tape
Sel0
Reserved, Bits 6 - 7
Bits 6 and 7 are RESERVED. Reserved bits cannot be written and return 0 when read.
Drive Type ID, Bits 4 - 5
The Drive Type ID bits depend on the last drive selected in the Digital Output Register and the Drive Type IDs that
are programmed in configuration register 6 (Table 15).
Table 15 - Drive Type ID
DIGITAL OUTPUT REGISTER TDR - DRIVE TYPE ID
Bit 1 Bit 0 Bit 5 Bit 4
0 0 CR6 - Bit 1 CR6 - Bit 0
0 1 CR6 - Bit 3 CR6 - Bit 2
1 0 CR6 - Bit 5 CR6 - Bit 4
1 1 CR6 - Bit 7 CR6 - Bit 6
Floppy Boot Drive, Bits 2 - 3
The Floppy Boot Drive bits come from Configuration Register 7: TDR Bit 3 = CR7 Bit 1; TDR Bit 2 = CR7 Bit 0.
Tape Drive Select, Bits 0 - 1
The Tape Drive Select bits are the same as in Normal mode. These bits are Read/Write.
MAIN STATUS REGISTER (MSR)
The Main Status Register (Base Address + 4: Read-only) indicates the status of the disk controller ( Table 16). The
Main Status Register is valid in all modes and can be read at any time. The MSR indicates when the disk
controller is ready to receive data via the Data Register. It should be read before transferring each byte to or from
the data register, except in DMA mode. No delay is required when reading the MSR after a data transfer.
Table 16 - Main Status Register
7 6 5 4 3 2 1 0
MSR RQM DIO NON DMA CMD
BUSY
DRV3
BUSY
DRV2
BUSY
DRV1
BUSY
DRV0
BUSY
DRVx Busy, Bits 0 - 3
These bits are set to a “1” when a drive is in the seek portion of a command, including implied and overlapped
seeks and recalibrates.
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Command Busy, Bit 4
This bit is set to a “1” when a command is in progress. This bit will go active after the command byte has been
accepted and goes inactive at the end of the results phase. If there is no result phase (Seek, Recalibrate
commands), this bit is returned to a “0” after the last command byte.
Non-DMA, Bit 5
This mode is selected in the SPECIFY command and will be set to a “1” during the execution phase of a
command. This is for polled data transfers and helps to differentiate between the data transfer phase and the
reading of result bytes.
DIO, Bit 6
Indicates the direction of a data transfer once an RQM is set. A “1” indicates a read and a “0” indicates a write is
required.
RQM, Bit 7
Indicates that the host can transfer data if set to a “1”. No access is permitted if set to a “0”.
DATA RATE SELECT REGISTER (DSR)
The Data Rate Select Register (Base Address + 4: Write-only) is used to program the data rate, amount of write
precompensation, power down status, and software reset (Table 17). Note: the data rate is programmed using
the Configuration Control Register (CCR) not the DSR, for PC/AT and PS/2 Model 30 and Microchannel
applications. Other applications can set the data rate in the DSR. The data rate of the floppy controller is the most
recent write of either the DSR or CCR. The DSR is unaffected by a software reset. A hardware reset will set the
DSR to 02H, which corresponds to the default precompensation setting and 250 Kbps.
Table 17 - Data Rate Select Register
7 6 5 4 3 2 1 0
RESET
S/W
RESET
0 0 0 0 0 0 1 0
POWER
DOWN
0 PRE-
COMP2
PRE-
COMP1
PRE-
COMP0
DRATE
SEL1
DRATE
SEL0
CONDITION
Data Rate Select, Bits 0 - 1
These bits control the data rate of the floppy controller. See Table 19 for the settings corresponding to the
individual data rates. The data rate select bits are unaffected by a software reset and are set to 250 Kbps after a
hardware reset.
Precompensation Select, Bits 2 - 4
These three bits select the value of write precompensation that will be applied to the WDATA output signal.
Table 18 shows the precompensation values for the combination of these bits settings. Track 0 is the default
starting track number to start precompensation. The starting track number can be changed using the Configure
command.
Undefined, Bit 5
Should be written as a logic “0”.
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Low Power, Bit 6
A logic “1” written to this bit will put the floppy controller into Manual Low Power mode. The floppy controller clock
and data separator circuits will be turned off. The controller will come out of manual low power mode after a
software reset or following access to the Data Register or Main Status Register.
Software Reset, Bit 7
This active high bit has the same function as the DOR RESET (DOR bit 2) except that this bit is self clearing.
Table 18 - Precompensation Delays
PRECOMP
SELECT PRECOMPENSATION DELAY
4 3 2
1 1 1 0.00 ns-DISABLED
0 0 1 41.67 ns
0 1 0 83.34 ns
0 1 1 125.00 ns
1 0 0 166.67 ns
1 0 1 208.33 ns
1 1 0 250.00 ns
0 0 0 Default (see Table 21)
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Table 19 - Data Rates
DRIVE RATE
SELECT
(CR0B)
DATA RATE
SELECT
(DSR) DATA RATE
DENSEL
(Note 1) DRATE
DRT1 DRT0 SEL1 SEL0 MFM FM IDENT=1 IDENT=0 1 0
0 0 1 1 1Meg --- 1 0 1 1
0 0 0 0 500 250 1 0 0 0
0 0 0 1 300 150 0 1 0 1
0 0 1 0 250 125 0 1 1 0
0 1 1 1 1Meg --- 1 0 1 1
0 1 0 0 500 250 1 0 0 0
0 1 0 1 500 250 0 1 0 1
0 1 1 0 250 125 0 1 1 0
1 0 1 1 1Meg --- 1 0 1 1
1 0 0 0 500 250 1 0 0 0
1 0 0 1 2Meg --- 0 1 0 1
1 0 1 0 250 125 0 1 1 0
Note 1: This is for DENSEL in normal mode (see section CR05 on page 108). The DENSEL pin is set high after
a hardware reset and is unaffected by the DOR and the DSR resets.
Table 20 - Drive Rate Table (Recommended)
DRIVE RATE FORMAT
DRT1 DRT0 (see section CR0B on page 110 to program Drive Rate)
0 0 360K, 1.2M, 720K, 1.44M and 2.88M Vertical Format
0 1 3-Mode Drive
1 0 2 Meg Tape
Table 21 - Default Precompensation Delays
PRECOMPENSATION
DATA RATE
DELAYS
2 Mbps 125 ns
1 Mbps 41.67 ns
500 Kbps 125 ns
300 Kbps 125 ns
250 Kbps 125 ns
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DATA REGISTER (FIFO)
The Data Register (Base Address + 5) is used to transfer all command parameter information, disk data and
result status between the host processor and the floppy disk controller. The Data Register is Read/Write. Data
transfers are governed by the RQM and DIO bits in the Main Status Register.
The Data Register defaults to FIFO disabled mode after any form of reset. This maintains PC/AT hardware
compatibility. The default values can be changed through the Configure command (enable full FIFO operation with
threshold control). The advantage of the FIFO is that it allows the system a larger DMA latency without causing a
disk error.
Table 22 gives several examples of service delays with a FIFO. The data is based upon the following formula:
Threshold# × (8 ÷ Data Rate) - 1.5µS = DELAY
At the start of a command the FIFO action is always disabled and command parameters must be sent based upon
the RQM and DIO bit settings. As the command execution phase is entered, the FIFO is cleared of any data to
ensure that invalid data is not transferred.
An overrun or underrun will terminate the current command and the transfer of data. Disk writes will complete the
current sector by generating a 00 pattern and valid CRC. Reads require the host to remove the remaining data so
that the result phase may be entered.
Table 22 - Example FIFO Service Delays
EXAMPLE DATA RATES
FIFO
THRESHOLD
2Mbps 1Mbps 500Kbps
EXAMPLES
1 byte 1 x 4µs - 1.5µs = 2.5µs 1 x 8µs - 1.5µs = 6.5µs 1 x 16µs - 1.5µs = 14.5µs
2 bytes 2 x 4µs - 1.5µs = 6.5µs 2 x 8µs - 1.5µs = 14.5µs 2 x 16µs - 1.5µs = 30.5µs
8 bytes 8 x 4µs - 1.5µs = 30.5µs 8 x 8µs - 1.5µs = 62.5µs 8 x 16µs - 1.5µs = 126.5µs
15 bytes 15 x 4µs - 1.5µs = 58.5µs 15 x 8µs - 1.5µs = 118.5µs 15 x 16µs - 1.5µs = 238.5µs
DIGITAL INPUT REGISTER (DIR)
The Digital Input Register (Bass Address + 7: Read-only) is read-only in all modes. Table 23 shows the DIR in
PC/AT mode, Table 24 shows the DIR in PS/2 mode, and Table 25 shows the DIR in Model 30 mode.
PC-AT Interface Mode
Table 23 - DIR PC/AT Interface Mode
7 6 5 4 3 2 1 0
DSK CHG
RESET
N/A N/A N/A N/A N/A N/A N/A N/A
CONDITION
Undefined, Bits 0 - 6
The data bus outputs D0 - 6 will remain in a high impedance state during a read of this register.
DSK CHG, Bit 7
The DSK CHG bit monitors the state of the pin of the same name and reflects the opposite value seen on the disk
cable. The DSK CHG bit also depends upon the Force Disk Change bits in the Force FDD Status Change register
(see section CR17 on page 109).
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PS/2 Interface Mode
Table 24 - DIR PS/2 Interface Mode
7 6 5 4 3 2 1 0
RESET
DSK CHG 1 1 1 1 DRATE
SEL1
N/A N/A N/A N/A N/A N/A N/A 1
DRATE
SEL0
nHIGH
DENS
CONDITION
nHIGH DENS, Bit 0
This bit is low whenever the 500 Kbps or 1 Mbps data rates are selected, and high when 250 Kbps and 300 Kbps
are selected.
Data Rate Select, Bits 1 - 2
These bits control the data rate of the floppy controller. See Table 19 for the settings corresponding to the
individual data rates. The data rate select bits are unaffected by a software reset, and are set to 250 Kbps after a
hardware reset.
Undefined, Bits 3 - 6
Always read as a logic “1”
DSK CHG, Bit 7
The DSK CHG bit monitors the pin of the same name and reflects the opposite value seen on the disk cable. The
DSK CHG bit also depends upon the Force Disk Change bits in the Force FDD Status Change register (see
section CR17 on page 109).
Model 30 Interface Mode
Table 25 - DIR Model 30 Interface Mode
7 6 5 4 3 2 1 0
DSK CHG 0 0 0 DMAEN NOPREC DRATE SEL1 DRATE SEL0
RESET
N/A 0 0 0 0 0 1 0
CONDITION
Data Rate Select, Bits 0 - 1
These bits control the data rate of the floppy controller. See Table 19 for the settings corresponding to the
individual data rates. The data rate select bits are unaffected by a software reset, and are set to 250kb/s after a
hardware reset
Noprec, Bit 2
This bit reflects the value of the NOPREC bit set in the CCR register.
DMAEN, Bit 3
This bit reflects the value of DMAEN bit set in the DOR register bit 3.
Undefined, Bits 4 - 6
Always read as a logic “0”
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DSK CHG, Bit 7
The DSK CHG bit monitors the pin of the same name and reflects the opposite value seen on the pin. The DSK
CHG bit also depends upon the Force Disk Change bits in the Force FDD Status Change register (see section
CR17 on page 109).
CONFIGURATION CONTROL REGISTER (CCR)
The Configuration Control Register (Bass Address + 7: Write-only) is write-only in all modes. Table 26 shows the
CCR in PC/AT mode and PS/2 mode. Table 27 shows the CCR in Model 30 mode.
PC/AT and PS/2 Interface Modes
Table 26 - CCR PC/AT and PS/2 Interface Modes
7 6 5 4 3 2 1 0
RESET
DRATE
SEL1
N/A N/A N/A N/A N/A N/A 1 0
DRATE
SEL0
CONDITION
Data Rate Select, Bits 0 - 1
These bits determine the data rate of the floppy controller. See Table 19 for the appropriate values.
Reserved, Bits 2 - 7
Bits 2 to 7 are RESERVED. Reserved bits cannot be written and return 0 when read.
Model 30 Interface Mode
Table 27 - CCR Model 30 Interface Mode
7 6 5 4 3 2 1 0
RESET
NOPREC DRATE
SEL1
N/A N/A N/A N/A N/A N/A 1 0
DRATE
SEL0
CONDITION
Data Rate Select, Bits 0 - 1
These bits determine the data rate of the floppy controller. See Table 19 for the appropriate values.
No Precompensation, Bit 2
This bit can be set by software, but it has no functionality. It can be read by bit 2 of the DSR when in Model 30
register mode. Unaffected by software reset.
RESERVED, Bits 3 - 7
Bits 3 to 7 are RESERVED. Reserved bits cannot be written and return 0 when read.
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Status Register Encoding
During the Result Phase of certain commands, the Data Register contains data bytes that give the status of the
command just executed.
Table 28 - Status Register 0
BIT
NO. SYMBOL NAME DESCRIPTION
7,6 IC Interrupt
Code
00 - Normal termination of command. The specified command was
properly executed and completed without error.
01 - Abnormal termination of command. Command execution was
started, but was not successfully completed.
10 - Invalid command. The requested command could not be executed.
11 - Abnormal termination caused by Polling.
5 SE Seek End The FDC completed a Seek, Relative Seek or Recalibrate command
(used during a Sense Interrupt Command).
4 EC Equipment
Check
The TRK0 pin failed to become a “1” after:
1. 80 step pulses in the Recalibrate command.
2. The Relative Seek command caused the FDC to step outward beyond
Track 0.
3 Unused. This bit is always “0”.
2 H Head
The current head address.
Address
1,0 DS1,0 Drive
The current selected drive.
Select
Table 29 - Status Register 1
BIT
NO. SYMBOL NAME DESCRIPTION
7 EN End of
Cylinder
The FDC tried to access a sector beyond the final sector of the track
(255D). Will be set if TC is not issued after Read or Write Data command.
6 Unused. This bit is always “0”.
5 DE Data Error The FDC detected a CRC error in either the ID field or the data field of a
sector.
4 OR Overrun/
Underrun
Becomes set if the FDC does not receive CPU or DMA service within the
required time interval, resulting in data overrun or underrun.
3 Unused. This bit is always “0”.
2 ND No Data Any one of the following:
1. Read Data, Read Deleted Data command - the FDC did not find the
specified sector.
2. Read ID command - the FDC cannot read the ID field without an error.
3. Read A Track command - the FDC cannot find the proper sector
sequence.
1 NW Not
Writable
0 MA Missing
Address
Mark
WP pin became a “1” while the FDC is executing a Write Data, Write
Deleted Data, or Format A Track command.
Any one of the following:
1. The FDC did not detect an ID address mark at the specified track after
encountering the index pulse from the IDX pin twice.
2. The FDC cannot detect a data address mark or a deleted data
address mark on the specified track.
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Table 30 - Status Register 2
BIT NO. SYMBOL NAME DESCRIPTION
7 Unused. This bit is always “0”.
6 CM Control
Mark
Any one of the following:
1. Read Data command - the FDC encountered a deleted data
address mark.
2. Read Deleted Data command - the FDC encountered a data
address mark.
5 DD Data Error
The FDC detected a CRC error in the data field.
in Data
Field
4 WC Wrong
Cylinder
The track address from the sector ID field is different from the track
address maintained inside the FDC.
3 Unused. This bit is always “0”.
2 Unused. This bit is always “0”.
1 BC Bad
Cylinder
The track address from the sector ID field is different from the track
address maintained inside the FDC and is equal to FF hex, which
indicates a bad track with a hard error according to the IBM soft-sectored
format.
0 MD Missing
Data
The FDC cannot detect a data address mark or a deleted data address
mark.
Address
Mark
Table 31 - Status Register 3
BIT NO. SYMBOL NAME DESCRIPTION
7 Unused. This bit is always “0”.
6 WP Write
Protected
Indicates the status of the WP pin. The Write Protected bit also depends
upon the state of the Force Write Protect bits in the Force FDD Status
Change configuration register (see section
CR17 on page 109).
5 Unused. This bit is always “1”.
4 T0 Track 0 Indicates the status of the TRK0 pin.
3 Unused. This bit is always “1”.
2 HD Head
Indicates the status of the HDSEL pin.
Address
1,0 DS1,0 Drive
Indicates the status of the DS1, DS0 pins.
Select
Reset
There are three sources of system reset on the FDC: the RESET pin of the FDC37N869, a reset generated via a bit
in the DOR, and a reset generated via a bit in the DSR. At power on, a Power On Reset initializes the FDC. All
resets take the FDC out of the power down state.
All operations are terminated upon a RESET, and the FDC enters an idle state. A reset while a disk write is in
progress will corrupt the data and CRC.
On exiting the reset state, various internal registers are cleared, including the Configure command information,
and the FDC waits for a new command. Drive polling will start unless disabled by a new Configure command.
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RESET Pin (Hardware Reset)
The RESET pin is a global reset and clears all registers except those programmed by the Specify command. The
DOR reset bit is enabled and must be cleared by the host to exit the reset state.
DOR Reset vs. DSR Reset (Software Reset)
These two resets are functionally the same. Both will reset the FDC core, which affects drive status information
and the FIFO circuits. The DSR reset clears itself automatically while the DOR reset requires the host to manually
clear it. DOR reset has precedence over the DSR reset. The DOR reset is set automatically upon a pin reset. The
user must manually clear this reset bit in the DOR to exit the reset state.
DMA Transfers
DMA transfers are enabled with the Specify command and are initiated by the FDC by activating the FDRQ pin
during a data transfer command. The FIFO is enabled directly by asserting nDACK and addresses need not be
valid.
Note that if the DMA controller (i.e. 8237A) is programmed to function in verify mode, a pseudo read is performed by
the FDC based only on nDACK. This mode is only available when the FDC has been configured into byte mode
(FIFO disabled) and is programmed to do a read. With the FIFO enabled, the FDC can perform the above
operation by using the new Verify command; no DMA operation is needed.
Controller Phases
For simplicity, command handling in the FDC can be divided into three phases: Command, Execution, and Result.
Each phase is described in the following sections.
Command Phase
After a reset, the FDC enters the command phase and is ready to accept a command from the host. For each of
the commands, a defined set of command code bytes and parameter bytes has to be written to the FDC before the
command phase is complete. (Refer to Table 33 for the command set descriptions). These bytes of data must be
transferred in the order prescribed.
Before writing to the FDC, the host must examine the RQM and DIO bits of the Main Status Register. RQM and DIO
must be equal to “1” and “0” respectively before command bytes may be written. RQM is set false by the FDC after
each write cycle until the received byte is processed. The FDC asserts RQM again to request each parameter byte
of the command unless an illegal command condition is detected. After the last parameter byte is received, RQM
remains “0” and the FDC automatically enters the next phase as defined by the command definition.
The FIFO is disabled during the command phase to provide for the proper handling of the “Invalid Command”
condition.
Execution Phase
All data transfers to or from the FDC occur during the execution phase, which can proceed in DMA or non-DMA
mode as indicated in the Specify command.
After a reset, the FIFO is disabled. Each data byte is transferred by an FINT or FDRQ depending on the DMA mode.
The Configure command can enable the FIFO and set the FIFO threshold value.
The following paragraphs detail the operation of the FIFO flow control. In these descriptions, <threshold> is
defined as the number of bytes available to the FDC when service is requested from the host and ranges from 1 to
16. The parameter FIFOTHR, which the user programs, is one less and ranges from 0 to 15.
A low threshold value (i.e. 2) results in longer periods of time between service requests, but requires faster
servicing of the request for both read and write cases. The host reads (writes) from (to) the FIFO until empty (full),
then the transfer request goes inactive. The host must be very responsive to the service request. This is the
SMSC DS – FDC37N869 Page 34 Rev. 11/09/2000
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desired case for use with a “fast” system. A high value of threshold (i.e. 12) is used with a “sluggish” system by
affording a long latency period after a service request, but results in more frequent service requests.
Non-DMA Mode Transfers
FIFO to Host
The FINT pin and RQM bits in the Main Status Register are activated when the FIFO contains (16-<threshold>)
bytes or the last bytes of a full sector have been placed in the FIFO. The FINT pin can be used for interrupt-driven
systems,and RQM can be used for polled systems. The host must respond to the request by reading data from
the FIFO. This process is repeated until the last byte is transferred out of the FIFO. The FDC will deactivate the
FINT pin and RQM bit when the FIFO becomes empty. Host to FIFO The FINT pin and RQM bit in the Main Status
Register are activated upon entering the execution phase of data transfer commands. The host must respond to
the request by writing data into the FIFO. The FINT pin and RQM bit remain true until the FIFO becomes full. They
are set true again when the FIFO has <threshold> bytes remaining in the FIFO. The FINT pin will also be
deactivated if TC and nDACK both go inactive. The FDC enters the result phase after the last byte is taken by the
FDC from the FIFO (i.e. FIFO empty condition).
DMA Mode Transfers
FIFO to Host
The FDC activates the DDRQ pin when the FIFO contains (16 - <threshold>) bytes, or the last byte of a full sector
transfer has been placed in the FIFO. The DMA controller must respond to the request by reading data from the
FIFO. The FDC will deactivate the DDRQ pin when the FIFO becomes empty. FDRQ goes inactive after nDACK
goes active for the last byte of a data transfer (or on the active edge of nIOR, on the last byte, if no edge is present
on nDACK). A data underrun may occur if FDRQ is not removed in time to prevent an unwanted cycle.
Host to FIFO
The FDC activates the FDRQ pin when entering the execution phase of the data transfer commands. The DMA
controller must respond by activating the nDACK and nIOW pins and placing data in the FIFO. FDRQ remains
active until the FIFO becomes full. FDRQ is again set true when the FIFO has <threshold> bytes remaining in the
FIFO. The FDC will also deactivate the FDRQ pin when TC becomes true (qualified by nDACK), indicating that no
more data is required. FDRQ goes inactive after nDACK goes active for the last byte of a data transfer (or on the
active edge of nIOW of the last byte, if no edge is present on nDACK). A data overrun may occur if FDRQ is not
removed in time to prevent an unwanted cycle.
Data Transfer Termination
The FDC supports terminal count explicitly through the TC pin and implicitly through the underrun/overrun and endof-track (EOT) functions. For full sector transfers, the EOT parameter can define the last sector to be transferred in
a single or multi-sector transfer. If the last sector to be transferred is a partial sector, the host can stop transferring
the data in mid-sector, and the FDC will continue to complete the sector as if a hardware TC was received. The
only difference between these implicit functions and TC is that they return “abnormal termination” result status.
Such status indications can be ignored if they were expected.
Note that when the host is sending data to the FIFO of the FDC, the internal sector count will be complete when the
FDC reads the last byte from its side of the FIFO. There may be a delay in the removal of the transfer request
signal of up to the time taken for the FDC to read the last 16 bytes from the FIFO. The host must tolerate this delay.
Result Phase
The generation of FINT determines the beginning of the result phase. For each of the commands, a defined set of
result bytes has to be read from the FDC before the result phase is complete. These bytes of data must be read
out for another command to start.
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RQM and DIO must both equal “1” before the result bytes may be read. After all the result bytes have been read,
the RQM and DIO bits switch to “1” and “0” respectively, and the CB bit is cleared, indicating that the FDC is ready
to accept the next command.
Command Set/Descriptions
Commands can be written whenever the FDC is in the command phase. Each command has a unique set of
needed parameters and status results. The FDC checks to see that the first byte is a valid command and, if valid,
proceeds with the command. If it is invalid, an interrupt is issued. The user sends a Sense Interrupt Status
command which returns an invalid command error. Refer to Table 32 for explanations of the various symbols
used. Table 33 lists the required parameters and the results associated with each command that the FDC is
capable of performing.
Table 32 - Description of Command Symbols
SYMBOL NAME DESCRIPTION
C Cylinder Address The currently selected address; 0 to 255.
D Data Pattern The pattern to be written in each sector data field during formatting.
D0, D1, D2,D3Drive Select 0-3 Designates which drives are perpendicular drives on the
Perpendicular Mode Command. A “1” indicates a perpendicular drive.
DIR Direction Control If this bit is “0”, then the head will step out from the spindle during a
relative seek. If set to a “1”, the head will step in toward the spindle.
DS0, DS1 Disk Drive Select DS1 DS0 DRIVE
0 0 Drive 0
0 1 Drive 1
1 0 Drive 2
1 1 Drive 3
DTL Special Sector
Size
By setting N to zero (00), DTL may be used to control the number of
bytes transferred in disk read/write commands. The sector size (N = 0)
is set to 128. If the actual sector (on the diskette) is larger than DTL,
the remainder of the actual sector is read but is not passed to the host
during read commands; during write commands, the remainder of the
actual sector is written with all zero bytes. The CRC check code is
calculated with the actual sector. When N is not zero, DTL has no
meaning and should be set to FF HEX.
EC Enable Count When this bit is “1” the “DTL” parameter of the Verify command
becomes SC (number of sectors per track).
EFIFO Enable FIFO This active low bit when a 0, enables the FIFO. A “1” disables the FIFO
(default).
EIS Enable Implied
Seek
When set, a seek operation will be performed before executing any
read or write command that requires the C parameter in the command
phase. A “0” disables the implied seek.
EOT End of Track The final sector number of the current track.
GAP Alters Gap 2 length when using Perpendicular Mode.
GPL Gap Length The Gap 3 size. (Gap 3 is the space between sectors excluding the
VCO synchronization field).
H/HDS Head Address Selected head: 0 or 1 (disk side 0 or 1) as encoded in the sector ID
field.
HLT Head Load Time The time interval that FDC waits after loading the head and before
initializing a read or write operation. Refer to the Specify command for
actual delays.
HUT Head Unload The time interval from the end of the execution phase (of a read or write
command) until the head is unloaded. Refer to the Specify command
SMSC DS – FDC37N869 Page 36 Rev. 11/09/2000
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SYMBOL NAME DESCRIPTION
Time for actual delays.
LOCK Lock defines whether EFIFO, FIFOTHR, and PRETRK parameters of
the CONFIGURE COMMAND can be reset to their default values by a
“software Reset” (A reset caused by writing to the appropriate bits of
either the DSR or DOR).
MFM MFM/FM Mode
Selector
MT Multi-Track
Selector
A one selects the double density (MFM) mode. A zero selects single
density (FM) mode.
When set, this flag selects the multi-track operating mode. In this
mode, the FDC treats a complete cylinder under head 0 and 1 as a
single track. The FDC operates as this expanded track started at the
first sector under head 0 and ended at the last sector under head 1.
With this flag set, a multitrack read or write operation will automatically
continue to the first sector under head 1 when the FDC finishes
operating on the last sector under head 0.
N Sector Size Code
This specifies the number of bytes in a sector. If this parameter is “00”,
then the sector size is 128 bytes. The number of bytes transferred is
determined by the DTL parameter. Otherwise the sector size is (2
raised to the “N’th” power) times 128. All values up to “07” hex are
allowable. “07”h would equal a sector size of 16k. It is the user’s
responsibility to not select combinations that are not possible with the
drive.
N SECTOR SIZE
00 128bytes
01 256bytes
02 512bytes
... ...
07 16Kbytes
NCN New Cylinder
The desired cylinder number.
Number
ND Non-DMA Mode
Flag
When set to “1”, indicates that the FDC is to operate in the non-DMA
mode. In this mode, the host is interrupted for each data transfer.
When set to 0, the FDC operates in DMA mode, interfacing to a DMA
controller by means of the DRQ and nDACK signals.
OW Overwrite The bits D0-D3 of the Perpendicular Mode Command can only be
modified if OW is set to “1”. OW id defined in the Lock command.
PCN Present Cylinder
Number
The current position of the head at the completion of Sense Interrupt
Status command.
POLL Polling Disable When set, the internal polling routine is disabled. When clear, polling
is enabled.
PRETRK Precompensatio
Programmable from track 00 to FFH.
n Start Track
Number
R Sector Address The sector number to be read or written. In multi-sector transfers, this
parameter specifies the sector number of the first sector to be read or
written.
RCN Relative Cylinder
Number
SC Number of
Sectors Per Track
Relative cylinder offset from present cylinder as used by the Relative
Seek command.
The number of sectors per track to be initialized by the Format
command. The number of sectors per track to be verified during a
Verify command when EC is set.
SMSC DS – FDC37N869 Page 37 Rev. 11/09/2000
Page 38
SYMBOL NAME DESCRIPTION
SK Skip Flag When set to “1”, sectors containing a deleted data address mark will
automatically be skipped during the execution of Read Data. If Read
Deleted is executed, only sectors with a deleted address mark will be
accessed. When set to “0”, the sector is read or written the same as
the read and write commands.
SRT Step Rate Interval The time interval between step pulses issued by the FDC.
Programmable from 0.5 to 8 milliseconds in increments of 0.5 ms at
the 1 Mbit data rate. Refer to the SPECIFY command for actual delays.
ST0
ST1
ST2
ST3
Status 0
Status 1
Status 2
Status 3
Registers within the FDC which store status information after a
command has been executed. This status information is available to
the host during the result phase after command execution.
WGATE Write Gate Alters timing of WE to allow for pre-erase loads in perpendicular drives.
Instruction Set
Table 33 - Instruction Set
READ DATA
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W MT MFM SK 0 0 1 1 0 Command Codes
W 0 0 0 0 0 HDS DS1 DS0
W -------- C -------- Sector ID information prior to
Command execution.
W -------- H -------W -------- R -------W -------- N -------W ------- EOT ------W ------- GPL ------W ------- DTL -------
Execution Data transfer between the
FDD and system.
Result R ------- ST0 ------- Status information after
Com mand execution.
R ------- ST1 ------R ------- ST2 ------R -------- C -------- Sector ID information after
Com mand execution.
R -------- H -------R -------- R -------R -------- N --------
SMSC DS – FDC37N869 Page 38 Rev. 11/09/2000
Page 39
READ DELETED DATA
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W MT MFM SK 0 1 1 0 0 Command Codes
W 0 0 0 0 0 HDS DS1 DS0
W -------- C -------- Sector ID information prior to
Command execution.
W -------- H -------W -------- R -------W -------- N -------W ------- EOT ------W ------- GPL ------W ------- DTL -------
Execution Data transfer between the
FDD and system.
Result R ------- ST0 ------- Status information after
Com mand execution.
R ------- ST1 ------R ------- ST2 ------R -------- C -------- Sector ID information after
Com mand execution.
R -------- H -------R -------- R -------R -------- N --------
WRITE DATA
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W MT MFM 0 0 0 1 0 1 Command Codes
W 0 0 0 0 0 HDS DS1 DS0
W -------- C -------- Sector ID information prior to
Command execution.
W -------- H -------W -------- R -------W -------- N -------W ------- EOT ------W ------- GPL ------W ------- DTL -------
Execution Data transfer between the
FDD and system.
Result R ------- ST0 ------- Status information after
Com mand execution.
R ------- ST1 ------R ------- ST2 ------R -------- C -------- Sector ID information after
Command execution.
R -------- H -------R -------- R -------R -------- N --------
SMSC DS – FDC37N869 Page 39 Rev. 11/09/2000
Page 40
WRITE DELETED DATA
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W MT MFM 0 0 1 0 0 1 Command Codes
W 0 0 0 0 0 HDS DS1 DS0
W -------- C -------- Sector ID information
prior to Command
execution.
W -------- H -------W -------- R -------W -------- N -------W ------- EOT ------W ------- GPL ------W ------- DTL -------
Execution Data transfer between
the FDD and system.
Result R ------- ST0 ------- Status information after
Com mand execution.
R ------- ST1 ------R ------- ST2 ------R -------- C -------- Sector ID information
after Command
execution.
R -------- H -------R -------- R -------R -------- N --------
READ A TRACK
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W 0 MFM 0 0 0 0 1 0 Command Codes
W 0 0 0 0 0 HDS DS1 DS0
W -------- C -------- Sector ID information
prior to Command
execution.
W -------- H -------W -------- R -------W -------- N -------W ------- EOT ------W ------- GPL ------W ------- DTL -------
Execution Data transfer between
the FDD and system.
FDC reads all of
cylinders’ contents from
index hole to EOT.
Result R ------- ST0 ------- Status information after
Com mand execution.
R ------- ST1 ------R ------- ST2 ------R -------- C -------- Sector ID information
after Command
execution.
R -------- H --------
SMSC DS – FDC37N869 Page 40 Rev. 11/09/2000
Page 41
READ A TRACK
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
R -------- R -------R -------- N --------
VERIFY
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W MT MFM SK 1 0 1 1 0 Command Codes
W EC 0 0 0 0 HDS DS1 DS0
W -------- C -------- Sector ID information
prior to Command
execution.
W -------- H -------W -------- R -------W -------- N -------W ------- EOT ------W ------- GPL ------W ------ DTL/SC ------
Execution No data transfer takes
place.
Result R ------- ST0 ------- Status information after
Com mand execution.
R ------- ST1 ------R ------- ST2 ------R -------- C -------- Sector ID information
after Command
execution.
R -------- H -------R -------- R -------R -------- N --------
VERSION
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W 0 0 0 1 0 0 0 0 Command Code
Result R 1 0 0 1 0 0 0 0 Enhanced Controller
SMSC DS – FDC37N869 Page 41 Rev. 11/09/2000
Page 42
FORMAT A TRACK
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W 0 MFM 0 0 1 1 0 1 Command Codes
W 0 0 0 0 0 HDS DS1 DS0
W -------- N -------- Bytes/Sector
W -------- SC -------- Sectors/Cylinder
W ------- GPL ------- Gap 3
W -------- D -------- Filler Byte
Execution for
Each Sector
W -------- C -------- Input Sector
Parameters
Repeat:
W -------- H -------W -------- R -------W -------- N --------
FDC formats an entire
cylinder
Result R ------- ST0 ------- Status information after
Command execution
R ------- ST1 ------R ------- ST2 ------R ------ Undefined -----R ------ Undefined -----R ------ Undefined -----R ------ Undefined ------
RECALIBRATE
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W 0 0 0 0 0 1 1 1 Command Codes
W 0 0 0 0 0 0 DS1 DS0
Execution Head retracted to Track 0
Interrupt.
SMSC DS – FDC37N869 Page 42 Rev. 11/09/2000
Page 43
SENSE INTERRUPT STATUS
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W 0 0 0 0 1 0 0 0 Command Codes
Result R ------- ST0 ------- Status information at the end
of each seek operation.
R ------- PCN -------
SPECIFY
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W 0 0 0 0 0 0 1 1 Command Codes
W --- SRT --- --- HUT --W ------ HLT ------ ND
SENSE DRIVE STATUS
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W 0 0 0 0 0 1 0 0 Command Codes
W 0 0 0 0 0 HDS DS1 DS0
Result R ------- ST3 ------- Status information about
FDD
SEEK
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W 0 0 0 0 1 1 1 1 Command Codes
W 0 0 0 0 0 HDS DS1 DS0
W ------- NCN -------
Execution Head positioned over
proper cylinder on
diskette.
CONFIGURE
DATA BUS
PHASE R/W D7 D6 D5 D4 D3 D2 D1 D0 REMARKS
Command W 0 0 0 1 0 0 1 1 Configure
Information
W 0 0 0 0 0 0 0 0
W 0 EIS EFIFO POLL --- FIFOTHR ---
Execution W --------- PRETRK ---------
SMSC DS – FDC37N869 Page 43 Rev. 11/09/2000
Page 44
RELATIVE SEEK
DATA BUS
PHASE R/W
D7 D6 D5 D4 D3 D2 D1 D0
REMARKS
Command W 1 DIR 0 0 1 1 1 1
W 0 0 0 0 0 HDS DS1 DS0
W ------- RCN -------
DUMPREG
DATA BUS
PHASE R/W
D7 D6 D5 D4 D3 D2 D1 D0
REMARKS
Command W 0 0 0 0 1 1 1 0 *Note:
Registers
placed in
FIFO
Execution
Result R ------ PCN-Drive 0 -------
R ------ PCN-Drive 1 ------R ------ PCN-Drive 2 ------R ------ PCN-Drive 3 ------R ---- SRT ---- --- HUT --R ------- HLT ------- ND
R ------- SC/EOT ------R LOCK 0 D3 D2 D1 D0 GAP WGATE
R 0 EIS EFIFO POLL -- FIFOTHR -R -------- PRETRK --------
SMSC DS – FDC37N869 Page 44 Rev. 11/09/2000
Page 45
READ ID
DATA BUS
PHASE R/W
D7 D6 D5 D4 D3 D2 D1 D0
REMARKS
Command W 0 MFM 0 0 1 0 1 0 Commands
W 0 0 0 0 0 HDS DS1 DS0
Execution The first correct ID
information on the
Cylinder is stored in
Data Register
Result R -------- ST0 -------- Status information after
Command execution.
Disk status after the
Command has
completed
R -------- ST1 -------R -------- ST2 -------R -------- C -------R -------- H -------R -------- R -------R -------- N --------
PERPENDICULAR MODE
DATA BUS
PHASE R/W
D7 D6 D5 D4 D3 D2 D1 D0
REMARKS
Command W 0 0 0 1 0 0 1 0 Command Codes
OW 0 D3 D2 D1 D0 GAP WGATE
SMSC DS – FDC37N869 Page 45 Rev. 11/09/2000
Page 46
INVALID CODES
DATA BUS
PHASE R/W
D7 D6 D5 D4 D3 D2 D1 D0
REMARKS
Command W ----- Invalid Codes ----- Invalid Command Codes
(NoOp - FDC37N869 goes
into Standby State)
Result R ------- ST0 ------- ST0 = 80H
LOCK
DATA BUS
PHASE R/W
D7 D6 D5 D4 D3 D2 D1 D0
REMARKS
Command W LOCK 0 0 1 0 1 0 0 Command Codes
Result R 0 0 0 LOCK 0 0 0 0
SC is returned if the last command that was issued was the Format command. EOT is returned if the last
command was a Read or Write.
Note: These bits are used internally only. They are not reflected in the Drive Select pins. It is the user’s
responsibility to maintain correspondence between these bits and the Drive Select pins (DOR).
Data Transfer Commands
All of the Read Data, Write Data and Verify type commands use the same parameter bytes and return the same
results information, the only difference being the coding of bits 0-4 in the first byte.
An implied seek will be executed if the feature was enabled by the Configure command. This seek is completely
transparent to the user. The Drive Busy bit for the drive will go active in the Main Status Register during the seek
portion of the command. If the seek portion fails, it will be reflected in the results status normally returned for a
Read/Write Data command. Status Register 0 (ST0) would contain the error code and C would contain the cylinder
on which the seek failed.
Read Data
A set of nine bytes is required to place the FDC in the Read Data Mode. After the Read Data command has been
issued, the FDC loads the head (if it is in the unloaded state), waits the specified head settling time (defined in the
Specify command), and begins reading ID Address Marks and ID fields. When the sector address read off the
diskette matches with the sector address specified in the command, the FDC reads the sector’s data field and
transfers the data to the FIFO.
After completion of the read operation from the current sector, the sector address is incremented by one and the
data from the next logical sector is read and output via the FIFO. This continuous read function is called “MultiSector Read Operation”. Upon receipt of TC, or an implied TC (FIFO overrun/underrun), the FDC stops sending
data but will continue to read data from the current sector, check the CRC bytes, and at the end of the sector,
terminate the Read Data Command. N determines the number of bytes per sector (see Table 34 below). If N is
set to zero, the sector size is set to 128. The DTL value determines the number of bytes to be transferred. If DTL is
less than 128, the FDC transfers the specified number of bytes to the host. For reads, it continues to read the
entire 128-byte sector and checks for CRC errors. For writes, it completes the 128-byte sector by filling in zeros. If
N is not set to 00 Hex, DTL should be set to FF Hex and has no impact on the number of bytes transferred.
SMSC DS – FDC37N869 Page 46 Rev. 11/09/2000
Page 47
Table 34 - Sector Sizes
N SECTOR SIZE
00
01
02
03
..
07
128 bytes
256 bytes
512 bytes
1024 bytes
...
16 Kbytes
The amount of data which can be handled with a single command to the FDC depends upon MT (multi-track) and
N (number of bytes/sector).
The Multi-Track function (MT) allows the FDC to read data from both sides of the diskette. For a particular cylinder,
data will be transferred starting at Sector 1, Side 0 and completing the last sector of the same track at Side 1.
If the host terminates a read or write operation in the FDC, the ID information in the result phase is dependent
upon the state of the MT bit and EOT byte. Refer to Table 38.
At the completion of the Read Data command, the head is not unloaded until after the Head Unload Time Interval
(specified in the Specify command) has elapsed. If the host issues another command before the head unloads,
then the head settling time may be saved between subsequent reads.
If the FDC detects a pulse on the nINDEX pin twice without finding the specified sector (meaning that the
diskette’s index hole passes through index detect logic in the drive twice), the FDC sets the IC code in Status
Register 0 to “01” indicating abnormal termination, sets the ND bit in Status Register 1 to “1” indicating a sector not
found, and terminates the Read Data Command.
After reading the ID and Data Fields in each sector, the FDC checks the CRC bytes. If a CRC error occurs in the
ID or data field, the FDC sets the IC code in Status Register 0 to “01” indicating abnormal termination, sets the DE
bit flag in Status Register 1 to “1”, sets the DD bit in Status Register 2 to “1” if CRC is incorrect in the ID field, and
terminates the Read Data Command. Table 36 describes the effect of the SK bit on the Read Data command
execution and results. Except where noted in Table 36, the C or R value of the sector address is automatically
incremented (see Table 38).
Table 35 - Affects of MT and N Bits
MT N
0
1
0
1
0
1
MAXIMUM TRANSFER
CAPACITY
1
256 x 26 = 6,656
1
256 x 52 = 13,312
2
512 x 15 = 7,680
2
512 x 30 = 15,360
3
1024 x 8 = 8,192
3
1024 x 16 = 16,384
FINAL SECTOR READ FROM
DISK
26 at side 0 or 1
26 at side 1
15 at side 0 or 1
15 at side 1
8 at side 0 or 1
16 at side 1
Table 36 - Skip Bit vs. Read Data Command
DATA ADDRESS
MARK TYPE
SK BIT VALUE
0
ENCOUNTERED RESULTS
Normal Data
SECTOR
READ?
Yes
CM BIT OF
ST2 SET? DESCRIPTION OF RESULTS
No
Normal termination
Address not incremented
0
Deleted Data
Yes
Yes
Next sector not searched for
1
1
Normal Data
Deleted Data
Yes
No
No
Yes
Normal termination
Normal termination. Sector
not read (“skipped”)
SMSC DS – FDC37N869 Page 47 Rev. 11/09/2000
Page 48
Read Deleted Data
This command is the same as the Read Data command, only it operates on sectors that contain a Deleted Data
Address Mark at the beginning of a Data Field.
Table 37 describes the effect of the SK bit on the Read Deleted Data command execution and results.
Except where noted in Table 37 the C or R value of the sector address is automatically incremented (see Table
38).
Table 37 - Skip Bit vs. Read Deleted Data Command
DATA ADDRESS
MARK TYPE
ENCOUNTERED
SK BIT VALUE SECTOR
READ?
0
Normal Data
Yes
RESULTS
CM BIT OF
ST2 SET?
Yes
DESCRIPTION OF
RESULTS
Address not
incremented.
Next sector not
searched for.
0
Deleted Data
Yes
No
Normal
termination.
1
Normal Data
No
Yes
Normal
termination.
Sector not read
(“skipped”).
1
Deleted Data
Yes
No
Normal
termination.
Read A Track
This command is similar to the Read Data command except that the entire data field is read continuously from
each of the sectors of a track. Immediately after encountering a pulse on the nINDEX pin, the FDC starts to
read all data fields on the track as continuous blocks of data without regard to logical sector numbers. If the FDC
finds an error in the ID or DATA CRC check bytes, it continues to read data from the track and sets the appropriate
error bits at the end of the command. The FDC compares the ID information read from each sector with the
specified value in the command and sets the ND flag of Status Register 1 to a “1” if there is no comparison.
Multi-track or skip operations are not allowed with this command. The MT and SK bits (bits D7 and D5 of the first
command byte respectively) should always be set to “0”.
This command terminates when the EOT specified number of sectors has not been read. If the FDC does not find
an ID Address Mark on the diskette after the second occurrence of a pulse on the IDX pin, then it sets the IC code
in Status Register 0 to “01” (abnormal termination), sets the MA bit in Status Register 1 to “1”, and terminates the
command.
SMSC DS – FDC37N869 Page 48 Rev. 11/09/2000
Page 49
Table 38 - Result Phase Table
FINAL SECTOR
TRANSFERRED TO
MT HEAD
HOST ID INFORMATION AT RESULT PHASE
C H R N
Less than EOT NC NC R + 1 NC
0 0
Equal to EOT C + 1 NC 01 NC
Less than EOT NC NC R + 1 NC
1
Equal to EOT C + 1 NC 01 NC
Less than EOT NC NC R + 1 NC
1 0
Equal to EOT NC LSB 01 NC
Less than EOT NC NC R + 1 NC
1
Equal to EOT C + 1 LSB 01 NC
NC: No Change, the same value as the one at the beginning of command execution.
LSB: Least Significant Bit, the LSB of H is complemented.
Write Data
After the Write Data command has been issued, the FDC loads the head (if it is in the unloaded state), waits the
specified head load time if unloaded (defined in the Specify command), and begins reading ID fields. When the
sector address read from the diskette matches the sector address specified in the command, the FDC reads the
data from the host via the FIFO and writes it to the sector’s data field.
After writing data into the current sector, the FDC computes the CRC value and writes it into the CRC field at the
end of the sector transfer. The Sector Number stored in “R” is incremented by one, and the FDC continues writing
to the next data field. The FDC continues this “Multi-Sector Write Operation”. Upon receipt of a terminal count
signal or if a FIFO over/under run occurs while a data field is being written, then the remainder of the data field is
filled with zeros.
The FDC reads the ID field of each sector and checks the CRC bytes. If it detects a CRC error in one of the ID
fields, it sets the IC code in Status Register 0 to “01” (abnormal termination), sets the DE bit of Status Register 1 to
“1”, and terminates the Write Data command.
The Write Data command operates in much the same manner as the Read Data command. The following items
are the same. Please refer to the Read Data Command for details:
• Transfer Capacity
• EN (End of Cylinder) bit
• ND (No Data) bit
• Head Load, Unload Time Interval
• ID information when the host terminates the command
• Definition of DTL when N = 0 and when N does not = 0
SMSC DS – FDC37N869 Page 49 Rev. 11/09/2000
Page 50
Write Deleted Data
This command is almost the same as the Write Data command except that a Deleted Data Address Mark is written
at the beginning of the Data Field instead of the normal Data Address Mark. This command is typically used to
mark a bad sector containing an error on the floppy disk.
Verify
The Verify command is used to verify the data stored on a disk. This command acts exactly like a Read Data
command except that no data is transferred to the host. Data is read from the disk and CRC is computed and
checked against the previously-stored value.
Because data is not transferred to the host, TC (pin 25) cannot be used to terminate this command. By setting the
EC bit to “1”, an implicit TC will be issued to the FDC. This implicit TC will occur when the SC value has
decremented to 0 (an SC value of 0 will verify 256 sectors). This command can also be terminated by setting the
EC bit to “0” and the EOT value equal to the final sector to be checked. If EC is set to “0”, DTL/SC should be
programmed to 0FFH. Refer to Table 38 and Table 39 for information concerning the values of MT and EC versus
SC and EOT value.
Definitions:
# Sectors Per Side = Number of formatted sectors per each side of the disk.
# Sectors Remaining = Number of formatted sectors left which can be read, including side 1 of the disk if MT is set
to “1”.
Table 39 - Verify Command Result Phase Table
MT EC SC/EOT VALUE TERMINATION RESULT
0 0 SC = DTL
EOT £ # Sectors Per Side
0 0 SC = DTL
EOT > # Sectors Per Side
0 1 SC £ # Sectors Remaining AND
EOT £ # Sectors Per Side
0 1 SC > # Sectors Remaining OR
EOT > # Sectors Per Side
1 0 SC = DTL
EOT £ # Sectors Per Side
1 0 SC = DTL
EOT > # Sectors Per Side
1 1 SC £ # Sectors Remaining AND
EOT £ # Sectors Per Side
1 1 SC > # Sectors Remaining OR
EOT > # Sectors Per Side
Success Termination
Result Phase Valid
Unsuccessful Termination
Result Phase Invalid
Successful Termination
Result Phase Valid
Unsuccessful Termination
Result Phase Invalid
Successful Termination
Result Phase Valid
Unsuccessful Termination
Result Phase Invalid
Successful Termination
Result Phase Valid
Unsuccessful Termination
Result Phase Invalid
Note: If MT is set to “1” and the SC value is greater than the number of remaining formatted sectors on Side 0,
verifying will continue on Side 1 of the disk.
SMSC DS – FDC37N869 Page 50 Rev. 11/09/2000
Page 51
Format A Track
The Format command allows an entire track to be formatted. After a pulse from the IDX pin is detected, the FDC
starts writing data on the disk including gaps, address marks, ID fields, and data fields per the IBM System 34 or
3740 format (MFM or FM respectively). The particular values that will be written to the gap and data field are
controlled by the values programmed into N, SC, GPL, and D which are specified by the host during the command
phase. The data field of the sector is filled with the data byte specified by D. The ID field for each sector is supplied
by the host; that is, four data bytes per sector are needed by the FDC for C, H, R, and N (cylinder, head, sector
number and sector size respectively).
After formatting each sector, the host must send new values for C, H, R and N to the FDC for the next sector on the
track. The R value (sector number) is the only value that must be changed by the host after each sector is
formatted. This allows the disk to be formatted with nonsequential sector addresses (interleaving). This
incrementing and formatting continues for the whole track until the FDC encounters a pulse on the IDX pin again
and it terminates the command. Table 41 contains typical values for gap fields which are dependent upon the size
of the sector and the number of sectors on each track. Actual values can vary due to drive electronics.
Table 40 - FORMAT FIELDS
SYSTEM 34 (DOUBLE DENSITY) FORMAT
DATA
GAP4
SYN
a
80x
4E
C
12x
00
IAM GAP
3x
FC 3xA1FE 3xA1FB
1
50x
4E
SYN
C
12x
00
IDAM C
HDS
NOC
GAP
SYN
Y
E
R
2
C
L
C
C
22x
12x
4E
00
C
AM
F8
DATA
C
GAP3
R
C
GAP
4b
2
GAP4
a
40x
FF
GAP4
a
80x
4E
SYN
C
6x
00
SYN
C
12x
00
SYSTEM 3740 (SINGLE DENSITY) FORMAT
DATA
IAM GAP
1
26x
FF
SYN
C
6x
00
IDAM C
HDS
NOC
GAP
SYN
Y
E
R
2
C
L
C
C
11x
6x
FF
00
FC FE FB or
PERPENDICULAR FORMAT
DATA
IAM GAP
3x
FC 3xA1FE 3xA1FB
1
50x
4E
SYN
C
12x
00
IDAM C
HDS
NOC
GAP
SYN
Y
E
R
2
C
L
C
C
41x
12x
4E
00
C
2
AM
F8
AM
F8
DATA
DATA
C
GAP3
R
C
GAP
4b
C
GAP3
R
C
GAP
4b
SMSC DS – FDC37N869 Page 51 Rev. 11/09/2000
Page 52
Table 41 - Typical Values for Formatting
FORMAT SECTOR SIZE N SC GPL1 GPL2
5.25”
Drives
3.5”
Drives
FM
MFM
FM
MFM
128
128
512
1024
2048
4096
...
256
256
512*
1024
2048
4096
...
128
256
512
256
512**
1024
00
00
02
03
04
05
...
01
01
02
03
04
05
...
12
10
08
04
02
01
12
10
09
04
02
01
0
1
2
1
2
3
0F
09
05
0F
09
05
07
10
18
46
C8
C8
0A
20
2A
80
C8
C8
07
0F
1B
0E
1B
35
09
19
30
87
FF
FF
0C
32
50
F0
FF
FF
1B
2A
3A
36
54
74
GPL1 = suggested GPL values in Read and Write commands to avoid splice point
between data field and ID field of contiguous sections.
GPL2 = suggested GPL value in Format A Track command.
*PC/AT values (typical)
**PS/2 values (typical). Applies with 1.0 MB and 2.0 MB drives.
Note: All values except sector size are in hex.
Control Commands
Control commands differ from the other commands in that no data transfer takes place. Three commands
generate an interrupt when complete: Read ID, Recalibrate, and Seek. The other control commands do not
generate an interrupt.
Read ID
The Read ID command is used to find the present position of the recording heads. The FDC stores the values
from the first ID field it is able to read into its registers. If the FDC does not find an ID address mark on the diskette
after the second occurrence of a pulse on the nINDEX pin, it then sets the IC code in Status Register 0 to “01”
(abnormal termination), sets the MA bit in Status Register 1 to “1”, and terminates the command.
The following commands will generate an interrupt upon completion. They do not return any result bytes. It is
highly recommended that control commands be followed by the Sense Interrupt Status command. Otherwise,
valuable interrupt status information will be lost.
Recalibrate
This command causes the read/write head within the FDC to retract to the track 0 position. The FDC clears the
contents of the PCN counter and checks the status of the nTR0 pin from the FDD. As long as the nTR0 pin is low,
the DIR pin remains 0 and step pulses are issued. When the nTR0 pin goes high, the SE bit in Status Register
0 is set to “1” and the command is terminated. If the nTR0 pin is still low after 79 step pulses have been issued,
the FDC sets the SE and the EC bits of Status Register 0 to “1” and terminates the command. Disks capable of
handling more than 80 tracks per side may require more than one Recalibrate command to return the head back
to physical Track 0. The Recalibrate command does not have a result phase. The Sense Interrupt Status
command must be issued after the Recalibrate command to effectively terminate it and to provide verification of the
SMSC DS – FDC37N869 Page 52 Rev. 11/09/2000
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head position (PCN). During the command phase of the recalibrate operation, the FDC is in the BUSY state, but
during the execution phase it is in a NON-BUSY state. At this time, another Recalibrate command may be issued,
and in this manner parallel Recalibrate operations may be done on up to four drives at once.
Upon power up, the software must issue a Recalibrate command to properly initialize all drives and the controller.
Seek
The read/write head within the drive is moved from track to track under the control of the Seek command. The FDC
compares the PCN, which is the current head position, with the NCN and performs the following operation if there
is a difference:
PCN < NCN: Direction signal to drive set to “1” (step in) and issues step pulses.
PCN > NCN: Direction signal to drive set to “0” (step out) and issues step pulses.
The rate at which step pulses are issued is controlled by SRT (Stepping Rate Time) in the Specify command. After
each step pulse is issued, NCN is compared against PCN, and when NCN = PCN the SE bit in Status Register 0
is set to “1” and the command is terminated.
During the command phase of the seek or recalibrate operation, the FDC is in the BUSY state, but during the
execution phase it is in the NON-BUSY state. At this time, another Seek or Recalibrate command may be issued,
and in this manner, parallel seek operations may be done on up to four drives at once.
Note that if implied seek is not enabled, the read and write commands should be preceded by:
1) Seek command - Step to the proper track
2) Sense Interrupt Status command - Terminate the Seek command
3) Read ID - Verify head is on proper track
4) Issue Read/Write command.
The Seek command does not have a result phase. Therefore, it is highly recommended that the Sense Interrupt
Status command be issued after the Seek command to terminate it and to provide verification of the head position
(PCN). The H bit (Head Address) in ST0 will always return to a “0”. When exiting POWERDOWN mode, the FDC
clears the PCN value and the status information to zero. Prior to issuing the POWERDOWN command, it is highly
recommended that the user service all pending interrupts through the Sense Interrupt Status command.
Sense Interrupt Status
An interrupt signal on FINT pin is generated by the FDC for one of the following reasons:
1) Upon entering the Result Phase of:
a. Read Data command
b. Read A Track command
c. Read ID command
d. Read Deleted Data command
e. Write Data command
f. Format A Track command
g. Write Deleted Data command
h. Verify command
2) End of Seek, Relative Seek, or Recalibrate command
3) FDC requires a data transfer during the execution phase in the non-DMA mode
The Sense Interrupt Status command resets the interrupt signal and, via the IC code and SE bit of Status Register
0, identifies the cause of the interrupt.
Table 42 - Interrupt Identification
SE IC INTERRUPT DUE TO
0 11 Polling
1 00 Normal termination of Seek
or Recalibrate command
1 01 Abnormal termination of
Seek or Recalibrate
command
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The Seek, Relative Seek, and Recalibrate commands have no result phase. The Sense Interrupt Status command
must be issued immediately after these commands to terminate them and to provide verification of the head
position (PCN). The H (Head Address) bit in ST0 will always return a “0”. If a Sense Interrupt Status is not issued,
the drive will continue to be BUSY and may affect the operation of the next command.
Sense Drive Status
Sense Drive Status obtains drive status information. It has not execution phase and goes directly to the result
phase from the command phase. Status Register 3 contains the drive status information.
Specify
The Specify command sets the initial values for each of the three internal times. The HUT (Head Unload Time)
defines the time from the end of the execution phase of one of the read/write commands to the head unload state.
The SRT (Step Rate Time) defines the time interval between adjacent step pulses. Note that the spacing between
the first and second step pulses may be shorter than the remaining step pulses. The HLT (Head Load Time)
defines the time between when the Head Load signal goes high and the read/write operation starts. The values
change with the data rate speed selection and are documented in
Table 43. The values are the same for MFM and FM.
Table 43 - Drive Control Delays (ms)
HUT SRT
2M 1M 500K 300K 250K 2M 1M 500K 300K 250K
0
64
128
1
4
..
..
E
56
112
F
60
120
256
8
..
224
240
16
426
26.7
..
373
400
512
32
..
..
448
480
4
3.75
..
0.5
0.25
8
7.5
1
0.5
16
26.7
15
..
25
..
2
3.33
1
1.67
32
30
..
..
4
2
HLT
2M 1M 500K 300K 250K
00
01
02
..
7F
7F
64
0.5
1
..
63
63.5
128
1
2
..
126
127
256
2
4
..
252
254
426
3.3
6.7
..
420
423
512
4
8
.
504
508
The choice of DMA or non-DMA operations is made by the ND bit. When this bit is “1”, the non-DMA mode is
selected, and when ND is “0”, the DMA mode is selected. In DMA mode, data transfers are signaled by the FDRQ
pin. Non-DMA mode uses the RQM bit and the FINT pin to signal data transfers.
Configure
The Configure command is issued to select the special features of the FDC. A Configure command need not be
issued if the default values of the FDC meet the system requirements.
Configure Default Values:
EIS - No Implied Seeks
EFIFO - FIFO Disabled
POLL - Polling Enabled
FIFOTHR - FIFO Threshold Set to 1 Byte
PRETRK - Pre-Compensation Set to Track 0
EIS - Enable Implied Seek. When set to “1”, the FDC will perform a Seek operation before executing a read or write
command. Defaults to no implied seek.
EFIFO - A “1” disables the FIFO (default). This means data transfers are asked for on a byte-by-byte basis.
Defaults to “1”, FIFO disabled. The threshold defaults to “1”.
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POLL - Disable polling of the drives. Defaults to “0”, polling enabled. When enabled, a single interrupt is
generated after a reset. No polling is performed while the drive head is loaded and the head unload delay has not
expired.
FIFOTHR - The FIFO threshold in the execution phase of read or write commands. This is programmable from 1 to
16 bytes. Defaults to one byte. A “00” selects one byte; “0F” selects 16 bytes.
PRETRK - Pre-Compensation Start Track Number. Programmable from track 0 to 255. Defaults to track 0. A “00”
selects track 0; “FF” selects track 255.
Version
The Version command checks to see if the controller is an enhanced type or the older type (765A). A value of 90 H
is returned as the result byte.
Relative Seek
The command is coded the same as for Seek, except for the MSB of the first byte and the DIR bit.
Table 44 - Head Step Direction Control
DIR ACTION
0 Step Head Out
1 Step Head In
RCN - Relative Cylinder Number that determines how many tracks to step the head in or out from the current track
number.
The Relative Seek command differs from the Seek command in that it steps the head the absolute number of
tracks specified in the command instead of making a comparison against an internal register. The Seek
command is good for drives that support a maximum of 256 tracks. Relative Seeks cannot be overlapped with
other Relative Seeks. Only one Relative Seek can be active at a time. Relative Seeks may be overlapped with
Seeks and Recalibrates. Bit 4 of Status Register 0 (EC) will be set if Relative Seek attempts to step outward
beyond Track 0. As an example, assume that a floppy drive has 300 useable tracks. The host needs to read track
300 and the head is on any track (0-255). If a Seek command is issued, the head will stop at track 255. If a
Relative Seek command is issued, the FDC will move the head the specified number of tracks, regardless of the
internal cylinder position register (but will increment the register). If the head was on track 40 (d), the maximum
track that the FDC could position the head on using Relative Seek will be 295 (D), the initial track + 255 (D). The
maximum count that the head can be moved with a single Relative Seek command is 255 (D).
The internal register, PCN, will overflow as the cylinder number crosses track 255 and will contain 39 (D). The
resulting PCN value is thus (RCN + PCN) mod 256. Functionally, the FDC starts counting from 0 again as the
track number goes above 255 (D). It is the user’s responsibility to compensate FDC functions (precompensation
track number) when accessing tracks greater than 255. The FDC does not keep track that it is working in an
“extended track area” (greater than 255). Any command issued will use the current PCN value except for the
Recalibrate command, which only looks for the TRACK0 signal. Recalibrate will return an error if the head is
farther than 79 due to its limitation of issuing a maximum of 80 step pulses. The user simply needs to issue a
second Recalibrate command. The Seek command and implied seeks will function correctly within the 44 (D)
track (299-255) area of the “extended track area”. It is the user’s responsibility not to issue a new track position
that will exceed the maximum track that is present in the extended area. To return to the standard floppy range (0-
255) of tracks, a Relative Seek should be issued to cross the track 255 boundary. A Relative Seek can be used
instead of the normal Seek, but the host is required to calculate the difference between the current head location
and the new (target) head location. This may require the host to issue a Read ID command to ensure that the
head is physically on the track that software assumes it to be. Different FDC commands will return different
cylinder results which may be difficult to keep track of with software without the Read ID command.
SMSC DS – FDC37N869 Page 55 Rev. 11/09/2000
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Perpendicular Mode
The Perpendicular Mode command should be issued prior to executing Read/Write/Format commands that
access a disk drive with perpendicular recording capability. With this command, the length of the Gap2 field and
VCO enable timing can be altered to accommodate the unique requirements of these drives.
Table 45 describes the affects of the WGATE and GAP bits for the Perpendicular Mode command. Upon a reset,
the FDC will default to the conventional mode (WGATE = 0, GAP = 0).
Selection of the 500 Kbps and 1 Mbps perpendicular modes is independent of the actual data rate selected in the
Data Rate Select Register. The user must ensure that these two data rates remain consistent.
The Gap2 and VCO timing requirements for perpendicular recording type drives are dictated by the design of the
read/write head. In the design of this head, a pre-erase head precedes the normal read/write head by a distance
of 200 micrometers. This works out to about 38 bytes at a 1 Mbps recording density. Whenever the write head is
enabled by the Write Gate signal, the pre-erase head is also activated at the same time. Thus, when the write head
is initially turned on, flux transitions recorded on the media for the first 38 bytes will not be preconditioned with the
pre-erase head since it has not yet been activated. To accommodate this head activation and deactivation time,
the Gap2 field is expanded to a length of 41 bytes. The format field shown on page 61 illustrates the change in
the Gap2 field size for the perpendicular format.
On the read back by the FDC, the controller must begin synchronization at the beginning of the sync field. For the
conventional mode, the internal PLL VCO is enabled (VCOEN) approximately 24 bytes from the start of the Gap2
field. But, when the controller operates in the 1 Mbps perpendicular mode (WGATE = 1, GAP = 1), VCOEN goes
active after 43 bytes to accommodate the increased Gap2 field size. For both cases, and approximate two-byte
cushion is maintained from the beginning of the sync field for the purposes of avoiding write splices in the
presence of motor speed variation.
For the Write Data case, the FDC activates Write Gate at the beginning of the sync field under the conventional
mode. The controller then writes a new sync field, data address mark, data field, and CRC as shown in Figure 4.
With the pre-erase head of the perpendicular drive, the write head must be activated in the Gap2 field to insure a
proper write of the new sync field. For the 1 Mbps perpendicular mode (WGATE = 1, GAP = 1), 38 bytes will be
written in the Gap2 space. Since the bit density is proportional to the data rate, 19 bytes will be written in the Gap2
field for the 500 Kbps perpendicular mode (WGATE = 1, GAP =0).
It should be noted that none of the alterations in Gap2 size, VCO timing, or Write Gate timing affect normal program
flow. The information provided here is just for background purposes and is not needed for normal operation.
Once the Perpendicular Mode command is invoked, FDC software behavior from the user standpoint is
unchanged.
The perpendicular mode command is enhanced to allow specific drives to be designated Perpendicular recording
drives. This enhancement allows data transfers between Conventional and Perpendicular drives without having to
issue Perpendicular mode commands between the accesses of the different drive types, nor having to change
write pre-compensation values.
When both GAP and WGATE bits of the PERPENDICULAR MODE COMMAND are both programmed to “0”
(Conventional mode), then D0, D1, D2, D3, and D4 can be programmed independently to “1” for that drive to be set
automatically to Perpendicular mode. In this mode the following set of conditions also apply:
1. The GAP2 written to a perpendicular drive during a write operation will depend upon the programmed data
rate.
2. The write pre-compensation given to a perpendicular mode drive will be 0ns.
3. For D0-D3 programmed to “0” for conventional mode drives any data written will be at the currently
programmed write pre-compensation.
Note: Bits D0-D3 can only be overwritten when OW is programmed as a “1”.
If either GAP or WGATE is a “1” then D0-D3 are ignored.
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Software and hardware resets have the following effect on the PERPENDICULAR MODE COMMAND:
1. “Software” resets (via the DOR or DSR registers) will only clear GAP and WGATE bits to “0”. D0-D3 are
unaffected and retain their previous value.
2. “Hardware” resets will clear all bits (GAP, WGATE and D0-D3) to “0”, i.e. all conventional mode.
Table 45 - Affects of WGATE and GAP Bits
WGATE
0
0
GAP MODE
0
Conventional
1
Perpendicular
LENGTH OF GAP2
FORMAT FIELD
22 Bytes
22 Bytes
PORTION OF GAP 2 WRITTEN BY
WRITE DATA OPERATION
0 Bytes
19 Bytes
(500 Kbps)
1
0
Reserved
22 Bytes
0 Bytes
(Conventional)
1
1
Perpendicular
41 Bytes
38 Bytes
(1 Mbps)
LOCK
In order to protect systems with long DMA latencies against older application software that can disable the FIFO
the LOCK Command has been added. This command should only be used by the FDC routines, and application
software should refrain from using it. If an application calls for the FIFO to be disabled then the CONFIGURE
command should be used.
The LOCK command defines whether the EFIFO, FIFOTHR, and PRETRK parameters of the CONFIGURE
command can be RESET by the DOR and DSR registers. When the LOCK bit is set to logic “1” all subsequent
“software RESETS by the DOR and DSR registers will not change the previously set parameters to their default
values. All “hardware” RESET from the RESET pin will set the LOCK bit to logic “0” and return the EFIFO,
FIFOTHR, and PRETRK to their default values. A status byte is returned immediately after issuing a LOCK
command. This byte reflects the value of the LOCK bit set by the command byte.
ENHANCED DUMPREG
The DUMPREG command is designed to support system run-time diagnostics and application software
development and debug. To accommodate the LOCK command and the enhanced PERPENDICULAR MODE
command the eighth byte of the DUMPREG command has been modified to contain the additional data from these
two commands.
COMPATIBILITY
The FDC37N869 was designed with software compatibility in mind. It is a fully backwards-compatible solution
with the older generation 765A/B disk controllers. The FDC also implements on-board registers for compatibility
with the PS/2, as well as PC/AT and PC/XT, floppy disk controller subsystems. After a hardware reset of the FDC,
all registers, functions and enhancements default to a PC/AT, PS/2 or PS/2 Model 30 compatible operating mode,
depending on how the IDENT and MFM bits are configured by the system BIOS.
Parallel Port Floppy Disk Controller
In this mode, the Floppy Disk Control signals are available on the parallel port pins. When this mode is selected,
the parallel port is not available. There are two modes of operation, PPFD1 and PPFD2. These modes can be
selected in Configuration Register 4. PPFD1 has only drive 1 on the parallel port pins; PPFD2 has drive 0 and 1 on
the parallel port pins.
PPFD1: Drive 0 is on the FDC pins
Drive 1 is on the Parallel port pins
PPFD2: Drive 0 is on the Parallel port pins
Drive 1 is on the Parallel port pins
When the PPFDC is selected the following pins are set as follows:
1. nDACK: Assigned to the parallel port device during configuration.
2. PDRQ (assigned to the parallel port): not ECP = high-Z, ECP & dmaEn = 0, ECP & not dmaEn = high-Z
SMSC DS – FDC37N869 Page 57 Rev. 11/09/2000
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3. IRQ assigned to the parallel port: not active, this is hi-Z or Low depending on settings.
The following parallel port pins are read as follows by a read of the parallel port register:
1. Data Register (read) = last Data Register (write)
2. Control Register are read as “cable not connected” STROBE, AUTOFD and SLC = 0 and nINIT = 1;
3. Status Register reads: nBUSY = 0, PE = 0, SLCT = 0, nACK = 1, nERR = 1.
The following FDC pins are all in the high impedance state when the PPFDC is actually selected by the drive select
register:
1. nWDATA, DENSEL, nHDSEL, nWGATE, nDIR, nSTEP, nDS1, nDS0, nMTRO, nMTR1.
2. If PPFDx is selected, then the parallel port can not be used as a parallel port until “Normal” mode is selected.
The FDC signals are muxed onto the Parallel Port pins as shown in Table 46
.
Table 46 - FDC Parallel Port Pins
CONNECTOR
PIN # CHIP PIN # SPP MODE PIN DIRECTION FDC MODE PIN DIRECTION
1 75 nSTB I/O (nDS0) I/(0)
1
2 69 PD0 I/O nINDEX I
3 68 PD1 I/O nTRK0 I
4 67 PD2 I/O nWP I
5 66 PD3 I/O nRDATA I
6 64 PD4 I/O nDSKCHG I
7 63 PD5 I/O
8 62 PD6 I/O (nMTR0) I/(0)
1
9 61 PD7 I/O
10 60 nACK I nDS1 0
11 59 BUSY I nMTR1 0
12 58 PE I nWDATA 0
13 57 SLCT I nWGATE 0
14 74 nAFD I/O nDENSEL 0
15 73 nERR I nHDSEL 0
16 72 nINIT I/O nDIR 0
17 71 nSLIN I/O nSTEP 0
Note1: These pins are outputs in mode PPFD2. Inputs in mode PPFD1
For ACPI compliance the FDD pins that are multiplexed onto the Parallel Port must function independently of the
state of the Parallel Port controller. For example, if the FDC is enabled onto the Parallel Port the multiplexed FDD
Interface should function normally regardless of the Parallel Port Power control CR01.2. Table 47 illustrates this
functionality.
Table 47 - Parallel Port FDD Control
PARALLEL
PORT POWER
PARALLEL PORT FDC
CONTROL
PARALLEL PORT
FDC STATE
PARALLEL
PORT STATE
CR01.2 CR04.3 CR04.2
1 0 0 OFF ON
0 0 0 OFF OFF
X 1 X ON OFF
1
X 1
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Note1: The Parallel Port Control register reads as “Cable Not Connected” when the PP FDC is enabled; i.e.,
STROBE = AUTOFD = SLC = 0 and nINIT = 1
SERIAL PORT (UART)
The FDC37N869 incorporates two full function UARTs. They are compatible with the NS16450, the 16450 ACE
registers and the NS16550A. The UARTs perform serial-to-parallel conversion on received characters and
parallel-to-serial conversion on transmit characters. The data rates are independently programmable from 115.2K
baud down to 50 baud. The character options are programmable for 1 start; 1, 1.5 or 2 stop bits; even, odd, sticky
or no parity; and prioritized interrupts. The UARTs each contain a programmable baud rate generator that is
capable of dividing the input clock or crystal by a number from 1 to 65535. The UARTs are also capable of
supporting the MIDI data rate. Refer to the FDC37N869 Configuration Registers for information on disabling,
powering down and changing the base address of the UARTs. The interrupt from a UART is enabled by
programming OUT2 of that UART to a logic “1”. When OUT2 is a logic “0” the UART Interrupt is disabled.
Register Description
Addressing of the accessible registers of the Serial Port is shown below (Table 48). The base addresses of the
serial ports are defined by the configuration registers (see section CONFIGURATION on page 101. The Serial Port
registers are located at sequentially increasing addresses above these base addresses. The FDC37N869
contains two serial ports, each of which contain a register set as described below.
Table 48 - Addressing the Serial Port
A2 A1 A0 REGISTER NAME
DLAB
1
0 0 0 0 Receive Buffer (read)
0 0 0 0 Transmit Buffer (write)
0 0 0 1 Interrupt Enable (read/write)
X 0 1 0 Interrupt Identification (read)
X 0 1 0 FIFO Control (write)
X 0 1 1 Line Control (read/write)
X 1 0 0 Modem Control (read/write)
X 1 0 1 Line Status (read/write)
X 1 1 0 Modem Status (read/write)
X 1 1 1 Scratchpad (read/write)
1 0 0 0 Divisor LSB (read/write)
1 0 0 1 Divisor MSB (read/write)
Note1: DLAB is Bit 7 of the Line Control Register
RECEIVE BUFFER REGISTER (RB)
The Receive Buffer register (Address Offset = 0H, DLAB = 0, READ ONLY) holds the received incoming data byte.
Bit 0 is the least significant bit, which is transmitted and received first. Received data is double buffered; this uses
an additional shift register to receive the serial data stream and convert it to a parallel 8 bit character which is
transferred to the Receive Buffer register. The shift register is not accessible.
TRANSMIT BUFFER REGISTER (TB)
The Transmit Buffer register (Address Offset = 0H, DLAB = 0, WRITE ONLY) contains the data byte to be
transmitted. The transmit buffer is double buffered, utilizing an additional shift register (not accessible) to convert
the 8 bit data character to a serial format. This shift register is loaded from the Transmit Buffer when the
transmission of the previous byte is complete.
INTERRUPT ENABLE REGISTER (IER)
The lower four bits of the Interrupt Enable register (Address Offset = 1H, DLAB = 0, READ/WRITE) control the
enables of the five interrupt sources of the Serial Port interrupt. It is possible to totally disable the interrupt system
by resetting bits 0 through 3 of this register. Similarly, by setting the appropriate bits of this register to a high
selected interrupts can be enabled. Disabling the interrupt system inhibits the Interrupt Identification Register and
SMSC DS – FDC37N869 Page 59 Rev. 11/09/2000
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disables any Serial Port interrupt out of the FDC37N869. All other system functions operate in their normal
manner, including the Line Status and MODEM Status Registers. The contents of the Interrupt Enable Register are
described below.
ERDAI, Bit 0
The ERDAI bit enables the Received Data Available Interrupt (and time-out interrupts in the FIFO mode) when set
to logic “1”.
ETHREI, Bit 1
The ETHREI bit enables the Transmitter Holding Register Empty Interrupt when set to logic “1”.
ELSI, Bit 2
The ELSI bit enables the Received Line Status Interrupt when set to logic “1”. The error sources causing the
interrupt are Overrun, Parity, Framing and Break. The Line Status Register must be read to determine the source.
EMSI, Bit 3
The EMSI bit enables the MODEM Status Interrupt when set to logic “1”. An MSI is caused when one of the Modem
Status Register bits changes state.
Reserved, Bits 4 - 7
Bits 4 to 7 are RESERVED. Reserved bits cannot be written and return 0 when read.
INTERRUPT IDENTIFICATION REGISTER (IIR)
By accessing the Interrupt Identification register (Address Offset = 2H, DLAB = X, READ), the host CPU can
determine the highest priority interrupt and its source. Four levels of interrupt priority exist. They are in descending
order of priority:
1. Receiver Line Status (highest priority)
2. Received Data Ready
3. Transmitter Holding Register Empty
4. MODEM Status (lowest priority)
Information indicating that a prioritized interrupt is pending and the source of that interrupt is stored in the Interrupt
Identification Register (refer to the Interrupt Control Table,
Table 49). When the CPU accesses the IIR, the Serial Port freezes all interrupts and indicates the highest priority
pending interrupt to the CPU. During this CPU access, even if the Serial Port records new interrupts, the current
indication does not change until access is completed.
Interrupt Pending, Bit 0
The Interrupt Pending bit can be used in either a hardwired prioritized or polled environment to indicate whether an
interrupt is pending. When bit 0 is a logic “0”, an interrupt is pending and the contents of the IIR may be used as a
pointer to the appropriate internal service routine. When bit 0 is a logic “1”, no interrupt is pending.
Interrupt ID, Bits 1 - 2
The Interrupt ID bits of the IIR are used to identify the highest priority interrupt pending as indicated by the Interrupt
Control Table (
Table 49).
Time-Out, Bit 3
In non-FIFO mode, the Time-Out bit is a logic “0”. In FIFO mode the Time-Out bit is set along with bit 2 when a
time-out interrupt is pending.
SMSC DS – FDC37N869 Page 60 Rev. 11/09/2000
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Reserved, Bits 4 - 5
Bits 4 to 5 are RESERVED. Reserved bits cannot be written and return 0 when read.
FIFOs Enabled, Bits 6 - 7
The FIFOs Enabled bits are set when the FIFO CONTROL Register bit 0 equals 1.
Table 49 - Interrupt Control
FIFO
MODE
ONLY
BIT3BIT 2 BIT 1 BIT
INTERRUPT
IDENTIFICATION
REGISTER
INTERRUPT SET AND RESET FUNCTIONS
PRIORITY
0
LEVEL
INTERRUPT
TYPE
INTERRUPT
SOURCE
0 0 0 1 - None None 0 1 1 0 Highest Receiver
Line Status
Overrun Error,
Parity Error,
Framing Error
or Break
Interrupt
0 1 0 0 Second Received
Data
Receiver Data
Available
Available
1 1 0 0 Second Character
Time-out
Indication
No Characters
Have Been
Removed
From or Input
to the RCVR
FIFO during
the last 4
Character
times and
there is at
least 1
character in it
during this
time
0 0 1 0 Third Transmitter
Holding
Register
Empty
0 0 0 0 Fourth MODEM
Status
Transmitter
Holding
Register
Empty
Clear to Send
or Data Set
Ready or Ring
Indicator or
Data Carrier
Detect
INTERRUPT RESET
CONTROL
Reading the Line
Status Register
Read Receiver
Buffer or the FIFO
drops below the
trigger level.
Reading the
Receiver Buffer
Register
Reading the IIR
Register (if Source
of Interrupt) or
Writing the
Transmitter
Holding Register
Reading the
MODEM Status
Register
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FIFO CONTROL REGISTER (FCR)
The FIFO Control register (Address Offset = 2H, DLAB = X, WRITE) appears at the same location as the IIR. This
register is used to enable and clear the FIFOs and set the RCVR FIFO trigger level. Note: DMA is not supported.
FIFO Enable, Bit 0
Setting the FIFO Enable bit to a logic “1” enables both the XMIT and RCVR FIFOs. Clearing this bit to a logic “0”
disables both the XMIT and RCVR FIFOs and clears all bytes from both FIFOs. When changing from FIFO Mode to
non-FIFO (16450) mode, data is automatically cleared from the FIFOs. This bit must be a 1 when other bits in this
register are written to or they will not be properly programmed.
RCVR FIFO Reset, Bit 1
Setting the RCVR FIFO Reset bit to a logic “1” clears all bytes in the RCVR FIFO and resets its counter logic to 0.
The shift register is not cleared. This bit is self-clearing.
XMIT FIFO Reset, Bit 2
Setting the XMIT FIFO Reset bit to a logic “1” clears all bytes in the XMIT FIFO and resets its counter logic to 0. The
shift register is not cleared. This bit is self-clearing.
DMA Mode Select, Bit 3
Writing to the DMA Mode Select bit has no effect on the operation of the UART. The RXRDY and TXRDY pins are
not available on this chip.
Reserved, Bits 4 - 5
Bits 4 to 5 are RESERVED. Reserved bits cannot be written and return 0 when read.
RCVR Trigger, Bits 6 - 7
The RCVR Trigger bits are used to set the trigger level for the RCVR FIFO interrupt (Table 50).
Table 50 - RCVR Trigger Encoding
RCVR
TRIGGER
RCVR FIFO Trigger Level
(BYTES)
Bit 7 Bit 6
0 0 1
0 1 4
1 0 8
1 1 14
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LINE CONTROL REGISTER (LCR)
The Line Control register (Address Offset = 3H, DLAB = 0, READ/WRITE) contains the formatting information for the
serial line.
Word Length Select, Bits 0 - 1
The Word Length Select bits specify the number of bits in each transmitted or received serial character. Note: the
Start, Stop and Parity bits are not included in the word length. The encoding of the Word Length bits is shown in
Table 51.
Table 51 - Word Length Encoding
WORD LENGTH
SELECT WORD LENGTH (Bits)
Bit 1 Bit 0
0 0 5
0 1 6
1 0 7
1 1 8
Stop Bits, Bit 2
The Stop Bits bit specifies the number of stop bits in each transmitted or received serial character. Table 52
describes the Stop Bits encoding.
Table 52 - STOP Bit Encoding
STOP BITS
(Bit 2)
WORD
LENGTH
NUMBER OF
STOP BITS
0 - 1
0 5 Bits 1.5
1 6 Bits 2
1 7 Bits 2
1 8 Bits 2
Note: The receiver ignores stop bits beyond the first, regardless of the number of stop bits used in transmi tting.
Parity Enable, Bit 3
When the Parity Enable bit is a logic “1” a parity bit is generated (transmit data) or checked (receive data) between
the last data word bit and the first stop bit of the serial data. The parity bit is used to generate an even or odd
number of 1s when the data word bits and the parity bit are summed.
Even Parity Select, Bit 4
When the Even Parity Select (EPS) bit is a logic “0” and the Parity Enable is a logic “1”, an odd number of logic “1”’s
is transmitted or checked in the data word and the parity bit. When the Parity Enable is a logic “1” and the EPS bit
is a logic “1” an even number of bits is transmitted and checked.
Stick Parity, Bit 5
When the Stick Parity bit is a logic “1” and the Parity Enable is a logic “1”, the parity bit is transmitted and then
detected by the receiver in the opposite state indicated by the EPS bit.
Set Break, Bit 6
When the Set Break Control bit is a logic “1”, the transmit data output (TXD) is forced to the Spacing or logic “0”
state and remains there until reset by a low level bit 6, regardless of other transmitter activity. This feature enables
the Serial Port to alert a terminal in a communications system.
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DLAB, Bit 7
The Divisor Latch Access Bit must be set high (logic “1”) to access the Divisor Latches of the Baud Rate Generator
during read or write operations. It must be set low (logic “0”) to access the Receiver Buffer Register, the
Transmitter Holding Register, or the Interrupt Enable Register.
MODEM CONTROL REGISTER (MCR)
The Modem Control register (Address Offset = 4H, DLAB = X, READ/WRITE) manages the interface for the MODEM,
data set, or device emulating a MODEM.
Data Terminal Ready, Bit 0
The Data Terminal Ready bit controls the Data Terminal Ready (nDTR) output. When bit 0 is set to a logic “1”,
the nDTR output is forced to a logic “0”. When bit 0 is a logic “0”, the nDTR output is forced to a logic “1”.
Request To Send, Bit 1
The Request To Send bit controls the Request To Send (nRTS) output. . When bit 1 is set to a logic “1”, the
nRTS output is forced to a logic “0”. When bit 1 is a logic “0”, the nRTS output is forced to a logic “1”.
OUT1, Bit 2
The OUT1 bit controls the Output 1 (OUT1) bit. This bit does not have an output pin and can only be read or written
by the CPU.
OUT2, Bit 3
The OUT2 bit is used to enable the UART interrupt. When OUT2 is a logic “0”, the serial port interrupt output is
forced to a high impedance state; i.e, disabled. When OUT2 is a logic “1”, the serial port interrupt outputs are
enabled.
Loop, Bit 4
The Loop bit provides the loopback feature for diagnostic testing of the Serial Port. When bit 4 is set to logic “1”,
the following occurs:
1. The TXD is set to the Marking State (logic “1”).
2. The receiver Serial Input (RXD) is disconnected.
3. The output of the Transmitter Shift Register is “looped back” into the Receiver Shift Register input.
4. All MODEM Control inputs (nCTS, nDSR, nRI and nDCD) are disconnected.
5. The four MODEM Control outputs (nDTR, nRTS, OUT1 and OUT2) are internally connected to the four
MODEM Control inputs (nDSR, nCTS, RI and DCD) respectively.
6. The Modem Control output pins are forced inactive.
7. Data that is transmitted is immediately received.
The Loopback feature allows the processor to verify the transmit and receive data paths of the Serial Port. The
receiver and the transmitter interrupts are fully operational in loopback mode. The MODEM Control Interrupts are
also operational but the interrupts’ sources are now the lower four bits of the MODEM Control Register instead of
the MODEM Control inputs. The interrupts are still controlled by the Interrupt Enable Register.
Reserved, Bits 5 - 7
Bits 5 to 7 are RESERVED. Reserved bits cannot be written and return 0 when read.
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LINE STATUS REGISTER (LSR)
Address Offset = 5H, DLAB = X, READ/WRITE
Data Ready, Bit 0
Data Ready (DR) is set to a logic “1” whenever a complete received data character has been transferred into the
Receiver Buffer Register or the FIFO. DR is reset to a logic “0” by reading all of the data in the Receive Buffer
Register or the FIFO.
Overrun Error, Bit 1
The Overrun Error (OE) bit indicates that data in the Receiver Buffer Register was not read before the next
character was transferred into the register, thereby destroying the previous character. In FIFO mode, an overrun
error will occur only when the FIFO is full and the next character has been completely received in the shift register:
the character in the shift register is overwritten but not transferred to the FIFO. The OE indicator is set to a logic “1”
immediately upon detection of an overrun condition and reset whenever the Line Status Register is read.
Parity Error, Bit 2
The Parity Error (PE) bit indicates that the received data character does not have the correct even or odd parity, as
selected by the even parity select bit. The PE is set to a logic “1” upon detection of a parity error and is reset to a
logic “0” whenever the Line Status Register is read. In the FIFO mode this error is associated with the particular
character in the FIFO it applies to. This error is indicated when the associated character is at the top of the FIFO.
Framing Error, Bit 3
The Framing Error (FE) bit indicates that the received character did not have a valid stop bit. Bit 3 is set to a logic
“1” whenever the stop bit following the last data bit or parity bit is detected as a zero bit (Spacing level). The FE is
reset to a logic “0” whenever the Line Status Register is read. In the FIFO mode this error is associated with the
particular character in the FIFO it applies to. This error is indicated when the associated character is at the top of
the FIFO. The Serial Port will try to resynchronize after a framing error. To do this, it assumes that the framing error
was due to the next start bit, so it samples this ‘start’ bit twice and then takes in the ‘data’.
Break Interrupt, Bit 4
The Break Interrupt (BI) bit is set to a logic “1” whenever the received data input is held in the Spacing state (logic
“0”) for longer than a full word transmission time (that is, the total time of the start bit + data bits + parity bits + stop
bits). The BI is reset after the CPU reads the contents of the Line Status Register. In the FIFO mode this error is
associated with the particular character in the FIFO it applies to. This error is indicated when the associated
character is at the top of the FIFO. When break occurs only one zero character is loaded into the FIFO. Restarting
after a break is received requires the serial data (RXD) to be logic “1” for at least ½ bit time.
Note: LSR Bits 1 through 4 produce a Receiver Line Status Interrupt whenever any of the corresponding conditions
are detected and the interrupt is enabled.
Transmitter Holding Register Empty, Bit 5
The Transmitter Holding Register Empty (THRE) bit indicates that the Serial Port is ready to accept a new character
for transmission. In addition, this bit causes the Serial Port to issue an interrupt when the Transmitter Holding
Register interrupt enable is set high. The THRE bit is set to a logic “1” when a character is transferred from the
Transmitter Holding Register into the Transmitter Shift Register. The bit is reset to logic “0” whenever the CPU
loads the Transmitter Holding Register. In the FIFO mode this bit is set when the XMIT FIFO is empty, it is cleared
when at least 1 byte is written to the XMIT FIFO. Bit 5 is read-only.
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Transmitter Empty, Bit 6
The Transmitter Empty (TEMT) bit is set to a logic “1” whenever the Transmitter Holding Register (THR) and
Transmitter Shift Register (TSR) are both empty. It is reset to logic “0” whenever either the THR or TSR contains a
data character. Bit 6 is read-only. In the FIFO mode this bit is set whenever the THR and TSR are both empty.
RCVR FIFO Error, Bit 7
The RCVR FIFO Error bit is permanently set to logic “0” in the 450 mode. In the FIFO mode this bit is set to a logic
“1” when there is at least one parity error, framing error or break indication in the FIFO. This bit is cleared when the
LSR is read if there are no subsequent errors in the FIFO.
MODEM STATUS REGISTER (MSR)
The Modem Status register (Address Offset = 6H, DLAB = X, READ/WRITE) provides the current state of the control
lines from the MODEM or peripheral device. In addition to this current state information, four bits of the MODEM
Status Register provide state change information. These four bits are set to logic “1” whenever a control input
from the MODEM changes state. They are reset to logic “0” whenever the MODEM Status Register is read.
Delta Clear To Send, Bit 0
The Delta Clear To Send (DCTS) bit indicates that the nCTS input to the chip has changed state since the last
time the MSR was read.
Delta Data Set Ready, Bit 1
The Delta Data Set Ready (DDSR) bit indicates that the nDSR input has changed state since the last time the MSR
was read.
Trailing Edge Of Ring Indicator, Bit 2
The Trailing Edge of Ring Indicator (TERI) bit indicates that the nRI input has changed from logic “0” to logic “1”.
Delta Data Carrier Detect, Bit 3
The Delta Data Carrier Detect (DDCD) bit indicates that the nDCD input to the chip has changed state.
Note: Whenever bits 0, 1, 2, or 3 are set to a logic “1”, a MODEM Status Interrupt is generated.
Clear To Send, Bit 4
The Clear To Send bit is the complement of the Clear To Send input (nCTS). If the Loop bit of the MCR is set to
logic “1”, this bit is equivalent to nRTS in the MCR.
Data Set Ready, Bit 5
The Data Set Ready bit is the complement of the Data Set Ready input (nDSR). If the Loop bit of the MCR is set to
logic “1”, this bit is equivalent to DTR in the MCR.
Ring Indicator, Bit 6
The Ring Indicator bit is the complement of the Ring Indicator input (nRI). If the Loop bit of the MCR is set to logic
“1”, this bit is equivalent to OUT1 in the MCR.
Data Carrier Detect, Bit 7
The Data Carrier Detect bit is the complement of the Data Carrier Detect input (nDCD). If the Loop bit of the MCR is
set to logic “1”, this bit is equivalent to OUT2 in the MCR.
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SCRATCHPAD REGISTER (SCR)
The Scratchpad register (Address Offset =7H, DLAB =X, READ/WRITE) has no effect on the operation of the Serial
Port. It is intended as a scratchpad register to be used by the programmer to hold data temporarily.
PROGRAMMABLE BAUD RATE GENERATOR DIVISOR LATCHES
The internal Baud Rate Generator (BRG) using the Programmable Baud Rate Generator Divisor Latches DDL and
DDM (Address Offset = 0 and 1, DLAB = 1, READ/WRITE) is capable of taking any clock input (DC to 3 MHz) and
dividing it by any divisor from 1 to 65535. The Baud Rate Generator output is 16x the baud rate. Two 8-bit latches
store the divisor in 16-bit binary format. These Divisor Latches must be loaded during initialization in order to
insure desired operation of the Baud Rate Generator. Upon loading either of the Divisor Latches, a 16 bit Baud
counter is immediately loaded. This prevents long counts on initial load. If a 0 is loaded into the DDL and DDM
registers the BRG clock is divided by 3. If a 1 is loaded the output is the inverse of the input oscillator. If a two is
loaded the clock is divided by 2 with a 50% duty cycle. If a 3 or greater is loaded the output is low for 2 bits and
high for the remainder of the count. The input clock to the BRG is a 1.8462 MHz clock.
Table 53 shows the baud rates possible with a 1.8462 MHz clock.
Table 53 - Baud Rates Using 1.8462 MHz Clock
DIVISOR USED TO
DESIRED
BAUD RATE
GENERATE 16X
CLOCK
PERCENT ERROR DIFFERENCE
BETWEEN DESIRED AND ACTUAL*
CROC:
BIT 7 OR 6
50 2307 0.03 X
75 1538 0.03 X
110 1049 0.005 X
134.5 858 0.01 X
150 769 0.03 X
300 384 0.16 X
600 192 0.16 X
1200 96 0.16 X
1800 64 0.16 X
2000 58 0.5 X
2400 48 0.16 X
3600 32 0.16 X
4800 24 0.16 X
7200 16 0.16 X
9600 12 0.16 X
19200 6 0.16 X
38400 3 0.16 X
57600 2 1.6 X
115200 1 0.16 X
230400 32770 0.16 1
460800 32769 0.16 1
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The Affects of RESET on the UART Registers
The RESET Function (Table 54) details the affects of RESET on each of the Serial Port registers.
Table 54 - RESET Function
REGISTER/SIGNAL RESET CONTROL RESET STATE
Interrupt Enable Register RESET All bits low
Interrupt Identification Reg. RESET Bit 0 is high; Bits 1 - 7 low
FIFO Control RESET All bits low
Line Control Reg. RESET All bits low
MODEM Control Reg. RESET All bits low
Line Status Reg. RESET All bits low except 5 - 6 high
MODEM Status Reg. RESET Bits 0 - 3 low; Bits 4 - 7 input
TXD1, TXD2 RESET High
INTRPT (RCVR errs) RESET/Read LSR Low
INTRPT (RCVR Data Ready) RESET/Read RBR Low
INTRPT (THRE) RESET/ReadIIR/Write THR Low
OUT2B RESET High
RTSB RESET High
DTRB RESET High
OUT1B RESET High
RCVR FIFO RESET/FCR1*FCR0/_FCR0 All bits low
XMIT FIFO RESET/FCR1*FCR0/_FCR0 All bits low
FIFO Interrupt Mode Operation
When the RCVR FIFO and receiver interrupts are enabled (FCR bit 0 = “1”, IER bit 0 = “1”), RCVR interrupts occur
as follows:
1. The receive data available interrupt will be issued when the FIFO has reached its programmed trigger
level; it is cleared as soon as the FIFO drops below its programmed trigger level.
2. The IIR receive data available indication also occurs when the FIFO trigger level is reached. It is
cleared when the FIFO drops below the trigger level.
3. The receiver line status interrupt (IIR=06H), has higher priority than the received data available
(IIR=04H) interrupt.
4. The data ready bit (LSR bit 0)is set as soon as a character is transferred from the shift register to the
RCVR FIFO. It is reset when the FIFO is empty.
When RCVR FIFO and receiver interrupts are enabled, RCVR FIFO time-out interrupts occur as follows:
1. A FIFO time-out interrupt occurs if all the following conditions exist:
• at least one character is in the FIFO
• The most recent serial character received was longer than 4 continuous character times ago. (If
2 stop bits are programmed, the second one is included in this time delay.)
• The most recent CPU read of the FIFO was longer than 4 continuous character times ago.
2. This will cause a maximum character received to interrupt issued delay of 160 msec at 300 BAUD
with a 12 bit character.
3. Character times are calculated by using the RCLK input for a clock signal (this makes the delay
proportional to the baud rate).
4. When a time-out interrupt has occurred it is cleared and the timer reset when the CPU reads one
character from the RCVR FIFO.
5. When a time-out interrupt has not occurred the time-out timer is reset after a new character is
received or after the CPU reads the RCVR FIFO.
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When the XMIT FIFO and transmitter interrupts are enabled (FCR bit 0 = “1”, IER bit 1 = “1”), XMIT interrupts occur
as follows:
1. The transmitter holding register interrupt (02H) occurs when the XMIT FIFO is empty; it is cleared as
soon as the transmitter holding register is written to (1 of 16 characters may be written to the XMIT
FIFO while servicing this interrupt) or the IIR is read.
2. The transmitter FIFO empty indications will be delayed 1 character time minus the last stop bit time
whenever the following occurs: THRE=1 and there have not been at least two bytes at the same time
in the transmit FIFO since the last THRE=1. The transmitter interrupt after changing FCR0 will be
immediate, if it is enabled.
Character time-out and RCVR FIFO trigger level interrupts have the same priority as the current received data
available interrupt; XMIT FIFO empty has the same priority as the current transmitter holding register empty
interrupt.
FIFO Polled Mode Operation
With FCR bit 0 = “1” resetting IER bits 0, 1, 2 or 3 or all to zero puts the UART in the FIFO Polled Mode of operation.
Since the RCVR and XMITTER are controlled separately, either one or both can be in the polled mode of operation.
In this mode, the user’s program will check RCVR and XMITTER status via the LSR. LSR definitions for the FIFO
Polled Mode are as follows:
1. Bit 0=1 as long as there is one byte in the RCVR FIFO.
2. Bits 1 to 4 specify which error(s) have occurred. Character error status is handled the same way as
when in the interrupt mode, the IIR is not affected since EIR bit 2=0.
3. Bit 5 indicates when the XMIT FIFO is empty.
4. Bit 6 indicates that both the XMIT FIFO and shift register are empty.
5. Bit 7 indicates whether there are any errors in the RCVR FIFO.
There is no trigger level reached or time-out condition indicated in the FIFO Polled Mode, however, the RCVR and
XMIT FIFOs are still fully capable of holding characters.
Table 55 - Individual UART Channel Register Summary
REGISTER
ADDRESS* REGISTER NAME
ADDR = 0
DLAB = 0
ADDR = 0
DLAB = 0
ADDR = 1
Receive Buffer Register
(Read Only)
Transmitter Holding
Register (Write Only)
Interrupt Enable Register IER Enable Received Data
DLAB = 0
ADDR = 2 Interrupt Ident. Register
REGISTER
SYMBOL BIT 0 BIT 1
RBR Data Bit 0 (Note 1) Data Bit 1
THR Data Bit 0 Data Bit 1
Enable Transmitter
Available Interrupt
(ERDAI)
Holding Register Empty
Interrupt (ETHREI)
IIR ”0” if Interrupt Pending Interrupt ID Bit
(Read Only)
ADDR = 2 FIFO Control Register
FCR FIFO Enable RCVR FIFO Reset
(Write Only)
ADDR = 3 Line Control Register LCR
ADDR = 4 MODEM Control Register MCR Data Terminal Ready
Word Length Select Bit 0
(WLS0)
Word Length Select Bit 1
(WLS1)
Request to Send (RTS)
(DTR)
ADDR = 5
Line Status Register LSR
ADDR = 6 MODEM Status Register MSR
ADDR = 7
ADDR = 0
Scratch Register (Note 4) SCR Bit 0 Bit 1
Divisor Latch (LS) DDL Bit 0 Bit 1
Data Ready (DR)
Delta Clear to Send
(DCTS)
Overrun Error (OE)
Delta Data Set Ready
(DDSR)
DLAB = 1
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REGISTER
ADDRESS* REGISTER NAME
ADDR = 1
Divisor Latch (MS) DLM Bit 8 Bit 9
REGISTER
SYMBOL BIT 0 BIT 1
DLAB = 1
*DLAB is Bit 7 of the Line Control Register (ADDR = 3).
Note 1: Bit 0 is the least significant bit. It is the first bit serially transmitted or received.
Note 2: When operating in the XT mode, this bit will be set any time that the transmitter shift register is empty.
Table 56 - Individual UART Channel Register Summary Continued
BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7
Data Bit 2
Data Bit 2
Enable
Receiver Line
Status
Interrupt
(ELSI)
Interrupt ID Bit Interrupt ID Bit
XMIT FIFO
Reset
Data Bit 3 Data Bit 4 Data Bit 5 Data Bit 6 Data Bit 7
Data Bit 3 Data Bit 4 Data Bit 5 Data Bit 6 Data Bit 7
Enable
0 0 0 0
MODEM
Status
Interrupt
(EMSI)
FIFOs
Enabled
(Note 5)
RCVR
Trigger MSB
(Note 5)
DMA Mode
Select (Note
0 0 FIFOs
Enabled (Note
5)
Reserved Reserved RCVR Trigger
LSB
6)
Number of
Stop Bits
(STB)
OUT1
(Note 3)
Parity Error
(PE)
Parity Enable
(PEN)
OUT2
(Note 3)
Framing Error
(FE)
Even Parity
Stick Parity Set Break
Select
(EPS)
Loop 0 0 0
Break
Interrupt (BI)
Transmitte
r Holding
Register
Transmitter
Empty (TEMT)
(Note 2)
Divisor Latch
Access Bit
(DLAB)
Error in
RCVR FIFO
(Note 5)
(THRE)
Trailing Edge
Ring Indicator
(TERI)
Bit 2
Bit 2
Bit 10
Delta Data
Carrier Detect
(DDCD)
Clear to
Send (CTS)
Data Set
Ready
(DSR)
Ring Indicator
(RI)
Bit 3 Bit 4 Bit 5 Bit 6 Bit 7
Bit 3 Bit 4 Bit 5 Bit 6 Bit 7
Bit 11 Bit 12 Bit 13 Bit 14 Bit 15
Data Carrier
Detect (DCD)
Note 3: This bit no longer has a pin associated with it.
Note 4: When operating in the XT mode, this register is not available.
Note 5: These bits are always zero in the non-FIFO mode.
Note 6: Writing a one to this bit has no effect. DMA modes are not supported in this chip.
Notes On Serial Port FIFO Mode Operation
GENERAL
The RCVR FIFO will hold up to 16 bytes regardless of which trigger level is selected.
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TX AND RX FIFO OPERATION
The Tx portion of the UART transmits data through TXD as soon as the CPU loads a byte into the Tx FIFO. The
UART will prevent loads to the Tx FIFO if it currently holds 16 characters. Loading to the Tx FIFO will again be
enabled as soon as the next character is transferred to the Tx shift register. These capabilities account for the
largely autonomous operation of the Tx.
The UART starts the above operations typically with a Tx interrupt. The chip issues a Tx interrupt whenever the Tx
FIFO is empty and the Tx interrupt is enabled, except in the following instance. Assume that the Tx FIFO is empty
and the CPU starts to load it. When the first byte enters the FIFO the Tx FIFO empty interrupt will transition from
active to inactive. Depending on the execution speed of the service routine software, the UART may be able to
transfer this byte from the FIFO to the shift register before the CPU loads another byte. If this happens, the Tx FIFO
will be empty again and typically the UART’s interrupt line would transition to the active state. This could cause a
system with an interrupt control unit to record a Tx FIFO empty condition, even though the CPU is currently servicing
that interrupt. Therefore, after the first byte has been loaded into the FIFO the UART will wait one serial
character transmission time before issuing a new Tx FIFO empty interrupt. This one character Tx interrupt
delay will remain active until at least two bytes have been loaded into the FIFO, concurrently. When the Tx FIFO
empties after this condition, the Tx interrupt will be activated without a one character delay.
Rx support functions and operation are quite different from those described for the transmitter. The Rx FIFO
receives data until the number of bytes in the FIFO equals the selected interrupt trigger level. At that time if Rx
interrupts are enabled, the UART will issue an interrupt to the CPU. The Rx FIFO will continue to store bytes until it
holds 16 of them. It will not accept any more data when it is full. Any more data entering the Rx shift register will
set the Overrun Error flag. Normally, the FIFO depth and the programmable trigger levels will give the CPU ample
time to empty the Rx FIFO before an overrun occurs.
One side-effect of having a Rx FIFO is that the selected interrupt trigger level may be above the data level in the
FIFO. This could occur when data at the end of the block contains fewer bytes than the trigger level. No interrupt
would be issued to the CPU and the data would remain in the UART. To prevent the software from having to
check for this situation the chip incorporates a time-out interrupt.
The time-out interrupt is activated when there is a least one byte in the Rx FIFO, and neither the CPU nor the Rx
shift register has accessed the Rx FIFO within 4 character times of the last byte. The time-out interrupt is cleared
or reset when the CPU reads the Rx FIFO or another character enters it.
These FIFO related features allow optimization of CPU/UART transactions and are especially useful given the
higher baud rate capability (256K baud).
INFRARED INTERFACE
The FDC37N869 infrared interface provides a two-way wireless communications port using infrared as the
transmission medium. Several infrared protocols have been provided in this implementation including IrDA v1.1
(SIR/FIR), ASKIR, and Consumer IR (Figure 3). For more information consult the SMSC Infrared Communication
Controller (IRCC) specification.
The IrDA v1.0 (SIR) and ASKIR formats are driven by the ACE registers found in UART2. The UART2 registers are
described in section
SERIAL PORT (UART) starting on page 59. The base address for UART2 is programmed in CR25, the UART2
Base Address Register (see section CR25 on page 116).
The IrDA V1.2 (FIR) and Consumer IR formats are driven by the SCE registers. Descriptions of these registers can
be found in the SMSC Infrared Communications Controller Specification. The Base Address for the SCE registers
is programmed in CR2B, the SCE Base Address Register (see section CR28 on page 117).
IrDA SIR/FIR and ASKIR
IrDA SIR (v1.0) specifies asynchronous serial communication at baud rates up to 115.2Kbps. Each byte is sent
serially LSB first beginning with a zero value start bit. A zero is signaled by sending a single infrared pulse at the
SMSC DS – FDC37N869 Page 71 Rev. 11/09/2000
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beginning of the serial bit time. A one is signaled by the absence of an infrared pulse during the bit time. Please
refer to section AC TIMING for the parameters of these pulses and the IrDA waveforms.
IrDA FIR (v1.2) includes IrDA v1.0 SIR and additionally specifies synchronous serial communications at data rates
up to 4Mbps.
Data is transferred LSB first in packets that can be up to 2048 bits in length. IrDA v1.2 includes .576Mbps and
1.152Mbps data rates using an encoding scheme that is similar to SIR. The 4Mbps data rate uses a pulse
position modulation (PPM) technique.
The ASKIR infrared allows asynchronous serial communication at baud rates up to 19.2Kbps. Each byte is sent
serially LSB first beginning with a zero value start bit. A zero is signaled by sending a 500KHz carrier waveform for
the duration of the serial bit time. A one is signaled by the absence of carrier during the bit time. Please refer to
section AC TIMING for the parameters of the ASKIR waveforms.
Consumer IR
The FDC37N869 Consumer IR interface is a general-purpose Amplitude Shift Keyed encoder/decoder with
programmable carrier and bit-cell rates that can emulate many popular TV Remote encoding formats; including,
38KHz PPM, PWM and RC-5. The carrier frequency is programmable from 1.6MHz to 6.25KHz. The bit-cell rate
range is 100KHz to 390Hz.
Hardware Interface
The FDC37N869 IR hardware interface is shown in Figure 3. This interface supports two types of external FIR
transceiver modules. One uses a mode pin (IR Mode) to program the data rate, while the other has a second Rx
data pin (IRR3). The FDC37N869 uses Pin 21 for these functions. Pin 21 has IR Mode and IRR3 as its first and
second alternate function, respectively. These functions are selected through CR29 as shown in
Table 57.
Table 57 - FIR Transceiver Module-Type Select
HP MODE
1
FUNCTION
0 IR Mode
1 IRR3
Note1: HPMODE is CR29, BIT 4 (see section CR29 on page 118). Refer to the Infrared Interface Block Diagram on
the following page for HPMODE implementation.
The FAST bit is used to select between the SIR mode and FIR mode receiver, regardless of the transceiver type. If
FAST = 1, the FIR mode receiver is selected; if FAST = 0, the SIR mode receiver is selected (Table 58).
Table 58 - IR Rx Data Pin Selection
CONTROL SIGNALS INPUTS
FAST HPMODE RX1 RX2
0 X RX1=RXD2 RX2=IRRX2
X 0 RX1=RXD2 RX2=IRRX2
1 1 RX1=IR Mode/IRR3 RX2=IR Mode/IRR3
IR Half Duplex Turnaround Delay Time
If the Half Duplex option is chosen there is an IR Half Duplex Time-out that constrains IRCC direction mode
changes. This time-out starts as each bit is transferred and prevents direction mode changes until the time-out
expires. The timer is restarted whenever new data arrives in the current direction mode. For example, if data is
loaded into the transmit buffer while a character is being received, the transmission will not start until the last bit
has been received and the time-out expires. If the start bit of another character is received during this time-out, the
timer is restarted after the new character is received. The Half Duplex Time-out is programmable from 0 to 25.5ms
in 100µs increments (see section CR2D on page 115).
SMSC DS – FDC37N869 Page 72 Rev. 11/09/2000
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IrCC Block
RXD2
IRTX2
IRRX2
TXD2
IR Mode
/IRR3
RAW
TV
ASK
IrDA
FIR
COM
TX1
COM
RX1
0
1
1
TX2
OUT
MUX
IR
RX2
1
2
0
TX3
AUX
G.P. Data
Fast Bit
RX3
IR MODE
FAST
FIGURE 3 - INFRARED INTERFACE BLOCK DIAGRAM
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PARALLEL PORT
The FDC37N869 incorporates an IBM XT/AT compatible parallel port. The FDC37N869 supports the optional PS/2
type bi-directional parallel port (SPP), the Enhanced Parallel Port (EPP) and the Extended Capabilities Port (ECP)
parallel port modes. Refer to the FDC37N869 Configuration Registers and the following hardware configuration
description for information on disabling, powering down, changing the base address, and selecting the mode of
operation of the parallel port.
The FDC37N869 also incorporates SMSC’s ChiProtect circuitry, which prevents possible damage to the parallel
port due to printer power-up.
The functionality of the Parallel Port is achieved through the use of eight addressable ports, with their associated
registers and control gating. The control and data port are read/write by the CPU, the status port is read/write in the
EPP mode. The address map and bit encoding of the Parallel Port registers is shown in Table 59; the Parallel
Port Connector is shown in Table 63.
Table 59 - Parallel Port Registers
BASE
ADDRESS
DATA PORT
STATUS PORT
1
1
CONTROL PORT
EPP ADDR
2,3
PORT
EPP DATA PORT
2,3
0
EPP DATA PORT
2,3
1
EPP DATA PORT
2,3
2
EPP DATA PORT
2,3
3
OFFSET D0 D1 D2 D3 D4 D5 D6 D7
00H PD0 PD1 PD2 PD3 PD4 PD5 PD6 PD7
01H TMOUT 0 0 nERR SLCT PE nACK nBUSY
1
02H STROBE AUTOFD nINIT SLC IRQE PCD 0 0
03H PD0 PD1 PD2 PD3 PD4 PD5 PD6 AD7
04H PD0 PD1 PD2 PD3 PD4 PD5 PD6 PD7
05H PD0 PD1 PD2 PD3 PD4 PD5 PD6 PD7
06H PD0 PD1 PD2 PD3 PD4 PD5 PD6 PD7
07H PD0 PD1 PD2 PD3 PD4 PD5 PD6 PD7
Note1: These registers are available in all modes.
Note2: These registers are only available in EPP mode.
Note3: For EPP mode, IOCHRDY must be connected to the ISA bus.
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Table 60 - Parallel Port Connector
HOST
CONNECTOR PIN NUMBER STANDARD EPP ECP
1 75 nStrobe nWrite nStrobe
2-9 69-66, 64-61 PData<0:7> PData<0:7> PData<0:7>
10 60 nAck Intr nAck
11 59 Busy nWait Busy, PeriphAck(3)
12 58 PE (NU) PError,
nAckReverse(3)
13 57 Select (NU) Select
14 74 nAutofd nDatastb nAutoFd,
HostAck(3)
15 73 nError (NU) nFault(1)
nPeriphRequest(3)
16 72 nInit (NU) nInit(1)
nReverseRqst(3)
17 71 nSelectin nAddrstrb nSelectIn(1,3)
(1) = Compatible Mode
(3) = High Speed Mode
Note: For the cable interconnection required for ECP support and the Slave Connector pin numbers, refer to the
IEEE 1284 Extended Capabilities Port Protocol and ISA Standard, Rev. 1.09, Jan. 7, 1993. This document is
available from Microsoft.
IBM XT/AT COMPATIBLE, BI-DIRECTIONAL AND EPP MODES
DATA PORT
ADDRESS OFFSET = 00H
The Data Port is located at an offset of ‘00H’ from the base address. The data register is cleared at initialization by
RESET. During a WRITE operation, the Data Register latches the contents of the data bus with the rising edge of
the nIOW input. The contents of this register are buffered (non inverting) and output onto the PD0 - PD7 ports.
During a READ operation in SPP mode, PD0 - PD7 ports are buffered (not latched) and output to the host CPU.
STATUS PORT
ADDRESS OFFSET = 01H
The Status Port is located at an offset of ‘01H’ from the base address. The contents of this register are latched for
the duration of an nIOR read cycle. The bits of the Status Port are defined as follows:
BIT 0 TMOUT - TIME OUT
This bit is valid in EPP mode only and indicates that a 10 usec time out has occurred on the EPP bus. A logic “0”
means that no time out error has occurred; a logic “1” means that a time out error has been detected. This bit is
cleared by a RESET. Writing a one to this bit clears the time out status bit. On a write, this bit is self clearing and
does not require a write of a zero. Writing a zero to this bit has no effect.
BITS 1, 2 - are not implemented as register bits, during a read of the Printer Status Register these bits are a low
level.
BIT 3 nERR - nERROR
The level on the nERROR input is read by the CPU as bit 3 of the Printer Status Register. A logic “0” means an
error has been detected; a logic “1” means no error has been detected.
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BIT 4 SLCT - PRINTER SELECTED STATUS
The level on the SLCT input is read by the CPU as bit 4 of the Printer Status Register. A logic “1” means the printer
is on line; a logic “0” means it is not selected.
BIT 5 PE - PAPER END
The level on the PE input is read by the CPU as bit 5 of the Printer Status Register. A logic “1” indicates a paper
end; a logic “0” indicates the presence of paper.
BIT 6 nACK - nACKNOWLEDGE
The level on the nACK input is read by the CPU as bit 6 of the Printer Status Register. A logic 0 means that the
printer has received a character and can now accept another. A logic “1” means that it is still processing the last
character or has not received the data.
BIT 7 nBUSY - nBUSY
The complement of the level on the nBUSY input is read by the CPU as bit 7 of the Printer Status Register. A logic
0 in this bit means that the printer is busy and cannot accept a new character. A logic “1” means that it is ready to
accept the next character.
CONTROL PORT
ADDRESS OFFSET = 02H
The Control Port is located at an offset of ‘02H’ from the base address. The Control Register is initialized by the
RESET input, bits 0 to 5 only being affected; bits 6 and 7 are hard wired low.
BIT 0 STROBE - STROBE
This bit is inverted and output onto the nSTROBE output.
BIT 1 AUTOFD – AUTOFEED
This bit is inverted and output onto the nAUTOFD output. A logic “1” causes the printer to generate a line feed
after each line is printed. A logic 0 means no autofeed.
BIT 2 nINIT - nINITIATE OUTPUT
This bit is output onto the nINIT output without inversion.
BIT 3 SLCTIN - PRINTER SELECT INPUT
This bit is inverted and output onto the nSLCTIN output. A logic “1” on this bit selects the printer; a logic “0” means
the printer is not selected.
BIT 4 IRQE - INTERRUPT REQUEST ENABLE
The interrupt request enable bit when set to a high level may be used to enable interrupt requests from the Parallel
Port to the CPU. An interrupt request is generated on the IRQ port by a positive going nACK input. When the
IRQE bit is programmed low the IRQ is disabled.
BIT 5 PCD - PARALLEL CONTROL DIRECTION
Parallel Control Direction is valid in extended mode only (CR#1<3>=0). In printer mode, the direction is always out
regardless of the state of this bit. In bi-directional mode, a logic “0” means that the printer port is in output mode
(write); a logic “1” means that the printer port is in input mode (read).
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Bits 6 and 7 during a read are a low level, and cannot be written.
EPP ADDRESS PORT
ADDRESS OFFSET = 03H
The EPP Address Port is located at an offset of ‘03H’ from the base address. The address register is cleared at
initialization by RESET. During a WRITE operation, the contents of DB0-DB7 are buffered (non inverting) and
output onto the PD0 - PD7 ports, the leading edge of nIOW causes an EPP ADDRESS WRITE cycle to be
performed, the trailing edge of IOW latches the data for the duration of the EPP write cycle. During a READ
operation, PD0 - PD7 ports are read, the leading edge of IOR causes an EPP ADDRESS READ cycle to be
performed and the data output to the host CPU, the deassertion of ADDRSTB latches the PData for the duration of
the IOR cycle. This register is only available in EPP mode.
EPP DATA PORT 0
ADDRESS OFFSET = 04H
The EPP Data Port 0 is located at an offset of ‘04H’ from the base address. The data register is cleared at
initialization by RESET. During a WRITE operation, the contents of DB0-DB7 are buffered (non inverting) and
output onto the PD0 - PD7 ports, the leading edge of nIOW causes an EPP DATA WRITE cycle to be performed, the
trailing edge of IOW latches the data for the duration of the EPP write cycle. During a READ operation, PD0 - PD7
ports are read, the leading edge of IOR causes an EPP READ cycle to be performed and the data output to the host
CPU, the deassertion of DATASTB latches the PData for the duration of the IOR cycle. This register is only
available in EPP mode.
EPP DATA PORT 1
ADDRESS OFFSET = 05H
The EPP Data Port 1 is located at an offset of ‘05H’ from the base address. Refer to EPP DATA PORT 0 for a
description of operation. This register is only available in EPP mode.
EPP DATA PORT 2
ADDRESS OFFSET = 06H
The EPP Data Port 2 is located at an offset of ‘06H’ from the base address. Refer to EPP DATA PORT 0 for a
description of operation. This register is only available in EPP mode.
EPP DATA PORT 3
ADDRESS OFFSET = 07H
The EPP Data Port 3 is located at an offset of ‘07H’ from the base address. Refer to EPP DATA PORT 0 for a
description of operation. This register is only available in EPP mode.
EPP 1.9 OPERATION
When the EPP mode is selected in the configuration register, the standard and bi-directional modes are also
available. If no EPP Read, Write or Address cycle is currently executing, then the PDx bus is in the standard or bidirectional mode, and all output signals (STROBE, AUTOFD, INIT) are as set by the SPP Control Port and direction
is controlled by PCD of the Control port.
In EPP mode, the system timing is closely coupled to the EPP timing. For this reason, a watchdog timer is
required to prevent system lockup. The timer indicates if more than 10µsec have elapsed from the start of the EPP
cycle (nIOR or nIOW asserted) to nWAIT being deasserted (after command). If a time-out occurs, the current EPP
cycle is aborted and the time-out condition is indicated in Status bit 0.
During an EPP cycle, if STROBE is active, it overrides the EPP write signal forcing the PDx bus to always be in a
write mode and the nWRITE signal to always be asserted.
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Software Constraints
Before an EPP cycle is executed, the software must ensure that the control register bit PCD is a logic “0” (i.e. a 04H
or 05H should be written to the Control port). If the user leaves PCD as a logic “1”, and attempts to perform an
EPP write, the chip is unable to perform the write (because PCD is a logic “1”) and will appear to perform an EPP
read on the parallel bus, no error is indicated.
EPP 1.9 Write
The timing for a write operation (address or data) is shown in timing diagram EPP 1.9 Write Data or Address cycle.
IOCHRDY is driven active low at the start of each EPP write and is released when it has been determined that the
write cycle can complete. The write cycle can complete under the following circumstances:
1. If the EPP bus is not ready (nWAIT is active low) when nDATASTB or nADDRSTB goes active then the write
can complete when nWAIT goes inactive high.
2. If the EPP bus is ready (nWAIT is inactive high) then the chip must wait for it to go active low before changing
the state of nDATASTB, nWRITE or nADDRSTB. The write can complete once nWAIT is determined inactive.
Write Sequence of Operation
1. The host selects an EPP register, places data on the SData bus and drives nIOW active.
2. The chip drives IOCHRDY inactive (low).
3. If WAIT is not asserted, the chip must wait until WAIT is asserted.
4. The chip places address or data on PData bus, clears PDIR, and asserts nWRITE.
5. Chip asserts nDATASTB or nADDRSTRB indicating that PData bus contains valid information, and the WRITE
signal is valid.
6. Peripheral deasserts nWAIT, indicating that any setup requirements have been satisfied and the chip may
begin the termination phase of the cycle.
7. A) The chip deasserts nDATASTB or nADDRSTRB, this marks the beginning of the termination phase.
If it has not already done so, the peripheral should latch the information byte now.
B) The chip latches the data from the SData bus for the PData bus and asserts (releases) IOCHRDY
allowing the host to complete the write cycle.
8. Peripheral asserts nWAIT, indicating to the host that any hold time requirements have been satisfied and
acknowledging the termination of the cycle.
9. Chip may modify nWRITE and nPDATA in preparation for the next cycle.
EPP 1.9 Read
The timing for a read operation (data) is shown in timing diagram EPP Read Data cycle. IOCHRDY is driven active
low at the start of each EPP read and is released when it has been determined that the read cycle can complete.
The read cycle can complete under the following circumstances:
1. If the EPP bus is not ready (nWAIT is active low) when nDATASTB goes active then the read can complete
when nWAIT goes inactive high.
2. If the EPP bus is ready (nWAIT is inactive high) then the chip must wait for it to go active low before changing
the state of WRITE or before nDATASTB goes active. The read can complete once nWAIT is determined
inactive.
Read Sequence of Operation
1. The host selects an EPP register and drives nIOR active.
2. The chip drives IOCHRDY inactive (low).
3. If WAIT is not asserted, the chip must wait until WAIT is asserted.
4. The chip tri-states the PData bus and deasserts nWRITE.
5. Chip asserts nDATASTB or nADDRSTRB indicating that PData bus is tri-stated, PDIR is set and the nWRITE
signal is valid.
6. Peripheral drives PData bus valid.
7. Peripheral deasserts nWAIT, indicating that PData is valid and the chip may begin the termination phase of
the cycle.
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8. A) The chip latches the data from the PData bus for the SData bus, deasserts DATASTB or
nADDRSTRB, this marks the beginning of the termination phase.
B) The chip drives the valid data onto the SData bus and asserts (releases) IOCHRDY allowing the host to
complete the read cycle.
9. Peripheral tri-states the PData bus and asserts nWAIT, indicating to the host that the PData bus is tri-stated.
10. Chip may modify nWRITE, PDIR and nPDATA in preparation for the next cycle.
EPP 1.7 OPERATION
When the EPP 1.7 mode is selected in the configuration register, the standard and bi-directional modes are also
available. If no EPP Read, Write or Address cycle is currently executing, then the PDx bus is in the standard or bidirectional mode, and all output signals (STROBE, AUTOFD, INIT) are as set by the SPP Control Port and direction
is controlled by PCD of the Control port.
In EPP mode, the system timing is closely coupled to the EPP timing. For this reason, a watchdog timer is
required to prevent system lockup. The timer indicates if more than10usec have elapsed from the start of the EPP
cycle (nIOR or nIOW asserted) to the end of the cycle nIOR or nIOW deasserted). If a time-out occurs, the
current EPP cycle is aborted and the time-out condition is indicated in Status bit 0.
Software Constraints
Before an EPP cycle is executed, the software must ensure that the control register bits D0, D1 and D3 are set to
zero. Also, bit D5 (PCD) is a logic “0” for an EPP write or a logic “1” for and EPP read.
EPP 1.7 Write
The timing for a write operation (address or data) is shown in timing diagram EPP 1.7 Write Data or Address cycle.
IOCHRDY is driven active low when nWAIT is active low during the EPP cycle. This can be used to extend the
cycle time. The write cycle can complete when nWAIT is inactive high.
Write Sequence of Operation
1. The host sets PDIR bit in the control register to a logic “0”. This asserts nWRITE.
2. The host selects an EPP register, places data on the SData bus and drives nIOW active.
3. The chip places address or data on PData bus.
4. Chip asserts nDATASTB or nADDRSTRB indicating that PData bus contains valid information, and the WRITE
signal is valid.
5. If nWAIT is asserted, IOCHRDY is deasserted until the peripheral deasserts nWAIT or a time-out occurs.
6. When the host deasserts nI0W the chip deasserts nDATASTB or nADDRSTRB and latches the data from the
SData bus for the PData bus.
7. Chip may modify nWRITE, PDIR and nPDATA in preparation of the next cycle.
EPP 1.7 Read
The timing for a read operation (data) is shown in timing diagram EPP 1.7 Read Data cycle. IOCHRDY is driven
active low when nWAIT is active low during the EPP cycle. This can be used to extend the cycle time. The read
cycle can complete when nWAIT is inactive high.
Read Sequence of Operation
1. The host sets PDIR bit in the control register to a logic “1”. This deasserts nWRITE and tri-states the PData
bus.
2. The host selects an EPP register and drives nIOR active.
3. Chip asserts nDATASTB or nADDRSTRB indicating that PData bus is tri-stated, PDIR is set and the nWRITE
signal is valid.
4. If nWAIT is asserted, IOCHRDY is deasserted until the peripheral deasserts nWAIT or a time-out occurs.
5. The Peripheral drives PData bus valid.
6. The Peripheral deasserts nWAIT, indicating that PData is valid and the chip may begin the termination phase
of the cycle.
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7. When the host deasserts nI0R the chip deasserts nDATASTB or nADDRSTRB.
8. Peripheral tri-states the PData bus.
9. Chip may modify nWRITE, PDIR and nPDATA in preparation of the next cycle.
Table 61 - EPP Pin Descriptions
EPP
SIGNAL EPP NAME TYPE DESCRIPTION
nWRITE nWrite O This signal is active low. It denotes a write operation.
PD<0:7> Address/Data I/O Bi-directional EPP byte wide address and data bus.
INTR Interrupt I This signal is active high and positive edge triggered. (Pass
through with no inversion, Same as SPP).
WAIT nWait I This signal is active low. It is driven inactive as a positive
acknowledgment from the device that the transfer of data is
completed. It is driven active as an indication that the device
is ready for the next transfer.
DATASTB nData Strobe O This signal is active low. It is used to denote data read or
write operation.
RESET nReset O This signal is active low. When driven active, the EPP device
is reset to its initial operational mode.
ADDRSTB nAddress
Strobe
O This signal is active low. It is used to denote address read
or write operation.
PE Paper End I Same as SPP mode.
SLCT Printer
I Same as SPP mode.
Selected
Status
NERR Error I Same as SPP mode.
PDIR Parallel Port
Direction
O This output shows the direction of the data transfer on the
parallel port bus. A low means an output/write condition and
a high means an input/read condition. This signal is
normally a low (output/write) unless PCD of the control
register is set or if an EPP read cycle is in progress.
Note 1: SPP and EPP can use 1 common register.
Note 2: nWrite is the only EPP output that can be over-ridden by SPP control port during an EPP cycle. For correct
EPP read cycles, PCD is required to be a low.
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EXTENDED CAPABILITIES PARALLEL PORT
ECP provides a number of advantages, some of which are listed below. The individual features are explained in
greater detail in the remainder of this section.
• High performance half -duplex forward and reverse channel
• Interlocked handshake, for fast reliable transfer
• Optional single byte RLE compression for improved throughput (64:1)
• Channel addressing for low-cost peripherals
• Maintains link and data layer separation
• Permits the use of active output drivers
• Permits the use of adaptive signal timing
• Peer-to-peer capability
Vocabulary
The following terms are used in this document:
assert When a signal asserts it transitions to a “true” state, when a signal deasserts it transitions to a
“false” state.
forward Host to Peripheral communication.
reverse Peripheral to Host communication.
Pword A port word; equal in size to the width of the ISA interface. For this implementation, PWord is always
8 bits.
1 A high level
0 A low level
These terms may be considered synonymous:
• PeriphClk, nAck
• HostAck, nAutoFd
• PeriphAck, Busy
• nPeriphRequest, nFault
• nReverseRequest, nInit
• nAckReverse, PError
• Xflag, Select
• ECPMode, nSelectln
• HostClk, nStrobe
Reference Document:
IEEE 1284 Extended Capabilities Port Protocol and ISA Interface Standard, Rev 1.09, Jan 7, 1993. This document
is available from Microsoft. The bit map of the Extended Parallel Port registers is shown in Table 65.
Table 62 - ECP Registers
D7 D6 D5 D4 D3 D2 D1 D0
data PD7 PD6 PD5 PD4 PD3 PD2 PD1 PD0
ecpAFifo
dsr
dcr
cFifo
ecpDFifo
tFifo
2
Addr/RLE Address or RLE field
1
1
2
2
nBusy nAck PError Select nFault 0 0 0
0 0 Direction ackIntEn SelectIn nInit
Parallel Port Data FIFO
2
ECP Data FIFO
Test FIFO
autofd strobe
cnfgA 0 0 0 1 0 0 0 0
cnfgB compress intrValue IRQ Software Select DMA Software Select
ecr MODE nErrIntrEn dmaEn
serviceIntr
full
empty
Note1: These registers are available in all modes.
Note2: All FIFOs use one common 16 byte FIFO.
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ISA IMPLEMENTATION STANDARD
This specification describes the standard ISA interface to the Extended Capabilities Port (ECP). All ISA devices
supporting ECP must meet the requirements contained in this section or the port will not be supported by
Microsoft. For a description of the ECP Protocol, please refer to the IEEE 1284 Extended Capabilities Port Protocol
and ISA Interface Standard, Rev. 1.09, Jan.7, 1993. This document is available from Microsoft.
Description
The port is software and hardware compatible with existing parallel ports so that it may be used as a standard LPT
port if ECP is not required. The port is designed to be simple and requires a small number of gates to implement.
It does not do any “protocol” negotiation, rather it provides an automatic high burst-bandwidth channel that
supports DMA for ECP in both the forward and reverse directions.
Small FIFOs are employed in both forward and reverse directions to smooth data flow and improve the maximum
bandwidth requirement. The size of the FIFO is 16 bytes deep. The port supports an automatic handshake for the
standard parallel port to improve compatibility mode transfer speed.
The port also supports run length encoded (RLE) decompression (required) in hardware. Compression is
accomplished by counting identical bytes and transmitting an RLE byte that indicates how many times the next byte
is to be repeated. Decompression simply intercepts the RLE byte and repeats the following byte the specified
number of times. Hardware support for compression is optional.
Table 63 - ECP Pin Descriptions
NAME TYPE DESCRIPTION
nSTROBE O During write operations nSTROBE registers data or address into the slave
on the asserting edge (handshakes with Busy).
Pdata 7:0 I/O Contains address or data or RLE data.
nACK I Indicates valid data driven by the peripheral when asserted. This signal
handshakes with nAUTOFD in reverse.
PeriphAck (Busy) I This signal deasserts to indicate that the peripheral can accept data. This
signal handshakes with nStrobe in the forward direction. In the reverse
direction this signal indicates whether the data lines contain ECP
command information or data. The peripheral uses this signal to flow
control in the forward direction. It is an “interlocked” handshake with
nStrobe. PeriphAck also provides command information in the reverse
direction.
Perror
(nAckReverse)
I Used to acknowledge a change in the direction the transfer (asserted =
forward). The peripheral drives this signal low to acknowledge
nReverseRequest. It is an “interlocked” handshake with
nReverseRequest. The host relies upon nAckReverse to determine when
it is permitted to drive the data bus.
Select I Indicates printer on line.
nAUTOFD
(HostAck)
O Requests a byte of data from the peripheral when asserted, handshaking
with nACK in the reverse direction. In the forward direction this signal
indicates whether the data lines contain ECP address or data. The host
drives this signal to flow control in the reverse direction. It is an
“interlocked” handshake with nACK. HostAck also provides command
information in the forward phase.
nFAULT
(nPeriphRequest)
I Generates an error interrupt when asserted. This signal provides a
mechanism for peer-to-peer communication. This signal is valid only in
the forward direction. During ECP Mode the peripheral is permitted (but
not required) to drive this pin low to request a reverse transfer. The request
is merely a “hint” to the host; the host has ultimate control over the transfer
direction. This signal would be typically used to generate an interrupt to
the host CPU.
SMSC DS – FDC37N869 Page 82 Rev. 11/09/2000
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NAME TYPE DESCRIPTION
nINIT O Sets the transfer direction (asserted = reverse, deasserted = forward).
This pin is driven low to place the channel in the reverse direction. The
peripheral is only allowed to drive the bi-directional data bus while in ECP
Mode and HostAck is low and nSelectIn is high.
nSELECTIN O Always deasserted in ECP mode.
Register Definitions
The register definitions are based on the standard IBM addresses for LPT. All of the standard printer ports are
supported. The additional registers attach to an upper bit decode of the standard LPT port definition to avoid
conflict with standard ISA devices. The port is equivalent to a generic parallel port interface and may be operated in
that mode. The port registers vary depending on the mode field in the ecr (Table 68). Table 67 lists these
dependencies. Operation of the devices in modes other that those specified is undefined.
Table 64 - ECP Register Definitions
NAME ADDRESS (Note 1) ECP MODES FUNCTION
data +000h R/W 000-001 Data Register
ecpAFifo +000h R/W 011 ECP FIFO (Address)
dsr +001h R/W All Status Register
dcr +002h R/W All Control Register
cFifo +400h R/W 010 Parallel Port Data FIFO
ecpDFifo +400h R/W 011 ECP FIFO (DATA)
tFifo +400h R/W 110 Test FIFO
cnfgA +400h R 111 Configuration Register A
cnfgB +401h R/W 111 Configuration Register B
ecr +402h R/W All Extended Control Register
Note 1: These addresses are added to the parallel port base address as selected by configuration register or
jumpers.
Note 2: All addresses are qualified with AEN. Refer to the AEN pin definition.
Table 65 - Mode Descriptions
DESCRIPTION
MODE
(Refer to ECR Register Description)
000 SPP mode
001 PS/2 Parallel Port mode
010 Parallel Port Data FIFO mode
011 ECP Parallel Port mode
100 EPP mode (If this option is enabled in the configuration registers)
101 (Reserved)
110 Test mode
111 Configuration mode
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DATA and ecpAFifo PORT
ADDRESS OFFSET = 00H
Modes 000 and 001 (Data Port)
The Data Port is located at an offset of ‘00H’ from the base address. The data register is cleared at initialization by
RESET. During a WRITE operation, the Data Register latches the contents of the data bus on the rising edge of
the nIOW input. The contents of this register are buffered (non inverting) and output onto the PD0 - PD7 ports.
During a READ operation, PD0 - PD7 ports are read and output to the host CPU.
Mode 011 (ECP FIFO - Address/RLE)
A data byte written to this address is placed in the FIFO and tagged as an ECP Address/RLE. The hardware at the
ECP port transmits this byte to the peripheral automatically. The operation of this register is only defined for the
forward direction (direction is 0). Refer to the ECP Parallel Port Forward Timing Diagram, located in the Timing
Diagrams section of this data sheet.
DEVICE STATUS REGISTER (dsr)
ADDRESS OFFSET = 01H
The Status Port is located at an offset of ‘01H’ from the base address. Bits 0 - 2 are not implemented as register
bits, during a read of the Printer Status Register these bits are a low level. The bits of the Status Port are defined
as follows:
BIT 3 nFault
The level on the nFault input is read by the CPU as bit 3 of the Device Status Register.
BIT 4 Select
The level on the Select input is read by the CPU as bit 4 of the Device Status Register.
BIT 5 PError
The level on the PError input is read by the CPU as bit 5 of the Device Status Register. Printer Status Register.
BIT 6 nAck
The level on the nAck input is read by the CPU as bit 6 of the Device Status Register.
BIT 7 nBusy
The complement of the level on the BUSY input is read by the CPU as bit 7 of the Device Status Register.
DEVICE CONTROL REGISTER (dcr)
ADDRESS OFFSET = 02H
The Control Register is located at an offset of ‘02H’ from the base address. The Control Register is initialized to
zero by the RESET input, bits 0 to 5 only being affected; bits 6 and 7 are hard wired low.
BIT 0 STROBE - STROBE
This bit is inverted and output onto the nSTROBE output.
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BIT 1 AUTOFD - AUTOFEED
This bit is inverted and output onto the nAUTOFD output. A logic 1 causes the printer to generate a line feed after
each line is printed. A logic 0 means no autofeed.
BIT 2 nINIT - nINITIATE OUTPUT
This bit is output onto the nINIT output without inversion.
BIT 3 SELECTIN
This bit is inverted and output onto the nSLCTIN output. A logic 1 on this bit selects the printer; a logic 0 means the
printer is not selected.
BIT 4 ackIntEn - INTERRUPT REQUEST ENABLE
The interrupt request enable bit when set to a high level may be used to enable interrupt requests from the
Parallel Port to the CPU due to a low to high transition on the nACK input.
Refer to the description of the interrupt under Operation, Interrupts.
BIT 5 DIRECTION
If mode=000 or mode=010, this bit has no effect and the direction is always out regardless of the state of this bit.
In all other modes, Direction is valid and a logic 0 means that the printer port is in output mode (write); a logic 1
means that the printer port is in input mode (read).
Bits 6 and 7
during a read are a low level, and cannot be written.
cFifo (Parallel Port Data FIFO)
ADDRESS OFFSET = 400h
Mode = 010
Bytes written or DMAed from the system to this FIFO are transmitted by a hardware handshake to the peripheral
using the standard parallel port protocol. Transfers to the FIFO are byte aligned. This mode is only defined for the
forward direction.
ecpDFifo (ECP Data FIFO)
ADDRESS OFFSET = 400H
Mode = 011
Bytes written or DMAed from the system to this FIFO, when the direction bit is 0, are transmitted by a hardware
handshake to the peripheral using the ECP parallel port protocol. Transfers to the FIFO are byte aligned.
Data bytes from the peripheral are read under automatic hardware handshake from ECP into this FIFO when the
direction bit is 1. Reads or DMAs from the FIFO will return bytes of ECP data to the system.
tFifo (Test FIFO Mode)
ADDRESS OFFSET = 400H
Mode = 110
Data bytes may be read, written or DMAed to or from the system to this FIFO in any direction.
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Data in the tFIFO will not be transmitted to the to the parallel port lines using a hardware protocol handshake.
However, data in the tFIFO may be displayed on the parallel port data lines.
The tFIFO will not stall when overwritten or underrun. If an attempt is made to write data to a full tFIFO, the new
data is not accepted into the tFIFO. If an attempt is made to read data from an empty tFIFO, the last data byte is reread again. The full and empty bits must always keep track of the correct FIFO state. The tFIFO will transfer data at
the maximum ISA rate so that software may generate performance metrics.
The FIFO size and interrupt threshold can be determined by writing bytes to the FIFO and checking the full and
serviceIntr bits.
The writeIntrThreshold can be determined by starting with a full tFIFO, setting the direction bit to 0 and emptying it a
byte at a time until serviceIntr is set. This may generate a spurious interrupt, but will indicate that the threshold has
been reached.
The readIntrThreshold can be determined by setting the direction bit to 1 and filling the empty tFIFO a byte at a time
until serviceIntr is set. This may generate a spurious interrupt, but will indicate that the threshold has been
reached.
Data bytes are always read from the head of tFIFO regardless of the value of the direction bit. For example if 44h,
33h, 22h is written to the FIFO, then reading the tFIFO will return 44h, 33h, 22h in the same order as was written.
cnfgA (Configuration Register A)
ADDRESS OFFSET = 400H
Mode = 111
This register is a read only register. When read, 10H is returned. This indicates to the system that this is an 8-bit
implementation. (PWord = 1 byte)
cnfgB (Configuration Register B)
ADDRESS OFFSET = 401H
Mode = 111
BIT 7 compress
This bit is read only. During a read it is a low level. This means that this chip does not support hardware RLE
compression. It does support hardware de-compression!
BIT 6 intrValue
Returns the value on the ISA iRq line to determine possible conflicts.
BITS 2:0 DMA Software Select
The DMA Software Select bits indicate the DMA channel number that has been allocated to the Parallel Port. The
channel encoding is shown in Table 66. The DMA Software select bits shadow the ECP DMA Select bits in the
ECP Software Select register CR22.
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Table 66 - DMA SOFTWARE SELECT ENCODING
DMA Software
Select
DMA
(cnfgB)
SELECTED
D2 D1 D0
3 0 1 1
2 0 1 0
1 0 0 1
Other 0 0 0
BITS 5:3 IRQ Software Select
The IRQ Software Select bits indicate the IRQ channel number that has been allocated to the Parallel Port. The
IRQ encoding is shown in Table 67. The IRQ Software select bits shadow the ECP IRQ Select bits in the ECP
Software Select register CR22.
Table 67 - IRQ SOFTWARE SELECT ENCODING
IRQ Software
IRQ SELECTED
Select
(cnfgB)
D5 D4 D3
15 1 1 0
14 1 0 1
11 1 0 0
10 0 1 1
9 0 1 0
7 0 0 1
5 1 1 1
Other 0 0 0
ecr (Extended Control Register)
ADDRESS OFFSET = 402H
Mode = all
This register controls the extended ECP parallel port functions (Table 69).
BITS 7,6,5
These bits are Read/Write and select the Mode.
BIT 4 nErrIntrEn
Read/Write (Valid only in ECP Mode)
1: Disables the interrupt generated on the asserting edge of nFault.
0: Enables an interrupt pulse on the high to low edge of nFault. Note that an interrupt will be generated if
nFault is asserted (interrupting) and this bit is written from a “1” to a “0”. This prevents interrupts from being
lost in the time between the read of the ecr and the write of the ecr.
BIT 3 dmaEn
Read/Write
1: Enables DMA (DMA starts when serviceIntr is “0”).
0: Disables DMA unconditionally.
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BIT 2 serviceIntr
Read/Write
1: Disables DMA and all of the service interrupts.
0: Enables one of the following 3 cases of interrupts. Once one of the 3 service interrupts has occurred
serviceIntr bit shall be set to a “1” by hardware, it must be reset to “0” to re-enable the interrupts. Writing this bit
to a “1” will not cause an interrupt.
case dmaEn=1:
During DMA (this bit is set to a “1” when terminal count is reached).
case dmaEn=0 direction=0:
This bit shall be set to “1” whenever there are writeIntrThreshold or more bytes free in the FIFO.
case dmaEn=0 direction=1:
This bit shall be set to “1” whenever there are readIntrThreshold or more valid bytes to be read from the FIFO.
BIT 1 full
Read only
1: The FIFO cannot accept another byte or the FIFO is completely full.
0: The FIFO has at least 1 free byte.
BIT 0 empty
Read only
1: The FIFO is completely empty.
0: The FIFO contains at least 1 byte of data.
Table 68 - Extended Control Register
R/W MODE
000: Standard Parallel Port mode. In this mode the FIFO is reset and common collector drivers
are used on the control lines (nStrobe, nAutoFd, nInit and nSelectIn). Setting the direction
bit will not tri-state the output drivers in this mode.
001: PS/2 Parallel Port mode. Same as above except that direction may be used to tri-state the
data lines and reading the data register returns the value on the data lines and not the
value in the data register. All drivers have active pull-ups (push -pull).
010: Parallel Port FIFO mode. This is the same as 000 except that bytes are written or DMAed
to the FIFO. FIFO data is automatically transmitted using the standard parallel port
protocol. Note that this mode is only useful when direction is 0. All drivers have active
pull-ups (push -pull).
011: ECP Parallel Port Mode. In the forward direction (direction is 0) bytes placed into the
ecpDFifo and bytes written to the ecpAFifo are placed in a single FIFO and transmitted
automatically to the peripheral using ECP Protocol. In the reverse direction (direction is 1)
bytes are moved from the ECP parallel port and packed into bytes in the ecpDFifo. All
drivers have active pull-ups (push -pull).
100: Selects EPP Mode: In this mode, EPP is selected if the EPP supported option is selected
in configuration register CR4. All drivers have active pull-ups (push -pull).
101: Reserved
110: Test Mode. In this mode the FIFO may be written and read, but the data will not be
transmitted on the parallel port. All drivers have active pull-ups (push -pull).
111: Configuration Mode. In this mode the confgA, confgB registers are accessible at 0x400
and 0x401. All drivers have active pull-ups (push -pull).
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OPERATION
Mode Switching/Software Control
Software will execute P1284 negotiation and all operation prior to a data transfer phase under programmed I/O
control (mode 000 or 001). Hardware provides an automatic control line handshake, moving data between the
FIFO and the ECP port only in the data transfer phase (modes 011 or 010).
Setting the mode to 011 or 010 will cause the hardware to initiate data transfer.
If the port is in mode 000 or 001 it may switch to any other mode. If the port is not in mode 000 or 001 it can only be
switched into mode 000 or 001. The direction can only be changed in mode 001.
Once in an extended forward mode the software should wait for the FIFO to be empty before switching back to
mode 000 or 001. In this case all control signals will be deasserted before the mode switch. In an ECP reverse
mode the software waits for all the data to be read from the FIFO before changing back to mode 000 or 001. Since
the automatic hardware ECP reverse handshake only cares about the state of the FIFO it may have acquired extra
data which will be discarded. It may in fact be in the middle of a transfer when the mode is changed back to 000 or
001. In this case the port will deassert nAutoFd independent of the state of the transfer. The design shall not cause
glitches on the handshake signals if the software meets the constraints above.
ECP Operation
Prior to ECP operation the Host must negotiate on the parallel port to determine if the peripheral supports the ECP
protocol. This is a somewhat complex negotiation carried out under program control in mode 000. After
negotiation, it is necessary to initialize some of the port bits. The following are required:
• Set Direction = 0, enabling the drivers.
• Set strobe = 0, causing the nStrobe signal to default to the deasserted state.
• Set autoFd = 0, causing the nAutoFd signal to default to the deasserted state.
• Set mode = 011 (ECP Mode)
ECP address/RLE bytes or data bytes may be sent automatically by writing the ecpAFifo or ecpDFifo respectively.
Note that all FIFO data transfers are byte wide and byte aligned. Address/RLE transfers are byte -wide and only
allowed in the forward direction.
The host may switch directions by first switching to mode = 001, negotiating for the forward or reverse channel,
setting direction to 1 or 0, then setting mode = 011. When direction is 1 the hardware shall handshake for each
ECP read data byte and attempt to fill the FIFO. Bytes may then be read from the ecpDFifo as long as it is not
empty .
ECP transfers may also be accomplished (albeit slowly) by handshaking individual bytes under program control in
mode = 001, or 000.
Termination from ECP Mode
Termination from ECP Mode is similar to the termination from Nibble/Byte Modes. The host is permitted to
terminate from ECP Mode only in specific well-defined states. The termination can only be executed while the bus
is in the forward direction. To terminate while the channel is in the reverse direction, it must first be transitioned
into the forward direction.
Command/Data
ECP Mode supports two advanced features to improve the effectiveness of the protocol for some applications. The
features are implemented by allowing the transfer of normal 8 bit data or 8-bit commands (Table 70).
When in the forward direction, normal data is transferred when HostAck is high and an 8 bit command is
transferred when HostAck is low.
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The most significant bit of the command indicates whether it is a run-length count (for compression) or a channel
address.
When in the reverse direction, normal data is transferred when PeriphAck is high and an 8 bit command is
transferred when PeriphAck is low. The most significant bit of the command is always zero. Reverse channel
addresses are seldom used and may not be supported in hardware.
Table 69 - Forward Channel Commands (HostAck Low) Reverse
Channel Commands (PeripAck Low) Data Compression
D7 D[6:0]
0 Run-Length Count (0-127)
(mode 0011 0X00 only)
1 Channel Address (0-127)
The FDC37N869 supports run length encoded (RLE) decompression in hardware and can transfer compressed
data to a peripheral. Run length encoded (RLE) compression in hardware is not supported. To transfer
compressed data in ECP mode, the compression count is written to the ecpAFifo and the data byte is written to the
ecpDFifo.
Compression is accomplished by counting identical bytes and transmitting an RLE byte that indicates how many
times the next byte is to be repeated. Decompression simply intercepts the RLE byte and repeats the following
byte the specified number of times. When a run-length count is received from a peripheral, the subsequent data
byte is replicated the specified number of times. A run-length count of zero specifies that only one byte of data is
represented by the next data byte, whereas a run-length count of 127 indicates that the next byte should be
expanded to 128 bytes. To prevent data expansion, however, run-length counts of zero should be avoided.
Pin Definition
The drivers for nStrobe, nAutoFd, nInit and nSelectIn are open-collector in mode 000 and are push-pull in all
other modes.
ISA Connections
The interface can never stall causing the host to hang. The width of data transfers is strictly controlled on an I/O
address basis per this specification. All FIFO-DMA transfers are byte wide, byte aligned and end on a byte
boundary. (The PWord value can be obtained by reading Configuration Register A, cnfgA, described in the next
section). Single byte wide transfers are always possible with standard or PS/2 mode using program control of
the control signals.
Interrupts
The interrupts are enabled by serviceIntr in the ecr register.
serviceIntr = 1 Disables the DMA and all of the service interrupts.
serviceIntr = 0Enables the selected interrupt condition. If the interrupting condition is valid, then the interrupt is
generated immediately when this bit is changed from a 1 to a 0. This can occur during Programmed I/O if the
number of bytes removed or added from/to the FIFO does not cross the threshold.
The interrupt generated is ISA friendly in that it must pulse the interrupt line low, allowing for interrupt sharing.
After a brief pulse low following the interrupt event, the interrupt line is tri-stated so that other interrupts may assert.
An interrupt is generated when:
1. For DMA transfers: When serviceIntr is 0, dmaEn is 1 and the DMA TC is received.
2. For Programmed I/O:
a. When serviceIntr is “0”, dmaEn is “0”, direction is “0” and there are writeIntrThreshold or more free bytes
in the FIFO. Also, an interrupt is generated when serviceIntr is cleared to “0” whenever there are
writeIntrThreshold or more free bytes in the FIFO.
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b(1) When serviceIntr is 0, dmaEn is 0, direction is “1” and there are readIntrThreshold or more bytes in the
FIFO. Also, an interrupt is generated when serviceIntr is cleared to “0” whenever there are readIntr
Threshold or more bytes in the FIFO.
3. When nErrIntrEn is “0” and nFault transitions from high to low or when nErrIntrEn is set from “1” to “0” and
nFault is asserted.
4. When ackIntEn is “1” and the nAck signal transitions from a low to a high.
FIFO Operation
The FIFO threshold is set in the chip configuration registers. All data transfers to or from the parallel port can
proceed in DMA or Programmed I/O (non-DMA) mode as indicated by the selected mode. The FIFO is used by
selecting the Parallel Port FIFO mode or ECP Parallel Port Mode. (FIFO test mode will be addressed separately.)
After a reset, the FIFO is disabled. Each data byte is transferred by a Programmed I/O cycle or PDRQ depending
on the selection of DMA or Programmed I/O mode.
The following paragraphs detail the operation of the FIFO flow control. In these descriptions, <threshold> ranges
from 1 to 16. The parameter FIFOTHR, which the user programs, is one less and ranges from 0 to 15.
A low threshold value (i.e. 2) results in longer periods of time between service requests, but requires faster
servicing of the request for both read and write cases. The host must be very responsive to the service request.
This is the desired case for use with a “fast” system.
A high value of threshold (i.e. 12) is used with a “sluggish” system by affording a long latency period after a service
request, but results in more frequent service requests.
DMA TRANSFERS
Note:
PDRQ - Currently selected Parallel Port DRQ channel
nPDACK - Currently selected Parallel Port DACK channel
PINTR - Currently selected Parallel Port IRQ channel
Typical DMA Mode Transfers
DMA transfers are always to or from the ecpDFifo, tFifo or CFifo. DMA utilizes the standard PC DMA services.
To use the DMA transfers, the host first sets up the direction and state as in the programmed I/O case. Then it
programs the DMA controller in the host with the desired count and memory address. Lastly it sets dmaEn to “1”
and serviceIntr to “0”. The ECP requests DMA transfers from the host by activating the PDRQ pin. The DMA will
empty or fill the FIFO using the appropriate direction and mode. When the terminal count in the DMA controller is
reached, an interrupt is generated and serviceIntr is asserted, disabling DMA. In order to prevent possible blocking
of refresh requests dReq shall not be asserted for more than 32 DMA cycles in a row. The FIFO is enabled directly
by asserting nPDACK and addresses need not be valid. PINTR is generated when a TC is received. PDRQ must
not be asserted for more than 32 DMA cycles in a row. After the 32nd cycle, PDRQ must be kept unasserted until
nPDACK is deasserted for a minimum of 350nsec. (Note: The only way to properly terminate DMA transfers is with
a TC).
DMA may be disabled in the middle of a transfer by first disabling the host DMA controller. Then setting serviceIntr
to 1, followed by setting dmaEn to 0, and waiting for the FIFO to become empty or full.
Restarting the DMA is accomplished by enabling DMA in the host, setting dmaEn to 1, followed by setting
serviceIntr to 0.
DMA Mode - Transfers from the FIFO to the Host
(Note: In the reverse mode, the peripheral may not continue to fill the FIFO if it runs out of data to transfer, even if
the chip continues to request more data from the peripheral).
The ECP activates the PDRQ pin whenever there is data in the FIFO. The DMA controller must respond to the
request by reading data from the FIFO. The ECP will deactivate the PDRQ pin when the FIFO becomes empty or
when the TC becomes true (qualified by nPDACK), indicating that no more data is required. PDRQ goes
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inactive after nPDACK goes active for the last byte of a data transfer (or on the active edge of nIOR, on the last byte,
if no edge is present on nPDACK). If PDRQ goes inactive due to the FIFO going empty, then PDRQ is active again
as soon as there is one byte in the FIFO. If PDRQ goes inactive due to the TC, then PDRQ is active again when
there is one byte in the FIFO, and serviceIntr has been re-enabled. (Note: A data underrun may occur if PDRQ is
not removed in time to prevent an unwanted cycle).
Programmed I/O Mode or Non-DMA Mode
The ECP or parallel port FIFOs may also be operated using interrupt driven programmed I/O. Software can
determine the writeIntrThreshold, readIntrThreshold, and FIFO depth by accessing the FIFO in Test Mode.
Programmed I/O transfers are to the ecpDFifo at 400H and ecpAFifo at 000H or from the ecpDFifo located at 400H,
or to/from the tFifo at 400H. To use the programmed I/O transfers, the host first sets up the direction and state,
sets dmaEn to 0 and serviceIntr to 0.
The ECP requests programmed I/O transfers from the host by activating the PINTR pin. The programmed I/O will
empty or fill the FIFO using the appropriate direction and mode.
Note: A threshold of 16 is equivalent to a threshold of 15. These two cases are treated the same.
Programmed I/O - Transfers from the FIFO to the Host
In the reverse direction an interrupt occurs when serviceIntr is 0 and readIntrThreshold bytes are available in the
FIFO. If at this time the FIFO is full it can be emptied completely in a single burst, otherwise readIntrThreshold
bytes may be read from the FIFO in a single burst.
readIntrThreshold =(16-<threshold>) data bytes in FIFO
An interrupt is generated when serviceIntr is 0 and the number of bytes in the FIFO is greater than or equal to (16<threshold>). (If the threshold = 12, then the interrupt is set whenever there are 4-16 bytes in the FIFO.) The PINT
pin can be used for interrupt-driven systems. The host must respond to the request by reading data from the FIFO.
This process is repeated until the last byte is transferred out of the FIFO. If at this time the FIFO is full, it can be
completely emptied in a single burst, otherwise a minimum of (16-<threshold>) bytes may be read from the FIFO
in a single burst.
Programmed I/O - Transfers from the Host to the FIFO
In the forward direction an interrupt occurs when serviceIntr is 0 and there are writeIntrThreshold or more bytes free
in the FIFO. At this time if the FIFO is empty it can be filled with a single burst before the empty bit needs to be
re-read. Otherwise it may be filled with writeIntrThreshold bytes.
writeIntrThreshold = (16-<threshold>) free bytes in FIFO
An interrupt is generated when serviceIntr is 0 and the number of bytes in the FIFO is less than or equal to
<threshold>. (If the threshold = 12, then the interrupt is set whenever there are 12 or less bytes of data in the
FIFO.) The PINT pin can be used for interrupt-driven systems. The host must respond to the request by writing
data to the FIFO. If at this time the FIFO is empty, it can be completely filled in a single burst, otherwise a minimum
of (16-<threshold>) bytes may be written to the FIFO in a single burst. This process is repeated until the last byte is
transferred into the FIFO.
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AUTO POWER MANAGEMENT
Power management is provided for the following FDC37N869 logical devices: Floppy Disk, UART1, UART2 and the
Parallel Port. For each logical device two types of power management are provided; direct powerdown and auto
powerdown.
Direct powerdown is controlled by the powerdown bits in the configuration registers. One bit is provided for each
logical device. Auto powerdown can be enabled for each logical device by setting the Auto Powerdown Enable bits
in the configuration registers. In addition, a chip-level hardware powerdown function has been provided through
the PWRGD pin. Refer to Table 1 and to other descriptions of the PWRGD function, for example section
CONFIGURATION, for more information.
FDC Power Management
Direct FDC power management is controlled by FDC Power (bit 3) of Configuration Register 0 (see section CR00
on page 104). FDC auto power management is enabled by Floppy Disk Enable (bit 7) in CR7 (see section CR07
on page 109). An internal timer is activated as soon as auto power management is enabled. During the timer
countdown any operation involving the MSR or the Data Register (FIFO) will re-initialize the timer. In auto
powerdown mode the FDC enters the powerdown state when all of the following conditions have been met:
1. The motor enable pins of the DOR register are inactive (zero).
2. The FDC is idle; MSR=80H and INT = 0 (INT may be high even if MSR = 80H due to polling interrupts).
3. The internal head unload timer has expired.
4. The 10msec auto powerdown timer has lapsed.
Disabling the FDC auto power management cancels the internal timer and prevents any of the above conditions
from re-enabling the powerdown state.
Note: At least 8us delay should be added when exiting FDC Auto Powerdown mode. If the operating
environment is such that this delay cannot be guaranteed, the auto powerdown mode should not be used and
Direct powerdown mode should be used instead. The Direct powerdown mode requires at least 8us delay at
250K bits/sec configuration and 4us delay at 500K bits/sec. The delay should be added so that the internal
microcontroller can prepare itself to accept commands.
DSR From Powerdown
If DSR powerdown is used when the part is in auto powerdown, the DSR powerdown will override the auto
powerdown. However, when the part is awakened from DSR powerdown, the auto powerdown will once again
become effective.
Wake Up From Auto Powerdown
If the FDC enters the powerdown state through the auto powerdown mode, wake up will occur after a reset or by
access to the specific registers shown below. If a hardware or software reset is used the part will follow the
normal reset sequence. If wake up occurs as a result of access through selected registers the FDC37N869 will
resume normal operation as if the FDC had never powered-down.
The following register accesses will wake up the FDC:
1. Enabling any one of the motor enable bits in the DOR register (reading the DOR does not awaken the
part).
2. A read from the MSR register.
3. A read or write to the Data register.
Once awake, the FDC37N869 will reinitiate the auto powerdown timer for 10ms. The FDC will powerdown again
when all of the powerdown conditions are met.
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Register Behavior
Table 71 reiterates the available FDC PC/AT and PS/2, including Model 30 mode, registers. In order to maintain
software transparency, access to all the registers must be maintained regardless of the power state. As Table 70
shows, two kinds of registers are identified based on whether access results in the FDC remaining in the
powerdown state or not.
Registers that will not awaken the FDC can be accessed during powerdown without changing the powerdown
state but will reflect the true register status as shown in the FDC register description. For example, a write to one
of these registers will result in the FDC retaining the data and subsequently using it appropriately when the block
reawakens. During powerdown accessing FDC registers that do not affect the power state may increase device
power consumption, but only until the register access has been completed.
Table 70 - Available FDC PC/AT and PS/2 Registers
AVAILABLE REGISTERS
BASE + ADDRESS PC-AT PS/2 (Model 30) ACCESS PERMITTED
Access to these registers DOES NOT wake up the FDC
00H ---- SRA R
01H ---- SRB R
02H DOR
1
DOR
1
R/W
03H --- --- --04H DSR
1
DSR
1
W
06H --- --- --07H DIR DIR R
07H CCR CCR W
Access to these registers wakes up the FDC
04H MSR MSR R
05H DATA DATA R/W
Note1: Writing to any of the motor enable bits in the DOR or doing a software reset via the DOR or DSR reset bits
will wake up the FDC. Writing to any other DOR or DSR bits will not wake up the FDC.
Pin Behavior
The FDC37N869 is specifically designed for portable PC systems where power conservation is a primary concern.
Consequently, the behavior of the device pins during powerdown very important.
The pins of the FDC37N869 FDC can be divided into two major categories: system interface and floppy disk drive
interface. When the FDC is powered down, the floppy disk drive pins are disabled so that no power will be drawn
through the part as a result of any voltage applied to the pin within the part’s power supply range. Most of the
system interface pins are left active to monitor system accesses that are intended to wake up the floppy controller.
System Interface Pins
Table 72 gives the state of the system interface pins in the powerdown state. Pins unaffected by the powerdown
are labeled “Unchanged”. Input pins are “Disabled” to prevent them from causing currents internal to the
FDC37N869 when they have indeterminate input values.
SMSC DS – FDC37N869 Page 94 Rev. 11/09/2000
Page 95
Table 71 - State of System Pins in Auto Powerdown
SYSTEM PINS STATE IN AUTO POWERDOWN
Input Pins
IOR Unchanged
IOW Unchanged
A[0:9] Unchanged
D[0:7] Unchanged
RESET Unchanged
IDENT Unchanged
DACK Unchanged
TC Unchanged
Output Pins
FINTR Unchanged (low)
DB[0:7] Unchanged
FDRQ Unchanged (low)
FDD Interface Pins
All pins in the FDD interface that can be connected directly to the floppy disk drive itself are either DISABLED or
TRISTATED. Pins used for local logic control or part programming are unaffected.
Table 73 depicts the state of the floppy disk drive interface pins in the powerdown state.
Table 72 - State of FDC Interface Pins in Powerdown
FDD PINS STATE IN AUTO POWERDOWN
Input Pins
RDATA Input
WP Input
TRK0 Input
INDX Input
DRV2 Input
DSKCHG Input
Output Pins
MOTEN[0:3] Tristated
DS[0:3} Tristated
DIR Active
STEP Active
WRDATA Tristated
WE Tristated
HDSEL Active
DENSEL Active
DRATE[0:1] Active
SMSC DS – FDC37N869 Page 95 Rev. 11/09/2000
Page 96
UART Power Management
Direct UART power management is controlled by the UART1 and UART2 Power Down bits in Configuration
Register 2. Refer to section CR02 on page 106 for more information.
UART Auto Power Management is enabled by the UART 1 and UART 2 Enable bits in Configuration Register 7
(see section CR07 on page 109). When set, these bits enable the following auto power management features:
1. The transmitter enters auto powerdown when the transmit buffer and transmit shift register are
empty.
2. The receiver enters powerdown when the following conditions are all met:
• Receive FIFO is empty
• The receiver is waiting for a start bit.
Note: While in the powerdown state, the Ring Indicator interrupts are still valid and are activated when the RI
inputs change.
The UART transmitters exit the powerdown state on a write to the XMIT buffer. The UART receivers exit the auto
powerdown state when RXDx changes state.
Parallel Port
Direct parallel port power management is controlled by the Parallel Port Power bit in Configuration Register 1.
Refer to section CR01 on page 104 for more information.
Parallel port Auto Power Management is enabled by the Parallel Port Enable bit in Configuration Register 7 (see
section CR07 on page 109). When set, this bit allows the ECP or EPP logical parallel port blocks to be placed into
the powerdown state as follows:
The EPP logic is in powerdown under any of the following conditions:
1. EPP is not enabled in the configuration registers.
2. EPP is not selected through ecr while in ECP mode.
The ECP logic is in powerdown under any of the following conditions:
1. ECP is not enabled in the configuration registers.
2. SPP, PS/2 Parallel port or EPP mode is selected through ecr while in ECP mode.
The parallel port logic can change powerdown modes when the ECP mode is changed through the ecr register or
when the parallel port mode is changed through the configuration registers.
SERIAL IRQ
Introduction
The FDC37N869 provides a serial interrupt interface to the host. This scheme adheres to the Serial IRQ
Specification for PCI Systems , Version 6.0. The CLK33, SIRQ, and nCLKRUN pins are required for this interface.
The Serial IRQ Enable bit D7 in CR29 activates the serial interrupt interface.
The IRQ/Data serializer is a Wired-OR structure that simply passes the state of one or more device IRQs and/or
Data to the Host Controller. The transfer can be initiated by either a device or the Host. Both high and low
transitions are reported in this protocol.
A transfer, called an IRQSER Cycle, consists of three frame types:
1. One START Frame
2. One or more IRQ/DATA Frames
3. One STOP Frame
The Serial IRQ protocol uses the PCI Clock as its clock source. The PCI clock conforms to the PCI bus electrical
specification.
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IRQSER Cycle Modes
There are two modes of operation for IRQSER cycles: Quiet (Active) Mode and Continuous (Idle) Mode. In Quiet
Mode any device may initiate an IRQSER cycle. In Continuous Mode only the host controller can initiate an IRQSER
cycle (FIGURE 4).
Following a system reset the SIRQ bus defaults to Continuous Mode. IRQSER cycle mode transitions can only
occur during the Stop Frame (FIGURE 5). Slaves must continuously sample the pulse width of the Stop Frame to
determine the mode of the next IRQSER cycle (see the Stop Cycle Control section on page 99).
SL
or
H
START FRAME
H
R T S R T S
IRQ0 FRAME IRQ1 FRAME
R T
PCICLK
1
IRQSER
Drive Source
FIGURE 4 - START FRAME TIMING W/SOURCE SAMPLED LOW PULSE ON IRQ1
Notes:
H=Host Control SL=Slave Control R=Recovery T=Turn-around S=Sample
1. Start Frame pulse can be 4-8 clocks wide
2. PCICLK = CLK33 pin (33MHz PCI Clock input)
3. IRQSER = SIRQ pin
IRQ14 IRQ15
S R T S
START
Host ControllerIRQ1 IRQ1
IOCHCK#
FRAMEFRAMEFRAME
R T
S R T
None
I
2
STOP FRAME
R T
H
PCICLK
IRQ2 FRAME
S R T
None
NEXT CYCLE
1
IRQSER
Driver
Notes:
H=Host Control R=Recovery T=Turn-around S=Sample I= Idle
1. STOP pulse is 2 clocks wide for Quiet mode, 3 clocks wide for Continuous mode.
2. There may be none, one or more Idle states during the Stop Frame.
3. The next IRQSER cycle’s Start Frame pulse may or may not start immediately after the
turn-around clock of the Stop Frame.
4. PCICLK = CLK33 pin (33MHz PCI Clock input)
5. IRQSER = SIRQ pin
Quiet (Active) Mode
In Quiet Mode any device may initiate a Start Frame by driving the IRQSER low for one clock while the IRQSER is
Idle (FIGURE 4). After driving low for one clock, slaves must immediately tristate IRQSER without at any time
driving high.
SMSC DS – FDC37N869 Page 97 Rev. 11/09/2000
None
FIGURE 5 - STOP FRAME TIMING W/HOST USING 17 IRQSER SAMPLING PERIOD
None
STOP
Host ControllerIRQ15
START
3
Page 98
A Start Frame may not be initiated while the IRQSER is Active. The IRQSER is Idle between Stop and Start
Frames. The IRQSER is Active between Start and Stop Frames. Quiet Mode operation allows the IRQSER to be
idle when there are no IRQ/Data transitions.
Once a Start Frame has been initiated, the host controller will take over driving the IRQSER low in the next clock
and will continue driving the IRQSER low for a programmable period of three to seven clocks. This makes a total
low pulse width of four to eight clocks. Finally, the host controller will drive the IRQSER back high for one clock,
then tri-state.
Any IRQSER device (e.g., The FDC37N869) which detects any transition on an IRQ/Data line for which it is
responsible must initiate a Start Frame in order to update the host controller unless the IRQSER is already in an
IRQSER Cycle and the IRQ/Data transition can be delivered in that IRQSER Cycle.
Continuous (Idle) Mode
In Continuous Mode only the host controller can initiate a Start Frame to update IRQ/Data line information. All other
IRQSER agents become passive and may not initiate a Start Frame. IRQSER Start Frame will be driven low for
four to eight clocks by the Host Controller.
Continuous Mode has serves two purposes: it can be used to stop or idle the IRQSER, or the host controller can
operate IRQSER continuously by initiating a Start Frame at the end of every Stop Frame.
IRQSER IRQ/Data Frames
Once a Start Frame has been initiated, the FDC37N869 will watch for the rising edge of the Start Pulse and start
counting IRQ/Data Frames.
Each IRQ/Data Frame has three phases. Each phase takes one PCI clock: Sample phase, Recovery phase, and
Turn-around phase. During the Sample phase the FDC37N869 must drive the IRQSER (SIRQ pin) low if and only
if the last detected IRQ/Data value was low. If the last detected IRQ/Data value was high IRQSER must be left tristated.
During the Recovery phase the FDC37N869 must drive the SIRQ high if and only if it had driven the IRQSER low
during the previous Sample Phase. During the Turn-around Phase the FDC37N869 must tri-state SIRQ.
The FDC37N869 will drive the IRQSER line low at the appropriate sample point if its associated IRQ/Data line is
low, regardless of which device initiated the Start Frame.
The Sample Phase for each IRQ/Data Frame follows the low to high transition of the Start Frame pulse by a
number of clocks equal to the IRQ/Data Frame times three, minus one. For example, the IRQ5 Sample Phase
occurs on 17th clock after the rising edge of the Start Pulse because IRQ5 is the sixth IRQ/Data Frame ((6 x 3) - 1 =
17).
Table 73 - IRQSER Sampling Periods
# OF CLOCKS PAST
IRQSER PERIOD SIGNAL SAMPLED
START
1 Not Used 2
2 IRQ1 5
3 IRQ2 8
4 IRQ3 11
5 IRQ4 14
6 IRQ5 17
7 IRQ6 20
8 IRQ7 23
9 IRQ8 26
10 IRQ9 29
11 IRQ10 32
12 IRQ11 35
13 IRQ12 38
SMSC DS – FDC37N869 Page 98 Rev. 11/09/2000
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# OF CLOCKS PAST
IRQSER PERIOD SIGNAL SAMPLED
START
14 IRQ13 41
15 IRQ14 44
16 IRQ15 47
The IRQSER IRQ/Data Frame will supports IRQ2 from a logical device. Previously, IRQSER Period 3 was reserved
for use by the System Management Interrupt (nSMI). When using Period 3 for IRQ2 the user should mask off the
SMI via the SMI Enable Register. Likewise, when using Period 3 for nSMI the user should not configure any logical
devices as using IRQ2. Note: There is no SMI support in the FDC37N869.
Stop Cycle Control
Once all IRQ/Data Frames have completed, the host controller will terminate IRQSER activity by initiating a Stop
Frame. Only the host controller can initiate the Stop Frame.
A Stop Frame is indicated when the IRQSER is low for two or three clocks. If the Stop Frame is low for two clocks
the next IRQSER Cycle operates in the Quiet mode and any IRQSER device may initiate a Start Frame in the
second clock or more after the rising edge of the Stop Frame pulse. If the Stop Frame is low for three clocks the
next IRQSER Cycle operates in Continuous mode and only the host controller may initiate a Start Frame in the
second clock or more after the rising edge of the Stop Frame pulse.
Latency
Latency for IRQ/Data updates over the IRQSER bus in bridge-less systems with the minimum IRQ/Data Frames of
seventeen will range up to 96 clocks (3.84uS with a 25MHz PCI Bus or 2.88uS with a 33MHz PCI Bus).
If one or more PCI to PCI Bridges are added to a system, the latency for IRQ/Data updates from the secondary or
tertiary buses will be a few clocks longer for synchronous buses, and approximately double for asynchronous
buses.
EOI/ISR Read Latency
Any serialized IRQ scheme has a potential implementation issue related to IRQ latency. IRQ latency could cause
an EOI or ISR Read to precede an IRQ transition that it should have followed. This could cause a system fault.
The host controller is responsible for ensuring that these latency issues are mitigated. The recommended
solution is to delay EOIs and ISR Reads to the interrupt controller by the same amount as the IRQSER Cycle
latency in order to ensure that these events do not occur out of order.
AC/DC Specification Issue
All IRQSER agents must drive/sample IRQSER synchronously relative to the rising edge of the PCI bus clock. The
IRQSER (SIRQ) pin uses the electrical specification of PCI bus.
Reset and Initialization
The IRQSER bus uses RESET_DRV as its reset signal. The IRQSER pin is tri-stated by all agents while
RESET_DRV is active. Following reset, IRQSER Slaves are put into Continuous (IDLE) mode. The host controller
is responsible for starting the initial IRQSER cycle to collect the system’s IRQ/Data default values.
The system then follows with the Continuous/Quiet mode protocol as determined by the Stop Frame pulse width
for subsequent IRQSER Cycles. It is the responsibility of the host controller to provide the default values to 8259’s
and other system logic before the first IRQSER Cycle is performed.
For IRQSER system suspend, insertion, or removal application, the host controller should be programmed in
Continuous (IDLE) mode first. This is to guarantee that the IRQSER bus is in the IDLE state before the system
configuration changes.
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ADD PCI nCLKRUN SUPPORT
Overview
The FDC37N869 supports the PCI nCLKRUN signal. nCLKRUN is used to indicate the PCI clock status as well
as to request that a stopped clock be started. See Figure 6 for an example of a typical system implementation
using nCLKRUN.
nCLKRUN support is required because the FDC37N869 interrupt interface relies entirely on Serial IRQs. If an SIO
interrupt occurs while the PCI clock is stopped, nCLKRUN must be asserted before the interrupt can be serviced.
If the FDC37N869 SIRQ_EN signal is inactive, nCLKRUN support is also disabled. The FDC37N869 nCLKRUN
signal is multiplexed with nADRx on TQFP pin number 92. See Configuration Register CR03 for a description of
the TQFP pin 92 multiplex controls.
nCLKRUN is an open drain output and an input. Refer to the PCI Mobile Design Guide Rev 1.0 for a description of
the nCLKRUN function.
Using nCLKRUN
If nCLKRUN is sampled “high”, the PCI clock is stopped or stopping. If nCLKRUN is sampled “low”, the PCI clock
is starting or started (running). If a device in the FDC37N869 asserts or de-asserts an interrupt and nCLKRUN is
sample “high”, the FDC37N869 can request the restoration of the clock by asserting the nCLKRUN signal
asynchronously Table 74). The FDC37N869 holds nCLKRUN low until it detects two rising edges of the clock.
After the second clock edge, the FDC37N869 must disable the open drain driver (Figure 7).
The FDC37N869 will not assert nCLKRUN under any conditions if SIRQ_EN is inactive (“0”). The SIRQ_EN bit is
D7 in CR29.
The FDC37N869 must not assert nCLKRUN if it is already driven low by the central resource; i.e., the PCI CLOCK
GENERATOR in Figure 6. The FDC37N869 must not assert nCLKRUN unless the line has been deasserted for
two successive clocks; i.e., before the clock was stopped (Figure 7).
Table 74 - FDC37N869 nCLKRUN Function
INTERNAL (PARALLEL)
SIRQ_EN
INTERRUPTS
nCLKRUN ACTION
1 X X None
0
NO CHANGE X None
CHANGE
1
0 None
1 Assert nCLKRUN
Note1: “Change” means either-edge change on any or all parallel IRQs routed to the SIRQ block.
The “change” detection logic must run asynchronously to the PCI Clock and regardless of the
SIRQ
mode; i.e., “continuous” or “quiet”.
SMSC DS – FDC37N869 Page 100 Rev. 11/09/2000
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