MPAC-100
RS-232 PCI
SYNCHRONOUS ADAPTER
for PCI Card Standard compatible machines
User's Manual
QUATECH, INC. TEL: (330) 434-3154
662 Wolf Ledges Parkway FAX: (330) 434-1409
Akron, Ohio 44311 www.quatech.com
WARRANTY INFORMATION
Quatech Inc. warrants the MPAC-100 to be free of defects for one (1) year from
the date of purchase. Quatech Inc. will repair or replace any board that fails to perform
under normal operating conditions and in accordance with the procedures outlined in
this document during the warranty period. Any damage that results from improper
installation, operation, or general misuse voids all warranty rights.
Although every attempt has been made to guarantee the accuracy of this manual,
Quatech Inc. assumes no liability for damages resulting from errors in this document.
Quatech Inc. reserves the right to edit or append to this document at any time without
notice.
Please complete the following information and retain for your records. Have
this information available when requesting warranty service.
DATE OF PURCHASE:
MODEL NUMBER: MPAC-100
PRODUCT DESCRIPTION: Single Channel PCI RS-232-D
Synchronous Communications Adapter
SERIAL NUMBER:
Copyright 2000 Quatech, Inc.
NOTICE
The information contained in this document is protected by copyright, and
cannot be reproduced in any form without the written consent of Quatech, Inc.
Likewise, any software programs that might accompany this document are protected
by copyright and can be used only in accordance with any license agreement(s)
between the purchaser and Quatech, Inc. Quatech, Inc. reserves the right to change this
documentation or the product to which it refers at any time and without notice.
The authors have taken due care in the preparation of this document and every
attempt has been made to ensure its accuracy and completeness. In no event will
Quatech, Inc. be liable for damages of any kind, incidental or consequential, in regard
to or arising out of the performance or form of the materials presented in this document
or any software programs that might accompany this document.
Quatech, Inc. encourages feedback about this document. Please send any
written comments to the Technical Support department at the address listed on the
cover page of this document.
14 FIFO Control Register
13 FIFO Status Register
12 Interrupt Status Register
11 Configuration Register
10 Communications Register
9.7 Receive FIFO timeout
9.6 Receive pattern detection
9.5 Accessing the SCC while FIFOs are enabled
9.4.4 Controlling the FIFOs
9.4.3 Reading current FIFO status
9.4.2 Resetting the FIFOs
9.4.1 Interrupt status
9.4 FIFO status and control
9.3.2 Using channel B for receive
9.3.1 Using channel A for both transmit and
9.3 SCC configuration for FIFO operation
9.2.2 Receive FIFO
9.2.1 Transmit FIFO
9.2 Accessing the FIFOs
9.1 Enabling and disabling the FIFOs
9 FIFO Operation
8.5.2 Software Interrupt Acknowledge
8.5.1 Register Pointer Bits
8.5 SCC Incompatibility Warnings
8.4.4 Other signals are not used
8.4.3 Extra handshaking for channel A
8.4.2 Extra clock support for channel A
8.4.1 Receive data and clock signals
8.4 Support for SCC Channel B
8.3 SCC Data Encoding Methods
8.2 Baud Rate Generator Programming
8.1 Accessing the registers
8 SCC General Information
7 Interrupts
6 Addressing
5 Using the MPAC-100 with Syncdrive
4 Other Operating Systems
3 Windows 95/98 Installation
2 Hardware Installation
1.1 System Requirements
1 Introduction
Table of Contents
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21 Specifications
20 PCI Resource Map
19 DTE Interface Signals
18.4 Null-modem cables
18.3 RING (pin 22)
18.2 SYNCA (pin 10)
18.1 5V fuse (pin 9)
18 External Connections
17 Receive FIFO Timeout Register
16 Receive Pattern Count Register
15 Receive Pattern Character Register
Table of Contents
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1 Introduction
Quatech MPAC-100 User's Manual
7
The Quatech MPAC-100 is a PCI Type card and is PCI PC Card Standard
Specification compliant. It provides a single-channel RS-232 synchronous
communication port. The base address and IRQ are configured through the PCI
hardware and software using utility programs provided by Quatech. There are no
switches or jumpers to set.
The MPAC-100 uses a Zilog 85230-compatible Serial Communications Controller
(SCC). The SCC can support asynchronous formats, byte-oriented synchronous
protocols such as IBM Bisync, and bit-oriented synchronous protocols such as HDLC
and SDLC. The SCC also offers internal functions such as on-chip baud rate generators,
and digital phase-lock loop (DPLL) for recovering data clocking from received data
streams.
Because the PCI standard does not include a direct memory access (DMA)
interface, the MPAC-100 supports only interrupt-driven communications. To
compensate for the lack of DMA, the MPAC-100 is equipped with 1024-byte FIFOs for
transmit and receive data. The FIFOs provide for high data throughput with very low
interrupt overhead.
1.1 System Requirements
16 bytes of contiguous I/O address space
one hardware interrupt (IRQ)
One available PCI expansion slot
2 Hardware Installation
Quatech MPAC-100 User's Manual
8
Hardware installation for the MPAC-100 is a very simple process:
1. Turn off the power of the computer system in which the MPAC-100 is to be
installed.
2. Remove the system cover according to the instructions provided by the
computer manufacturer.
3. Install the MPAC-100 in any empty PCI expansion slot. The board should be
secured by installing the Option Retaining Bracket (ORB) screw.
4. Replace the system cover according to the instructions provided by the
computer manufacturer.
5. Attach and secure the cable connectors to the desired equipment.
6. Turn on the power of the computer system.
3 Windows 95/98 Installation
Quatech MPAC-100 User's Manual
9
Windows 95/98 maintains a registry of all known hardware installed in your
computer. Inside this hardware registry Windows keeps track of all of your system
resources, such as I/O locations, IRQ levels, and DMA channels. The "Add New
Hardware Wizard" utility was designed to add new hardware and update this registry.
An "INF" configuration file is included with the MPAC-100 to allow easy
configuration in the Windows 95/98 environment. Windows uses the "INF" file to
determine the system resources required by the MPAC-100, searches for available
resources to fill the boards requirements, and then updates the hardware registry with
an entry that allocates these resources. The Syncdrive DLL and VxD can then be used
to access the card.
3.1 Using the "Add New Hardware" Wizard
The following instructions provide step-by-step instructions on installing the
MPAC-100 in Windows 98 using the "Add New Hardware" wizard. Windows 95 uses a
similar process to load the INF file from a CD with slightly different dialog boxes.
1. After inserting an MPAC-100 for the first time, the "Add New Hardware" wizard
will start. Click the "Next" button.
2. Click the "Next" button. Select the radio button for "Search for the best driver for
your device." Click the "Next" button to continue.
3. On the next dialog, select the "CD-ROM drive" checkbox. Insert the Quatech
Quatech MPAC-100 User's Manual
10
COM CD (shipped with the card) into the CD-ROM drive. Click the "Next"
button.
4. Windows should locate the INF file on the CD and display a dialog that looks
like this. Click the "Next" button.
5. Windows will copy the INF file from the CD and display a final dialog
Quatech MPAC-100 User's Manual
11
indicating that the process is complete. Click the "Finish" button.
3.2 Viewing Resources with Device Manager
Quatech MPAC-100 User's Manual
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The following instructions provide step-by-step instructions on viewing
resources used by the MPAC-100 in Windows 95/98 using the "Device Manager"
utility.
1. Double click the "System" icon inside the Control Panel folder. This opens up
the System Properties box.
2. Click the "Device Manager" tab located along the top of the System Properties
box.
3. Double click the device group "Synchronous_Communication". The MPAC-100
model name should appear in the list of adapters.
4. Double click the MPAC-100 model name and a properties box should open for
the hardware adapter.
5. Click the "Resources" tab located along the top of the properties box to view the
Quatech MPAC-100 User's Manual
13
resources Windows has allocated for the MPAC-100 match the hardware
configuration. Click "Cancel" to exit without making changes.
6. If changes to the automatic configuration are necessary for compatibility with
existing programs, uncheck the "Use Automatic Settings" box and double-click
on the Resource Type that needs to be changed. Caution should be used to
avoid creating device conflicts with other hardware in the system.
4 Other Operating Systems
Quatech MPAC-100 User's Manual
14
Device drivers for Windows NT and OS/2 are also available for the MPAC-100.
The board can be used under DOS and other operating systems as well in many
circumstances. The software described below can be downloaded from the Quatech
web site if it did not come with the board.
4.1 Windows NT
The Windows NT device driver is installed by running the SETUP program. Up
to 256 serial ports are supported. There is a command line-based configuration utility
which is used for adding PCI bus and ISA bus serial ports. Please refer to the
documentation included with the device driver for full installation and configuration
details.
4.2 OS/2
The OS/2 device driver supports up to 32 serial ports in a system. Installation is
a manual, but simple, process. Please refer to the documentation included with the
device driver for full installation and configuration details.
4.3 DOS and other operating systems
The MPAC-100 is not a direct drop-in replacement for a legacy serial port
because its base address and IRQ cannot be fixed at values such as 3F8 hex, IRQ 4
(COM1) or 2F8 hex, IRQ 3 (COM2), etc. Rather, the system BIOS assigns the address
and the IRQ in a plug-and-play fashion at boot time. Software which is to use the
MPAC-100 must be able to accommodate any valid assignments of these resources.
For Windows 95, Windows NT and OS/2, the Quatech device drivers determine
what the resource assignments are and proceed accordingly. In other cases, however,
the user must intervene. The discussion below will center on DOS, but the concepts
can be applied to other operating systems as well.
Many DOS applications support user configuration of the base address and IRQ
of a serial port. Such applications can generally make use of the MPAC-100. Older
applications, as well as some custom software, may use hard-coded standard legacy
serial port addresses. These applications will require modifications if they are to use
the MPAC-100.
Custom applications for which the customer has source code can be modified to
make just a few PCI BIOS function calls to obtain all the necessary configuration
information. The PCI BIOS specification can be
obtained from the PCI Special Interest Group. Contact Quatech technical support for
more information.
4.4 QTPCI.EXE
Quatech's "QTPCI" utility supplies the information required when modifying
Quatech MPAC-100 User's Manual
15
the serial port settings of the application. This program should be run from real DOS,
not in a Windows DOS box.
Figure 13 shows the Basic Mode display for the MPAC-100 after the "Q" key has
been pressed. In this example, the MPAC-100 uses I/O base address FF80 hex and IRQ
11. The hardware revision of the MPAC-100 is also displayed. Pressing the "N" key
will show similar information for all non-Quatech PCI devices in the system, including
those devices integrated on the motherboard.
The QTPCI program is capable only of displaying the PCI configuration. It cannot
Quatech MPAC-100 User's Manual
16
be used to make changes.
Quatech PCI Configuration Information Display Software
Version 1.03
INSTRUCTIONS:
-----------------------Press keys listed in the menu at the bottom of the screen.
This program only displays information. It cannot make changes.
Numbers preceeded by "0x" are hexadecimal.
PCI BIOS detected, version 2.10
Quatech PCI adapters detected
--------------------------------------------MPAC-100 Single Port Synch RS-232 Serial Adapter (Hardware Revision A1)
Uses IRQ 12
Base addr 1 = 0xD800 I/O
_
Q - Quatech PCI adapters
N - Other PCI devices
X - EXIT
Figure 14 --- QTPCI.EXE Basic Mode display
Figure 14 shows the Expert Mode display for the MPAC-100 after the "Q" key
has been pressed. The information from the Basic Mode display is presented along
with more details such as the Vendor and Device IDs, PCI Class Code, size of memory
M - Change to Expert Mode
and I/O regions, etc. Pressing the "N" key will show similar information for all
Quatech MPAC-100 User's Manual
17
non-Quatech PCI devices in the system, including those devices integrated on the
motherboard. In this example, the "Base addr 0" resource is reserved.
For users interested in even more details, PCI BIOS information can be
displayed by pressing the "B" key. Pressing the "I" key displays the PCI interrupt
routing table.
Quatech PCI Configuration Information Display Software
Version 1.00
Quatech PCI adapters detected
---------------------------------------------
MPAC-100 Single Port Synch RS-232 Serial Adapter
Vendor ID 0x135c, Device id 0x00F0 found in slot 0x04 on bus 0x00
Device/function code = 0x48, Revision ID = 0x01 (Hardware revision A1)
PCI Class Code = 0xff0000
Subsystem Vendor ID 0x135c, Subsystem Id 0x00F0
INTA# mapped to IRQ 12 (route 0x04)
Base addr 0 = 0xe000 I/O 0X80 bytes allocated
Base addr 1 = 0xd800 I/O 0X10 bytes allocated
_
Q - Quatech PCI adapters
N - Other PCI devices
X - EXIT
Figure 15 --- QTPCI.EXE Expert Mode display
M - Change to Basic Mode
B - PCI BIOS details
I - Interrupt routing details
5 Using the MPAC-100 with Syncdrive
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Syncdrive is a synchronous communications software driver package designed
to aid users of Quatech synchronous communication hardware in the development of
their application software. Syncdrive is included free of charge with all Quatech
MPA-series synchronous communication products. The MPAC-100 is
backward-compatible with software written for Quatech ISA-bus synchronous adapters
and it operates with Syncdrive.
Syncdrive, however, is not aware of the plug-and-play nature of PCI cards. A
Syncdrive application will expect to see the MPAC-100 at a specific base address and a
specific IRQ. When using Syncdrive with PCI cards, it is necessary to obtain the base
address and IRQ assigned to the card by using the QTPCI.EXE software utility
previously discussed.
For DOS, Windows 3.1, or OS/2, QTPCI.EXE must be used to obtain the base
address and IRQ needed by the Syncdrive application before the application tries to
use the card.
Under Windows 95/98, the card is automatically configured. To find the
settings, click the right mouse button on the My Computer icon and select Properties.
Select the Device Manager tab and double-click the card's entry under the "Synchronous
Communication" section. Select the Resources tab to see the card's base address and
IRQ. Use these settings with the Syncdrive application. Windows 95/98 may allow
changes to the settings if the "Use Automatic Settings" box is unchecked.
Syncdrive does not receive notifications of card insertion or card
removal events. Therefore it cannot support hot swapping without the user taking
some kind of action to force the Syncdrive application to initialize a newly-inserted
card.
A future release of Syncdrive may permit automatic configuration by retrieving
hardware settings from the MPAC-100. For now, the user should consider the
QTPCI.EXE program, it reflects the location (base address and IRQ) the card is in before
the Syncdrive application is started.
6 Addressing
Reserved
Base + E
Receive FIFO Timeout Register
Base + D
FIFO Control Register
Base + A
FIFO Status Register
Base + 9
Reserved
Base + 6
Configuration Register
Base + 5
SCC Data Port, Channel B
Base + 2
SCC Control Port, Channel A
Base + 1
Register Description
Address
Quatech MPAC-100 User's Manual
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The MPAC-100 occupies a continuous 16-byte block of I/O addresses. For
example, if the base address is set to 300 hex, then the MPAC-100 will occupy address
locations 300 hex to 30F hex. If the computer in which the MPAC-100 is installed is
running PCI Card and Socket Services, the base address is set by the client driver. If
PCI Card and Socket Services are not being used, the base address is set by the
MPAC-100 enabler program.
The first four bytes of address space on the MPAC-100 contain the internal
registers of the SCC. Other Quatech architecture-specific registers occupy eight more
bytes. The remainder of the address space is reserved for future use. The MPAC-100
address map is shown in Table 2.
SCC Data Port, Channel ABase + 0
SCC Control Port, Channel BBase + 3
Communications RegisterBase + 4
ReservedBase + 7
Interrupt Status RegisterBase + 8
Receive Pattern Character RegisterBase + B
Receive Pattern Count RegisterBase + C
ReservedBase + F
Table 2 --- MPAC-100 Address Assignments
Information on the internal registers of the SCC can be found in Table 3 and
Table 4 and in the technical reference manuals available from Zilog. The other onboard
registers are fully described in subsequent chapters of this manual.
7 Interrupts
Quatech MPAC-100 User's Manual
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The MPAC-100 will operate using the interrupt level (IRQ) assigned by the PCI
system. Interrupts can come from the SCC, the internal FIFOs or RS-232 test mode. The
interrupt source is selected by bits 4 and 5 of the Configuration Register (see page 41).
When using interrupts with the MPAC-100, the application must have an
interrupt service routine (ISR). There are several things that an ISR must do to allow
proper system operation:
1. If the internal FIFOs are enabled, read the Interrupt Status Register (see page 43)
to determine whether the interrupt was caused by a FIFO event or by the SCC.
2. If the TX_FIFO bit is set, at least 512 bytes can be written to the Tx FIFO. If the
RX_FIFO bit is set, at least 512 bytes can be read from the Rx FIFO. I/O block
move instructions may be useful. Check the FIFO Status Register (see page 44)
after servicing the FIFO(s) to see if further FIFO service is required.
3. If the SCC bit is set, do an SCC software interrupt acknowledge by reading Read
Register 2 in channel B of the SCC. The value read can also be used to vector to
the appropriate part of the ISR.
4. Service the SCC interrupt by reading the receiver buffer, writing to the transmit
buffer, issuing commands to the SCC, etc.
5. Write a Reset Highest Interrupt Under Service (IUS) command to the SCC by
writing 0x38 to Write Register 0.
6. Check for other interrupts pending in the SCC by reading Read Register 3.
Perform further interrupt servicing if necessary.
7. For applications running under DOS, a nonspecific End of Interrupt must be
submitted to the interrupt controller. For Interrupts 2-7 this is done by writing a
0x20 to port 0x20. For Interrupts 10-12, 14 and 15 this is done by writing a 0x20
to port 0x60, then a 0x20 to port 0x20 (due to the interrupt controllers being
cascaded). Device drivers running under other operating systems may have
varying requirements concerning the End of Interrupt command.
For further information on these subjects or any others involving the SCC contact
Zilog for a complete technical manual.
8 SCC General Information
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21
The Serial Communications Controller (SCC) is a dual channel, multi-protocol
data communications peripheral. The MPAC-100 provides a single channel for
communications, however, portions of the second channel can be utilized to support
some special circumstances. The SCC can be configured to satisfy a wide variety of
serial communications applications. Some of its protocol capabilities include:
SDLC/HDLC (Bit Synchronous) Communications
Abort sequence generation and checking
Automatic zero insertion and deletion
Automatic flag insertion between messages
Address field recognition
I-field residue handling
CRC generation and detection
SDLC loop mode with EOP recognition/loop entry and exit
Byte-oriented Synchronous Communications
Internal/external character synchronization
1 or 2 sync characters in separate registers
Automatic Cyclic Redundancy Check (CRC) generation/detection
Asynchronous Communications
5, 6, 7, or 8 bits per character
1, 1-1/2, or 2 stop bits
Odd, even, or no parity
Times 1, 16, 32, or 64 x clock modes
Break generation and detection
Parity, overrun and framing error detection
NRZ, NRZI, or FM encoding/decoding
8.1 Accessing the registers
Quatech MPAC-100 User's Manual
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The mode of communication desired is established and monitored through the
bit values of the internal read and write registers. The register set of the SCC includes
16 write registers and 9 read registers. These registers only occupy four address
locations, which start at the MPAC-100's physical base address that is configured via
the on board switches. This and all other addresses are referenced from this base
address in the form Base+Offset. An example of this is Base+1 for the SCC Control
Port, Channel A.
There are two register locations per SCC channel, a data port and a control port.
Accessing the internal SCC registers is a two step process that requires loading a
register pointer to perform the addressing to the correct data register. The first step is
to write to the control port the operation and address for the appropriate channel. The
second step is to either read data from or write data to the control port. The only
exception to this rule is when accessing the transmit and receive data buffers. These
registers can be accessed with the two step process described or with a single read or
write to the data port. The following examples illustrate how to access the internal
registers of the SCC. Table 3 on page 26 describes the read registers and Table 4 on
page 27 describes the write registers for each channel.
The MPAC-100 has been designed to assure that all back to back access timing
requirements of the SCC are met without the need for any software timing control. The
standard of adding jmp $+2 between I/O port accesses is not required when accessing
the MPAC-100.
Example 1: Enabling the transmitter on channel A.
mov dx, base ; load base address
add dx, ContA ; add control reg A offset (1)
mov al, 05H ; write the register number
out dx, al
mov al, 08H ; write the data to the register
out dx, al
Example 2: Monitoring the status of the transmit and receive buffers in RR0 of
Channel A. Register 0 is addressed by default if no register number is
written to WR0 first.
mov dx, base ; load base address
add dx, ContA ; add control reg A offset (1)
in ax, dx ; read the status
Example 3: Write data into the transmit buffer of channel A.
Lower byte of baud rate time constant
RR12
Miscellaneous status parameters
RR10
MSB of frame byte count and FIFO status register
RR7
LSB of frame byte count register
RR6
Special Receive Condition status, residue codes, error
RR1
Transmit, Receive buffer statuses and external status
RR0
Quatech MPAC-100 User's Manual
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mov dx, base ; load base address
out dx, al ; write data in ax to buffer
Example 4: Read data from the receive buffer of channel A.
mov dx, base ; load base address
in al, dx ; write data in ax to buffer
conditions
RR2
Modified Channel B interrupt vector and Unmodified
Channel A interrupt vector
Interrupt Pending bits RR3
Receive buffer RR8
Upper byte of baud rate time constantRR13
External/Status interrupt information RR15
Table 3 --- SCC read register description
The SCC can perform three basic forms of I/O operations: polling, interrupts,
and block transfer. Polling transfers data, without interrupts, by reading the status of
RR0 and then reading or writing data to the SCC buffers via CPU port accesses.
Interrupts on the SCC can be sourced from the receiver, the transmitter, or
External/Status conditions. At the event of an interrupt, Status can be determined, then
data can be written to or read from the SCC via CPU port accesses. Further information
on this subject is found on page 23. For block transfer mode, DMA transfers are used,
so this type of operation is not supported on the MPAC-100.
The SCC incorporates additional circuitry supporting serial communications.
This circuitry includes clocking options, baud rate generator (BRG), data encoding, and
internal loopback. The SCC may be programmed to select one of several sources to
provide the transmit and receive clocks. These clocks can be programmed in WR11 to
come from the RTxC pin, the TRxC pin, the output of the BRG, or the transmit output of
the DPLL. The MPAC-100 uses the TRxC pin for its clock-on-transmit and the RTxC pin
for its clock-on-receive. Programming of the clocks should be done before enabling the
External/Status interrupt control
WR15
Miscellaneous control bits: baud rate generator, DPLL control,
WR14
Clock mode and source control
WR11
Miscellaneous transmitter/receiver control bits, NRZI, NRZ,
WR10
Special HDLC Enhancement Register
WR7'
Sync character (2nd byte) or SDLC Flag
WR7
Transmitter initialization and control
WR5
Transmit/Receive miscellaneous parameters and codes, clock
WR4
Interrupt control, Wait/DMA request control
WR1
Command Register, Register Pointer, CRC initialization, and
WR0
Quatech MPAC-100 User's Manual
24
receiver, transmitter, BRG, or DPLL.
resets for various modes
Interrupt vectorWR2
Receiver initialization and control WR3
rate, stop bits, parity
Sync character (1st byte) or SDLC address field WR6
Transmit bufferWR8
Master interrupt control and reset WR9
FM coding, CRC reset
Lower byte of baud rate time constant WR12
Lower byte of baud rate time constant WR13
auto echo
Table 4 --- SCC write register description
For complete information regarding the SCC registers please refer to Zilog's
Z85230 technical manual.
8.2 Baud Rate Generator Programming
3FFE
(hex)
16382
300
1FFE
(hex)
8190
600
07FE
(hex)
2046
2400
03FE
(hex)
1022
4800
007E (hex)
126
38400
Time Constant
Baud Rate
Quatech MPAC-100 User's Manual
25
The baud rate generator (hereafter referred to as the BRG) of the SCC consists of
a 16-bit down counter, two 8-bit time constant registers, and an output divide-by-two.
The time constant for the BRG is programmed into WR12 (least significant byte) and
WR13 (most significant byte). The equation relating the baud rate to the time constant
is given below while Table 5 shows the time constants associated with a number of
popular baud rates when using the standard MPAC-100 9.8304 MHz clock.
Time_Const = Clock_Frequency/ 2* Baud_Rate*Clock_Mode
Where: Clock_Frequency = 9.8304 x 10
Clock_Mode = 1, 16, 32, or 64
Baud_Rate = desired baud rate
(for Clock_Frequency = 9.8304 MHz )
Table 5 --- time constants for common baud rates
6
00FE (hex) 25419200
01FE (hex) 5109600
0FFE (hex) 40941200
8.3 SCC Data Encoding Methods
The SCC provides four different data encoding methods, selected by bits 6 and 5
in WR10. These four include NRZ, NRZI, FM1 and FM0. The SCC also features a
digital phase-locked loop (DPLL) that can be programmed to operate in NRZI or FM
modes. Also, the SCC contains two features for diagnostic purposes, controlled by bits
in WR14. They are local loopback and auto echo.
For further information on these subjects or any others involving the SCC contact
Zilog for a complete technical manual.
8.4 Support for SCC Channel B
Quatech MPAC-100 User's Manual
26
The MPAC-100 is a single-channel device. Portions of SCC channel B are used to
augment channel A. Channel B cannot be used for transmit, but may be used for
receive, subject to certain limitations.
8.4.1 Receive data and clock signals
The receive data signals RXDA and RXDB are tied together. The receive clock
input signals RTxCA and RTxCB are also tied together. This can be useful in unusual
applications. It would be possible to run the receiver and transmitter at different baud
rates, using channel B's baud rate generator and receiver for the received data. Of
course, the channel A transmitter and receiver can be run at different speeds simply by
having external data clocks supplied to TRxCA and RTxCA from the cable.
The W/REQB signal is used to generate DMA requests between the SCC and the
internal FIFOs if channel B is used for receive.
8.4.2 Extra clock support for channel A
The TRxCB clock output can be routed back to RTxCA as another way to use the
channel B baud rate generator to derive an independent clock for the channel A
receiver. This is controlled by the RCKEN bit in the Communications Register (see
page 39).
8.4.3 Extra handshaking for channel A
The SCC does not provide a DSR input for either channel. The MPAC-100 routes
the DSR signal from the connector to the DCDB input of the SCC. Software can
therefore use DCDB as a surrogate for DSR on channel A.
8.4.4 Other signals are not used
All channel B signals not listed above are not available at the connector. The
CTSB and SYNCB inputs are tied to their inactive states. The TXDB, DTR/REQB, and
RTSB outputs are left open.
8.5 SCC Incompatibility Warnings
It would be highly irregular for code to be written in
Quatech MPAC-100 User's Manual
27
Due to the SCC implementation used by the MPAC-100, there are two minor
incompatibilities that the software programmer must avoid.
8.5.1 Register Pointer Bits
In a Zilog 85230, the control port register pointer bits can be set in either channel.
With the implementation on the MPAC-100, however, both parts of an SCC control port
access must use the same I/O address.
IMPORTANT
The programmer must be certain not to mix channel
usage during the two-part access of SCC control ports.
The following sequences will work:
Write Control Port A (set pointer bits for desired register)
Read or Write Control Port A (read or write desired channel A register)
Write Control Port B (set pointer bits for desired register)
Read or Write Control Port B (read or write desired channel B register)
The following sequences will NOT work:
Write Control Port A (set pointer bits for desired register)
Read or Write Control Port B (read or write desired channel B register)
Write Control Port B (set pointer bits for desired register)
Read or Write Control Port A (read or write desired channel A register)
8.5.2 Software Interrupt Acknowledge
The 85230's software interrupt acknowledge mechanism is not supported. Bit 5
of Write Register 9 (Software INTACK Enable) is forced to 0. Software must employ the
"Interrupt Without Acknowledge" interrupt method using Read Registers 2 and 3 to
process interrupts.
9 FIFO Operation
Quatech MPAC-100 User's Manual
28
The MPAC-100 is equipped with 1024-byte internal FIFOs in the transmit and
receive data paths. These FIFOs are implemented as extensions of the SCC's small
internal FIFOs. They have been designed to be as transparent as possible to the
software operating the MPAC-100. By using these FIFOs, it is possible to achieve high
data rates despite the MPAC-100 not supporting DMA.
The FIFOs are disabled by default after card insertion, power-up, or a system
reset.
9.1 Enabling and disabling the FIFOs
The FIFOs must be enabled or disabled as a pair. It is not possible to operate
only the transmit FIFO or only the receive FIFO. The FIFOs are enabled by setting bit 2
of the Configuration Register to a logic 1. The FIFOs are disabled by clearing the same
bit.
9.2 Accessing the FIFOs
When the FIFOs are enabled, they are accessed through either the channel A or
channel B SCC Data Port address. Writing to Base+0 or Base+2 will cause a byte to be
written into the transmit FIFO. Reading from Base+0 or Base+2 will cause a byte to be
read from the receive FIFO.
The FIFOs cannot be accessed if they are disabled. If the FIFOs are disabled,
reads or writes of the SCC Data Ports access the receive or transmit register of the
appropriate SCC channel. Any control port writes of SCC write register 8 (transmit
buffer) or control port reads of SCC read register 8 (receive buffer) directly access the
SCC, whether the FIFOs are enabled or not.
9.2.1 Transmit FIFO
The transmit FIFO always services the transmitter of channel A of the SCC. If the
FIFOs are enabled, an I/O write to either SCC Data Port (channel A or channel B) will
write a byte to the transmit FIFO. If the FIFOs are not enabled, an I/O write to the SCC
Data Port will instead write directly to the internal transmit buffer of the specified
channel of the SCC.
9.2.2 Receive FIFO
IMPORTANT
Quatech MPAC-100 User's Manual
29
The receive FIFO can service the receiver of either channel A or channel B of the
SCC. If RXSRC (bit 1) of the Configuration Register (see page 41) is logic 1, the receive
FIFO will service SCC channel B. If RXSRC is logic 0, the receive FIFO will service SCC
channel A.
If the FIFOs are enabled, an I/O read from either SCC Data Port (channel A or
channel B) will read a byte from the receive FIFO. If the FIFOs are not enabled, an I/O
read from the SCC Data Port will instead read directly from the internal receive buffer
of the specified channel of the SCC.
9.3 SCC configuration for FIFO operation
The interface between the SCC and the internal FIFOs uses the SCC's DMA
request functions. The SCC must therefore be configured for DMA operation in order
to use the internal FIFOs. In order to properly configure the SCC, certain bits in various
SCC registers need to be set in a specific manner, as shown on the following pages.
Because the data transfer between the FIFOs and the SCC is controlled entirely
by hardware, per-character transmit and receive interrupts should be disabled.
Interrupts on transmit underruns and/or special receive conditions should usually be
enabled so that end-of-frame conditions can be detected.
The DMA operation described in this
section is between the SCC and the
internal FIFOs, and is handled entirely by
the MPAC-100 hardware.
The MPAC-100 is a single-channel device. Accordingly, most applications will
use SCC channel A for both transmit and receive operations. It is possible, however, to
use a limited portion of SCC channel B for receive operations (see page 29). The
channel used for receive will determine how the SCC must be configured.
Do not enable the FIFOs until the SCC has been properly configured for DMA
operation!
9.3.1 Using channel A for both transmit and receive
Set DTR/REQA for W/REQA timing.
1
4
Enable
WR7A'
.10
WR15A
Enable DMA request-on-transmit on
Enable receive interrupts on special
Use W/REQA for receive.
1
5
Enable DMA request on W/REQA. This bit
Function
Value
Bit(s)
Registe
Quatech MPAC-100 User's Manual
30
This is the mode in which most applications will run. Set RXSRC (bit 1) in the
Configuration Register to logic 0. This will configure the MPAC-100 to use W/REQA
for receive DMA and DTR/REQA for transmit DMA. In addition to any other desired
SCC configuration, ensure that the following bits are set according to Table 6:
r
should be set after the other bits in WR1 are
17
set as desired.
Set W/REQA for DMA Request mode.16
WR1A
4-3
11 or
00
conditions only (recommended), or disable
them completely.
Disable transmit interrupts.01
12WR14A
DTR/REQA.
Assert transmit DMA request when entry
05
WR7A'
location of internal FIFO is empty.
Table 6 --- Configuring the SCC for FIFO use with channel A only
9.3.2 Using channel B for receive
Enable receive interrupts on special
Set W/REQB for DMA Request mode.
16Enable DMA request on W/REQB. This bit
Assert transmit DMA request when entry
Disable DMA request-on-transmit on
Disable transmit interrupts.
01Use W/REQA for transmit.
0
5
Enable DMA request on W/REQA. This bit
Function
Value
Bit(s)
Register
Quatech MPAC-100 User's Manual
31
The MPAC-100 supplies only limited support for SCC channel B. This mode,
therefore, is not recommended for most applications. Set RXSRC (bit 1) in the
Configuration Register to logic 1. This will configure the MPAC-100 to use W/REQA
for transmit DMA and W/REQB for receive DMA. In addition to any other desired
SCC configuration, ensure that the following bits are set according to Table 7:
should be set after the other bits in WR1 are
17
WR1A
set as desired.
Set W/REQA for DMA Request mode.16
02WR14A
DTR/REQA.
Enable WR7A'.10WR15A
WR1B
05WR7A'
location of internal FIFO is empty.
should be set after the other bits in WR1 are
17
set as desired.
Use W/REQB for receive.15
4-3
11 or
00
conditions only (recommended), or disable
them completely.
Table 7 --- Configuring the SCC for Rx DMA on channel B
9.4 FIFO status and control
Table 10
on page
41
for details.
Software can read at
Quatech MPAC-100 User's Manual
32
Several registers are used to control the FIFOs and monitor their status. These
registers are detailed in other chapters of this manual.
9.4.1 Interrupt status
Three interrupt statuses, listed in Table 8, can be generated by four events
related to FIFO activity. In each case, a latched bit in the Interrupt Status Register is set
to a logic 1 (see page 43). These bits are write-clear, meaning that software must write a
1 to a bit in order to clear it.
IMPORTANT
FIFO-related interrupts will occur only when the
MPAC-100 interrupt source is set to INTSCC. See
Event
Transmit FIFO drained
past the half-full mark
Receive FIFO filled
past the half-full mark
Receive data timeout
with non-empty FIFO
Special receive pattern
detected
Table 8 --- FIFO-related interrupt statuses
Interrupt Status
Register Bit
TX_FIFO
(bit 1)
RX_FIFO
(bit 2)
RX_PAT
(bit 3)
Comment
Software can write at
least 512 bytes to the
transmit FIFO.
least 512 bytes from the
receive FIFO.
Software can read bytes
from the receive FIFO
until the FIFO is empty.
Software can read data
from the receive FIFO as
desired.
IMPORTANT
Quatech MPAC-100 User's Manual
33
Software can differentiate between the two types of
RX_FIFO interrupts by examining the RXH bit in
the FIFO Status Register. If RXH is clear (logic 0),
the interrupt occurred because of a timeout.
9.4.2 Resetting the FIFOs
The FIFOs are automatically disabled and reset at powerup or when the
MPAC-100 is inserted into a PCI socket. The transmit and receive FIFOs can also be
independently reset by setting and clearing the appropriate bits in the FIFO Control
Register. Resetting a FIFO sets the appropriate FIFO empty status bit and resets the
FIFO's internal read and write pointers. The SCC's internal FIFOs are not affected when
the internal FIFOs are reset.
The internal FIFOs cannot be reset while they are enabled! FIFO reset
commands will be ignored if the internal FIFOs are enabled.
9.4.3 Reading current FIFO status
The FIFO Status Register is a read-only register which always indicates the
current status of both the transmit and receive internal FIFOs. Each FIFO can be
checked for empty, full, and half-full (or more) status at any time. For details, see Table
12 on page 44.
9.4.4 Controlling the FIFOs
The FIFO Control Register is a read-write register which can be used to reset
either or both the receive and transmit internal FIFOs. Receive pattern detection and
receive FIFO timeout modes are also controlled with this register. For details, see
Table 13 on page 45.
9.5 Accessing the SCC while FIFOs are enabled
The SCC channel A and channel B control port registers are always accessible
regardless of whether the internal FIFOs are enabled or disabled. While the FIFOs are
enabled, SCC data port accesses are redirected to the FIFOs. Access to the SCC's
transmit or receive registers while the FIFOs are enabled is possible indirectly by using
the control port and register 8. Any writes of SCC Write Register 8 (transmit buffer) or
reads of SCC Read Register 8 (receive buffer) will bypass the internal FIFOs.
9.6 Receive pattern detection
NOTE
Quatech MPAC-100 User's Manual
34
The internal FIFOs are most useful in bit-synchronous operational modes
because the SCC can generate a Special Condition interrupt when the closing flag of a
bit-synchronous frame is received. This allows the SCC to run with per-character
receive interrupts disabled while DMA transfers occur between the SCC and internal
FIFOs.
Byte-synchronous modes such as bisync, however, do not benefit from such a
hardware assist for detecting the end-of-frame condition. On the contrary, with
byte-oriented protocols it is usually necessary to check each byte received against a
table of special function codes (e.g. SYNC, PAD, SDI, STX, EDI, ETX, etc.) to determine
where data and frames begin and end. Unless the frames are of a fixed length, it is
therefore difficult to use DMA with byte-synchronous modes. This would seem to
preclude the use of the MPAC-100's internal FIFOs with byte-oriented protocols.
To make the internal FIFOs more useful in byte-synchronous modes, the
MPAC-100 can watch for a given character to be transferred consecutively a specific
number of times from the SCC into the receive FIFO. When this occurs, the RX_PAT bit
in the Interrupt Status Register (see page 43) is set. For instance, the MPAC-100 can
watch for the end-of-text character to be received, or for three consecutive pad
characters to be received.
For byte-synchronous operation with simple unique markers in the data stream,
this feature may be quite useful. Even if it is not, however, the MPAC-100 can certainly
be operated with per-character interrupts enabled and the internal FIFOs disabled. The
tradeoff will be a heavier interrupt burden and possibly somewhat lower throughput.
modes, the receive pattern detection feature
While most useful in byte-synchronous
can be used in any operational mode.
9.7 Receive FIFO timeout
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35
With asynchronous operational modes, the same problem exists. Namely, how
is one to determine when a reception is complete? While the receive pattern detection
may be useful here, the MPAC-100 also offers a timeout feature on the internal receive
FIFO.
If the internal FIFO is not empty and a time interval equal to a specified number
of character-times has elapsed without any further data being received, a receive FIFO
interrupt is generated and RX_FIFO bit in the Interrupt Status Register (see page 43) is
set. A character-time is approximated by counting eight ticks of the bit clock.
To use this feature, the receive clock must be output on TRxCA. It can come
from either an internal source or from the channel A baud rate generator. While the
RTxCA signal is typically used for a receive clock, it is not capable of being an output,
so the TRxCA signal must be used instead. Depending on the application, this may
force the transmit and receive clocks to be the same. For most asynchronous
applications, this should not pose a problem.
10 Communications Register
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
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The Communications Register is used to set options pertaining to the clocks.
The source and type of clock to be transmitted or received can be specified. External
synchronization and RS-232 DTE test modes and can also be controlled with this
register. The address of the Communications Register is Base+4. Table 9 details its bit
definitions.
RLEN
LLENEXTSYNCTM ST
or
SW_SYNC
Table 9 --- Communications Register - Read/Write
Bit 7: TM ST --- Test Mode Status:
This bit can be used to read the status of the Test Mode signal on a DTE,
allowing the user to monitor the signal without generating any interrupts.
00TCKENRCKEN
Bit 6: EXTSYNC --- External Sync Enable:
If this bit is set (logic 1), software-controlled sync is disabled and the
SCC's SYNCA input is driven by the signal coming on pin 10 of the DB-25
connector.
Bit 5: LLEN --- Local Loopback Enable:
When set (logic 1), this bit allows the DTE to test the functioning of the
DTE/DCE interface and the transmit and receive sections of the local
DCE. The DCE device must support local loopback for this to work.
When cleared (logic 0), no testing occurs. LLEN can also be used as a
software-controlled general-purpose output.
Bit 4: RLEN --- Remote Loopback Enable: SW_SYNC
--- Software Sync On:
When the 'C' option is used with the client driver or enabler, this bit
functions as SW_SYNC, otherwise it functions as RLEN.
RLEN ('C' option not used)
If this bit is set (logic 1), the DTE can test the transmission path through
the remote DCE to the remote DTE interface and the return transmission
path. The remote device must support remote loopback for this to work.
When cleared (logic 0), no testing occurs.
SW_SYNC ('C' option is used)
IMPORTANT
(logic 1) simultaneously.
Quatech MPAC-100 User's Manual
37
This bit is used to drive the active-low SYNC input of the channel A
receiver. The SYNC signal is asserted when this bit is set (logic 1), and is
deasserted when this bit is clear (logic 0). This is useful in situations
where it is necessary to receive unformatted serial data, as it allows the
SCC receiver to be manually placed into sync under program control.
This bit is ignored if bit 6 is set (logic 1).
Bit 3: RCKEN --- Receive Clock Source:
When set (logic 1), this bit allows the receive clock (RCLK) signal to be
generated by the TRxC pin on channel B of the SCC. When cleared (logic
0), RCLK is received on pin 17 of the DB-25 connector. In either case,
RCLK is always transmitted on pin 11 of the DB-25 connector.
Bit 2: TCKEN --- Transmit Clock Source:
When set (logic 1), this bit allows the transmit clock (TCLK) to be
generated by the TRxC pin on channel A of the SCC. When cleared (logic
0), the DTE receives TCLK on pin 15 of the DB-25 connector. In either
case, TCLK is always transmitted on pin 24 of the DB-25 connector.
Bits 1-0: Reserved, always 0.
Local Loopback and Remote Loopback cannot be
enabled simultaneously. Bits 5 and 4 of the
Communications Register should therefore not be set
11 Configuration Register
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
INTTM
11INTSCC
0
1
Interrupts disabled
0
0
Quatech MPAC-100 User's Manual
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The Configuration Register is used to set the interrupt source and enable the
interface between the SCC and the internal FIFOs. The address of this register is
Base+5. Table 10 details the bit definitions of the register.
0RXSRCFIFOEN0INTS0INTS101
Table 10 --- Configuration Register - Read/Write
Bit 7: Internal Data FIFOs Present --- Reserved, always 1. This
bit can be used as an indicator that internal data FIFOs are present. Other
MPA-series products that are not equipped with internal or external data
FIFOs will return 0 in this bit location.
Bit 6: Reserved, always 0.
Bits 5-4: INTS1, INTS0 --- Interrupt Source and Enable Bits: These
two bits determine the source of the interrupt. The two sources are
interrupt from the SCC (INTSCC), and interrupt on Test Mode (INTTM).
Only one interrupt source can be active at a time. Below is the mapping
for these bits. Note that FIFO-related interrupts will occur only when
INTSCC is chosen.
Interrupt SourceINTS0INTS1
reserved00
Bit 3: Reserved, always 0.
Bit 2: FIFOEN --- Internal data FIFO enable: If this
bit is set (logic 1), the internal data FIFOs are enabled. If this bit is clear
(logic 0), the internal data FIFOs are disabled. (See page 31 for full details
on FIFO use.)
Bit 1: RXSRC --- Receive FIFO DMA Source: This
RXSRC = 1
RXSRC = 0
Quatech MPAC-100 User's Manual
39
bit determines which SCC pins are used to control transmit and receive
DMA transactions between the SCC and the internal FIFOs (when
enabled). The transmit data FIFO is always used with SCC channel A.
The receive data FIFO may be used with SCC channel A by setting RXSRC
to logic 0, or with SCC channel B by setting RXSRC to logic 1. (See page
29 for information on using channel B.)
Receive
DMA
Transmit
DMA
Bit 0: Reserved, always 0.
W/REQBW/REQA
W/REQADTR/REQA
12 Interrupt Status Register
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
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40
The Interrupt Status Register is used to determine the cause of an interrupt
generated by the MPAC-100. The address of this register is Base+8. Table 11 details
the bit definitions of the register. The interrupt source in the Configuration Register
(see page 41) must be set to INTSCC for any of the statuses indicated by this register
to occur. This register can be ignored if the internal FIFOs are not being used.
SCCTX_FIFORX_FIFORX_PAT0000
Table 11 --- Interrupt Status Register - Read Only/Write Clear
Bits 7-4: Reserved, always 0.
Bit 3: RX_PAT --- Receive Pattern Interrupt: The
receive pattern interrupt occurs when the character set in the Receive
Pattern Character Register is detected 'n' consecutive times in the received
data stream, where 'n' is the value set in the Receive Pattern Count
Register. This bit is set (logic 1) to indicate the interrupt. It remains set
until cleared by writing a '1' to this bit.
Bit 2: RX_FIFO --- Receive FIFO Interrupt:
The receive FIFO interrupt occurs when the number of bytes held in the
internal receive FIFO rises above the half-full mark, or when a receive
FIFO timeout occurs. This bit is set (logic 1) to indicate the interrupt. It
remains set until cleared by writing a '1' to this bit.
Bit 1: TX_FIFO --- Transmit FIFO Interrupt: The
transmit FIFO interrupt occurs when the number of bytes held in the
internal transmit FIFO falls below the half-full mark. This bit is set (logic
1) to indicate the interrupt. It remains set until cleared by writing a '1' to
this bit.
Bit 0: SCC --- SCC Interrupt:
If this bit is set (logic 1), the SCC has generated an interrupt. Software
should clear the interrupt condition by performing appropriate service on
the SCC. This bit is not latched.
13 FIFO Status Register
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Quatech MPAC-100 User's Manual
41
The FIFO Status Register is used to return current status information about the
internal FIFOs. The address of this read-only register is Base+9. Table 12 details the
bit definitions of the register. This register can be ignored if the internal FIFOs are not
being used.
TXETXHTXF0RXERXHRXF0
Table 12 --- FIFO Status Register - Read Only
Bit 7: Reserved, always 0.
Bit 6: RXF --- Receive FIFO Full: This
bit is set (logic 1) when the internal receive FIFO is completely full. The
FIFO will accept no more data from the SCC.
Bit 5: RXH --- Receive FIFO Half Full:
This bit is set (logic 1) while the internal receive FIFO is at least half-full.
Bit 4: RXE --- Receive FIFO Empty:
This bit is set (logic 1) when the internal receive FIFO is completely
empty.
Bit 3: Reserved, always 0.
Bit 2: TXF --- Transmit FIFO Full:
This bit is set (logic 1) when the internal transmit FIFO is completely full.
Further writes to the internal transmit FIFO will be ignored.
Bit 1: TXH --- Transmit FIFO Half Full:
This bit is set (logic 1) while the internal transmit FIFO is at least half-full.
Bit 0: TXE --- Transmit FIFO Empty:
This bit is set (logic 1) when the internal transmit FIFO is completely
empty.
14 FIFO Control Register
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Quatech MPAC-100 User's Manual
42
The FIFO Control Register is used to control the internal data FIFOs. The
address of this register is Base+A (hex). Table 13 details the bit definitions of the
register. This register can be ignored if the internal FIFOs are not being used.
TX_RESET000RX_RESETEN_TOEN_PAT0
Table 13 --- FIFO Control Register - Read/Write
Bit 7: Reserved, always 0.
Bit 6: EN_PAT --- Enable Receive Pattern Detection: Set
this bit (logic 1), to enable the receive pattern detection circuitry. Clear
this bit (logic 0), to disable pattern detection. See page 37 for details on
the receive pattern detection feature.
Bit 5: EN_TO --- Enable Receive Timeout:
Set this bit (logic 1), to enable the internal receive FIFO timeout. Clear this
bit (logic 0), to disable the receive FIFO timeout. See page 38 for details
on the receive FIFO timeout feature.
Bit 4: RX_RESET --- Reset Receive FIFO:
Set (logic 1), then clear (logic 0) this bit to reset the internal receive FIFO.
The FIFO can be reset only when it is disabled.
Bits 3-1: Reserved, always 0.
Bit 0: TX_RESET --- Reset Transmit FIFO:
Set (logic 1), then clear (logic 0) this bit to reset the internal transmit FIFO.
The FIFO can be reset only when it is disabled.
15 Receive Pattern Character Register
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Quatech MPAC-100 User's Manual
43
The Receive Pattern Character Register is used to set the character value to be
used in receive pattern detection. The address of this register is Base+B (hex). This
register can be ignored if the internal FIFOs are not being used.
character value (0-255)
Table 14 --- Receive Pattern Character Register - Read/Write
Bits 7-0: Receive Pattern Character: This is
the numeric value of the character to be detected. See page 37 for details
on the receive character pattern detection feature.
16 Receive Pattern Count Register
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Quatech MPAC-100 User's Manual
44
The Receive Pattern Count Register is used to set the counter value to be used in
receive pattern detection. The address of this register is Base+C (hex). This register can
be ignored if the internal FIFOs are not being used.
counter value (0-255)
Table 15 --- Receive Pattern Count Register - Read/Write
Bits 7-0: Receive Pattern Count:
This value is the number of times that the character stored in the Receive
Pattern Character Register (see page 46) must be consecutively detected
for the receive character pattern detect interrupt to be generated. See page
37 for details on the receive character pattern detection feature.
17 Receive FIFO Timeout Register
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Quatech MPAC-100 User's Manual
45
The Receive FIFO Timeout Register is used to control the operation of the
internal receive FIFO timeout feature. The address of this register is Base+D (hex).
This register can be ignored if the internal FIFOs are not being used. See page 38 for
details on the receive FIFO timeout feature.
timeout interval (0-63)0X16_MODE
Table 16 --- Receive FIFO Timeout Register - Read/Write
Bit 7: X16_MODE --- Clock Mode:
If this bit is set (logic 1), the data clock is divided by 16 (prescaled) before
it is fed to the timeout circuitry. This is useful for asynchronous
operation. If this bit is clear (logic 0), the data clock is not prescaled.
Bit 6: Reserved, always 0.
Bits 5-0: Timeout Interval:
This is the number of character-times that must elapse before a non-empty
internal receive FIFO will trigger a timeout condition. This interval
assumes eight bits per character, so it will be an approximation for modes
running at settings other than eight bits per character.
18 External Connections
Quatech MPAC-100 User's Manual
46
The MPAC-100 is configured as a Data Terminal Equipment (DTE) device,
meeting the RS-232-D standard using a DB-25 male connector. There is no DCE version
available.
The control signals the DTE can generate are Request To Send (RTS) and Data
Terminal Ready (DTR). It can receive the signals Carrier Detect (DCD), Clear to Send
(CTS), and Data Set Ready (DSR). All the control signals are controlled through channel
A of the SCC, with the exception of the DSR signal, which is received on the DCDB pin
on channel B. (The SCC has no actual DSR inputs.)
The DTE can transmit its transmit clock (TCLK) from the TRxCA pin of the SCC,
or receive TCLK on the same pin. The DTE can also receive its receive clock (RCLK) on
the RTxC pins on channels A & B of the SCC, or can generate RCLK using the TRxCB
pin. TCLK and RCLK can also be internally sourced from the channel A baud rate
generator.
Figure 1 shows the DTE clock configuration. On the left are the SCC clock pins
and the clock enable bits from the Communications Register. On the right are the
signals at the DB-25 connector. Figure 2 illustrates the connector pinout.
RTxCA
(RCLK)
RTxCB
TRxCB
RCKEN
TRxCA
(TCLK)
TCKEN
RXCLK (DCE)
RXCLK (DTE)
TXCLK (DTE)
TXCLK (DCE)
Figure 1 --- MPAC-100 Clock Configuration
13
Quatech MPAC-100 User's Manual
47
N/C
N/C
12
RxCLK (DTE)
SYNCA
N/C
DGND
CGND
Figure 2 --- MPAC-100 Output Connector
The testing signals the DTE can generate are Local Loopback (LL) and Remote
Loopback (RL). These signals are asserted with certain bits in the Communications
Register. When a Test Mode (TM) condition is received from the DCE, an interrupt can
optionally be generated.
CD
DSR
CTS
RTS
RxD
TxD
11
10
9
8
7
6
5
4
3
2
1
25
TM (OUTPUT)
24
TxCLK (DTE)
23
N/C
22
RING
21
RLBK (OUTPUT)
20
DTR
19
N/C
18
LLBK (OUTPUT)
17
RxCLK (DCE)
16
N/C
15
TxCLK (DCE)
14
N/C
18.1 5V fuse (pin 9)
Pin 9 will have a 5volt fuse tied to VDD on the other end. This is compatible
with the MPAP-100 series cards.
18.2 SYNCA (pin 10)
If EXTSYNC (bit 6) in the Communications Register is set to a logic 1, the SYNCA
signal from the connector is used to drive the active-low SYNC input of SCC channel A.
The signal is inverted by the RS-232 receiver, so a positive voltage on pin 10 will assert
SYNCA. The SCC must be specifically programmed to recognize external
synchronization.
18.3 RING (pin 22)
If Card and Socket Services has set the SIGCHG bit in the PCI Configuration
* Not included in the official RS-232-D specification
TRxCA pin
DA
TXCLK
(DTE)
X24N/C
23
Comm. Reg. bit 4
RL
RLBK
X21DTR/REQ
A pin
CD
DTR
X
20
Comm. Reg. bit 5
LL
LLBK
X18RTxCA pin
DD
RXCLK
(DCE)
X
17
TRxCA pin
DB
TXCLK
(DCE)
X15N/C
14
N/C
12
RTxCA or TRxCB pin
*
RXCLK
(DTE)
X
11
N/C
9
DCDA pin
CFCDX
8
DCDB pin
CC
DSR
X6CTSA pin
CB
CTS
X
5
RxDA pin
BB
RXD
X3TxDA pin
BA
TXD
X
2
RS-232-D
From
To
Quatech MPAC-100 User's Manual
48
Status Register to a logic 1, the RING signal is routed to the STSCHG line on the PCI
bus. The signal is inverted by the RS-232 receiver, so a positive voltage on pin 22 will
assert STSCHG.
Table 17 shows the pin configuration of the MPAC-100 DTE connector. The
definitions of the interchange circuits according to the RS-232-D standard can be found
starting on page 52.
Pin
DTE
DTE
Signal
CGND1
N/C13
N/C16
Circuit
ABDGND7
SCC Pin or Register Bit
RTSA pinCARTSX4
SYNCA pin*SYNCAX10
N/C19
Table 17 --- Connector Pin Definitions
PCI STSCHG signalCERINGX22
Comm. Reg. bit 7TMTEST MODEX25
18.4 Null-modem cables
Quatech MPAC-100 User's Manual
49
The MPAC-100 does not use a standard asynchronous PC serial port connector
pinout. Typical off-the-shelf null-modem cables cannot be used with this card!
19 DTE Interface Signals
Quatech MPAC-100 User's Manual
50
CIRCUIT AB - SIGNAL GROUND
CONNECTOR NOTATION: DGND
DIRECTION: Not applicable
This conductor directly connects the DTE circuit ground to the DCE circuit
ground.
CIRCUIT BA - TRANSMITTED DATA
CONNECTOR NOTATION: TXD
DIRECTION: To DCE
This signal transfers the data generated by the DTE through the communication
channel to one or more remote DCE data stations.
CIRCUIT BB - RECEIVED DATA
CONNECTOR NOTATION: RXD
DIRECTION: From DCE
This signal transfers the data generated by the DCE, in response to data channel
line signals received from a remote DTE data station, to the DTE.
CIRCUIT CA - REQUEST TO SEND
CONNECTOR NOTATION: RTS
DIRECTION: To DCE
This signal controls the data channel transmit function of the local DCE and, on a
half-duplex channel, the direction of the data transmission of the local DCE.
CIRCUIT CB - CLEAR TO SEND
CONNECTOR NOTATION: CTS
DIRECTION: From DCE
This signal indicates to the DTE whether the DCE is conditioned to transmit data
on the communication channel.
CIRCUIT CC - DCE READY (DATA SET READY)
Quatech MPAC-100 User's Manual
51
CONNECTOR NOTATION: DSR
DIRECTION: From DCE
This signal indicates the status of the local DCE by reporting to the DTE device
that a communication channel has been established.
CIRCUIT CD - DTE READY (DATA TERMINAL READY)
CONNECTOR NOTATION: DTR
DIRECTION: To DCE
This signal controls the switching of the DCE to the communication channel. The
DTE will generate this signal to prepare the DCE to be connected to or removed
from the communication channel.
CIRCUIT CE - RING INDICATOR
CONNECTOR NOTATION: RING
DIRECTION: From DCE
This signal indicates that a ringing signal is being received on the
communication channel.
CIRCUIT CF - RECEIVED LINE SIGNAL DETECT (CARRIER DETECT)
CONNECTOR NOTATION: CD
DIRECTION: From DCE
This signal indicates to the DTE whether the DCE is conditioned to receive data
from the communication channel, but does not indicate the relative quality of the
data signals being received.
CIRCUIT DA - TRANSMIT SIGNAL ELEMENT TIMING (DTE SOURCE)
CONNECTOR NOTATION: TXCLK (DTE)
DIRECTION: To DCE
This signal, generated by the DTE, provides the DCE with element timing
information pertaining to the data transmitted by the DTE. The DCE can use this
information for its received data.
CIRCUIT DB - TRANSMIT SIGNAL ELEMENT TIMING (DCE SOURCE)
Quatech MPAC-100 User's Manual
52
CONNECTOR NOTATION:TXCLK (DCE)
DIRECTION: From DCE
This signal, generated by the DCE, provides the DTE with element timing
information pertaining to the data transmitted to the DCE. The DCE can use this
information for its received data.
CIRCUIT DD - RECEIVER SIGNAL ELEMENT TIMING (DCE SOURCE)
CONNECTOR NOTATION: RXCLK (DCE)
DIRECTION: From DCE
This signal, generated by the DCE, provides the DTE with element timing
information pertaining to the data transmitted by the DCE. The DTE can use this
information for its received data.
CIRCUIT LL - LOCAL LOOPBACK
CONNECTOR NOTATION: LLBK
DIRECTION: To DCE
This signal provides a means whereby a DTE may check the functioning of the
DTE/DCE interface and the transmit and receive sections of the local DCE.
CIRCUIT RL - REMOTE LOOPBACK
CONNECTOR NOTATION: RLBK
DIRECTION: To DCE
This signal provides a means whereby a DTE or a facility test center may check
the transmission path up to and through the remote DCE to the DTE interface
and the similar return transmission path.
CIRCUIT TM - TEST MODE
CONNECTOR NOTATION: TEST MODE
DIRECTION: From DCE
This signal indicates to the DTE that the DCE is in a test condition. The DCE
generates this signal when it has received a local loopback or remote loopback
signal from the DTE.
20 PCI Resource Map
Quatech MPAC-100 User's Manual
53
Listed below are the PCI resources used by the MPAC-100. Such information
may be of use to customers writing their own device drivers or other custom software.
(all numbers in hex)
PCI Vendor ID: 0x135C Quatech, Inc.
PCI Device ID: 0x00F0 MPAC-100
PCI Class Code
Base class: 0xFF Undefined Class
Subclass: 0x00
Interface: 0x00
IRQ sourced by: INTA#
Base address 0: 0x80 bytes I/O Reserved region
Base address 1: 0x10 bytes I/O MPAC-100 I/O Address Space
21 Specifications
Quatech MPAC-100 User's Manual
54
Bus interface: PCI, 32-bit bus, 5 volt only
AMCC 5920 PCI Controller
Physical Dimensions: approx. 4.5” x 2.5”
Controller: Zilog Z85230 20-MHz Serial
Communications Controller (SCC)
DTE Interface: Male D-25 connector
5 volt fuse on pin 9
Transmit drivers: SP211HB RS-232 compatible,
600 kbps typical maximum data rate
Receive buffers: SP211HB RS-232 compatible,
600 kbps typical maximum data rate
I/O Address range: Sixteen-byte contiguous range required,
determined by PCI system
Interrupt levels: One IRQ required, determined by
PCI system
DMA channels: Not supported by PCI bus
Power requirements: 115 mA at +5 volts, typical
MPAC-100 User's Manual
Revision 1.01
June 2001
P/N 940-0090-220
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