Datasheet DP83905AVQB Datasheet (NSC)

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Page 1

PRELIMINARY

November 1995

DP83905 AT/LANTIC AT Local Area Network Twisted-Pair Interface Controller

DP83905 AT/LANTIC

AT Local Area Network Twisted-Pair Interface Controller

General Description

The AT/LANTIC AT Local Area Network Twisted-pair Interface Controller is a CMOS VLSI device designed for easy implementation of CSMA/CD local area networks.

Unique to the AT/LANTIC is the integration of the entire bus interface for PC-AT bus based systems. Hardware and software selectable options allow the AT/LANTIC’s bus interface to be configured software compatible to either an NE2000 or Ethercard

PLUS16

. All bus drivers and control logic are integrated

to reduce board cost and area.

Supported network interfaces include 10BASE5 or 10BASE2 Ethernet via an external transciever connected to its AUI port, and Twisted-pair Ethernet (10BASE-T) using the on-board transceiver. The AT/LANTIC provides the Ethernet Media Access Control (MAC), Encode-Decode (ENDEC) with an AUI interface, and 10BASE-T transceiver functions in accordance with the IEEE 802.3 standards.

The AT/LANTIC’s integrated 10BASE-T transceiver fully complies with the IEEE standard.This functional block incorporates the receiver, transmitter, collision, heartbeat, Ioopback, jabber, and link integrity blocks as defined in the standard. The transceiver when combined with equalization resistors, transmit/receive filters, and pulse transformers provides a complete physical interface from the AT/LANTIC Controller’s ENDEC module and the twisted pair medium.

ISA (Industry Standard Architecture)

(Continued)

Features

Controller and integrated bus interface solution for IEEE

802.3, 10BASE5, 10BASE2, and 10BASE-T

Software compatible with try standard Ethernet Adapters

Selectable buffer memory size

No external bus logic or drivers

Integrated controller, ENDEC, and transceiver

Full IEEE 802.3 AUI interface

Single 5V supply

10BASE-T TRANSCEIVER MODULE:

Integrates transceiver functionality: Ð Transmitter and receiver functions Ð Collision detect, heartbeat and jabber Ð Selectable link integrity test or link disable Ð Polarity Detection/Correction

ENDEC MODULE:

10 Mbit/s Manchester encoding/decoding

Squelch on receive and collision pairs

MAC/CONTROLLER MODULE:

Software compatible with DP8390, DP83901, DP83902

Efficient buffer management implementation

NovellÉ’s NE2000/Plus

indus-

1.0 System Diagram

TL/F/11498– 1

TRI-STATEÉis a registered trademark of National Semiconductor Corporation.

AT/LANTIC PC-AT Novell EtherCard PLUS

1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.

is a trademark of National Semiconductor Corporation.

is a registered trademark of International Business Machines Corp.

is a registered trademark of Novell, Inc.

and EtherCard PLUS 16TMare trademarks of Standard Microsystems Corp.

TL/F/11498

Page 2

General Description (Continued)

The integrated ENDEC module allows Manchester encoding and decoding via a differential transceiver and phase lock Ioop decoder at 10 Mbit/sec. Also included are a collision detect translator and diagnostic loopback capability. The ENDEC module interfaces directly to the transceiver module, and also provides a fully IEEE compliant AUI (Attachment Unit Interface) for connection to other media transceivers.

Table of Contents

1.0 SYSTEM DIAGRAM

1.1 Connection Diagram

2.0 PIN DESCRIPTION

3.0 SIMPLIFIED APPLICATION DIAGRAM

4.0 FUNCTIONAL DESCRIPTION

4.1 Bus Interface Block

4.2 Power on RESET operation

4.3 EEPROM Operation

4.4 Jumpered and Jumperless Operation Support

4.5 Low Power Operation

4.6 Boot PROM Operation

4.7 DP8390 Core (Network Interface Controller)

4.8 Twisted Pair Interface Module

4.9 Encoder/Decoder (ENDEC) Module

The Media Access Control function which is provided by the Network Interface Control module (NIC) provides simple and efficient packet transmission and reception control by means of off-board memory which can be accessed either through an I/O port or mapped into the system memory.

AT/LANTIC Controller provides a comprehensive solution for 10BASE-T IEEE 802.3 networks. Due to the inherent constraints of CMOS processing, isolation is required at the AUI differential signal interface for 10BASE5 and 10BASE2 applications.

5.0 REGISTER DESCRIPTIONS

5.1 Configuration Registers

5.2 Shared Memory Mode Control Registers

5.3 NIC Core Registers

5.4 DP8390 Core DMA Registers

6.0 OPERATION OF AT/LANTIC CONTROLLER

6.1 Transmit/Receive Packet Encapsulation/ Decapsulation

6.2 Buffer Memory Access Control (DMA)

6.3 Packet Reception

6.4 Packet Transmission

6.5 Loopback Diagnostics

6.6 Memory Arbitration and Bus Operation

6.7 Functional Bus Timing

7.0 PRELIMINARY ELECTRICAL CHARACTERISTICS

8.0 PRELIMINARY SWITCHING CHARACTERISTICS

9.0 AC TIMING TEST CONDITIONS

Page 3

1.0 System Diagram (Continued)

1.1 CONNECTION DIAGRAM

Order Number DP83905AVQB

See NS Package Number VUL160A

TL/F/11498– 2

Page 4

2.0 Pin Description

Pin No. Pin Name Type* Description

ISA BUS INTERFACE PINS

94–97 SA0–SA1 9 I LATCHED ADDRESS BUS: Low-order 20 bits of the system’s 24 bit address bus. 99–106 TTL 108–115

76–82 LA17–LA23 I UNLATCHED ADDRESS BUS: High order 7 bits of the 24-bit system address bus.

127, 128, SD0–SD15 I/O SYSTEM DATA BUS: 16-bit system data bus. Used to transfer data between the 130, 131, 3SH 133, 134, 136, 137, 73, 72, 70, 69, 67, 66, 64, 63

88 BALE I BUS ADDRESS LATCH ENABLE: This signal indicates when the system address

83 SBHE I SYSTEM BUS HIGH ENABLE: This signal indicates that the system expects a

86 M16 O 16-BIT MEMORY TRANSFER: In 16-bit shared memory mode this signal indicates

84 IO16 O 16-BIT I/O TRANSFER: In I/O mode this signal indicates that the AT/LANTIC

74 MWR I MEMORY WRITE STROBE: Strobe from system to write to AT/LANTIC Controller’s

75 MRD I MEMORY READ STROBE: Strobe from system to read from AT/LANTIC Controller’s

119, SMRD &ILOW MEMORY STROBES: In Memory mode these signals strobe memory transfers 120 SMWR

118 IOWR I I/O WRITE STROBE: Strobe from system to write to the AT/LANTIC Controller’s I/O

117 IORD I I/O READ STROBE: Strobe from system to read from the AT/LANTIC Controller’s

126 RESET I RESET: This signal is output by the system to reset all devices on the bus.

*Driver Types are: IeInput, OeOutput, I/OeBi-directional Output, OCHeOpen Collector, 3SHeTRI-STATE Output, TTLeTTL Compatible, AUI Attachment Unit Interface, TPIeTwisted Pair Interface, LEDeLED Drive, MOSeCMOS Level Compatible, XTALeCrystal.

These lines are enabled onto the bus, by the system, when BALE is high and are Iatched when BALE returns Iow. These bits are used to decode accesses to the AT/LANTIC Controller’s I/O map and to the boot PROM. In addition they are used to decode accesses to the AT/LANTIC Controller’s memory in shared memory mode.

These Iines are valid on the falling edge of BALE. These bits are used to decode

TTL

accesses to the AT/LANTIC Controller’s memory in shared memory mode.

system and the AT/LANTIC Controller.

lines are valid.

TTL

transfer on the upper byte lane.

TTL

that the AT/LANTIC Controller has decoded an address within the 128 kbyte space

OCH

that it occupies part of.

Controller is responding to a 16-bit I/O access by driving 16-bits of data on the bus.

OCH

memory map.

TTL

to operate correctly

memory map.

TTL

to operate correctly

in the same manner as MRD

TTL

This pin should be connected to allow the CHRDY fix in 16-bit I/O mode

. (See Section 6.0)

This pin should be connected to allow the CHRDY fix in 16-bit I/O mode

. (See Section 6.0)

and MWR except that these signals only occur if the access is to the lowest 1 Megabyte. This partial address decode means that these signals can be used in an 8-bit slot to properly decode an access to this area.

AT/LANTIC Controller will use MRD

and SMWR in Memory mode when DWID is low (8-bit mode).

SMRD

SMWR

are also used to access the BOOT PROM.

map.

TTL

I/O map.

TTL

and MWR in 16-bit Memory mode and will use

TTL

The

SMRD and

Page 5

2.0 Pin Description (Continued)

Pin No. Pin Name Type* Description

ISA BUS INTERFACE PINS (Continued)

123 CHRDY O CHANNEL READY: This signal is used to insert wait states into system accesses.

122 AEN I DMA ACTIVE: This signal indicates that the system’s DMA controller has control

89–92 INT0–3 O INTERRUPT REQUEST: The operation of these 4 outputs is determined by the

61 DWID I DATA WIDTH: This input specifies whether the AT/LANTIC Controller is

93 lSACLK I ISA CLOCK: Clock from ISA bus. This signal is only required if CHRDY timing has

NETWORK INTERFACE PINS

156–153 TXOda, TXOb,OTWISTED PAIR TRANSMIT OUTPUTS: These high drive CMOS level outputs

, TXOd

TXO

150, 151 RXIa, RXI

141, TX 142 TX

145, RX 146 RX

147, CD 148 CD

b a

5 TXLED O TRANSMIT: An open-drain active Iow output. It is asserted for approximately

4 RXLED O RECEIVE: An open-drain active low output. It is asserted for approximately 50 ms

3 COLED O COLLISION: An open-drain active Iow output. It is asserted for approximately 50

1 GDLNK O GOOD LINK: An open-drain active low output. This pin operates as an output to

2 POLED O POLARITY: An open-drain active low output. This signal is normally inactive.

OCH

of the bus.

TTL

Configuration registers. They can either be used to directly drive the interrupt lines

3SH

or used as a 3-bit code with a strobe to generate up to 8 interrupts.

interfacing to an 8- or 16-bit ISA bus. When high it is in 16-bit mode. It has an

MOS

internal pull-down resistor.

to be altered, by changing the CHRDY bit of Configuration Register B.

TTL

are resistively combined external to the chip to produce a differential output signal

TPI

with equalization to compensate for Intersymbol Interference (lSI) on the twisted pair medium.

I TWISTED PAIR RECEIVE INPUTS: These inputs feed a differential amplifier

which passes valid data to the ENDEC module.

TPI

O AUI TRANSMIT OUTPUT: Differential driver which sends the encoded data to the

transceiver. The outputs are source followers which require 270X pull-down

AUI

resistors.

I AUI RECEIVE INPUT: Differential receive input pair from the transceiver.

AUI

I AUI COLLISION INPUT: Differential collision pair input from the transceiver.

AUI

50 ms whenever the AT/LANTIC Controller transmits data in either AUI or TPI

LED

modes.

whenever receive data is detected in either AUI or TPI mode.

LED

ms whenever the AT/LANTIC Controller detects a collision in either AUI or TPI

LED

modes.

display link integrity status if this function has not been disabled by the GDLNK bit

LED

in Configuration Register B.

This output is off if the AT/LANTIC Controller is in AUI mode or if link testing is enabled and the link integrity is bad (i.e. the twisted pair link has been broken). This output is on if the AT/LANTIC Controller is in Twisted Pair Interface (TPI) mode, link integrity checking is enabled and the link integrity is good (i.e. the twisted pair link has not been broken) or if the link testing is disabled.

When the TPI module detects seven consecutive link pulses or three consecutive

LED

received packets with reversed polarity POLED

is asserted.

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2.0 Pin Description (Continued)

Pin No. Pin Name Type* Description

NETWORK INTERFACE PINS (Continued)

7 X1 (OSCIN) I CRYSTAL OR EXTERNAL OSCILLATOR INPUT

8 X2 (OSCOUT) O CRYSTAL FEEDBACK OUTPUT: Used in crystal connections only. Should be left

10 THIN O THIN CABLE: This output is high if AT/LANTIC Controller is configured for thin

EXTERNAL MEMORY SUPPORT

58–50 MSD0–7, I/O, I, O MEMORY SUPPORT DATA BUSÐCONFIGURATION REGISTER A INPUT

CA0–7, MOS DO, DI, SK

48–45 MSD8–15 or I/O, I MEMORY SUPPORT DATA BUSÐCONFIGURATION REGISTER B INPUT: 43-40 CB0– 7 MOS MSD8– 15: When RESET is inactive these pins can be used to access external

31–25, MSA1 –8 or O, I MEMORY SUPPORT ADDRESS BUSÐCONFIGURATION REGISTER C INPUT: 22 CC0 –7 MOS MSA1– 8: When RESET is inactive these pins drive the memory support address

21–15 MSA9–15 O MEMORY SUPPORT ADDRESS BUS: MSA9– 15: When RESET is inactive these

33 MSRD O MEMORY SUPPORT BUS READ: Strobes data from the external RAM into the AT/

32 MSWR O MEMORY SUPPORT BUS WRITE: Strobes data from the AT/LANTIC Controller

37 BPCS O BOOT PROM CHIP SELECT: Selects the boot PROM on the memory support data

XTAL

DCDC

MOS

completely unconnected when using an oscillator module.

cable. It can be used to enable the DC-DC converter required by the thin ethernet configuration.

EEPROM SIGNALS:

MSD0–7: When RESET is inactive these pins can be used to access external memory and boot PROM. CA0–7: When RESET is active Configuration Register A is loaded with the data value on these pins. If the user puts an external pull-up on any of these pins then the corresponding register bit is set to a 1. If the pin is left unconnected then the register bit is 0. DO, DI, SK: When RESET goes from an active to an inactive level AT/LANTIC Controller will read the contents of an EEPROM, using these signals, and load the contents into internal registers. These internal registers will then be mapped into the space taken up by the PROM in the NE2000 and Ethercard PLUS16. After the EEPROM read operation has completed these pins will revert to MSD0 –2 (D0

MSD0, DIeMSD1, SKeMSD2).

memory. CB0–7: When RESET is active Configuration Register B is loaded with the data value on these pins. If the user puts an external pull-up on any of these pins then the corresponding register bit is set to a 1. If the pin is left unconnected then the register bit is 0.

bus. CC0–7: When RESET is active Configuration Register C is loaded with the data value on these pins. If the user puts an external pull-up on any of these pins then the corresponding register bit is set to a 1. If the pin is left unconnected then the register bit is 0.

pins drive the memory support address bus. When the memory is only 8 bits wide A0 will appear on A13, in compatible mode, and on A15, in non-compatible mode.

LANTIC Controller via the memory support data bus.

into the external RAM via the memory support data bus.

bus.

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2.0 Pin Description (Continued)

Pin No. Pin Name Type* Description

EXTERNAL MEMORY SUPPORT (Continued)

36 RCS1 O RAM CHIP SELECT 1: Drives the chip select of the external RAM on the lower half

34 RCS2 O RAM CHIP SELECT 2: Drives the chip select of the external RAM on the upper half

38 EECS O EEPROM CHIP SELECT: Strobes data from the EEPROM onto the memory support

39 EECONFIG I CONFIGURE FROM EEPROM: When this pin is tied high the AT/LANTIC Controller

12 BSCLK I INTERNAL BUS CLOCK: This controls the speed of the NIC core if it is not running

LOW POWER SUPPORT

62 LOWPWR I LOW POWER: Instructs AT/LANTIC Controller to enter its low power mode, as

TEST SUPPORT

11 TEST I TEST: This input is only used for test mode. It should be left unconnected as it has

POWER SUPPLY PINS

160 PLLV

159 PLLGND PLL NEGATIVE (GROUND) SUPPLY PINS

157, 152, PV 144, 143,

139

158, 149, PGND PHYSICAL LAYER NEGATIVE (GROUND) SUPPLY PINS: These pins are the 140, 138

9OV

6 OGND OSCILLATOR NEGATIVE (GROUND) SUPPLY PINS: This pin is the ground to the

59, 49, V 24, 13

60, 54, 44, GND NEGATIVE (GROUND) SUPPLY PINS: These are the supply pins for the 35, 23, 14

132, 121, IFV 107, 87, 68

135, 129, lFGND INTERFACE NEGATIVE (GROUND) SUPPLY PINS: These are the supply pins for 125, 124, 116, 98, 85, 71, 65

of the memory support data bus.

MOS

of the memory support data bus.

MOS

data bus.

MOS

loads the configuration from an EEPROM.

TTL

off of an internal clock (see Configuration Register C). This pin should be tied to

TTL

ground if it is unused.

detailed in Section 4.5. Should be tied to ground for normal operation.

TTL

an internal pull-down resistor which will enable correct operation.

MOS

PLL 5V SUPPLY PINS: This pin supplies 5V to the AT/LANTIC’s analog PLL inside the ENDEC block. To maximize data recovery it is recommended that analog layout and decoupling rules be applied between this pin and PLLGND.

PHYSICAL MEDIA 5V SUPPLY PINS: These pins supply 5V to the AT/LANTIC’s analog physical media interface circuitry.

ground to the AT/LANTIC’s analog physical media interface circuitry.

OSClLLATOR 5V SUPPLY PINS: This pin supplies 5V to the AT/LANTIC’s oscillator and LED circuitry.

AT/LANTIC’s oscillator and LED circuitry.

POSITIVE 5V SUPPLY PINS: These pins supply power to the AT/LANTIC Controller’s logic.

AT/LANTIC Controller’s logic. It is suggested that decoupling capacitors be connected between the V for the GND pins with the lowest possible impedance.

and GND pins. It is essential to provide a path to ground

INTERFACE POSITIVE 5V SUPPLY PINS: These pins supply power to the AT/LANTIC Controller’s ISA interface.

the AT/LANTIC Controller’s ISA interface. It is suggested that decoupling capacitors be connected between the IFV ground for the IFGND pins with the lowest possible impedance.

and IFGND pins. It is essential to provide a path to

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3.0 Simplified Application Diagram

4.0 Functional Description

The AT/LANTIC Controller is a highly integrated and configurable Ethernet controller making it suitable for most Ethernet applications. The AT/LANTIC Controller integrates the functions of the following blocks:

1. DP8390 Ethernet Controller Core and Media Access Control logic.

2. ISA Bus Interface containing all logic required to connect the DP8390 core to a packet buffer RAM and the ISA bus.

3. Media Interface which includes an Encoder/Decoder block with an AUI (Attachment Unit Interface) and a 10BASE-T Twisted Pair Interface.

TL/F/11498– 3

4.1 BUS INTERFACE BLOCK

The AT/LANTIC Controller’s Bus interface block provides the circuitry to interface the Ethernet controller logic, and the external packet buffer RAM to an ISA (Industry Standard Architecture) Bus. The bus interface provides several configuration modes which offer various different features depending on the designer’s specific design requirements. The possible modes are:

1. 16-Bit or 8-Bit Shared Memory Compatible Mode

2. 16-Bit or 8-Bit Shared Memory Enhanced Mode

3. 16-Bit or 8-Bit I/O Port Compatible Mode

4. 16-Bit or 8-Bit I/O Port Enhanced Mode

This section describes the function of each of these modes.

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4.0 Functional Description (Continued)

FIGURE 1. Block Diagram of AT/LANTIC Controller

DETERMINING 8- OR 16-BIT WIDE DATA

AT/LANTIC Controller can treat the system data bus and all internal data busses as 8 or 16 bits wide. 8- or 16-bit mode is determined by the DWlD pin. For an adapter card this bit can be used to automatically detect if the card has been plugged into an 8- or 16-bit slot. If this pin is connected to a V

on the upper connector it will be high when plugged

into a 16-bit slot, enabling 16-bit mode, and floating when plugged into an 8-bit slot. When floating the internal pulldown resistor will enable 8-bit mode.

SHARED MEMORY ARCHITECTURE

FIGURE 2. Shared Memory

TL/F/11498– 5

TL/F/11498– 4

In this mode the AT/LANTIC Controller’s internal memory map, using external RAM devices, is mapped into the host system’s memory map. Both the AT/LANTIC Controller and the host system can directly access this memory. The AT/LANTIC Controller controls the arbitration for this memory area, giving priority to its internal accesses. It also has an internal FIFO to allow for any latency on internal transfers introduced by system accesses. If a system access occurs while an internal access is current the AT/LANTIC Controller will insert wait states into the system cycle until the internal transfer is complete.

In this mode the AT/LANTIC Controller’s internal registers are accessed within the system’s I/O map. The address within this I/O map is set by Configuration Register A. The user programs the address of the shared memory within the host systems memory map by writing to a register in AT/LANTIC Controller. The memory is not accessible by the user until after this register has been programmed.

There are two basic Shared Memory modes, compatible mode, and non-compatible mode, as described in the following text.

Page 10

4.0 Functional Description (Continued)

Shared Memory Compatible Mode I/O Address Mapping

The shared memory is at an address decided by the Address Decode Register and the base I/O address of AT/LANTIC Controller is configured in Configuration Register A. At that address the following structure appears.

Addr D7– 0

00 Control 1

01 AT detect (Read only)

02 Unused

03 Unused

04 Unused

05 Control 2

06 Unused

07 Unused

08 Node addr 0 (Read only)

09 Node addr 1 (Read only)

0A Node addr 2 (Read only)

0B Node addr 3 (Read only)

0C Node addr 4 (Read only)

0D Node addr 5 (Read only)

0E 05h (Read only)

0F Checksum (Read only)

0000H

NIC

registers

(a)

D15 D0

8kx16

Buffer RAM

specified as the PROM space for compatibility with the Ethercard PLUS16. This is actually an array of 8-bit registers which are loaded from an external EEPROM after AT/LANTIC Controller is initialized by a reset pulse. The user should program the EEPROM to contain these values.

The 8k words of memory can be accessed directly by the host system in the same manner as any other memory. Typically the programmer would remove data from this buffer using a ‘‘MOV’’ or ‘‘MOVSW’’ instruction.

8-BIT SHARED MEMORY COMPATIBLE MODE

In this mode the I/O map remains the same. The NIC core can still operate in 16-bit mode, if bit 6 of Control Register 2 is set high and the full 16 kbytes of RAM are still available. However, only 8-bit system accesses are allowed. If bit 6 of Control register 2 is low the NIC core must operate in 8-bit mode and only 8k of memory is available. The NIC Core data width is set by the WTS bit in the Data Configuration Register.

A low cost card, using only one 8 kbyte RAM, can be designed. If the DWlD pin is left unconnected, or tied to GND, then the AT/LANTIC Controller will always operate in 8-bit mode, regardless of the slot the board is in.

If DWID is low the address bits of Control Register 2 should not be written to as they have no effect. In this mode the address comparator assumes that SA19 is to be compared to a logic high, with the other address comparisons programmed into Control Register 1.

SHARED MEMORY NON-COMPATIBLE MODE

These modes are similar to the compatible mode. The difference is that they map a full 64 kbytes of RAM into the PC’s memory address space. The I/O map remains the same.

I/O PORT ARCHITECTURE

4000H

8000H

C000H

FFFFH

FIGURE 3. Shared Memory Mode a) Register

Mapping and b) NIC Core Memory Map

The AT Detect Register indicates whether AT/LANTIC Controller is in an 8- or 16-bit slot. The least significant bit of this register is set high when AT/LANTIC Controller is in 16-bit mode and low in 8-bit mode. Addresses 08H to 10H are

Aliased

Buffer RAM

Aliased

Buffer RAM

Aliased

Buffer RAM

(b)

FIGURE 4. I/O Port

TL/F/11498– 6

This is the architecture used by Novell’s NE2000. In this mode the AT/LANTIC Controller’s internal memory map is accessed byte or word at a time, via a port within the system’s I/O space. AT/LANTIC Controller is programmed by the user to control the transfers between its internal memory and the I/O port.

In this mode the AT/LANTIC Controller’s internal registers and the memory access port are accessed within the system’s I/O map. The address within this I/O map is set by Configuration Register A.

Page 11

4.0 Functional Description (Continued)

16-BIT I/O PORT COMPATIBLE MODE I/O ADDRESS MAPPING

This mode is compatible with Novell’s NE2000. The base I/O address of the AT/LANTIC Controller is configured by Configuration Register A (either upon power up or by software writing to this register). At that address the following structure appears.

Basea00H

DP8390

Core

Registers

Basea0FH

Basea10H

Base

17H

Basea18H

Base

1FH

FIGURE 5. I/O Port Mode Register I/O Map

The registers within this area are 8 bits wide, but the data transfer port is 16 bits wide. The AT/LANTIC Controller’s registers can be programmed to control the passing of data between its internal memory and the data transfer port. By accessing the data transfer port (using I/O instructions) the user can transfer data to or from the AT/LANTIC Controller’s internal memory. The AT/LANTIC Controller’s internal memory map is as shown in

AT/LANTIC Controller actually has a 64k address range but only does partial decoding on these devices. The PROM data is mirrored at all decodes up to 4000H and the entire map is repeated at 8000H. To access either the PROM or the RAM the user must initiate a Remote DMA transfer between the I/O port and memory.

On a remote read the AT/LANTIC Controller moves data from its internal memory map to the I/O port and the host system reads it by using an ‘‘INW’’ or ‘‘INSW’’ instruction from the I/O address of the data transfer port. If the system attempts to read the port before AT/LANTIC Controller has written the next word of data to it AT/LANTIC Controller will insert wait states into the system cycle, using the CHRDY

Data Transfer Port

Reset Port

Figure 6

0000H

001FH

D15 D0

PROM

Aliased PROM

4000H

8kx16

7FFFH

Buffer RAM

8000H

Aliased PROM

C000H

Aliased

FFFFH

Buffer RAM

(a)

D15 D0

1EH 00 57H

1CH 00 57H

00 RESERVED

0AH 00 E’net Address 5

08H 00 E’net Address 4

06H 00 E’net Address 3

04H 00 E’net Address 2

02H 00 E’net Address 1

00H 00 E’net Address 0

(b)

FIGURE 6. a) NIC Core’s Memory Map

b) 16-Bit Prom Map

Page 12

4.0 Functional Description (Continued)

line. AT/LANTIC Controller will not begin the next memory read until the previous word of data has been read.

On a remote write the system writes data to the I/O port, using an ‘‘OUTW’’ or ‘‘OUTSW’’ instruction, and AT/LANTIC Controller moves it to its buffer memory. If the system attempts to write to the port before AT/LANTIC Controller has moved the data to memory AT/LANTIC Controller will insert wait states into the system cycle, using the CHRDY line. AT/LANTIC Controller will not begin the next memory write until a new word has been written to the I/O port.

Addresses 00H to 1FH are specified as the PROM space for compatibility with the NE2000. This is actually an array of 8-bit registers which are loaded from an external EEPROM after AT/LANTIC Controller is initialized by an ISA RESET. They should contain the same data as the PROM did in the NE2000 and in the same format. As can be seen the PROM registers are only 8-bits wide. To transfer the data out the user must initiate a 16-bit DMA read transfer and discard the most significant byte of data on each transfer.

At address 00H of the PROM is a six byte Ethernet address for this node. The upper two addresses of the PROM store contain bytes which identify whether the AT/LANTIC Controller is in 8- or 16-bit mode. For 16-bit mode these bytes both contain the value 57H, for 8-bit mode they both contain 42H.

8-BIT I/O PORT COMPATIBLE MODE

This mode is compatible with the 8-bit mode offered by Novell’s NE2000. The NE2000 automatically detects whether it is in an 8- or 16-bit slot and configures itself appropriately. As explained in the previous paragraphs, the user can determine whether the board is in 8- or 16-bit mode by reading the PROM. In 8-bit mode only 8 kbytes of RAM are addressable, as in the 8-bit mode of the NE2000. The I/O map is the same as the 16-bit mode, the memory map is shown in code, so is mirrored at all addresses up to 4000H. The PROM still occupies 32 bytes of address space, although it only has 16 bytes of data, as the data at all odd address locations is merely a mirror of the data at the previous even address location. The RAM is mirrored at 6000H and the entire map mirrored at 8000H.

I/O PORT NON-COMPATIBLE MODE

This mode is similar to Novell’s NE2000, but this mode allows the user to use the full 64 kbytes of address space except for an initial page for the PROM. The memory map for this board is shown in same for both 8- and 16-bit modes. Although the PROM store occupies 256 bytes, it is only 16 bytes long. The entire map is mirrored at 8000H.

A low cost card, using only one 8 kbyte RAM, can be designed. If the DWID pin is left unconnected, or tied to GND, then the AT/LANTIC Controller will always operate in 8-bit mode, regardless of the slot the board is in.

Figure 7

. Again the PROM has only a partial de-

Figure 8

. The memory map is the

0000h

0020h

4000h

6000h

8000h

1EH 42H 42H

1CH 42H 42H

PROM

Aliased PROM

8k x 8 BUFFER RAM

RESERVED

(a)

D15 D0

RESERVED RESERVED

0AH E’net Address 5 E’net Address 5

08H E’net Address 4 E’net Address 4

06H E’net Address 3 E’net Address 3

04H E’net Address 2 E’net Address 2

02H E’net Address 1 E’net Address 1

00H E’net Address 0 E’net Address 0

(b)

FIGURE 7. a) 8-Bit NIC Core’s Memory Map

0000H

00FFH

0100H

FFFFH

b) 8-Bit PROM Map

PROM

BUFFER RAM

FIGURE 8. I/O Port Enhanced Mode

DP8390 Core Memory Map

Page 13

4.0 Functional Description (Continued)

4.2 POWER ON RESET OPERATION

The AT/LANTIC Controller configures itself after a Reset signal is applied. To be recognized as a valid Power-On-Reset the Reset signal must be active for at least 415 ms.

Figure 9

shows how the RESET circuitry operates.

FIGURE 9. RESET Operation

The ISA standard determines that within 500 ns of RESET going active all devices should enter the appropriate reset condition. The AT/LANTIC Controller will generate the internal signal IOinactive after RESET has been active for 415 ns, which will disable all outputs and cause RESET to be the only input monitored. The AT/LANTIC Controller will not respond to a RESET pulse of shorter duration than this. An internal timer continues to monitor the amount of time RESET is active. After 415 ms it is considered a valid PowerOn-Reset and an internal signal called RegLoad is generated.

When a Power-On-Reset occurs the AT/LANTIC Controller latches in the values on the configuration pins and uses these to configure the internal registers and options. Internally these pins contain pull-down resistors, which are enabled when IOinactive goes active. If any pins are unconnected they default to a logic zero. The internal pull-down resistor has a high resistance to allow the external pull-up resistors to be of a high value. This limits the current taken by the memory support bus. The suggested external resistor value is 10 kX. The configuration registers are loaded from the memory support bus when RESET goes inactive if RegLoad is active. The internal pull-down resistors are enabled onto the bus until RegLoad has gone inactive.

A Power-On-Reset also causes the AT/LANTIC Controller to load the internal PROM store from the EEPROM, which can take up to 320 ms. This occurs after RegLoad has gone inactive. The AT/LANTIC Controller will be inaccessible during this time. If EECONFIG is held high the configuration data loaded on the falling edge of RESET will be overwritten with data read from the serial EEPROM. Regardless of the level on EECONFIG the PROM store will always be loaded with data from the serial EEPROM during the time specified as EELoad.

4.3 EEPROM OPERATION

The AT/LANTIC Controller uses an NM93C06, or EEPROM with compatible timings. The NM93C06 is a 256bit device, arranged as 16 words each 16 bits wide. The programmed contents of the EEPROM is shown in

Mapping EEPROM Into PROM Space

Data is read from the EEPROM at boot time and stored in registers within the AT/LANTIC Controller. While this operation takes place the AT/LANTIC Controller can not be ac-

TL/F/11498– 7

Figure

D15 D0

0FH 73H Config. C

0EH Config B Config. A

## ## ##

08H 42H 42H

07H 57H 57H

## ## ##

03H Reserved Reserved

(Checksum) (Board Type)

02H E’net Address 5 E’net Address 4

01H E’net Address 3 E’net Address 2

00H E’net Address 1 E’net Address 0

Note 1: The contents of locations 03H and 04H differ between I/O Mode and Shared Memory Mode. The Shared Memory Mode values are shown in parentheses. For compatibility with both modes default to the shared memory mode values.

Note 2: Programming 73H into the upper address is not absolutely required but is strongly recommended for future compatibility of manufacturing process.

FIGURE 10. EEPROM Programming Map

cessed by the system. These registers are mapped into the space traditionally occupied by the PROM in the NE2000 or the EtherCard PLUS16. The size and format of this data read is determined by the mode of operation.

SHARED MEMORY MODE

In this mode, program the EEPROM to contain the node’s Ethernet address in the first six bytes, a byte identifying the type of board AT/LANTIC Controller is emulating in byte 7 and a checksum byte in byte 8. The two’s complement sum of these eight bytes should equal FFH.

In this Mode the AT/LANTIC Controller reads the first 4 words from the EEPROM and maps them into the I/O map at the appropriate address.

I/O PORT MODE

In this mode, program the EEPROM to contain the node’s Ethernet address in the first six bytes. The user should then program 5757H and 4242H into the subsequent bytes. The AT/LANTIC Controller will decide which of these values should be loaded into the PROM store depending on the DWlD pin. (The data width is programmed in this mode by setting the WTS bit in the Data Configuration Register and setting the DWlD pin for the proper mode.) If some other numerical values are preferred to indicate the mode then they can be programmed at this location in the EEPROM and AT/LANTIC Controller will put them at the correct address.

In this mode the AT/LANTIC Controller reads the first 7 words from the EEPROM and maps them into the memory map at the appropriate address. If in 16-bit mode it also

Page 14

4.0 Functional Description (Continued)

reads the next word in the EEPROM and appends this. If in 8-bit mode it skips a word, then reads and appends the next word.

Storing and Loading Configuration from EEPROM

If the EECONFIG pin is high during boot up the AT/LANTIC Controller’s configuration is read from the EEPROM, before the PROM data is read. The configuration data is stored within the upper two words of the EEPROM’s address space. Configuration Registers A and B are located in the lower of these words, Register C in the lower byte of the upper word, as shown in

To write this configuration into the EEPROM the user must follow the routine specified in the pseudo code below. This operation will work regardless of the level on EECONFIG. The EELOAD bit of Configuration Register B being set starts the EEPROM write process. Care should be taken not to accidently set the GDLINK bit and therefore disable link integrity checking. The next 3 writes to this register load the values that will be stored in the configuration register (note that the last 2 of these writes do not have to follow the normal practice of preceding a write to this register with a read to this address). The AT/LANTIC Controller will then commence the EEPROM write. The write has been completed when the EELOAD bit goes to zero. This loading procedure should be followed exactly and interrupts should be disabled until it has completed, to prevent any accidental accesses to the AT/LANTIC Controller.

EEPROMÐLOAD()

DISABLEÐINTERRUPTS();

value

READ(CONFIGÐB);

value

value AND 1 GDLINK;

value

value OR EELOAD; WRITE(CONFIGÐB, value); READ(CONFIGÐB); WRITE(CONFlGÐB, configÐforÐA); WRITE(CONFIGÐB, configÐforÐB); WRITE(CONFIGÐB, configÐforÐC); while (value AND EELOAD)

valueeREAD(CONFIGÐB); WAIT();

ENABLEÐINTERRUPTS();

4.4 JUMPERED AND JUMPERLESS OPERATION SUPPORT

The AT/LANTIC Controller supports several options that enable the implementation of either a ‘‘jumpered’’ or ‘‘jumperless’’ power on configuration when installed into a standard PC compatible’s ISA bus. A wide range of options are provided to ensure that the AT/LANTIC Controller can be configured by an end user to function in all possible PC-AT system configurations. Several types of configuration options can be implemented examples including:

1. Full jumper options: All programmable options are selected by utilizing jumpers on the board. Option selection requires no special software. An example of this is shown in the

Figure 11

Figure 10

2. I/O address jumpers only: All other options configurable via software. This option simplifies installation while maximizing compatibility.

3. Jumperless: Special scheme provides contention-free I/O address selection.

The AT/LANTIC Controller’s Configuration Registers are the key to providing the ability to implement various configuration options. These registers are configured by the same method in shared memory and I/O port modes, 8- or 16-bit modes. The bit definitions of these registers are provided in Section 5. All three registers are configured by hardware selection during the Power-On-Reset of the system. Two of these registers can be configured via software (the Mode Configuration Registers A and B). The third register (Hardware Configuration Register C) is only configured during reset.

The following table indicates troller options that a designer may like to have user configurable. (This list does not represent the complete list. For the full list see the Configuration register descriptions in Section 5.)

TABLE I. Some Configuration Options

for AT/LANTIC Controller

most

of the AT/LANTIC Con-

Option Selections

I/O Base Address 0300H 02C0H

Software 0320H

0240H 0340H 0280H 0360H

Interrupt No. 4 Interrupts 8 Interrupts

Boot PROM Disabled 0CC00H

Address 0C000H 0D000H

0C400H 0D400H 0C800H 0D800H

0DC00H

Boot PROM Size None 32k

16k 64k

Media Selection Twisted Pair Thin Ethernet

AUI Port

Architecture I/O Mode Shared RAM

Mode

Bus Timing IOCHRDY MEM16 Mode

Options Mode

The three basic options are described below. Because of the variety of programmable options there are a number of variations possible, only a few typical examples will be discussed.

FULLY JUMPERED OPERATION

This option is shown in options are selected by jumpers on the AT/LANTIC Controller’s memory bus. For this option all configuration options are set upon power-on by the AT/LANTIC Controller as described in Section 4.2. Accessing the configuration registers is unnecessary and the EEPROM need only contain the

Figure 11

. In this configuration most

Page 15

4.0 Functional Description (Continued)

JP1. .JP3 I/O Address JP4..JP5 INTR Jumper JP6 IO OR Shared RAM JP7, JP8 Thin, Thick or TP Interface JP9, CHRDY Assertion JP10..JP13 EPROM Address and Size

FIGURE 11. Example of Jumper Configuration

Ethernet ID address (Configuration Register B bit 7 should be set to disable EEPROM configuration mode, and Configuration Register C bit 7 could be set to disable software configuration completely).

MINIMAL JUMPERS

The AT/LANTIC Controller’s configuration registers provide the capability to enable software to configure various options (some may be hardwired). For the one option that is not easily configured on the ISA bus is the I/O address options. The reason for this is that the I/O locations must first be known by the software in order for the software (usually a device driver) to access the AT/LANTIC Controller. However, upon power up, in order to access a register to configure the I/O base address to avoid conflicts some default location must be given (typically set in hardware on the memory bus). It is possible that this default location conflicts with an already installed device. If this is the case then one possible solution, is to provide a jumper option for only the I/O Addresses. A similar situation exists for the boot PROM memory addresses.

In this application all options except the I/O address and the boot PROM are hardwired on the memory bus to a default setting. After power up software can change the con-

TL/F/11498– 8

figuration to avoid conflicts on these settings. The advantage of this approach is that for most systems the default I/O address setting is the correct one and no installation will be required in this case. This approach minimizes any compatibility issues.

NO JUMPERS

The conflicts possible in the I/O base selection can be overcome by a special mode for software configuration of the I/O base address. By using this mode, and by using the configuration storage capability of the EEPROM a fully software configurable design on the ISA bus can be realized without address conflict problems.

This mode is invoked by having the AT/LANTIC Controller default to jumperless software configuration option in the I/O base selection. This mode enables configuration register A to be mapped to address location 278H which is defined to be a printer port’s data register. If software writes to this location four consecutive times on the fourth write the AT/LANTIC Controller will load the data written into the I/O address bits of Configuration Register A. This data should set the I/O base address to a known conflict-free value. The AT/LANTIC Controller can now be configured and operated

Page 16

4.0 Functional Description (Continued)

at the desired base I/O address. If desired the configuration software could change the EEPROM content to the new values eliminating the need to reconfigure upon each power up. Alternately the software could leave the EEPROM alone and execute the configuration using the printer port’s data register upon each power up. This configuration scheme will only work once after each power-up. Therefore the user cannot enable the AT/LANTIC Controller from reserved mode, change it back into reserved mode, and enable it again. A power-on reset must occur between the first time it is enabled from the reserved mode and the second.

A second consideration is the location of the boot PROM in the system memory map, which also has the same conflict and programming considerations as the I/O address selection. However the solution is different, primarily because the boot PROM must be configured before power up. This is because during normal usage of the boot PROM the PC’s BIOS will look for the ROM immediately after reset, not allowing configuration software to first select the boot PROM addressing prior to usage.

To configure the boot PROM without jumpers the configuration software must first power up the AT/LANTIC Controller, configure the EEPROM to the desired location, then hardware reset the AT/LANTIC Controller. After the reset the AT/LANTIC Controller’s EEPROM will load in the desired boot PROM configuration automatically during the reset. Now after reset when the PC scans for the boot PROM, the ROM will be correctly mapped in the memory space enabling the network boot operation to proceed.

Ethernet Cable Configuration

AT/LANTIC Controller offers the choice of all the possible Ethernet cabling options, that is Ethernet (10BASE5), Thin Ethernet (10BASE2) and Twisted-pair Ethernet (10BASE-T). The type of cabling used is controlled by Configuration Register B. AT/LANTIC Controller also supplies a THIN output signal which can be used to disable/enable an external DC–DC converter which is required for 10BASE2.

4.5 LOW POWER OPERATION

The AT/LANTIC Controller has a low power support mode that can be used to disable the Ethernet port and conserve power. It should be noted that the device is not operational in this mode and requires to be initialized after exiting this mode.

The power and ground pins to the AT/LANTIC Controller are split up into two groups, interface and core. By switching the power off to the core logic while still powering the interface logic the AT/LANTIC Controller can be powered down without crashing the ISA bus. The LOWPWR pin should be driven high to indicate that the device is about to go into low power then the power to the V off. The same signal that is used to drive the LOWPWR pin can be used to drive a p-channel load switch to disable power to the core. This switch must have a very low on resistance to minimize the voltage difference between the V

and the lFVCC. All devices on the memory support bus

should also be powered from the V

pins should be switched

supply.

4.6 BOOT PROM OPERATION

The AT/LANTIC Controller supports an optional boot PROM, the address and size of which can be set in Configuration Register C. This boot PROM can be any 8 bits wide storage device implemented with a non-volatile technology. Write cycles to this device can be enabled and disabled by programming Configuration Register B. This can be used to prevent unwanted write cycles to certain devices, such as a Flash EEPROM. It should be noted that the address pins

for the boot PROM should be connected directly to the ISA bus. The AT/LANTIC Controller supplies the chip se-

lect to the device and buffers the data onto and from the ISA bus, so the memory support data bus should be connected to the boot PROM’s data pins.

4.7 DP8390 CORE (NETWORK INTERFACE

CONTROLLER)

The DP8390 Core logic, Deserializer which is controlled by the Protocol PLA, DMA Control, FIFO, Address Comparator, Multicast Hashing Register. The DP8390 core implements all of the IEEE 802.3 Media access control functions for the AT/LANTIC Controller, and interfaces to the internal ENDEC (on the left of the block diagram) and also interfaces to the Bus Interface and memory support bus via a number of address, data and control signal (and the right side of the block diagram). The following sections describe the functions of the DP8390 core.

Receive Deserializer

The Receive Deserializer is activated when the input signal Carrier Sense is asserted to allow incoming bits to be shifted into the shift register by the receive clock. The serial receive data is also routed to the CRC generator/checker. The Receive Deserializer includes a synch detector which detects the SFD (Start of Frame Delimiter) to establish where byte boundaries within the serial bit stream are located. After every eight receive clocks, the byte wide data is transferred to the 16-byte FlFO and the Receive Byte Count is incremented. The first six bytes after the SFD are checked for valid comparison by the Address Recognition Logic. If the Address Recognition Logic does not recognize the packet, the FlFO is cleared.

CRC Generator/Checker

During transmission, the CRC logic generates a local CRC field for the transmitted bit sequence. The CRC encodes all fields after the synch byte. The CRC is shifted out MSB first following the last transmit byte. During reception the CRC logic generates a CRC field from the incoming packet. This local CRC is serially compared to the incoming CRC appended to the end of the packet by the transmitting node. If the local and received CRC match, a specific pattern will be generated and decoded to indicate no data errors. Transmission errors result in different patterns and are detected, resulting in rejection of a packet.

Figure 12

, contains the Serializer/

Page 17

4.0 Functional Description (Continued)

FIGURE 12. DP8390 Controller Core Simplified Block Diagram

Transmit Serializer

The Transmit Serializer reads parallel data from the FIFO and serializes it for transmission. The serializer is clocked by the transmit clock generated internally. The serial data is also shifted into the CRC generator/checker. At the beginning of each transmission, the Preamble and Synch Generator append 62 bits of 1,0 preamble and a 1,1 synch pattern. After the last data byte of the packet has been serialized the 32-bit FCS (Frame Check Sequence) field is shifted directly out of the CRC generator. In the event of a collision the Preamble and Synch generator is used to generate a 32-bit JAM pattern of all 1’s.

Comparator-address Recognition Logic

The address recognition logic compares the Destination Address Field (first 6 bytes of the received packet) to the Physical address registers stored in the Address Register Array. If any one of the six bytes does not match the pre-programmed physical address, the Protocol Control Logic rejects the packet. All multicast destination addresses are filtered using a hashing technique. (See register description.) If the multicast address indexes a bit that has been set in the filter bit array of the Multicast Address Register Array the packet is accepted, otherwise it is rejected by the Protocol Control Logic. Each destination address is also checked for all 1’s which is the reserved broadcast address.

FIFO and Packet Data Operations

OVERVIEW

To accommodate the different rates at which data comes from (or goes to) the network and goes to (or comes from) the packet buffer memory, the AT/LANTIC Controller contains a 16-byte FIFO for buffering data between the media and the buffer RAM located on the memory support bus. The FIFO threshold is programmable, allowing filling (or emptying) the FIFO at different rates. When the FIFO has filled to its programmed threshold, the local DMA channel transfers these bytes (or words) into local memory (via the

TL/F/11498– 9

memory bus). It is crucial that the local DMA is given access to the bus within a minimum bus latency time; otherwise a FIFO underrun (or overrun) occurs.

FIFO underruns or overruns are caused when a local DMA request is issued while an ISA bus access is current and the ISA cycle takes longer to complete than the local DMA’s tolerable latency. This tolerable latency depends on the FIFO threshold, whether it is in byte or word wide mode and the speed of the DMA clock (BSCLK frequency). Note that this refers to standard ISA cycles NOT those where the CHRDY is deasserted extending the cycle.

FIFO THRESHOLD DETECTION

To assure that there is no overwriting of data in the FIFO, the FIFO logic flags a FIFO overrun as the 13th byte is written into the FIFO, effectively shortening the FIFO to 13 bytes. The FIFO logic also operates differently in Byte Mode and in Word Mode. In Byte Mode, a threshold is indicated when the n

1 byte has entered the FIFO; thus, with an 8 byte threshold, the AT/LANTIC Controller issues a request to the buffer RAM when the 9th byte has entered the FIFO, making the effective threshold 9 bytes. For Word Mode, the request is not generated until the n

2 bytes have entered the FIFO. Thus, with a 4 word threshold (equivalent to 8 byte threshold), a request to the buffer RAM is issued when the 10th byte has entered the FIFO, making the effective threshold 10 bytes.

TOLERABLE LATENCY CALCULATION

To prevent a FIFO overrun a byte (or word) of data must be removed from the FIFO before the 13th byte is written. Therefore the worst case tolerable latency is the time from the effective threshold being reached to the time the 13th byte is written minus the time taken to load the first byte (or word) of data to the FIFO during a local DMA burst (8 BSCLKs).

tolerable latency

((overrunbeffective) threshold

time to transfer byte on network)

time to fill 1st FIFO location

Page 18

4.0 Functional Description (Continued)

For the case of a 4 word threshold using a 20 MHz BSCLK:

tolerable latency

To prevent a FIFO underrun a byte (or word) of data must be added from the FIFO before the last byte is removed. Therefore the worst case tolerable latency is the time from the effective threshold being reached to the time the last byte is removed minus the time taken to load the first byte (or word) of data to the FIFO during a local DMA burst (8 BSCLKs).

tolerable latency

For the case of a 4 word threshold using a 20 MHz BSCLK:

tolerable latencye(4c800)b(8c50) ns

The worst case latency, either overrun or underrun, ultimately limits the overall latency that the AT/LANTIC Controller can tolerate. If the standard ISA cycles are shorter than the worst case latency then no FIFO overruns or underruns will occur.

BEGINNING OF RECEIVE

At the beginning or reception, the AT/LANTIC Controller stores entire Address field of each incoming packet in the FIFO to determine whether the packet matches its Physical Address Registers or maps to one of its Multicast Registers. This causes the FIFO to accumulate 8 bytes.

Furthermore, there are some synchronization delays in the DMA PLA. Thus, the actual time that a request to access the buffer RAM is asserted from the time the Start of Frame Delimiter (SFD) is detected is 7.8 ms. This operation affects the bus latencies at 2 byte and 4 byte thresholds during the first receive request since the FIFO must be filled to 8 bytes (or 4 words) before issuing a request to the buffer RAM.

END OF RECEIVE

When the end of a packet is detected by the ENDEC module, the AT/LANTIC Controller enters its end of packet processing sequence, emptying its FIFO and writing the status information at the beginning of the packet. The AT/LANTIC Controller holds onto the memory bus for the entire sequence. The longest time that local DMA will hold the buffer RAM occurs when a packet ends just as the AT/LANTIC Controller performs its last FIFO burst. The AT/LANTIC Controller, in this case, performs a programmed burst transfer followed by flushing the remaining bytes in the FIFO, and completed by writing the header information to the buffer memory. The following steps occur during this sequence.

((13b10)c800)b(8c50) ns

2 ms

(threshold

time to transfer byte on network)

time to fill 1st FIFO location

2.8 ms

1. AT/LANTIC Controller issues request to access the RAM because the FIFO threshold has been reached.

2. During the burst, packet ends, resulting in the request being extended.

3. AT/LANTIC Controller flushes remaining bytes from FIFO.

4. AT/LANTIC Controller performs internal processing to prepare for writing the header.

5. AT/LANTIC Controller writes 4-byte (2-word) header

6. AT/LANTIC Controller de-asserts access to the buffer RAM.

BEGINNING OF TRANSMIT

Before transmitting, the AT/LANTIC Controller performs a prefetch from memory to load the FIFO. The number of bytes prefetched is the programmed FIFO threshold. The next request to the buffer RAM is not issued until after the AT/LANTIC Controller actually begins transmitting data, i.e., after SFD.

READING THE FIFO

If the FIFO is read during normal operation the AT/LANTIC Controller will ‘‘hang’’ the ISA bus by deasserting CHRDY and never asserting it. The FIFO should only be read during loopback diagnostics, when it will operate normally.

PROTOCOL PLA

The Protocol PLA is responsible for implementing the IEEE

802.3 protocol, including collision recovery with random

backoff. The Protocol PLA also formats packets during transmission and strips preamble and synch during reception.

DMA AND BUFFER CONTROL LOGIC

The DMA and Buffer Control Logic is used to control two 16-bit DMA channels. During reception, the Local DMA stores packets in a receive buffer ring, located in buffer memory. During transmission the Local DMA uses programmed pointer and length registers to transfer a packet from local buffer memory to the FIFO.

A second DMA channel is used when the AT/LANTIC Controller is used in I/O Port mode. This DMA is used as a slave DMA to transfer data between the local buffer memory and the host system. The Local DMA and Remote DMA are internally arbitrated, with the Local DMA channel having highest priority. Both DMA channels use a common external bus clock to generate all required bus timing. External arbitration is performed with a standard bus request, bus acknowledge handshake protocol.

In the shared memory mode the Remote DMA is not used, because in this mode the system has direct read/write access to the buffer RAM.

Page 19

4.0 Functional Description (Continued)

4.8 TWISTED PAIR INTERFACE MODULE

The TPI consists of five main logical functions:

a) The Receiver/Smart Squelch, responsible for determin-

ing when valid data is present on the differential receive inputs (RXI

b) The Collision function checks for simultaneous transmis-

sion and reception of data on the TXO

c) The Link Detector/Generator checks the integrity of the

cable connecting the two twisted pair MAUs.

d) The Jabber disables the transmitter if it attempts to

transmit a longer than legal packet.

e) The TX Driver and Pre-emphasis transmits Manchester

encoded data to the twisted pair network via the summing resistors and transformer/filter.

) and receiving the data.

and RXIgpins.

Receiver and Smart Squelch

The AT/LANTIC Controller implements an intelligent receive squelch on the RXI

differential inputs to ensure that impulse noise on the receive inputs will not be mistaken for a valid signal.

The squelch circuitry employs a combination of amplitude and timing measurements to determine the validity of data on the twisted pair inputs. There are two voltage level options for the smart squelch. One mode, 10BASE-T mode, uses levels that meet the 10BASE-T specification. The second mode, reduced squelch mode, uses a lower squelch threshold level, and can be used in longer cable applications where smaller signal levels may be applied. The squelch level mode can be selected in the AT/LANTIC Controller configuration registers.

Figure 14

shows the operation of the smart squelch in

10BASE-T mode.

FIGURE 13. Twisted Pair Interface Module Block Diagram

TL/F/11498– 10

Page 20

4.0 Functional Description (Continued)

FIGURE 14. Twisted Pair Squelch Waveform

The signal at the start of packet is checked by the smart squelch and any pulses not exceeding the squelch level (either positive or negative, depending upon polarity) will be rejected. Once this first squelch level is overcome correctly the opposite squelch level must then be exceeded within 150 ns later. Finally the signal must exceed the original squelch level within a further 150 ns to ensure that the input waveform will not be rejected. The checking procedure results in the loss of typically three bits at the beginning of each packet.

Only after all these conditions have been satisfied will a control signal be generated to indicate to the remainder of the circuitry that valid data is present. At this time the smart squelch circuitry is reset.

In the reduced squelch mode the operation is identical except that the lower squelch levels shown in

Figure 14

are

used.

Valid data is considered to be present until either squelch level has not been generated for a time longer than 150 ns, indicating End of Packet. Once good data has been detected the squelch levels are reduced to minimize the effect of noise causing premature End of Packet detection.

Collision

A collision is detected by the TPI module when the receive and transmit channels are active simultaneously. If the TPI is receiving when a collision is detected it is reported to the controller immediately. If, however, the TPI is transmitting when a collision is detected the collision is not reported until seven bits have been received while in the collision state. This prevents a collision being reported incorrectly due to noise on the network. The signal to the controller remains for the duration of the collision.

Approximately 1 ms after the transmission of each packet a signal called the Signal Quality Error (SQE) consisting of typically 10 cycles of 10 MHz is generated. This 10 MHz signal, also called the Heartbeat, ensures the continued functioning of the collision circuitry.

TL/F/11498– 11

Link Detector/Generator

The link generator is a timer circuit that generates a link pulse as defined by the 10 Base-T specification that will be generated by the transmitter section. The pulse which is 100 ns wide is transmitted on the TXO

output, every

16 ms, in the absence of transmit data.

The pulse is used to check the integrity of the connection to the remote MAU. The link detection circuit checks for valid pulses from the remote MAU and if valid link pulses are not received the link detector will disable the transmit, receive and collision detection functions.

The GDLNK

output can directly drive a LED to show that there is a good twisted pair link. For normal conditions the LED will be on. The link integrity function can be disabled by setting the GDLNK

bit of Configuration Register B.

Jabber

The jabber timer monitors the transmitter and disables the transmission if the transmitter is active for greater than 26 ms. The transmitter is then disabled for the whole time that the Endec module’s internal transmit enable is asserted. This signal has to be deasserted for approximately 750 ms (the unjab time) before the Jabber re-enables the transmit outputs.

Transmitter

The transmitter consists of four signals, the true and compliment Manchester encoded data (TXO delayed by 50 ns (TXOd

These four signals are resistively combined TXOawith

TXOd

and TXObwith TXOda. This is known as digital

)

) and these signals

pre-emphasis and is required to compensate for the twisted pair cable which acts like a low pass filter causing greater attenuation to the 10 MHz (50 ns) pulses of the Manchester encoded waveform than the 5 MHz (100 ns) pulses.

An example of how these siqnals are combined is shown in the following diagram.

Page 21

4.0 Functional Description (Continued)

FIGURE 15. Typical Summed Transmit Waveform

The signal with pre-emphasis shown above is generated by resistively combining TXO compliment is passed to the transmit filter.

FIGURE 16. External Circuitry to Connect AT/LANTIC Controller to Twisted Pair Cable

TL/F/11498– 12

and TXOdb. This signal along with its

TL/F/11498– 13

Page 22

4.0 Functional Description (Continued)

FIGURE 17. Typical AT/LANTIC Controller LED Connection

TL/F/11498– 15

FIGURE 18. Encoder/Decode Block Diagram

TL/F/11498– 14

Page 23

4.0 Functional Description (Continued)

Status Information

Status information is provided by the AT/LANTIC Controller on the RXLED, TXLED, COLED and POL outputs as described in the pin description table. These outputs are suitable for driving status LED’s as shown in puts are open drain.

Recommended integrated Filter-Transformer-choke modules:

1. Pulse Engineering PE65424

2. Valor FL1012 or FL1030.

4.9 ENCODER/DECODER (ENDEC) MODULE

The ENDEC consists of four main logical blocks:

a. The oscillator generates the 10 MHz transmit clock sig-

nal for system timing.

b. The Manchester encoder accepts NRZ data from the

controller, encodes the data to Manchester, and transmits the data differentially to the transceiver, through the differential transmit driver.

c. The Manchester decoder receives Manchester data from

the transceiver, converts it to NRZ data and clock pulses, and sends it to the controller.

d. The collision translator indicates to the controller the

presence of a valid 10 MHz collision signal to the PLL.

Oscillator

The oscillator is controlled by a 20 MHz parallel resonant crystal connected between X1 and X2 or by an external clock on X1. The 20 MHz output of the oscillator is divided by 2 to generate the 10 MHz transmit clock for the controller. The oscillator also provides internal clock signals to the encoding and decoding circuits.

CRYSTAL OPERATION

If the crystal used with the internal oscillator circuit is not properly selected, the AT/LANTIC Controller oscillator may not reliably start oscillation under all conditions.

If this occurs, it could be deceiving to a designer, since his prototypes may work fine. However, when the designer does qualification testing or starts production, he may encounter a higher than expected board yield loss due to the oscillator not starting. The AT/LANTIC Controller’s oscillator circuit clocks the Encoder-Decoder logic. The AT/LANTIC Controller’s oscillator also clocks the twisted pair interface block. If the oscillator does not start, the AT/LANTIC Controller will not be able to transmit or receive.

If a crystal is connected to the AT/LANTIC Controller, it is recommended that the circuit shown in and that the components used meet the following:

Crystal XT1: AT cut parallel resonant crystal

Series Resistance: Specified Load Capacitance: Accuracy: 0.005% (50 ppm) Typical Load: 50 mW–75 mW

The recommended values for capacitors C1 and C2 are 26 pF minus the board capacitance on that pin. Therefore if both X1 and X2 have 4 pF of board capacitance, then a 22 pF capacitor should be used.

According to the IEEE 802.3 standard, the entire oscillator circuit (crystal and amplifier) must be accurate to 0.01%. When using a crystal, the X2 pin is not guaranteed to provide a TTL compatible logic output, and should not be used

Figure 17

. All out-

Figure 19

25X

be used

20 pF

FIGURE 19. Crystal Connection to AT/LANTIC

Controller (see text for component values)

to drive external standard logic. If additional logic needs to be driven, then an external oscillator should be used, as described in the following section.

OSCILLATOR MODULE OPERATION

If the designer wishes to use a crystal clock oscillator, one that provides the following should be employed:

1. TTL or CMOS output with a 0.01% frequency tolerance

2. 40% – 60% duty cycle

The circuit is shown in

Figure 20

. When using a clock oscillator it is recommended that the designer connect the oscillator output to the X1 pin and leave the X2 pin floating.

FIGURE 20. AT/LANTIC Controller

Connection for Oscillator Module

Manchester Encoder and Differential Driver

The differential transmit pair, on the secondary of the employed transformer, drives up to 50 meters of twisted pair AUI cable. These outputs are source followers which require two 270X pull-down resistors to ground (see

The AT/LANTIC Controller allows full-step to be compatible with IEEE 802.3. Transmit

and Transmitbare equal in the

Figure 21

idle state, providing zero differential voltage to operate with transformer coupled loads.

Manchester Decoder

The decoder consists of a differential receiver and a PLL to separate a Manchester encoded data stream into internal

TL/F/11498– 16

TL/F/11498– 17

Page 24

4.0 Functional Description (Continued)

FIGURE 21. Connection from AT/LANTIC Controller’s AUI Port to the AUI Connector

clock signals and data. The differential input must be externally terminated with two 39X resistors connected in series if the standard 78X transceiver drop cable is used, in thin Ethernet applications, these resistors are optional. To prevent noise from falsely triggering the decoder, a squelch circuit at the input rejects signals with levels less than

175 mV. Data becomes valid typically within 6 bit times. The AT/LANTIC Controller may tolerate bit jitter up to 20 ns in the received data. The decoder detects the end of a frame when no more mid-bit transitions are detected.

Collision Translator

When in AUI Mode, the Ethernet transceiver (DP8392 CTl) detects a collision, it generates a 10 MHz signal to the differential collision inputs (CD

) of the AT/LANTIC Controller. When these inputs are detected active, the AT/LANTIC Controller uses this signal to back off its current transmission and reschedule another one.

In this mode the COLED

output will indicate when the CD lines are active during activity on the network. This means it will correctly indicate any collision on the network, but will not be lit for heartbeat or if there is no cable connected.

The collision differential inputs are terminated the same way as the differential receive inputs. The squelch circuitry is also similar, rejecting pulse levels less than

PLL V

Power Supply Consideration

175 mV.

The PLL VCCpin is thea5V power supply for the phase lock loop (PLL) of the ST-NIC ENDEC unit. Since this is an

TL/F/11498– 19

analog circuit, excessive noise on the PLL V fect the performance of the PLL. This noise, if in the

pin can af-

10 kHz–400 kHz range, can reduce the jitter performance of the ENDEC, resulting in missing packets or CRC errors.

If the power supply noise is causing significant packet reception error, a low pass filter could be added to reduce the power supply noise and hence improve the jitter performance. Standard analog design techniques should be utilized when laying out the power supply traces on the board. If the digital power supply is used, it may be desirable to add a one pole RC filter (designed to have a cut-off frequency of 1 kHz) as shown in ance. The PLL V across the resister is less than 90 mV, which will not affect

Figure 4

only draws 3 mA – 4 mA so the voltage

to improve the jitter perform-

the PLL’s operation.

TL/F/11498– 18

FIGURE 22. Filtering Power Supply Noise

Page 25

5.0 Register Descriptions

5.1 CONFIGURATION REGISTERS

These registers are used to configure the operation of the AT/LANTIC Controller typically after power up. These registers control the configuration of bus interface, setting options like interrupt selection, I/O base address, and other specific modes.

MODE CONFIGURATION REGISTER A

To prevent any accidental writes of this register it is ‘‘hidden’’ behind a previously unused register. Register 0AH in the AT/LANTIC Controller’s Page 0 of registers was previously reserved on a read. Now Configuration Register A can be read at that address and can be written to by following a read to 0AH with a write to 0AH. If any other AT/LANTIC Controller register accesses take place between the read and the write then the write to 0AH will access the Remote Byte Count Register 0.

76543210

MEMIO FREAD INT2 INT1 INT0 IOAD2 IOAD1 IOAD0

Bits Symbols Function

0–2 IOAD0 – I/O ADDRESS: These three bits determine the base I/O address of the AT/LANTIC Controller, within

IOAD2

3–5 INT0 – INTERRUPT LINE USED: There are two interrupt modes which can be enabled by setting bit 5 of

INT2

6 FREAD FAST READ: When this bit is set high the AT/LANTIC Controller, in I/O mode, will begin the next port

7 MEMIO MEMORY OR I/O MODE: If this bit is set high then the AT/LANTIC Controller is in shared memory

the system’s I/O map. The AT/LANTIC Controller occupies 20H bytes of the system’s address space.

0 0 0 0300H 0 0 1 Software (Note 1) 0 1 0 0240H 0 1 1 0280H 1 0 0 02C0H 1 0 1 0320H 1 1 0 0340H 1 1 1 0360H

Note 1: When 001 is selected the AT/LANTIC controller will not respond to any I/O Addresses, but will allow 4 consecutive writes to 278H to write these three bits of this register. This sequence will only operate once after a power-on reset. This mode allows the AT/LANTIC Controller to be configured via software without conflicting with other peripherals.

Configuration Register C to the appropriate level. DIRECT DRIVE MODE: In this mode an interrupt output pin will be driven active on a valid interrupt condition. Only one pin may be driven, the other three will remain at TRI-STATE

. The pin driven is

determined by the value in this register.

Bit 5 Bit 4 Bit 3 Interrupt

X 0 0 INT0 X 0 1 INT1 X 1 0 INT2

X 1 1 INT3 CODED OUTPUT MODE: In this mode INT3 is the active interrupt output while pins INT0 to INT2 are programmable outputs reflecting the values on bits 3 to 5.

fetch before the current IORD has completed. In slow ISA systems this may cause the data in the port to be overwritten before the ISA cycle has been completed.

mode. If it is set low it is in I/O mode.

Page 26

5.0 Register Descriptions (Continued)

Mode Configuration Register B

To prevent any accidental writes of this register it is ‘‘hidden’’ behind a previously unused register. Register 0BH in the AT/LANTIC Controller’s Page 0 of registers was previously reserved on a read. Now Configuration Register B can be read at that address and can be written to by following a read to 0BH with a write to 0BH. If any other AT/LANTIC Controller register accesses take place between the read and the write then the write to 0BH will access the Remote Byte Count Register 1. Care should be taken when writing to this register as GDLINK and BE are not simple read/write bits, e.g., the user cannot change the physical layer by reading B, or-ing the returned value with the bits to be set, and writing this value to B. This could inadvertently disable link integrity generation and clear a bus error indication before it was noted.

7654 3 210

EELOAD BPWR BE CHRDY IO16CON GDLINK PHYS1 PHYS0

Bits Symbols Function

0–1 PHYS0 – PHYSICAL LAYER INTERFACE: These 2 bits determine which type of physical interface the AT/LANTIC

PHYS1

2 GDLNK GOOD LINK: Whena1iswritten to this bit the link test pulse generation and integrity checking is disabled.

3 IO16CON IO16 CONTROL: When this bit is set high the AT/LANTIC Controller generates IO16 after IORD or IOWR go

4 CHRDY CHRDY FROM IORD OR IOWR OR FROM BALE: When this bit is low the AT/LANTIC Controller will generate

5BE BUS ERROR: This bit shows that the AT/LANTIC Controller has detected a bus error condition. This will go

6 BPWR BOOT PROM WRITE: When this bit is low no write cycles are generated to the boot PROM.

7 EELOAD EEPROM LOAD: Writinga1tothis bit enables the EEPROM load algorithm as detailed in Section 4. This bit

Controller is using. The 2 TPI interfaces use twisted pair outputs and inputs, while the other 2 interfaces use the AUI outputs and inputs. In 10BASE5 mode the THIN output pin is driven low, in 10BASE2 mode it is driven high. This can be used to enable the DC–DC converter required by the 10BASE2 specification to provide electrical isolation. The Non spec TPI mode is a twisted pair mode with reduced receive squelch levels. This allows the use of longer cable lengths than specified in the twisted pair specification, or use of cable with higher losses.

0 0 TPI (10BASE-T Compatible Squelch Level) 0 1 Thin Ethernet (10BASE2) 1 0 Thick Ethernet (10BASE5) (AUI Port) 1 1 TPI (Reduced Squelch Level)

When this bit is read it will indicate link status, reflecting the value shown on the LED output. It is 0 if the AT/LANTIC Controller is in AUI mode or if link testing is enabled and the link integrity is bad (i.e., the twisted pair link has been broken). It is 1 if the AT/LANTIC Controller is in TPI mode, link integrity checking is enabled and the link integrity is good (i.e., the twisted pair link has not been broken) or if the link testing is disabled.

active. If low this output is generated only on address decode.

CHARDY after the command strobe. When high it will generate it after BALE goes high.

high if the AT/LANTIC Controller attempts to insert wait states into a system access and the system terminates the cycle without inserting the wait states. Writing a one to this bit clears it to zero. Writing a zero has no effect.

should not be configured to be high, either from switches or an EEPROM.

Page 27

5.0 Register Descriptions (Continued)

Hardware Configuration Register C

This register is configured during a RESET and can not be accessed by software.

7 6 5 4 3210

SOFEN CLKSEL INTMOD COMP BPS3 BPS2 BPS1 BPS0

Bits Symbols Function

0–3 BPS0b3 BOOT PROM SELECT: Selects address at which boot PROM begins and the size. When the system reads

4 COMP COMPATIBLE: This bit determines if the AT/LANTIC Controller’s memory and I/O maps are compatible with

5 INTMOD INTERRUPT MODE: When this bit is low the AT/LANTIC Controller is in Direct Drive interrupt mode. When it is

6 CLKSEL CLOCK SELECT: If this bit is low the NIC core is clocked by the 20 MHz. If this bit is high the NIC core is

7 SOFEN SOFTWARE ENABLE: If this bit is set low then the user can program configuration registers A and B in

within the selected memory area AT/LANTIC Controller reads the data in through MSD0–7 and drives it onto the system data bus. The following are valid addresses and sizes:

Bit 3 Bit 2 Bit 1 Bit 0 Address Size (I/O / Shared Mem.)

0 0 0 X X No boot PROM 0 0 1 0 0C000H 8k/16k 0 0 1 1 0C400H 8k/16k 0 1 0 0 0C800H 8k/16k 0 1 0 1 0CC00H 8k/16k 0 1 1 0 0D000H 8k/16k 0 1 1 1 0D400H 8k/16k 1 0 0 0 0D800H 8k/16k 1 0 0 1 0DC00H 8k/16k 1 0 1 0 0C000H 32k/32k 1 0 1 1 0C800H 32k/32k 1 1 0 0 0D000H 32k/32k 1 1 0 1 0D800H 32k/32k 1 1 1 0 0C000H 64k/64k 1 1 1 1 0D000H 64k/64k

the EtherCard PLUS and Novell boards or if they use the full 64k address space available to the NIC. A low level indicates compatible mode.

high Coded Output interrupt mode is used.

clocked by the signal on the BSCLK pin.

software. If this bit is set high then the configuration registers are not accessible. If EECONFIG is high, the configuration from the switches will be overwritten by the configuration from the EEPROM even if this bit is pulled high.

Page 28

5.0 Register Descriptions (Continued)

5.2 SHARED MEMORY MODE CONTROL REGISTERS

The following tables describe the functionality of the two control registers and the 8/16 detection registers.

Shared Memory AT Detect Register (Read only)

76543210

xxxxxxxATDET

Bits Symbols Function

D0 ATDET ATDET: This bit shows the value on the DWID pin and can be read by software to determine whether the

Shared Memory Control Register 1

Bits Symbols Function

D0-D5 A13– A18 A13–18: Lower part of the address register used to determine the position of the AT/LANTIC

D6 MEME MEMORY ENABLE: Enables external memory accesses when held high. This bit will power up low,

D7 RESET RESET: Resets NIC core of AT/LANTIC Controller.

AT/LANTIC Controller is operating in an 8- or 16-bit slot. When this bit is read as a 1 the AT/LANTIC Controller is in a 16-bit slot (PC-AT system bus) and when read asa0itisinan8-bit slot.

76543210

RESET MEME A18 A17 A16 A15 A14 A13

Controller’s memory within the system memory map.

so the user must program the base memory address and set this bit high to enable the memory into the system’s memory map.

Shared Memory Control Register 2

765 43210

8/16 MEMW Unused LA23 LA22 LA21 LA20 LA19

Bits Symbols Function

D0–D4 LA19 –LA23 LA19 – 23: Upper part of the address register used to determine the position of the AT/LANTIC

Controller’s memory within the system memory map.

D5 UNUSED

D6 MEMW MEMORY WIDTH: Sets width of external memory. When set low external memory is accessed as

byte wide, so only 8 kbytes of memory are available. When set high external memory is accessed as word wide, so 16 kbytes are available. In non-compatible mode up to 64 kbytes of external memory is allowed when this bit is set high, or 32 kbytes when low. When bit 7 is set high this bit must also be set high.

D7 8/16 8/16-BIT: Allows 16-bit system accesses to external memory when set high. When low only 8-bit

accesses are allowed. When high the generation of the M16 output is allowed.

Page 29

5.0 Register Descriptions (Continued)

5.3 NIC CORE REGISTERS

All registers are 8-bit wide and mapped into two pages which are selected in the Command Register (PS0, PS1). Pins SA0 – SA3 are used to address registers within each page. Page 0 registers are those registers which are commonly accessed during AT/LANTIC Controller operation while page 1 registers are used primarily for initialization. The registers are partitioned to avoid having to perform two write/read cycles to access commonly used registers.

TL/F/11498– 20

FIGURE 23. NIC Core Register Mapping

Page 30

5.0 Register Descriptions (Continued)

Page 0 Address Assignments (PS1

SA0–SA3 RD WR

00H Command (CR) Command (CR)

01H Current Local DMA Page Start Register

Address 0 (CLDA0) (PSTART)

02H Current Local DMA Page Stop Register

Address 1 (CLDA1) (PSTOP)

03H Boundary Pointer Boundary Pointer

(BNRY) (BNRY)

04H Transmit Status Transmit Page Start

05H Number of Collisions Transmit Byte Count

06H FIFO (FIFO) Transmit Byte Count

07H Interrupt Status Interrupt Status

08H Current Remote DMA Remote Start Address

Address 0 (CRDA0) Register 0 (RSAR0)

09H Current Remote DMA Remote Start Address

Address 1 (CRDA1) Register 1 (RSAR1)

0AH Reserved Remote Byte Count

0BH Reserved Remote Byte Count

0CH Receive Status Receive Configuration

0DH Tally Counter 0 Transmit Configuration

(Frame Alignment Register (TCR) Errors) (CNTR0)

0EH Tally Counter 1 Data Configuration

(CRC Errors) Register (DCR) (CNTR1)

0FH Tally Counter 2 Interrupt Mask

Missed Packet Register (IMR) Errors) (CNTR2)

0, PS0e0)

Page 31

5.0 Register Descriptions (Continued)

Page 1 Address Assignments (PS1

SA0–SA3 RD WR

00H Command (CR) Command (CR)

01H Physical Address Physical Address

02H Physical Address Physical Address

03H Physical Address Physical Address

04H Physical Address Physical Address

05H Physical Address Physical Address

06H Physical Address Physical Address

07H Current Page Current Page

08H Multicast Address Multicast Address

09H Multicast Address Multicast Address

0AH Multicast Address Multicast Address

0BH Multicast Address Multicast Address

0CH Multicast Address Multicast Address

0DH Multicast Address Multicast Address

0EH Multicast Address Multicast Address

0FH Multicast Address Multicast Address

0, PS0e1)

Page 32

5.0 Register Descriptions (Continued)

Page 2 Address Assignments (PS1

SA0–SA3 RD WR

00H Command (CR) Command (CR)

01H Page Start Register Current Local DMA

02H Page Stop Register Current Local DMA

03H Remote Next Packet Remote Next Packet

04H Transmit Page Start Reserved

05H Local Next Packet Local Next Packet

06H Address Counter Address Counter

07H Address Counter Address Counter

08H Reserved Reserved

09H Reserved Reserved

0AH Reserved Reserved

0BH Reserved Reserved

0CH Receive Configuration Reserved

0DH Transmit Reserved

OEH Data Configuration Reserved

0FH Interrupt Mask Reserved

Note: Page 2 registers should only be accessed for diagnostic purposes. They should not be modified during normal operation.

Page 3 should never be modified.

(PSTART) Address 0 (CLDA0)

(PSTOP) Address 1 (CLDA1)

Pointer Pointer

Address (TPSR)

Pointer Pointer

(Upper) (Upper)

(Lower) (Lower)

Configuration Register (TCR)

1, PS0e0)

Page 33

5.0 Register Descriptions (Continued)

COMMAND REGISTER (CR) 00H (READ/WRITE)

The Command Register is used to initiate transmissions, enable or disable Remote DMA operations and to select register pages. To issue a command the microprocessor sets the corresponding bit(s) (RD2, RDl, RD0, TXP). Further commands may be overlapped, but with the following rules: (1) If a transmit command overlaps with a remote DMA operation, bits RD0, RD1, and RD2 must be maintained for the remote DMA command when setting the TXP bit. Note, if a remote DMA command is re-issued when giving the transmit command, the DMA will complete immediately if the remote byte count register has not been re-initialized. (2) If a remote DMA operation overlaps a transmission, RD0, RD1, and RD2 may be written with the desired values and a ‘‘0’’ written to the TXP bit. Writing a ‘‘0’’ to this bit has no effect. (3) A remote write DMA may not overlap remote read operation or visa versa. Either of these operations must either complete or be aborted before the other operation may start. Bits PS1, PS0, RD2, and STP may be set any time.

765 4 3210

PS1 PS0 RD2 RD1 RD0 TXP STA STP

Bits Symbols Description

D0 STP STOP: Software reset command, takes the controller offline, no packets will be received or

D1 STA START: This bit is used to activate the NIC Core after either power up, or when the NIC Core has

D2 TXP TRANSMIT PACKET: This bit must be set to initiate transmission of a packet. TXP is internally

D3–D5 RD0 –RD2 REMOTE DMA COMMAND: These three encoded bits control operation of the Remote DMA

D6, D7 PS0, PS1 PAGE SELECT: These two encoded bits select which register page is to be accessed with

Note 1: If a remote DMA operation is aborted and the remote byte count has not decremented to zero, the data transfer port should be read, for a remote read or send packet, or written to, for a remote write. This is required to ensure future correct operation.

transmitted. Any reception or transmission in progress will continue to completion before entering the reset state. To exit this state, the STP bit must be reset and the STA bit must be set high. To perform a software reset, this bit should be set high. The software reset has executed only when indicated by the RST bit in the ISR being set to at 1. STP powers up high.

Note: If the AT/LANTIC Controller has previously been in start mode and the STP is set, both the STP and STA bits will remain set.

been placed in a reset mode by software command or error. STA powers up low.

reset either after the transmission is completed or aborted. This bit should be set only after the Transmit Byte Count and Transmit Page Start registers have been programmed.

channel. RD2 can be set to abort any Remote DMA command in progress. The Remote Byte Count Registers should be cleared when a Remote DMA has been aborted. The Remote Start Addresses are not restored to the starting address if the Remote DMA is aborted.

RD2 RD1 RD0

0 0 0 Not Allowed 0 0 1 Remote Read 0 1 0 Remote Write 0 1 1 Send Packet 1 X X Abort/Complete Remote DMA (Note 1)

addresses RA0–3.

PS1 PS0

0 0 Register Page 0 0 1 Register Page 1 1 0 Register Page 2 1 1 Reserved

Page 34

5.0 Register Descriptions (Continued)

INTERRUPT STATUS REGISTER (ISR) 07H (READ/WRITE)

This register is accessed by the host processor to determine the cause of an interrupt. Any interrupt can be masked in the Interrupt Mask Register (IMR). Individual interrupt bits are cleared by writing a ‘‘1’’ into the corresponding bit of the ISR. The valid interrupt output is active as long as any unmasked signal is set, and will not go low until all unmasked bits in this register have been cleared. The ISR must be cleared after power up by writing it with all 1’s.

765 43210

RST RDC CNT OVW TXE RXE PTX PRX

Bits Symbols Description

D0 PRX PACKET RECEIVED: Indicates packet received with no errors.

D1 PTX PACKET TRANSMITTED: Indicates packet transmitted with no errors.

D2 RXE RECEIVE ERROR: Indicates that a packet was received with one or more of the following errors:

D3 TXE TRANSMIT ERROR: Set when packet transmitted with one or more of the following errors:

D4 OVW OVERWRITE WARNING: Set when receive buffer ring storage resources have been exhausted. (Local

D5 CNT COUNTER OVERFLOW: Set when MSB of one or more of the Network Tally Counters has been set.

D6 RDC REMOTE DMA COMPLETE: Set when Remote DMA operation has been completed.

D7 RST RESET STATUS: Set when AT/LANTIC Controller enters reset state and cleared when a Start

ÐCRC Error ÐFrame Alignment Error ÐFIFO Overrun ÐMissed Packet

ÐExcessive Collisions ÐFIFO Underrun

DMA has reached Boundary Pointer)

Command is issued to the CR. This bit is also set when a Receive Buffer Ring overflow occurs and is cleared when one or more packets have been removed from the ring. Writing to this bit has no effect.

Note: This bit does not generate an interrupt, it is merely a status indicator.

Page 35

5.0 Register Descriptions (Continued)

INTERRUPT MASK REGISTER (IMR) 0FH (WRITE)

The Interrupt Mask Register is used to mask interrupts. Each interrupt mask bit corresponds to a bit in the Interrupt Status Register (ISR). If an interrupt mask bit is set, an interrupt will be issued whenever the corresponding bit in the ISR is set. If any bit in the IMR is set low, an interrupt will not occur when the bit in the ISR is set. The IMR powers up all zeros.

76 5 4 3 2 1 0

Ð RDCE CNTE OVWE TXEE RXEE PTXE PRXE

Bits Symbols Description

D0 PRXE PACKET RECEIVED INTERRUPT ENABLE

D1 PTXE PACKET TRANSMITTED INTERRUPT ENABLE

D2 RXEE RECEIVE ERROR INTERRUPT ENABLE

D3 TXEE TRANSMIT ERROR INTERRUPT ENABLE

D4 OVWE OVERWRITE WARNING INTERRUPT ENABLE

D5 CNTE COUNTER OVERFLOW INTERRUPT ENABLE

D6 RDCE DMA COMPLETE INTERRUPT ENABLE

D7 reserved reserved

0: Interrupt Disabled 1: Enables Interrupt when packet received

0: Interrupt Disabled 1: Enables Interrupt when packet is transmitted

0: Interrupt Disabled 1: Enables Interrupt when packet received with error

0: Interrupt Disabled 1: Enables Interrupt when packet transmission results in error

0: Interrupt Disabled 1: Enables Interrupt when Buffer Management Logic lacks sufficient buffers to store incoming packet

0: Interrupt Disabled 1: Enables Interrupt when MSB of one or more of the Network Statistics counters has been set

0: Interrupt Disabled 1: Enables Interrupt when Remote DMA transfer has been completed

Page 36

5.0 Register Descriptions (Continued)

DATA CONFIGURATION REGISTER (DCR) 0EH (WRITE)

This Register is used to program the AT/LANTIC Controller for 8- or 16-bit memory interface, select byte ordering in 16-bit applications and establish FIFO thresholds. The DCR must be initialized prior to loading the Remote Byte Count Registers.

LAS is set on power up.

76 5 4 3 2 1 0

Ð FT1 FT0 ARM LS LAS BOS WTS

Bits Symbols Description

D0 WTS WORD TRANSFER SELECT

D1 BOS BYTE ORDER SELECT

D2 LAS LONG ADDRESS SELECT

D3 LS LOOPBACK SELECT

D4 ARM AUTO-INITIALIZE REMOTE

D5 and D6 FT0 and FT1 FlFO THRESHOLD SELECT: Encoded FIFO threshold. Establishes point at which the

0: Selects byte-wide DMA transfers 1: Selects word-wide DMA transfers ;WTS establishes byte or word transfers for both Remote and Local DMA transfers

Note: When word-wide mode is selected, up to 32k words are addressable; A0 remains low.

0: MS byte placed on AD15 – AD8 and LS byte on AD7 – AD0. (32xxx, 80x86) 1: MS byte placed on AD7 – AD0 and LS byte on AD15 – AD8. (680x0) :Ignored when WTS is low

0: Dual 16-bit DMA mode 1: Single 32-bit DMA mode

;When LAS is high, the contents of the Remote DMA registers RSAR0, 1 are issued as A16–A31 Power up high

0: Loopback mode selected. Bits D1 and D2 of the TCR must also be programmed for

Loopback operation

1: Normal Operation

0: Send Command not executed, all packets removed from Buffer Ring under

program control

1: Send Command executed, Remote DMA auto-initialized to remove packets from

Buffer Ring

Note: Send Command cannot be used with 680x0 byte processors.

memory bus is requested when filling or emptying the FIFO. During reception, the FIFO threshold indicates the number of bytes (or words) the FIFO has filled serially from the network before the FIFO is emptied onto the memory bus.

Note: FIFO threshold setting determines the DMA burst length.

Receive Thresholds

FT1 FT0 Word Wide Byte Wide

0 0 1 Word 2 Bytes 0 1 2 Words 4 Bytes 1 0 4 Words 8 Bytes

1 1 6 Words 12 Bytes During transmission, the FIFO threshold indicates the number of bytes (or words) the FIFO has filled from the Local DMA before being transferred to the memory. Thus, the transmission threshold is 13 bytes less the received threshold.

Page 37

5.0 Register Descriptions (Continued)

TRANSMIT CONFIGURATION REGISTER (TCR) ODH (WRITE)

The transmit configuration establishes the actions of the transmitter section of the AT/LANTIC Controller during transmission of a packet on the network. LB1 and LB0 which select Ioopback mode power up as 0.

765 4 3 2 1 0

Ð Ð Ð OFST ATD LB1 LB0 CRC

Bits Symbols Description

D0 CRC INHIBIT CRC

D1 and LB0 and ENCODED LOOPBACK CONTROL: These encoded configuration bits set the type of loopback that is to be

D2 LB1

D3 ATD AUTO TRANSMIT DISABLE: This bit allows another station to disable the AT/LANTIC Controller’s

D4 OFST COLLISION OFFSET ENABLE: This bit modifies the backoff algorithm to allow prioritization of nodes.

D5 reserved reserved

D6 reserved reserved

D7 reserved reserved

0: CRC appended by transmitter 1: CRC inhibited by transmitter

In loopback mode CRC can be enabled or disabled to test the CRC logic

performed. Note that loopback in mode 2 places the ENDEC Module in loopback mode and that D3 of the DCR must be set to zero for loopback operation.

Mode 0 0 0 Normal Operation (LPBK Mode 1 0 1 Internal NIC Module Loopback (LPBK Mode 2 1 0 Internal ENDEC Module Loopback (LPBK Mode 3 1 1 External Loopback (LPBK

transmitter by transmission of a particular multicast packet. The transmitter can be re-enabled by resetting this bit or by reception of a second particular multicast packet. 0: Normal Operation 1: Reception of multicast address hashing to bit 62 disables transmitter, reception of multicast address

hashing to bit 63 enables transmitter.

0: Backoff Logic implements normal algorithm. 1: Forces Backoff algorithm modification to 0 to 2

follows standard backoff. (For the first three collisions, the station has higher average backoff delay making a low priority mode.)

LB1 LB0

min(3an, 10)

slot times for first three collisions, then

Page 38

5.0 Register Descriptions (Continued)

TRANSMIT STATUS REGISTER (TSR) 04H (READ)

This register records events that occur on the media during transmission of a packet. It is cleared when the next transmission is initiated by the host. All bits remain low unless the event that corresponds to a particular bit occurs during transmission. Each transmission should be followed by a read of this register. The contents of this register are not specified until after the first transmission.

76543210

OWC CDH FU CRS ABT COL Ð PTX

Bits Symbols Description

D0 PTX PACKET TRANSMITTED: Indicates transmission without error. (No excessive

collisions or FIFO underrun)(ABT

D1 reserved reserved

D2 COL TRANSMIT COLLIDED: Indicates that the transmission collided at least once with

another station on the network. The number of collisions is recorded in the Number of Collisions Registers (NCR).

D3 ABT TRANSMIT ABORTED: Indicates the AT/LANTIC Controller aborted transmission

because of excessive collisions. (Total number of transmissions including original transmission attempt equals 16.)

D4 CRS CARRIER SENSE LOST: This bit is set when carrier is lost during transmission of the

packet. Transmission is not aborted on loss of carrier.

D5 FU FIFO UNDERRUN: If the AT/LANTIC Controller cannot gain access of the bus

before the FIFO empties, this bit is set. Transmission of the packet will be aborted.

D6 CDH CD HEARTBEAT: Failure of the transceiver to transmit a collision signal after

transmission of a packet will set this bit. The Collision Detect (CD) heartbeat signal must commence during the first 6.4 ms of the Interframe Gap following a transmission. In certain collisions, the CD Heartbeat bit will be set even though the transceiver is not performing the CD heartbeat test.

D7 OWC OUT OF WINDOW COLLISION: Indicates that a collision occurred after a slot time

(51.2 ms). Transmissions rescheduled as in normal collisions.

‘‘0’’, FUe‘‘0’’)

Page 39

5.0 Register Descriptions (Continued)

RECEIVE CONFIGURATION REGISTER (RCR) 0CH (WRITE)

This register determines operation of the AT/LANTIC Controller during reception of a packet and is used to program what types of packets to accept.

76 5 4 3 2 1 0

Ð Ð MON PRO AM AB AR SEP

Bits Symbols Description

D0 SEP SAVE ERRORED PACKETS

D1 AR ACCEPT RUNT PACKETS: This bit allows the receiver to accept packets that are smaller than 64

D2 AB ACCEPT BROADCAST: Enables the receiver to accept a packet with an all 1’s destination address.

D3 AM ACCEPT MULTICAST: Enables the receiver to accept a packet with a multicast address, all multicast

D4 PRO PROMISCUOUS PHYSICAL: Enables the receiver to accept all packets with a physical address.

D5 reserved reserved (program to 0)

D6 reserved reserved

D7 reserved reserved

Note: D2 and D3 are ‘‘OR’d’’ together, i.e., if D2 and D3 are set the AT/LANTIC Controller will accept broadcast and multicast addresses as well as its own physIcal address. To establish full promiscuous mode, bits D2, D3, and D4 should be set. In addition the multicast hashing array must be set to all 1’s in order to accept all multicast addresses.

0: Packets with receive errors are rejected. 1: Packets with receive errors are accepted. Receive errors are CRC and Frame Alignment errors.

bytes. The packet must be at least 8 bytes long to be accepted as a runt. 0: Packets with fewer than 64 bytes rejected. 1: Packets with fewer than 64 bytes accepted.

0: Packets with broadcast destination address rejected. 1: Packets with broadcast destination address accepted.

addresses must pass the hashing array. 0: Packets with multicast destination address not checked. 1: Packets with multicast destination address checked.

0: Physical address of node must match the station address programmed in PAR0– PAR5. 1: All packets with physical addresses accepted.

Page 40

5.0 Register Descriptions (Continued)

RECEIVE STATUS REGISTER (RSR) 0CH (READ)

This register records status of the received packet, including information on errors and the type of address match, either physical or multicast. The contents of this register are written to buffer memory by the DMA after reception of a good packet. If packets with errors are to be saved the receive status is written to memory at the head of the erroneous packet if an erroneous packet is received. If packets with errors are to be rejected the RSR will not be written to memory. The contents will be cleared when the next packet arrives. CRC errors, Frame Alignment errors and missed packets are counted internally by the AT/LANTIC Controller which relinquishes the Host from reading the RSR in real time to record errors for Network Management Functions. The contents of this register are not specified until after the first reception.

765 432 1 0

DFR DIS PHY MPA FO FAE CRC PRX

Bits Symbols Description

D0 PRX PACKET RECEIVED INTACT: Indicates packet received without error. (Bits CRC, FAE, FO, and MPA

D1 CRC CRC ERROR: Indicates packet received with CRC error. Increments Tally Counter (CNTR1). This bit

D2 FAE FRAME ALIGNMENT ERROR: Indicates that the incoming packet did not end on a byte boundary and

D3 FO FIFO OVERRUN: This bit is set when the FIFO is not serviced causing overflow during reception.

D4 MPA MISSED PACKET: Set when packet intended for node cannot be accepted by SNIC because of a lack

D5 PHY PHYSICAL/MULTICAST ADDRESS: Indicates whether received packet had a physical or multicast

D6 DIS RECEIVER DISABLED: Set when receiver disabled by entering Monitor mode. Reset when receiver is

D7 DFR DEFERRING: Set when internal Carrier Sense or Collision signals are generated in the ENDEC module.

Note: Following coding applies to CRC and FAE bits

FAE CRC Type of Error

0 0 No Error (Good CRC and 0 1 CRC Error 1 0 Illegal, wil not occur 1 1 Frame Alignment Error and CRC Error

are zero for the received packet.)

will also be set for Frame Alignment errors.

the CRC did not match at last byte boundary. Increments Tally Counter (CNTR0).

Reception of the packet will be aborted.

of receive buffers or if the controller is in monitor mode and did not buffer the packet to memory. Increments Tally Counter (CNTR2).

address type. 0: Physical Address Match 1: Multicast/Broadcast Address Match

re-enabled when exiting Monitor mode.

If the transceiver has asserted the CD line as a result of the jabber, this bit will stay set indicating the jabber condition.

6 Dribble Bits)

Page 41

5.0 Register Descriptions (Continued)

FIGURE 24. DMA Register

TL/F/11498– 21

Note: In the figure above, registers are shown as 8- or 16-bits wide. Although some registers are 16-bit intemal registers, all registers are accessed as 8-bit

registers. Thus the 16-bit Transmit Byte Count Register is broken into two 8-bit registers, TBCR0 and TBCR1. Also TPSR, PSTART, PSTOP, CURR and BNRY only check or control the upper 8 bits of address information on the bus. Thus they are shifted to positions 15 – 8 in the diagram above.

5.4 DP8390 Core DMA Registers

The DMA Registers are partitioned into groups; Transmit, Receive and Remote DMA Registers. The Transmit registers are used to initialize the Local DMA Channel for transmission of packets while the Receive Registers are used to initialize the Local DMA Channel for packet Reception. The Page Stop, Page Start, Current and Boundary Registers are used by the Buffer Management Logic to supervise the Receive Buffer Ring. The Remote DMA Registers are used to initialize the Remote DMA.

Transmit DMA Registers

TRANSMIT PAGE START REGISTER (TPSR)

This register points to the assembled packet to be transmitted. Only the eight higher order addresses are specified since all transmit packets are assembled on 256-byte page boundaries. The bit assignment is shown below. The values placed in bits D7 –D0 will be used to initialize the higher order address (A8 – A15) of the Local DMA for transmission.

Bit Assignment

76543210

TPSR A15 A14 A13 A12 A11 A10 A9 A8

(A7–A0 Initialized to 0) TRANSMIT BYTE COUNT REGISTER 0,1 (TBCR0, TBCR1)

These two registers indicate the length of the packet to be transmitted in bytes. The count must include the number of bytes in the source, destination, length and data fields. The maximum number of transmit bytes allowed is 64 kbytes. The AT/LANTIC Controller will not truncate transmissions longer than 1500 bytes. The bit assignment is shown below:

76543210

TBCR1 L15 L14 L13 L12 L11 L10 L9 L8

76543210

TBCR0 L7 L6 L5 L4 L3 L2 L1 L0

The lower order bits (A7–A0) are initialized to zero.

Local DMA Receive Registers

PAGE START STOP REGISTERS (PSTART, PSTOP)

The Page Start and Page Stop Registers program the starting and stopping address of the Receive Buffer Ring. Since

Page 42

5.0 Register Descriptions (Continued)

the AT/LANTIC Controller uses fixed 256-byte buffers aligned on page boundaries only the upper eight bits of the start and stop address are specified.

PSTART, PSTOP bit assignment

PSTART

PSTOP

BOUNDARY (BNRY) REGISTER

This register is used to prevent overflow of the Receive Buffer Ring. Buffer management compares the contents of this register to the next buffer address when linking buffers together. If the contents of this register match the next buffer address the Local DMA operation is aborted.

BNRY A15 A14 A13 A12 A11 A10 A9 A8

CURRENT PAGE REGISTER (CURR)

This register is used internally by the Buffer Management Logic as a backup register for reception. CURR contains the address of the first buffer to be used for a packet reception and is used to restore DMA pointers in the event of receive errors. This register is initialized to the same value as PSTART and should not be written to again unless the controller is Reset.

CURR A15 A14 A13 A12 A11 A10 A9 A8

CURRENT LOCAL DMA REGISTER 0,1 (CLDA0,1)

These two registers can be accessed to determine the current Local DMA Address.

CLDA1 A15 A14 A13 A12 A11 A10 A9 A8

CLDA0 A7 A6 A5 A4 A3 A2 A1 A0

Remote DMA Registers

REMOTE START ADDRESS REGISTERS (RSAR0,1)

Remote DMA operations are programmed via the Remote Start Address (RSAR0,1) and Remote Byte Count (RBCR0,1) registers. The Remote Start Address is used to point to the start of the block of data to be transferred and the Remote Byte Count is used to indicate the length of the block (in bytes).

RSAR1 A15 A14 A13 A12 A11 A10 A9 A8

RSAR0 A7 A6 A5 A4 A3 A2 A1 A0

76543210

A15 A14 A13 A12 A11 A10 A9 A8

76543210

REMOTE BYTE COUNT REGISTERS (RCB0,1)

76543210

RBCR1 A15 A14 A13 A12 A11 A10 A9 A8

76543210

RBCR0 A7 A6 A5 A4 A3 A2 A1 A0

Notes:

RSAR0 programs the start address bits A0 –A7.

RSAR1 programs the start address bits A8 –A15.

Address incremented by two for word transfers, and by one for byte transfers. Byte count decremented by two for word transfers and by one for byte transfers.

RBCR0 programs LSB byte count.

RBCR1 programs MSB byte count.

CURRENT REMOTE DMA ADDRESS (CRDA0, CRDA1)

The Current Remote DMA Registers contain the current address of the Remote DMA. The bit assignment is shown below:

76543210

CRDA1 A15 A14 A13 A12 A11 A10 A9 A8

76543210

CRDA0 A7 A6 A5 A4 A3 A2 A1 A0

Physical Address Registers (PAR0–PAR5)

The physical address registers are used to compare the destination address of incoming packets for rejecting or accepting packets. Comparisons are performed on a bytewide basis. The bit assignment shown below relates the sequence in PAR0 –PAR5 to the bit sequence of the received packet.

D7 D6 D5 D4 D3 D2 D1 D0

PAR0 DA7 DA6 DA5 DA4 DA3 DA2 DA1 DA0

PAR1 DA15 DA14 DA13 DA12 DA11 DA10 DA9 DA8

PAR2 DA23 DA22 DA21 DA20 DA19 DA18 DA17 DA16

PARC DA31 DA30 DA29 DA28 DA27 DA26 DA25 DA24

PAR4 DA39 DA38 DA37 DA36 DA35 DA34 DA33 DA32

PAR5 DA47 DA46 DA45 DA44 DA43 DA42 DA41 DA40

Destination Address Source

P/S DA0 DA1 DA2 DA3 . . . DA46 DA47 SA0 . . .

Note: P/SePreamble, Synch

Physical/Multicast Bit

DA0

Multicast Address Registers (MAR0–MAR7)

The multicast address registers provide filtering of multicast addresses hashed by the CRC logic. All destination addresses are fed through the CRC logic and as the last bit of the destination address enters the CRC, the 6 most significant bits of the CRC generator are latched. These 6 bits are then decoded bya1of64decode to index a unique filter bit (FB0–63) in the multicast address registers. If the filter bit selected is set, the multicast packet is accepted. The system designer would use a program to determine which filter

Page 43

5.0 Register Descriptions (Continued)

bits to set in the multicast registers. All multicast filter bits that correspond to multicast address accepted by the node are then set to one. To accept all multicast packets all of the registers are set to all ones.

Note: Although the hashing algorithm does not guarantee pertect filtering of

multicast address, it will pertectly filter up to 64 multicast addresses if these addresses are chosen to map into unique locations in the multicast filter.

FIGURE 25. Multicast Addressing

TL/F/11498– 22

6.0 Operation of AT/LANTIC Controller

This section details the operation of the AT/LANTIC Controller. The operations discussed are packet reception and transmission, bus operations, and loopback diagnostics.

6.1 TRANSMIT/RECEIVE PACKET ENCAPSULATION/ DECAPSULATION

A standard IEEE 802.3 packet consists of the following fields: preamble, Start of Frame Delimiter (SFD), destination address, source address, length, data, and Frame Check Sequence (FCS). The typical format is shown in the figure following. The packets are Manchester encoded and decoded by the ENDEC module and transferred serially to the NIC module using NRZ data with a clock. All fields are of fixed length except for the data field. The AT/LANTIC Controller generates and appends the preamble, SFD and FCS field during transmission. The Preamble and SFD fields are stripped during reception. (The CRC is passed through to buffer memory during reception.)

FIGURE 26. Ethernet Packet

TL/F/11498– 23

PREAMBLE AND START OF FRAME DELIMITER (SFD)

The Manchester encoded alternating 1,0 preamble field is used by the ENDEC to acquire bit synchronization with an incoming packet. When transmitted each packet contains 62 bits of alternating 1,0 preamble. Some of this preamble will be lost as the packet travels through the network. The preamble field is stripped by the NIC module. Byte alignment is performed with the Start of Frame Delimiter (SFD) pattern which consists of two consecutive 1’s. The AT/LANTIC Controller does not treat the SFD pattern as a byte, it detects only the two-bit pattern. This allows any preceding preamble within the SFD to be used for phase locking.

Destination Address

The destination address indicates the destination of the packet on the network and is used to filter unwanted packets from reaching a node. There are three types of address formats supported by the AT/LANTIC: physical, multicast and broadcast. The physical address is a unique address that corresponds only to a single node. All physical addresses have an MSB of ‘‘0’’. These addresses are compared to the internally stored physical address registers. Each bit in the destination address must match in order for the AT/LANTIC Controller to accept the packet. Multicast addresses begin with an MSB of ‘‘1’’. The AT/LANTIC Controller filters multicast addresses using a standard hashing algorithm that maps all multicast addresses into a 6-bit value. This 6-bit value indexes a 64-bit array that filters the value. If the address consists of all 1’s it is a broadcast address, indicating that the packet is intended for all nodes. A promiscuous mode allows reception of all packets: the destination address is not required to match any filters. Physical, broadcast, multicast, and promiscuous address modes can be selected.

Source Address

The source address is the physical address of the node that sent the packet. Source addresses cannot be multicast or broadcast addresses. This field is simply passed to buffer memory.

Length Field

The 2-byte length field indicates the number of bytes that are contained in the data field of the packet. This field is not interpreted by the AT/LANTIC Controller.

Data Field

The data field consists of anywhere from 46 to 1500 bytes. Messages longer than 1500 bytes need to be broken into multiple packets. Messages shorter than 46 bytes will require appending a pad to bring the data field to the minimum length of 46 bytes. If the data field is padded, the number of valid data bytes is indicated in the length field. The

AT/LANTIC Controller does not strip or append pad bytes for short packets, or check for oversize packets.

FCS Field

The Frame Check Sequence (FCS) is a 32-bit CRC field calculated and appended to a packet during transmission to allow detection of errors when a packet is received. During reception, error free packets result in a specific pattern in

Page 44

6.0 Operation of AT/LANTIC Controller (Continued)

the CRC generator. Packets with improper CRC will be rejected. The AUTODlN II (X

polynomial is used for the CRC calculations.

6.2 BUFFER MEMORY ACCESS CONTROL (DMA)

The buffer memory control capabilities of the AT/LANTIC Controller greatly simplify the use of the AT/LANTIC Controller in typical configurations. The local DMA channel transfers data between the FIFO and memory. On transmission, the packet is DMA’d from memory to the FIFO in bursts. Should a collision occur (up to 15 times), the packet is re-transmitted with no processor intervention. On reception, packets are moved via DMA from the FIFO to the receive buffer ring (as explained below).

A Remote DMA channel is also provided on the AT/LANTIC Controller to accomplish transfers between a buffer memory and an internal Data Port when using the AT/LANTIC Controller in I/O Mode. This Remote DMA channel is not used when the AT/LANTIC Controller is used in a shared Memory mode. In this second mode the buffer memory is dual ported, and directly mapped into the system memory. In this mode the system CPU directly accesses the RAM under software control to transfer packet data.

The following sections describe the operation of the Local DMA channel for packet reception which is used in both modes. For Shared Memory mode the description of the Remote DMA does not apply.

For reference an example configuration using the AT/LANTIC Controller is shown in

Figure 27

FIGURE 27. AT/LANTIC Controller Bus Architecture

TL/F/11498– 24

Page 45

6.0 Operation of AT/LANTIC Controller (Continued)

FIGURE 28. AT/LANTIC Controller Receiver Buffer Ring

6.3 PACKET RECEPTION

The Local DMA receive channel uses a Buffer Ring Structure comprised of a series of contiguous fixed length 256 byte (128 word) buffers for storage of received packets. The location of the Receive Buffer Ring is programmed in two registers, a Page Start and a Page Stop Register. Ethernet packets consist of a distribution of shorter link control packets and longer data packets, the 256 byte buffer length provides a good compromise between short packets and longer packets to most efficiently use memory. In addition these buffers provide memory resources for storage of back-toback packets in loaded networks.The assignment of buffers for storing packets is controlled by Buffer Management Logic in the AT/LANTIC Controller. The Buffer Management Logic provides three basic functions: linking receive buffers for long packets, recovery of buffers when a packet is rejected, and recirculation of buffer pages that have been read by the host.

At initialization, a portion of the 64 kbyte (or 32 kword) address space is reserved for the receive buffer ring. Two eight bit registers, the Page Start Address Register (PSTART) and the Page Stop Address Register (PSTOP) define the physical boundaries of where the buffers reside. The AT/LANTIC Controller treats the list of buffers as a logical ring; whenever the DMA address reaches the Page Stop Address, the DMA is reset to the Page Start Address.

TL/F/11498– 25

TL/F/11498– 26

FIGURE 29. Buffer Ring at Initialization

Initialization of the Buffer Ring

Two static registers and two working registers control the operation of the Buffer Ring. These are the Page Start Register, Page Stop Register (both described previously), the Current Page Register and the Boundary Pointer Register. The Current Page Register points to the first buffer used to store a packet and is used to restore the DMA for writing status to the Buffer Ring or for restoring the DMA address in the event of a Runt packet, a CRC, or Frame Alignment error. The Boundary Register points to the first packet in the

Page 46

6.0 Operation of AT/LANTIC Controller (Continued)

Ring not yet read by the host. If the local DMA address ever reaches the Boundary, reception is aborted. The Boundary Pointer is also used to initialize the Remote DMA for removing a packet and is advanced when a packet is removed. A simple analogy to remember the function of these registers is that the Current Page Register acts as a Write Pointer and the Boundary Pointer acts as a Read Pointer.

Note 1: At initialization, the Page Start Register value should be loaded into

both the Current Page Register and the Boundary Pointer Register.

Note 2: The Page Start Register mut not be initalized to 00H.

Beginning of Reception

When the first packet begins arriving the AT/LANTIC Controller begins storing the packet at the location pointed to by the Current Page Register. An offset of 4 bytes is saved in this first buffer to allow room for storing receive status corresponding to this packet.

Linking Buffers

Before the DMA can enter the next contiguous 256 byte buffer, the address is checked for equality to PSTOP and to the Boundary Pointer. If neither are reached, the DMA is allowed to use the next buffer.

FIGURE 30. Received Packet Enters the Buffer Pages

TL/F/11498– 27

Linking Receive Buffer Pages

If the length of the packet exhausts the first 256 byte buffer, the DMA performs a forward link to the next buffer to store the remainder of the packet. For a maximal length packet the buffer logic will link six buffers to store the entire packet. Buffers cannot be skipped when linking, a packet will always be stored in contiguous buffers. Before the next buffer can be linked, the Buffer Management Logic performs two conparisons. The first comparison tests for equality between the DMA address of the next buffer and the contents of the Page Stop Register. If the buffer address equals the Page Stop Register, the buffer management logic will restore the DMA to the first buffer in the Receive Buffer Ring value programmed in the Page Start Address Register. The second comparison tests for equality between the DMA address of the next buffer address and the contents of the Boundary Pointer Register. If the two values are equal the reception is aborted. The Boundary Pointer Register can be used to protect against overwriting any area in the receive buffer ring that has not yet been read. When linking buffers, buffer management will never cross this pointer, effectively avoiding any overwrites. If the buffer address does not match either the Boundary Pointer or Page Stop Address, the link to the next buffer is performed.

FIGURE 31. Linking Receive Buffer Pages

Buffer Ring Overflow

If the Buffer Ring has been filled and the DMA reaches the Boundary Pointer Address, reception of the incoming packet will be aborted by the AT/LANTIC Controller. Thus, the packets previously received and still contained in the Ring will not be destroyed.

In heavily loaded networks which cause overflows of the Receive Buffer Ring, the AT/LANTIC Controller may disable the local DMA and suspend further receptions even if the Boundary register is advanced beyond the Current register. In the event that the AT/LANTIC Controller should encounter a receive buffer overflow, it is necessary to implement the following routine. A receive buffer overflow is indicated by the AT/LANTIC Controller’s assertion of the overflow bit (OVW) in the Interrupt Status Register (ISR).

If this routine is not adhered to, the AT/LANTIC Controller may act in an unpredictable manner. It should also be noted that it is not permissible to service an overflow interrupt by continuing to empty packets from the receive buffer without implementing the prescribed overflow routine. A flow chart of the AT/LANTIC found in

Figure 32

Note: It is necessary to define a variable in the driver, which will be called

‘‘Resend’’.

Controller’s overflow routine can be

1. Read and store the value of the TXP bit in the AT/LANTIC Controller’s Command Register.

2. Issue the STOP command to the AT/LANTIC Controller. This is accomplished by setting the STP bit in the AT/LANTIC Controller’s Command Register. Writing 21 H to the Command Register will stop the AT/LANTIC Controller.

3. Wait for at least 1.6 ms. Since the AT/LANTIC Controller will complete any transmission or reception that is in progress, it is necessary to time out for the maximum possible duration of an Ethernet transmission or reception. By waiting 1.6 ms this is achieved with some guard band added. Previously, it was recommended that the RST bit of the Interrupt Status Register be polled to insure that the pending transmission or reception is completed. This bit is not a reliable indicator and subsequently should be ignored.

TL/F/11498– 28

Page 47

6.0 Operation of AT/LANTIC Controller (Continued)

4. Clear the AT/LANTIC Controller’s Remote Byte Count registers (RBCR0 and RBCR1).

5. Read the stored value of the TXP bit from step 1, above.

If this value is a 0, set the ‘‘Resend’’ variable toa0and jump to step 6.

If this value is a 1, read the AT/LANTIC Controller’s Interrupt Status Register. If either the Packet Transmitted bit (PTX) or Transmit Error bit (TXE) is set to a 1, set the ‘‘Resend’’ variable to a 0 and jump to step 6. If neither of these bits is set, place a 1 in the ‘‘Resend’’ variable and jump to step 6.

This step determines if there was a transmission in progress when the stop command was issued in step 2. If there was a transmission in progress, the AT/LANTIC Controller’s ISR is read to determine whether or not the packet was recognized by the AT/LANTIC Controller. If neither the PTX nor TXE bit was set, then the packet will essentially be lost and re-transmitted only after a time-out takes place in the upper level software. By determining that the packet was lost at the driver level, a transmit command can be reissued to the AT/LANTIC Controller once the overflow routine is completed (as in step 11). Also, it is possible for the AT/LANTIC Controller to defer indefinitely, when it is stopped on a busy network. Step 5 also alleviates this problem. Step 5 is essential and should not be omitted from the overflow routine, in order for the AT/LANTIC Controller to operate correctly.

6. Place the AT/LANTIC Controller in either mode 1 or mode 2 Ioopback. This can be accomplished by setting bits D2 and D1, of the Transmit Configuration Register, to 0,1 or 1,0 respectively.

7. Issue the START command to the AT/LANTIC Controller. This can be accomplished by Writing 22H to the Command Register. This is necessary to activate the AT/LANTIC Controller’s Remote DMA channel.

8. Remove one or more packets from the receive buffer ring.

9. Reset the overwrite warning (OVW, overflow) bit in the Interrupt Status Register.

10. Take the AT/LANTIC Controller out of loopback. This is done by Writing the Transmit Configuration Register with the value it contains during normal operation. (Bits D2 and D1 should both be programmed to 0.)

11. lf the ‘‘Resend’’ variable is set to a 1, reset the ‘‘Resend’’ variable and reissue the transmit command. This is done by writing a value of 26H to the Command Register. If the ‘‘Resend’’ variable is 0, nothing needs to be done.

Note 1: If Remote DMA is not being used, the AT/LANTIC Controller does

not need to be started before packets can be removed from the receive buffer ring. Hence, step 8 could be done before step 7, eliminating or reducing the time spent polling in step 5.

Note 2: When the AT/LANTIC Controller is in STOP mode, the Missed

Packet Tally counter is disabled.

FIGURE 32. Overflow Routine

TL/F/11498– 29

Page 48

6.0 Operation of AT/LANTIC Controller (Continued)

FIGURE 33. Received Packet Aborted if it Hits Boundary

TL/F/11498– 30

Enabling the AT/LANTIC Controller on an Active Network

After the AT/LANTIC Controller has been initialized the procedure for disabling and then re-enabling the AT/LANTIC Controller on the network is similar to handling Receive Buffer Ring overflow as described previously.

1. Program Command Register for page 0 (Command Register

21H)

2. Initialize Data Configuration Register (DCR)

3. Clear Remote Byte Count Registers (RBCR0, RBCR1) if using Remote DMA

4. Initialize Receive Configuration Register (RCR)

5. Place the AT/LANTIC Controller in LOOPBACK mode 1 or 2 (Transmit Configuration Register

02H or 04H)

6. Initialize Receive Buffer Ring: Boundary Pointer (BNDRY), Page Start (PSTART), and Page Stop (PSTOP)

7. Clear Interrupt Status Register (ISR) by writing 0FFH to it

8. Initialize Interrupt Mask Register (IMR)

9. Program Command Register for page 1 (Command Register

61H)

i) Initialize Physical Address Registers (PAR0 – PAR5)

ii) Initialize Multicast Address Registers (MAR0 –

MAR7)

iii) Initialize CURRENT pointer

10. Put AT/LANTIC Controller in START mode (Command Register

22H). The local receive DMA is still not ac-

tive since the AT/LANTIC Controller is in LOOPBACK.

11. Initialize the Transmit Configuration for the intended value. The AT/LANTIC Controller is now ready for transmission and reception.

End of Packet Operations

At the end of the packet the AT/LANTIC Controller determines whether the received packet is to be accepted or rejected. It either branches to a routine to store the Buffer Header or to another routine that recovers the buffers used to store the packet.

FIGURE 34. Termination of Received

TL/F/11498– 31

PacketÐPacket Accepted

Successful Reception

If the packet is successfully received, the DMA is restored to the first buffer used to store the packet (pointed to by the Current Page Register). The DMA then stores the Receive Status, a Pointer to where the next packet will be stored (Buffer 4) and the number of received bytes. Note that the remaining bytes in the last buffer are discarded and reception of the next packet begins on the next empty 256-byte buffer boundary. The Current Page Register is then initialized to the next available buffer in the Buffer Ring. (The location of the next buffer had been previously calculated and temporarily stored in an internal scratchpad register.)

Buffer Recovery for Rejected Packets

If the packet is a runt packet or contains CRC or Frame Alignment errors, it is rejected. The buffer management logic resets the DMA back to the first buffer page used to store the packet (pointed to by CURR), recovering all buffers that had been used to store the rejected packet. This operation will not be performed if the AT/LANTIC Controller is programmed to accept either runt packets or packets with CRC or Frame Alignment errors. The received CRC is always stored in buffer memory after the last byte of received data for the packet.

TL/F/11498– 32

FIGURE 35. Termination of Receive

PacketÐPacket Reject

Page 49

6.0 Operation of AT/LANTIC Controller (Continued)

Error Recovery

If the packet is rejected as shown, the DMA is restored by the AT/LANTIC Controller by reprogramming the DMA starting address pointed to by the Current Page Register.

Storage Format for Received Packets

The following diagrams describe the format for how received packets are placed into memory by the local DMA channel. These modes are selected in the Data Configuration Register.

AD15 AD8 AD7 AD0

Next Packet Pointer Receive Status

Receive Byte Count 1 Receive Byte Count 0

Byte 2 Byte 1

BOSe0, WTSe1 in Data Configuration Register. This format is used with Series 32xxx, or 808xx processors.

AD15 AD8 AD7 AD0

Next Packet Pointer Receive Status

Receive Byte Count 0 Receive Byte Count 1

Byte 1 Byte 2

BOSe1, WTSe1 in Data Configuration Register. This format is used with 680x0 type processors. (Note: The Receiver Count ordering remains the same for BOS

0or1.)

Receive Status

Next Packet Pointer

Receive Byte Count 0

Receive Byte Count 1

Byte 0

Byte 1

BOSe0, WTSe0 in Data Configuration Register. This format is used with general 8-bit processors.

6.4 PACKET TRANSMISSION

The Local DMA is also used during transmission of a packet. Three registers control the DMA transfer during transmission, a Transmit Page Start Address Register (TPSR) and the Transmit Byte Count Registers (TBCR0,1). When the AT/LANTIC Controller receives a command to transmit the packet pointed to by these registers, buffer memory data will be moved into the FIFO as required during transmission. The AT/LANTIC Controller will generate and append the preamble, synch and CRC fields.

General Transmit Packet Format

Transmit Destination Address 6 Bytes

Byte Source Address 6 Bytes

Count Type/Length 2 Bytes

TBCR0, 1 Data

Pad (If data

46 Bytes)

46 Bytes

Transmit Packet Assembly

The AT/LANTIC Controller requires a contiguous assembled packet with the format shown. The transmit byte count includes the Destination Address, Source Address, Length Field and Data. It does not include preamble and CRC.

When transmitting data smaller than 46 bytes, the packet must be padded to a minimum size of 64 bytes. The programmer is responsible for adding and stripping pad bytes.

The packets are placed in the buffer RAM by the system. In I/O Mode the system programs the NIC Core’s Remote DMA to mode the data from the data port to the RAM handshaking with system transfers loading the I/O data port. In Shared Memory Mode the packets are written directly to the RAM by system using standard memory transfer instructions (MOV).

For I/O mode the data transfer must be 16 bits (1 word) when in 16-bit mode, and 8 bits when the AT/LANTIC Controller is set in 8-bit mode. The data width is selected by setting the WTS bit in the Data Configuration Register and setting the DWlD pin for the proper mode.

In Shared Memory mode data transfer can be accomplished by using either 8- or 16-bit data transfer instructions, because this mode responds to 8/16-bit data signalling on the ISA bus. In this mode Shared Memory Control Register 2-bit 6 sets the bus interface data width, and the NIC Core’s data width is set by the WTS bit in the Data Configuration Register.

Transmission

Prior to transmission, the TPSR (Transmit Page Start Register) and TBCR0, TBCR1 (Transmit Byte Count Registers) must be initialized. To initiate transmission of the packet the TXP bit in the Command Register is set. The Transmit Status Register (TSR) is cleared and the AT/LANTIC Controller begins to prefetch transmit data from memory (unless the AT/LANTIC Controller is currently receiving). If the interframe gap has timed out the AT/LANTIC Controller will begin transmission.

Conditions Required to Begin Transmission

In order to transmit a packet, the following three conditions must be met:

1. The Interframe Gap Timer has timed out the first 6.4 ms of the Interframe Gap

2. At least one byte has entered the FIFO. (This indicates that the burst transfer has been started)

3. If a collision had been detected then before transmission the packet time must have timed out.

In typical systems the AT/LANTIC Controller prefetches the first burst of bytes before the 6.4 ms timer expires. The time during which AT/LANTIC Controller transmits preamble can also be used to load the FIFO.

Note: If carrier sense is asserted before a byte has been loaded into the

FIFO, the AT/LANTIC Controller will become a receiver.

Collision Recovery

During transmission, the Buffer Management logic monitors the transmit circuitry to determine if a collision has occurred. If a collision is detected, the Buffer Management logic will reset the FIFO and restore the Transmit DMA pointers for retransmission of the packet. The COL bit will be set in the TSR and the NCR (Number of Collisions Register) will be incremented. If 15 retransmissions each result in a collision the transmission will be aborted and the ABT bit in the TSR will be set.

Note: NCR reads as zeroes if excessive collisions are encountered.

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6.0 Operation of AT/LANTIC Controller (Continued)

Transmit Packet Assembly Format

The following diagrams describe the format for how packets must be assembled prior to transmission for different byte ordering schemes. The various formats are selected in the Data Configuration Register.

D15 D8 D7 D0

Destination Address 1 Destination Address 0

Desitination Address 3 Destination Address 2

Desitination Address 5 Destination Address 4

Source Address 1 Source Address 0

Source Address 3 Source Address 2

Source Address 5 Source Address 4

Type/Length 1 Type Length 0

Data 1 Data 0

BOSe1, WTSe1 in Data Configuration Register.

This format is used with Series 32xxx, or 808xx processors.

D15 D8 D7 D0

Destination Address 0 Destination Address 1

Desitination Address 2 Destination Address 3

Desitination Address 4 Destination Address 5

Source Address 0 Source Address 1

Source Address 2 Source Address 3

Source Address 4 Source Address 5

Type/Length 0 Type Length 1

Data 0 Data 1

BOSe1, WTSe1 in Data Configuration Register.

This format is used with 680x0 type processors.

D7 D0

Destination Address 0

Destination Address 1

Destination Address 2

Destination Address 3

Destination Address 4

Destination Address 5

Source Address 0

Source Address 1

Source Address 2

Source Address 3

Source Address 4

Source Address 5

BOSe0, WTSe0 in a Data Configuration Register.

This format is used with 8-bit processors.

Note: All examples above will result in a transmission of a packet in order of DA0, DA1, DA3 . . . bits within each byte will be transmitted least significant bit first.

Destination Address

6.5 LOOPBACK DIAGNOSTICS

Three forms of local Ioopback are provided on the AT/LANTIC Controller. The user has the ability to loopback through the deserializer on the controller, through the ENDEC module or tranceiver. Because of the half duplex

architecture of the AT/LANTIC Controller, loopback testing is a special mode of operation with the following restrictions:

Restrictions during Loopback

The FIFO is split into two halves, one half is used for transmission the other for reception. Only 8-bit fields can be fetched from memory so two tests are required for 16-bit systems to verify integrity of the entire data path. During loopback the maximum latency to obtain access to the buffer memory is 2.0 ms. Systems that wish to use the loopback test yet do not meet this latency can limit the loopback packet to 7 bytes without experiencing underflow. Only the last 8 bytes of the loopback packet are retained in the FIFO. The last 8 bytes can be read through the FIFO register which will advance through the FIFO to allow reading the receive packet sequentially.

Destination Address

Source Address

When in word-wide mode with Byte Order Select set, the Ioopback packet must be assembled in the even byte locations as shown below. (The loopback only operated with byte wide transfers.)

6 bytes Station Physical Address

Length 2 bytes

Data

CRC

46 to 1500 bytes

Appended by AT/LANTIC Controller if CRC

0inTCR

TL/F/11498– 64

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6.0 Operation of AT/LANTIC Controller (Continued)

When in word-wide mode with Byte Order Select low, the following format must be used for the loopback packet.

This process is continued until the last byte is received. The AT/LANTIC Controller then appends the received byte count in the next two locations of the FIFO. The contents of the Upper Byte Count are also copied to the next FIFO location. The number of bytes used in the loopback packet determined the alignment of the packet in the FIFO. The alignment for a 64-byte packet is shown below.

Note: When using loopback in word mode 2n bytes must be programmed in

the TBCR0, 1. When n or odd location.

To initiate a loopback the user first assembles the loopback packet then selects the type of loopback using the Transmit Configuration register bits LB0, LB1. The transmit configuration register must also be set to enable or disable CRC generation during transmission. The user then issues a normal transmit command to send the packet. During loopback the receiver checks for an address match and if CRC bit in the TCR is set, the receiver will also check the CRC. The last 8 bytes of the loopback packet are buffered and can read out of the FIFO using FIFO read port.

Loopback Modes

MODE1: Loopback through the AT/LANTIC Controller Module (LB1 AT/LANTIC Controller Module’s serializer is connected to the deserializer.

MODE 2: Loopback through the ENDEC Module (LB1 LB0 SNI, the AT/LANTIC Controller provides a control (LPBK) that forces the ENDEC module to loopback all signals.

MODE 3: Loopback to the external coax interface or twisted pair interface module (LB1 transmitted to the cable in loopback mode to check all of the transmit and receive paths and the cable itself. If, in twisted pair mode, there is a link fail the transmitter will be disabled which could give misleading results in Mode 3. The link integrity should be checked, by reading Configuration Register B, before this test.

Note: Collision and Carrier Sense can be generated by the ENDEC module

Reading the Loopback Packet

The last eight bytes of a received packet can be examined by 8 consecutive reads of the FIFO register. The FIFO pointer is increment after the rising edge of the CPU’s read strobe by internally synchronizing and advancing the pointer. This may take up to four bus clock cycles, if the pointer has not been incremented by the time the CPU reads the FIFO register again, the AT/LANTIC Controller will insert wait states.

Note: The FIFO may only be read during Loopback. Reading the FIFO at

Alignment of the Received Packet in the FlFO

Reception of the packet in the FIFO begins at location zero, after the FIFO pointer reaches the last location in the FIFO, the pointer wraps to the top of the FIFO overwriting the previously received data.

0, LB0e1): If this loopback is used, the

0): If the loopback is to be performed through the

and are masked by the NIC module. It is not possible to go directly between the loopback modes, it is necessary to return to normal operation (00H) when changing modes.

any other time will cause the AT/LANTIC Controller to malfunction.

actual number of bytes assembled in even

1, LB0e1). Packets can be

TL/F/11498– 65

FIFO

Location

For the following alignment in the FIFO the packet length should be (N TCR is set, CRC will not be appended by the transmitter. If the CRC is appended by the transmitter, the 1st four bytes, bytes N-3 to N, correspond to the CRC.

FIFO

Location

FIFO Contents

0 Lower Byte Count

1 Upper Byte count

2 Upper Byte Count

3 Last Byte

4 CRC1

5 CRC2

6 CRC3

7 CRC4

8)a5 Bytes. Note that if the CRC bit in the

FIFO Contents

0 Byte N-4

1 Byte N-3 (CRC1)

2 Byte N-2 (CRC2)

3 Byte N-1 (CRC3)

4 Byte N (CRC4)

5 Lower Byte Count

6 Upper Byte Count

7 Upper Byte Count

Loopback Tests

Loopback capabilities are provided to allow certain tests to be performed to validate operation of the AT/LANTIC Controller prior to transmitting and receiving packets on a live network. Typically these tests may be performed during power up of a node. The diagnostic provides support to verify the following:

1. Verify integrity of data path. Received data is checked against transmitted data.

2. Verify CRC logic’s capability to generate good CRC on transmit, verify CRC on receive (good or bad CRC).

3. Verify that the Address Recognition Logic can

a. Recognize address match packets

b. Reject packets that fail to match an address

Loopback Operation in the AT/LANTIC Controller

Loopback is a modified form of transmission using only half of the FIFO. This places certain restrictions on the use of

First Byte Read

Second Byte Read

Last Byte Read

First Byte Read

Second Byte Read

Last Byte Read

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6.0 Operation of AT/LANTIC Controller (Continued)

loopback testing. When loopback mode is selected in the TCR, the FIFO is spilt. A packet should be assembled in memory with programming of TPSR and TBCR0, TBCR1 registers. When the transmit command is issued the following operations occur:

TRANSMITTER ACTIONS

1. Data is transferred from memory by the DMA until the FIFO is filled. For each transfer TBCR0 and TBCR1 are decremented. (Subsequent burst transfers are initiated when the number of bytes in the FIFO drops below the programmed threshold.)

2. The AT/LANTIC Controller generates 56 bits of preamble followed by an 8-bit synch pattern.

3. Data transferred from FIFO to serializer.

4. If CRC

1 in TCR, no CRC calculated by AT/LANTIC Controller, the last byte transmitted is the last byte from the FIFO (allows software CRC to be appended). If

CRC

0, AT/LANTIC Controller calculates and ap-

pends four bytes of CRC.

5. At end of Transmission PTX bit set in ISR.

RECEIVER ACTIONS

1. Wait for synch, all preamble stripped.

2. Store packet in FIFO, increment receive byte count for each incoming byte.

3. If CRC

0 in TRC, receiver checks incoming packet for

CRC errors. If CRC

1 in TCR, receiver does not check CRC errors, CRC error bit always set in RSR (for address matching packets).

4. At end of receive, receive byte count written into FIFO, receive status register is updated. The PRX bit is typically set in the RSR even if the address does not match. If CRC errors are forced, the packet must match the address filters in order for the CRC error bit in the RS to be set.

EXAMPLES

The following examples show what results can be expected from a properly operating AT/LANTIC Controller during loopback. The restrictions and results of each type of Ioopback are listed for reference. The loopback tests are divided into two sets of tests. One to verify the data path, CRC generation and byte count through all three paths. The second set of tests uses internal loopback to verify the receiver’s CRC checking and address recognition. For all of the tests the DCR was programmed to 40H.

Path TCR RCR TSR RSR ISR

AT/LANTIC 02 1F 53 02 02

Controller (Note 1) (Note 2) (Note 3)

Internal

Note 1: Since carrier sense and collision detect are generated in the

ENDEC module. They are blocked during internal loopback, carrier and CD heartbeat are not seen and the CRS and CDH bits are set.

Note 2: CRC errors are always indicated by receiver if CRC is appended by

the transmitter.

Note 3: Only the PTX bit in the ISR is set, the PRX bit is only set if status is

written to memory. In loopback this action does not occur and the PRx bit remains 0 for all loopback modes.

Note 4: All values are hex.

Path TCR RCR TSR RSR ISR

AT/LANTIC 04 1F 43 02 02

Controller (Note 1)

Internal

Note 1: CDH is set, CRS is not set since it is generated by the external

encoder/decoder.

Path TCR RCR TSR RSR ISR

AT/LANTIC 06 1F 03 02 02

Controller (Note 1) (Note 2)

External

Note 1: CDH and CRS should not be set. The TSR however, could also

contain 01H,03H,07H and a variety of other values depending on whether collisions were encountered or the packet was deferred.

Note 2: Will contain 08H if packet is not transmittable.

Note 3: During extemal loopback the AT/LANTIC Controller is now ex-

posed to network traffic, it is therefore possible for the contents of both the Receive portion of the FIFO and the RSR to be corrupted by any other packet on the network. Thus in a live network the contents of the FIFO and RSR should not be depended on. The AT/LANTIC Controller will still abide by the standard CSMA/CD protocol in external loopback mode (i.e. the network will not be disturbed by the loopback packet).

Note 4: All values are hex.

CRC and Address Recognition

The next three tests exercise the address recognition logic and CRC. These tests should be performed using internal Ioopback only so that the AT/LANTIC Controller is isolated from interference from the network. These tests also require the capability to generate CRC in software.

The address recognition logic cannot be directly tested. The CRC and FAE bits in the RSR are only set if the address in the packet matches the address filters. If errors are expected to be set and they are not set, the packet has been rejected on the basis of an address mismatch. The following sequence of packets will test the address recognition logic. The DCR should be set to 40H, the TCR should be set to 03H with a software generated CRC.

Packet Contents Results

Test Address CRC RSR

Test A Matching Good 01 (Note 1) Test B Matching Bad 02 (Note 2) Test C Non-Matching Bad 01

Note 1: Status will read 21H if multicast address used.

Note 2: Status will read 22H if multicast address used.

Note 3: In test A, the RSR is set up. In test B the address is found to match

since the CRC is flagged as bad. Test C proves that the address recognition logic can distinguish a bad address and does not notify the RSR of the bad CRC. The receiving CRC is proven to work in test A and test B.

Note 4: All values are hex.

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6.0 Operation of AT/LANTIC Controller (Continued)

Figure 36

TL/F/11498– 33

FIGURE 36. Tally Counters

Network Management Functions

Network management capabilities are required for maintenance and planning of a local area network. The AT/LANTIC Controller supports the minimum requirement for network management in hardware, the remaining requirements can be met with software. Software alone can not track during reception of packets: CRC errors, Frame Alignment errors, and missed packets,

Since errored packets can be rejected, the status associated with these packets is lost unless the CPU can access the Receive Status Register before the next packer arrives. In situations where another packet arrives very quickly, the CPU may have no opportunity to do this. The AT/LANTIC Controller counts the number of packets with CRC errors and Frame Alignment errors. 8-bit counters have been selected to reduce overhead. The counters will generate interrupts whenever their MSBs are set so that a software routine can accumulate the network statistics and reset the counter before overflow occurs. The counters are sticky so that when they reach a count of 192 (C0H) counting is halted. An additional counter is provided to count the number of packets the AT/LANTIC Controller misses due to buffer overflow or being offline.

The structure of the counters is shown in

Additional information required for network management is available in the Receive and Transmit Status Registers. Transmit status is available after each transmission for information regarding events during transmission.

Typically, the following statistics might be gathered in software:

Traffic: Frames Sent OK

Frames Received OK

Multicast Frames Received

Packets Lost Due to Lack of Resources

Retries/Packet

Errors: CRC Errors

Alignment Errors

Excessive Collisions

Packet with Length Errors

Heartbeat Failure

6.6 MEMORY ARBITRATION AND BUS OPERATION

The AT/LANTIC Controller will always operate as a slave device on its peripheral interface to the ISA bus. However on the memory bus, the AT/LANTIC Controller operates in three possible modes:

1. Bus Master of Local Packet Buffer RAM

2. Bus Slave when accessed by the CPU via the Bus Interface

3. Idle, when no activity is occurring.

FIGURE 37. DP8390 Core Bus States

TL/F/11498– 34

Upon power-up the AT/LANTIC Controller is in an indeterminate state. After receiving a hardware reset the AT/LANTIC Controller is a bus slave in the Reset State, the receiver and transmitter are both disabled in this state. The reset state can be re-entered under four conditions, soft reset (Stop Command), register reset (reset port in I/O mode, bit in Control Register 1 in shared memory mode), hard reset (RESET input) or an error that shuts down the receiver or transmitter (FIFO underflow or overflow, receive buffer ring overflow).

After initialization of registers, the AT/LANTIC Controller is issued a Start command and the AT/LANTIC Controller enters Idle state. Until the DMA is required the AT/LANTIC Controller remains in idle state.

The idle state is exited and the AT/LANTIC Controller will drive the local memory bus when a request from the FIFO in the DP8390 (NIC) core causes the memory bus interface logic to issue a read or write operation, such as when the AT/LANTIC Controller is transmitting or receiving data.

In I/O mode the NIC Core’s Remote DMA also requests access from the memory bus. When software programs an I/O mode data transfer between the CPU and the buffer RAM, the Remote DMA controls this request.

In Shared Memory Mode, the memory bus is accessed via the CPU interface directly.

All Local DMA transfers are burst transfers, the DMA will transfer an exact burst of bytes programmed in the Data Configuration Register (DCR) then relinquish the memory bus. If there are remaining bytes in the FIFO the next burst will not be initiated until the FIFO threshold is exceeded.

I/O Mode Operation

In I/O mode the AT/LANTIC Controller transfers data to and from the packet buffer RAM by utilizing the Remote DMA logic which is programmed by the main system CPU to transfer data through the AT/LANTIC Controller’s internal data port register.

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6.0 Operation of AT/LANTIC Controller (Continued)

I/O MODE REMOVING PACKETS FROM RING

Network activity is isolated on a local bus, where the AT/LANTIC Controller’s local DMA channel performs burst transfers between the buffer memory and the AT/LANTIC Controller’s FIFO. The Remote DMA transfers data between the buffer memory and the host memory via the internal bidirectional I/O port. The Remote DMA provides local addressing capability and is used as a slave DMA by the host. The host system reads the I/O port to transfer data between the system and I/O port. The AT/LANTIC Controller allows Local and Remote DMA operations to be interleaved.

FIGURE 38. I/O Operation: All Data Transfers and

TL/F/11498– 35

Arbitration is Controlled by the NIC Core

INTERLEAVED LOCAL/REMOTE OPERATION

When in I/O mode the remote DMA is used to transfer data to/from the main system. If a remote DMA transfer is initiated or in progress when a packet is being received or transmitted, the Remote DMA transfers will be interrupted for higher priority Local DMA transfers. When the Local DMA transfer is completed the Remote DMA will rearbitrate for the bus and continue its transfers.

If the FIFO requires service while a remote DMA is in progress the Local DMA burst is appended to the Remote Transfer. When switching from a local transfer to a remote transfer there is a break to allow the CPU to fairly contend for the bus.

REMOTE DMA BI-DIRECTIONAL PORT

The Remote DMA transfers data between the local buffer memory and the internal bidirectional port (memory to I/O transfer).

This transfer is arbitrated on a transfer by transfer basis versus the burst transfer mode used for Local DMA transfers. This bidirectional port is integrated onto the AT/LANTIC Controller, and is read/written by the host. All transfers through this port are asynchronous. At any one time transfers are limited to one direction, either from the port to local buffer memory (Remote Write) or from local buffer memory to the port (Remote Read).

TL/F/11498– 36

FIGURE 39. 1st Received Packet

Removed by Remote DMA

Packets are removed from the ring using the Remote DMA. When using the Remote DMA the Send Packet command can be used. This programs the Remote DMA to automatically remove the received packet pointed to by the Boundary Pointer. At the end of the transfer, the AT/LANTIC Controller moves the Boundary Pointer, freeing additional buffers for reception. The Boundary Pointer can also be moved manually by programming the Boundary Register. Care should be taken to keep the Boundary Pointer at least one buffer behind the Current Page Pointer.

Data transfer by the Remote DMA to the integrated I/O data port is dependent on whether the AT/LANTIC Controller is set into 8-bit mode or 16-bit mode. In 8-bit mode all transfers are 8 bits (1 byte) wide. When in 16-bit mode all transfers are 16 bits (1 word) wide. The data width is selected by setting the WTS bit in the Data Configuration Register and setting the DWID pin for the proper mode.

The following is a suggested method for maintaining the Receive Buffer Ring pointers if in shared memory mode or if remote read is used in I/O mode.

1. At initialization, set up a software variable (nextÐpkt) to indicate where the next packet will be read. At the beginning of each Remote Read DMA operation, the value of nextÐpkt will be loaded into RSAR0 and RSAR1.

2. When initializing the AT/LANTIC Controller set:

BNDRY CURR nextÐpkt

3. After a packet is DMAed from the Receive Buffer Ring, the Next Page Pointer (second byte in the AT/LANTIC Controller buffer header is used to update BNDRY and nextÐpkt. nextÐpkt BNDRY

If BNDRYkPSTART then BNDRYePSTOPb1

Note the size of the Receive Buffer Ring is reduced by one 256 byte buffer, this will not, however, impede the operation of the AT/LANTIC Controller. The advantage of this scheme is that it easily differentiates between buffer full and buffer empty: it is full if BNDRY BNDRY to empty the buffer ring this scheme cannot be used. BNDRY must be initialized equal to CURR, or the first executed send packet will not return data from the received packet, which will be written at CURR. The Overwrite Warning bit of the Interrupt Status Register must be used in this mode to differentiate between buffer full and buffer empty.

PSTART

PSTARTa1

Next Page Pointer

Next Page Pointerb1

CURRb1. If, in I/O mode, send packet is used

CURR; empty when

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6.0 Operation of AT/LANTIC Controller (Continued)

FIGURE 40. Remote DMA Autoinitialization from Buffer Ring

I/O MODE REMOTE DMA COMMANDS

The Remote DMA channel is used in the I/O Mode to both assemble packets for transmission, and to remove received packets from the Receive Buffer Ring. It may also be used for moving blocks of data or commands between host memory and local buffer memory. (In Shared Memory Mode, the Remote DMA should be disabled, and not used. Packet transfer to/from the system is accomplished by normal CPU read/write operations.)

There are three modes of Remote DMA operation: Remote Write, Remote Read, or Send Packet.

Two register pairs are used to control the Remote DMA, a Remote Start Address (RSAR0, RSAR1) and a Remote Byte Count (RBCR0, RBCRl) register pair. The Start Address Register pair points to the beginning of the block to be moved while the Byte Count Register pair is used to indicate the number of bytes to be transferred. Full handshake logic is provided to move data between local buffer memory and a bidirectional I/O port.

Remote Write: A Remote Write transfer is used to move a block of data from the host into local buffer memory. The Remote DMA will read data from the I/O port and sequentially write it to local buffer memory beginning at the Remote Start Address. The DMA Address will be incremented and the Byte Counter will be decremented after each transfer. The DMA is terminated when the Remote Byte Count Register reaches a count of zero.

Remote Read: A Remote Read transfer is used to move a block of data from local buffer memory to the host. The Remote DMA will sequentially read data from the local buffer memory, beginning at the Remote Start Address, and write data to the I/O port. The DMA Address will be incremented and the Byte Counter will be decremented after each transfer. The DMA is terminated when the Remote Byte Count Register reaches zero.

TL/F/11498– 37

Send Packet Command: The Remote DMA channel can be automatically initialized to transfer a single packet from the Receive Buffer Ring. The CPU begins this transfer by issuing a ‘‘Send Packet’’ Command. The DMA will be initialized to the value of the Boundary Pointer Register and the Remote Byte Count Register pair (RBCR0, RBCR1) will be initialized to the value of the Receive Byte Count fields found in the Buffer Header of each packet. After the data is transferred, the Boundary Pointer is advanced to allow the buffers to be used for new receive packets. The Remote Read will terminate when the Byte Count equals zero. The Remote DMA is then prepared to read the next packet from the Receive Buffer Ring. If the DMA pointer crosses the Page Stop Register, it is reset to the Page Start Address. This allows the Remote DMA to remove packets that have wrapped around to the top of the Receive Buffer Ring.

Note 1: In order for the AT/LANTIC Controller to correctly execute the

Send Packet command, the upper Remote Byte Count Register (RBCR1) must first be loaded with 0FH.

Note 2: The Send Packet command cannot be used with 680x0 type proc-

essors.

I/O MODE READ TIMING

1. The DMA reads a word from local buffer memory and writes the word into the internal latch, increments the DMA address and decrements the byte count (RBCR0,1).

2. Internally a request line is asserted to enable the system to read the port. If the system reads this port before the data has been written, then the system is sent a wait signal to wait until the data has been written to the port. Once written the system’s read is allowed to complete.

3. The system reads the port, the read strobe for the port is used as an acknowledge to the Remote DMA and it goes back to step 1.

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6.0 Operation of AT/LANTIC Controller (Continued)

Steps 1–3 are repeated until the remote DMA is complete (i.e. the byte count has gone to zero).

Note that in order for the Remote DMA to transfer a word from memory to the latch, it must arbitrate access to the local buffer RAM. After each word is transferred to the internal latch, access to the RAM is relinquished. If a Local DMA is in progress, the Remote DMA is held off until the local DMA is complete.

I/O MODE WRITE TIMING

A Remote Write operation transfers data from the I/O port to the local buffer RAM. The system transfers a byte-word to the latch via IOWR AT/LANTIC Controller and the byte/word is transferred to local buffer memory. The Remote DMA holds off further transfers into the latch until the current byte/word has been transferred from the latch.

1. AT/LANTIC Controller awaits data to be written by the system. System writes byte/word into latch.

2. Remote DMA reads contents of port and writes byte/ word to local buffer memory, increments address and decrements byte count (RBCR0,1).

3. Go back to step 1.

Steps 1 – 3 are repeated until the remote DMA is complete.

FIGURE 41. Shared Memory Mode the

ISA Bus Directly Access the RAM

Shared Memory Mode Operation

In shared memory mode the AT/LANTIC Controller transfers data to or from the packet buffer RAM directly from or to the ISA bus. The buffer RAM is mapped into system memory with the AT/LANTIC Controller doing all address decoding, synchronization and handshaking.

INTERLEAVED SHARED/LOCAL OPERATION

When in shared memory mode the local DMA is used to transfer data to or from the FIFO in the NIC core and ultimately the network. If a local DMA transfer is in progress when a shared memory access occurs the system is sent a wait state signal until the local DMA has been completed. If the shared memory access begins first then it will be completed before any local DMA is allowed.

. This write strobe is detected by the

TL/F/11498– 38

SHARED MEMORY HOST DATA TRANSFER

In Shared Memory Mode the system reads data from the RAM directly, usually using memory string move instructions. The memory is enabled by setting D6 of Shared Memory Control Register 1. The base address of the memory is programmed by writing to the Control Registers.

If DWlD is low only Control Register 1 is used to program base address, so the memory must exist in the lower 1 Mbytes of system memory. A19 is always Compared to a 1 when DWlD is low. The A13 –18 bits are compared to the address lines, if there is 8k of memory. A13 is not compared in 16k mode, A13–14 are not compared in 32k mode (8-bit non-compatible) and A13 – 15 are not compare in 64k mode (16-bit non-compatible).

If DWID is high both Control Registers must be programmed to set the base address, so the memory can exist anywhere in up to 16 Gbytes of system memory. LA19 can be either 1 or 0. The same limited decode, as detailed above, also occurs depending on the memory size.

SHARED MEMORY READ TIMING

The system executes a normal memory read cycle which the AT/LANTIC Controller will complete immediately, if idle, or insert wait states into if local DMA is current. The byte or word of data is fetched from the buffer RAM via the memory support bus.

SHARED MEMORY WRITE TIMING

The system executes a normal memory write cycle which the AT/LANTIC Controller will complete immediately, if idle, or insert wait states into if local DMA is current. The byte or word of data is written to the buffer RAM via the memory support bus.

6.7 FUNCTIONAL BUS TIMING

This section describes the bus cycles that the AT/LANTIC Controller performs. These timings can be subdivided into 3 basic categories:

1. ISA I/O Access: There are register accesses in both modes, and I/O data accesses in I/O mode.

2. Shared RAM ISA Accesses: These are the timing for the ISA bus accesses through the AT/LANTIC Controller to the memory bus and buffer RAM.

3. Boot PROM ISA Accesses: These are the timing for the ISA bus accesses through the AT/LANTIC Controller to the memory bus and boot PROM.

4. Local and I/O RAM Accesses: This is the timing of the Local DMA, accesses from the NIC Core FIFO to the RAM, and the Remote DMA accesses to the RAM over the memory bus.

ISA Bus I/O Accesses

The AT/LANTIC Controller is designed to directly interface to the ISA bus (PC-AT backplane bus). The CPU can read or write any internal registers. All register accesses are byte wide. The functional timing for AT/LANTIC Controller accesses are shown in the following pages.

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6.0 Operation of AT/LANTIC Controller (Continued)

8-Bit I/O Mode Slave Read

TL/F/11498– 39

This is the type of cycle used to read from a register or, in 8-bit I/O mode, from a data transfer port. These accesses are entirely asynchronous, with the AT/LANTIC Controller responding when it decodes the correct address on SA0–9 and an IORD is high the cycle will be ignored. CHRDY is deasserted if the AT/LANTIC Controller is not ready to respond and asserted when ready. If it is ready immediately CHRDY is not deasserted. The data will always appear on SD0 – 7.

8-Bit I/O Mode Slave Write

.IfAEN

TL/F/11498– 40

This is the type of cycle used to write to a register or, in 8-bit I/O mode, to a data transfer port. These accesses are entirely asynchronous, with the AT/LANTIC Controller responding when it decodes the correct address on SA0 – 9 and an IOWR

.IfAEN is high the cycle will be ignored. CHRDY is deasserted if the AT/LANTIC Controller is not ready to respond and asserted when ready. If it is ready immediately CHRDY is not deasserted. The data will always be taken from SD0 –7.

Page 58

6.0 Operation of AT/LANTIC Controller (Continued)

16-Bit I/O Mode Slave Read

TL/F/11498– 41

This is the type of cycle used to read from a data transfer port in 16-bit I/O mode. These accesses are entirely asynchronous, with the AT/LANTIC Controller responding when it decodes the correct address on SA0–9 and an IORD cycle will be ignored. CHRDY is deasserted if the AT/LANTIC Controller is not ready to respond and asserted when ready. If it is ready immediately CHRDY is not deasserted. IO16

is generated, when an address within the AT/LANTIC Controller’s data transfer port is decoded, to indicate to the system that this is a 16-bit transfer. If the IO16CON bit in Configuration Register B is low then it will be a straight decode of the SA0 – 9 lines. If that bit is high the I016 active. SBHE

must be low, to indicate that this is a 16-bit transfer, and the address should be even, SA0 low. The data will

output will be generated after IORD goes

appear on SD0 –15.

16-Bit I/O Mode Slave Write

. If AEN is high the

TL/F/11498– 42

This is the type of cycle used to write to a data transfer port in 16-bit I/O mode. These accesses are entirely asynchronous, with the AT/LANTIC Controller responding when it decodes the correct address on SA0 –9 and an IOWR

. If AEN is high the cycle will be ignored. CHRDY is deasserted if the AT/LANTIC Controller is not ready to respond and asserted when ready. If it is ready immediately CHRDY is not deasserted. I016

output will be generated after IOWR goes active. SBHE must

be low, to indicate that this is a 16-bit transfer, and the address should be even, SA0 low. The data will be taken from SD0 – 15.

Page 59

6.0 Operation of AT/LANTIC Controller (Continued)

16-Bit I/O Cycle with CHRDY Fix

Some Chips and Technologies and VLSI Technologies PC-AT chip sets have timing requirements in 16-bit I/O cycles that cannot be achieved by the default AT/LANTIC cycle, described on the previous page. When that cycle is executed with these chip sets the system does not recognize the CHRDY signal and does not insert wait states. The system executes a standard cycle and deasserts IORD or IOW even if CHRDY is still deasserted. The AT/LANTIC recognizes if this situation has occurred, asserts CHRDY and sets a bus error bit in Configuration Register B to flag this error. Thus the user can test any new system to see if this error occurs and then take some remedial action. There are two ways of overcoming this problem, which are implemented by various board vendors. The AT/LANTIC supports both methods to allow the user to decide. Either fix can be selected by software, by writing to Configuration Register B.

The first fix is enabled by setting the IO16-bit of Configuration Register B. In normal operation any time a valid address exists on SA0–9 IO16 is generated. Delaying IO16 until after the IORD or IOW can cure the problem on non-compliant machines. The theory is that the system is fooled into thinking an 8-bit peripheral is responding, since IO16 is not generated for the valid address, and accepts 8-bit I/O cycle timings for CHRDY. It then rechecks IO16 after the IORD or IOW strobe and correctly determines it is a 16-bit peripheral. If a system did not recheck IO16 it would generate 2 8-bit cycles instead of 1 16-bit cycle. The AT/LANTIC would interpret each 8-bit access as a 16-bit transfer and decrement it’s DMA byte count by 2. Eventually the system would attempt to access the data transfer port when the AT/LANTIC had finished transferring data and CHRDY would be deasserted indefinitely. To prevent misoperation, this fix should only be implemented on systems that require it.

The above figure shows the second fix to the problem with non-compliant machines. It is enabled by setting the CHRDY bit of Configuration Register B. This approach works on the theory that CHRDY deassertion is not fast enough and should be faster. In fact, it must be deasserted before the IORD or IOW strobe to operate correctly in some machines. All of the signals shown above are the same as a normal 16-bit I/O cycle, except CHRDY. BALE goes active and the address becomes valid after a falling edge of ISACLK. This causes the AT/LANTIC to generate IO16 if the address decodes to the data transfer port. BALE goes inactive after the next rising edge of ISACLK and IORD or IOW is asserted after the following falling edge. Normally CHRDY would be deasserted after the IORD or IOW strobe, if the AT/LANTIC was not ready. With this fix implemented CHRDY is deasserted as soon as the address becomes valid and BALE is active. If a memory cycle is in operation, instead of an I/O, CHRDY is asserted after the command strobe (MRD, MWR, SMRD or SMWR). If the address becomes invalid CHRDY is asserted. To prevent CHRDY being asserted for the half clock between BALE going inactive and IORD or IOW going active the AT/LANTIC holds CHRDY asserted as long as ISACLK is high between these signals. If the delay between the falling edge of ISACLK and the falling edge of IORD or IOW is too great, there may be a period where CHRDY is not held deasserted. This should not cause a problem. To prevent misoperation, this fix should only be implemented on systems that require it.

TL/F/11498– 63

Page 60

6.0 Operation of AT/LANTIC Controller (Continued)

ISA Bus Shared Memory Access Timing

Shared Memory Mode Read Bus Timing with DWID Low

TL/F/11498– 43

This is the type of cycle used to read from buffer RAM in shared memory mode when DWlD is low. These accesses are entirely asynchronous, with the AT/LANTIC Controller responding when it decodes the address on SA0 –19 matches Control Register 1 and an SMRD respond and asserted when ready. If it is ready immediately CHRDY is not deasserted. If the memory width bit in Control Register 2 is low then 8 kbytes of RAM are accessible, so only RCS1 If this bit is high 16 kbytes of RAM are accessible, so both chip selects and byte lanes are used. If the memory address is even RCS1

. If AEN is high the cycle will be ignored. CHRDY is deasserted if the AT/LANTIC Controller is not ready to

is used to strobe data and the data is always on MSD0 –7.

and MSD0 – 7 are used, if odd RCS2 and MSD8 –15 are used. System data is always output on SD0 – 7.

Page 61

6.0 Operation of AT/LANTIC Controller (Continued)

Shared Memory Mode Write Bus Timing with DWID Low

TL/F/11498– 44

This is the type of cycle used to write to buffer RAM in shared memory mode when DWlD is low. These accesses are entirely asynchronous, with the AT/LANTIC Controller responding when it decodes the address on SA0 –19 matches Control Register 1 and an SMWR respond and asserted when ready. If it is ready immediately CHRDY is not deasserted. If the memory width bit in Control Register 2 is low then 8 kbytes of RAM are accessible, so only RCS1 If this bit is high 16 kbytes of RAM are accessible, so both chip selects and byte lanes are used. If the memory address is even RCS1

. If AEN is high the cycle will be ignored. CHRDY is deasserted if the AT/LANTIC Controller is not ready to

is used to strobe data and the data is always on MSD0 –7.

and MSD0 – 7 are used, if odd RCS2 and MSD8 –15 are used. System data is always taken from SD0 – 7.

Page 62

6.0 Operation of AT/LANTIC Controller (Continued)

16-Bit Shared Memory Mode Read Bus Timing with DWID High

TL/F/11498– 45

This is the type of cycle used to read 16 bits from buffer RAM is shared memory mode when DWID is high. These accesses are entirely asynchronous, with the AT/LANTIC Controller responding when it decodes the correct address on LA17 –23, SA0 –19 and a MRD and asserted when ready. If it is ready immediately CHRDY is not deasserted. The 8/16-bit in Control Register 2 must be set to allow generation of M16 Register 2. It will therefore be generated for a full 128 kbytes of address space, although the AT/LANTIC Controller will occupy less than that. It may be preferable to only set the 8/16-bit for the duration of a transfer from the buffer RAM. The AT/LANTIC Controller will also compare the address line programmed in Control Register 1 before allowing accesses to buffer RAM and therefore do a complete decode. The system indicates that this is a 16-bit transfer by asserting SBHE address, SA0 low. The full 16 bits of data bus are used on both system and memory support busses.

. If AEN is high the cycle will be ignored. CHRDY is deasserted if the AT/LANTIC Controller is not ready to respond

. This will be generated whenever the LA17 –23 lines match the corresponding values in Control

and accessing an even

Page 63

6.0 Operation of AT/LANTIC Controller (Continued)

16-Bit Shared Memory Mode Write Bus Timing with DWID High

TL/F/11498– 46

This is the type of cycle used to write 16 bits to buffer RAM in shared memory mode when DWID is high. These accesses are entirely asynchronous, with the AT/LANTIC Controller responding when it decodes the correct address on LA17 –23, SA0 –19 and a MWR and asserted when ready. If it is ready immediately CHRDY is not deasserted. The 8/16-bit in Control Register 2 must be set to allow generation of M16 Register 2. It will therefore be generated for a full 128 kbytes of address space, although the AT/LANTIC Controller will occupy less than that. It may be preferable to only set the 8/16-bit for the duration of a transfer to the buffer RAM. The AT/LANTIC Controller will also compare the address line programmed in Control Register 1 before allowing accesses to buffer RAM and therefore do a complete decode. The system indicates that this is a 16-bit transfer by asserting SBHE address, SA0 low. The full 16 bits of data bus are used on both system and memory support busses.

. If AEN is high the cycle will be ignored. CHRDY is deasserted if the AT/LANTIC Controller is not ready to respond

. This will be generated whenever the LA17 –23 lines match the corresponding values in Control

and accessing an even

Page 64

6.0 Operation of AT/LANTIC Controller (Continued)

8-Bit Shared Memory Mode Read Bus Timing with DWID High

TL/F/11498– 47

This is the type of cycle used to read 8 bits from buffer RAM in shared memory mode when DWID is high. These accesses are entirely asynchronous, with the AT/LANTIC Controller responding when it decodes the correct address on LA17 –23, SA0 –19 and a MRD and asserted when ready. If it is ready immediately CHRDY is not deasserted. The 8/16-bit in Control Register 2 must be set to allow generation of M16 Register 2. It will therefore be generated for a full 128 kbytes of address space, although the AT/LANTIC Controller will occupy less than that. It may be preferable to only set the 8/16-bit for the duration of a transfer from the buffer RAM. The AT/LANTIC Controller will also compare the address line programmed in Control Register 1 before allowing accesses to buffer RAM and therefore do a complete decode. The system indicates that this is an 8-bit transfer by not asserting SBHE SA0 low, or by accessing an odd address, SA0 high. If the 8/16-bit is low the AT/LANTIC Controller will only drive data onto SD0–7. Even addresses will use RCS1 AT/LANTIC Controller can drive either SD0 –7 or SD8 –15. Even addresses are fetched using RCS1 onto SD0 – 7. Odd addresses are fetched using RCS2

. If AEN is high the cycle will be ignored. CHRDY is deasserted if the AT/LANTIC Controller is not ready to respond

. This will be generated whenever the LA17 –23 lines match the corresponding values in Control

for an even address,

and MSD0 – 7, odd addresses will use RCS2 and MSD8 –15. If 8/16-bit is high the

and MSD0 – 7 and driven

and MSD8 – 15 and driven onto SD8–15.

Page 65

6.0 Operation of AT/LANTIC Controller (Continued)

8-Bit Shared Memory Mode Write Bus Timing with DWID High

TL/F/11498– 48

This is the type of cycle used to write 8 bits to buffer RAM in shared memory mode when DWID is high. These accesses are entirely asynchronous, with the AT/LANTIC Controller responding when it decodes the correct address on LA17 –23, SA0 –19 and a IORD and asserted when ready. If it is ready immediately CHRDY is not deasserted. The 8/16-bit in Control Register 2 must be set to allow generation of M16 Register 2. It will therefore be generated for a full 128 kbytes of address space, although the AT/LANTIC Controller will occupy less than that. It may be preferable to only set the 8/16-bit for the duration of a transfer to the buffer RAM. The AT/LANTIC Controller will also compare the address line programmed in Control Register 1 before allowing accesses to buffer RAM and therefore do a complete decode. The system indicates that this is an 8-bit transfer by not asserting SBHE SA0 low, or by accessing an odd address, SA0 high. If the 8/16-bit is low the AT/LANTIC Controller will only read data from SD0–7. Even addresses will use RCS1 AT/LANTIC Controller can read from either SD0 – 7 or SD8–15. Even addresses are read from SD0 –7 and written to RAM using RCS1

. If AEN is high the cycle will be ignored. CHRDY is deasserted if the AT/LANTIC Controller is not ready to respond

. This will be generated whenever the LA17 –23 lines match the corresponding values in Control

for an even address,

and MSD0 – 7, odd addresses will use RCS2 and MSD8 –15. If 8/16-bit is high the

and MSD0 – 7. Odd addresses are read from SD8 – 15 and written to RAM using RCS2 and MSD8 –15.

Page 66

6.0 Operation of AT/LANTIC Controller (Continued)

ISA Bus Boot PROM Access Timing

Boot PROM Read Bus Timing

TL/F/11498– 49

This is the type of cycle used to read the boot PROM. These accesses are entirely asynchronous, with the AT/LANTIC Controller responding when it decodes the correct address on SA0 – 19 and a SMRD CHRDY is deasserted if the AT/LANTIC Controller is not ready to respond and asserted when ready. If it is ready immediately CHRDY is not deasserted. M16

is high AND 3)8/16-bit in Control Register 2 is high AND 4) the LA17 –23 lines match the corresponding values in Control Register 2. The data will normally be driven onto SD0 –7. However, if M16

address the data will be driven onto SD8 –15. The data will always be taken from MSD0–7.

is only generated if the AT/LANTIC Controller is 1) in shared memory mode AND 2) DWID

. If AEN is high the cycle will be ignored.

is generated and the access is to an odd

Page 67

6.0 Operation of AT/LANTIC Controller (Continued)

Boot PROM Write Bus Timing

TL/F/11498– 50

This is the type of cycle used to write to the boot PROM. These accesses are entirely asynchronous, with the AT/LANTIC Controller responding when it decodes the correct address on SA0– 19 and a SMWR CHRDY is deasserted if the AT/LANTIC Controller is not ready to respond and asserted when ready. If it is ready immediately CHRDY is not deasserted. M16

is high AND 3) 8/16-bit in Control Register 2 is high AND 4) the LA17 –23 lines match the corresponding values in Control Register 2. The data will normally be taken from SD0 –7. However, if M16

address the data will be taken from SD8 –15. The data will always be driven onto MSD0 –7. The BPWR bit of Configuration Register B must be high to allow write cycles to the boot PROM.

is only generated if the AT/LANTIC Controller is 1) in shared memory mode AND 2) DWID

. If AEN is high the cycle will be ignored.

is generated and the access is to an odd

Page 68

6.0 Operation of AT/LANTIC Controller (Continued)

RAM Access Timing

Memory Support Read

TL/F/11498– 51

This is a memory read cycle executed by the AT/LANTIC Controller’s internal DMA. This is used to either load the data transfer port, during a Remote Read in I/O mode, or to load the FIFO, for a transmission on the network, in both modes. This transfer is synchronized to BSCLK, which can be either driven from the 20 MHz input on X1 or by the BSCLK input. This is selected by the CLKSEL bit in Configuration Register C. If there is 8 kbytes of RAM only RCS1 RCS2

are used.

Memory Support Write

is used, if 16 kbytes are available RCS1 and

TL/F/11498– 52

This is a memory write cycle executed by the AT/LANTIC Controller’s internal DMA. This is used to either write from the data transfer port, during a Remote Write in I/O mode, or to empty the FIFO, during a reception from the network, in both modes. This transfer is synchronized to BSCLK, which can be either driven from the 20 MHz input on X1 or by the BSCLK input. This is selected by the CLKSEL bit in Configuration Register C. If there is 8 kbytes of RAM only RCS1 RCS1

and RCS2 are used.

is used, if 16 kbytes are available

Page 69

7.0 Preliminary Electrical Characteristics

Absolute Maximum Ratings

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales

Operating Conditions

Supply Voltage (V Operating Temperature (T ESD Tolerance: 1.25 kV

ZAP

) 4.75 5.25 V

100 pF, R

ZAP

1.5 kX

Min Max Units

70§C

Office/Distributors for availability and specifications.

Supply Voltage (V

)

Storage Temperature (T

STG

)

0.5V toa7.0V

65§Ctoa150§C

Package Power Dissipation (PD) 800 mW

Lead Temperature (T

(Soldering, 10 seconds)

) 260§C

Preliminary DC Specifications

Symbol Description Conditions Min Max Units

SUPPLY CURRENT

CCIDLE

CCLP

TTL INPUTS

3SH TRI-STATE HIGH DRIVE I/O

MOS INPUTS, OUTPUTS AND I/O

ILD

IHD

IND

IN2

IN3

Average Active (Transmitting/Receiving) X1e20 MHz Clock Supply Current V

Switching

Average Idle Supply Current X1e20 MHz Clock

VCCor GND

Low Power Supply Current X1eUndriven

Undriven

100 mA

80 mA

35 mA

Maximum Low Level Input Voltage 0.8 V

Minimum High Level Input Voltage 2.0 V

Input Current V

Minimum High Level Output Voltage I

Maximum Low Level Output Voltage I

VCCor GND

3 mA 2.4 V

24 mA 0.5 V

1.0

1.0 mA

Maximum Low Level Input Voltage 0.8 V

Minimum High Level Input Voltage 2.0 V

Input Current V

Maximum TRI-STATE Output Leakage Current V

Minimum High Level Output Voltage I

Maximum Low Level Output Voltage I

VCCor GND

OUT

20 mAV

20 mA 0.1 V

1.0

10.0

0.1 V

1.0 mA

10.0 mA

Maximum Low Level Input Voltage 0.8 V

Minimum High Level Input Voltage 2.0 V

Maximum Low Level Input Voltage DWID 1.0 V

Minimum High Level Input Voltage DWID 4.0 V

Input Current V

Input Current TEST, DWlD Pull Down Resister V

Input Current TEST, MSD0–7 V

Input Current TEST, MSD8–15, MSA1 –8 V

Maximum TRI-STATE Output Leakage Current V

VCCor GND

VCCor GND 2000 mA

VCCor GND

RESET

OUT

Active

VCCor GND

1.0

1.0 mA

2000 mA

10.0

10.0 mA

Page 70

7.0 Preliminary Electrical Characteristics (Continued)

Preliminary DC Specifications (Continued)

Symbol Description Conditions Min Max Units

OCH OPEN COLLECTOR HIGH DRIVE OUTPUT

Maximum Low Level Output Voltage I

LED DRIVER OUTPUT

Maximum Low Level Output Voltage I

THIN DRIVER OUTPUT

Minimum High Level Output Voltage I

Maximum Low Level Output Voltage I

OSCILLATOR PINS (X1 AND X2)

OSC

X1 Input High Voltage X1 is Connected to an 2.0 V

X1 Input Low Voltage X1 is Connected to an 0.8 V

X1 Input Current X1 is Connected to an 1 mA

AUI

Differential Output Voltage (TXg)78XTermination and 270Xg550g1200 mV

Differential Idle Output Voltage 78X Termination and 270X Typical: 40 mV

Imbalance (TX

) from Each to GND (Note 1)

Undershoot Voltage (TXg)78XTermination and 270X Typical: 80 mV

Diff. Squelch Threshold (RXg,CDg)

Diff. Input Common Mode Voltage (RXg,CDg) (Note 1) 0 5.25 V

TPI

TOL

TOH

SRON1

SRON2

SROFF

DIFF

Note 1: These parameters are not guaranteed by production testing.

TXOdg, TXOgLow Level Output Resistance I

TXOdg, TXOgHigh Level Output Resistance

Receive Threshold Turn-On Voltage 10BASE-T Mode

Receive Threshold Turn-On Voltage Reduced Threshold

Receive Threshold Turn-Off Voltage (Note 1)

Differential Mode Input Voltage Range V

24 mA 0.5 V

16 mA 0.5 V

8 mA 2.4 V

2 mA 0.5 V

Oscillator

VCCor GND

from Each to GND (Note 1)

175

25 mA 15 X

300

175

5.0 V (Note 1)

3.1

300 mV

585 mV

300 mV

3.1 V

Page 71

8.0 Preliminary Switching Characteristics

Memory Support Bus Accesses (for I/O port or FIFO transfers)

TL/F/11498– 53

Symbol Description Transfers Transfers Units

8-Bit 16-Bit

Min Max Min Max

T1 MSA1b15 Valid before RCS

Asserted (Note 1)

T2 MSA1b15 Valid before

MSRDbWR Asserted

20 20 ns

30 30 ns

T3 MSRDbWR Width 70 70 ns

T4 RCS and MSA1b15 Valid to

Deasserted (Note 1)

MSWR

T5 MSA1b15 Valid after

WR Deasserted

MSRD

T6 RCS Held after MSRDbWR

Deasserted (Note 1)

T7 RCS and MSA1b15 Valid to

15 Valid (Note 1)

MSD0

105 105 ns

10 10 ns

100 100 ns

T8 Read Data Hold from MSRD Deasserted 0 0 ns

T9 Write Data Set-Up to MSWR Deasserted 50 50 ns

T10 Write Data Held from MSWR Deasserted 10 10 ns

T11 Time Between Transfers 4 4 bcyc

T12 Minimum Bus Clock High Time (bch) 20 20 ns

T13 Minimum Bus Clock Low Time (bcl) 20 20 ns

T14 Minimum Bus Clock Cycle Time (bcyc) 50 50 ns

Note 1: In 8-bit mode RCS refers to RCS1 only. In 16-bit mode RCS refers to both RCS1 and RCS2.

Page 72

8.0 Preliminary Switching Characteristics (Continued)

ISA Slave Accesses

TL/F/11498– 54

Page 73

8.0 Preliminary Switching Characteristics (Continued)

ISA Slave Accesses

Symbol Description Transfers Transfers Units

T1 BALE Width 20 20 ns

T2 AEN Valid before Command Strobe Active 60 60 ns

T3a SBHE and SA0–9 Valid before IORD, IOWR Asserted 40 20 ns

T3b SA0 – 9 Valid before MRD, MWR Asserted 32 32 ns

T4a IORD, MRD Asserted to SD0 –15 Driven (Note 3) 0 0 ns

T5a SBHE and SA0–9 Valid before IO16 Valid (Notes 1, 9) 60 ns

T5b LA17 – 23 Valid to M16 Valid (Note 1) 55 ns

T5c SBHE and SA0–9 Valid and IORD or IOWR

Active before IO16 Valid (Notes 1, 10)

T6a IORD, IOWR Asserted to CHRDY Deasserted (Notes 2, 5) 100 50 ns

T6b MRD, MWR Asserted to CHRDY Deasserted (Note 2) 45 45 ns

T6c BALE Asserted and SA0 –9 Valid to

CHRDY Deasserted (Notes 2, 4)

T7 IORD, IOWR Deasserted before SBHE and SA0 –9 Invalid 15 15 ns

T8a SBHE and SA0–9 Invalid to IO16 Invalid 0 0 ns

T8b LA17 – 23 Invalid to M16 Invalid (Note 1) 0 ns

T9 IORD, MRD Deasserted to SD0 –15 Read Data Invalid (Note 3) 0 0 ns

T10 IORD, MRD Deasserted to SD0 –15 Floating (Note 3) 45 45 ns

T11a D0 –15 Write Data Valid to IOWR Deasserted (Note 3) 60 20 ns

T12 IOWR, MWR Deasserted to SD0 –15 Write Data Invalid (Note 3) 20 20 ns

T13a IORD, IOWR Active Width (Note 8) 300 140 ns

T14a IORD, IOWR Inactive Width 85 85 ns

T14b SMRD, SMWR, MRD, MWR Inactive Width ns

T15 BALE Asserted before MRD, MWR Asserted 25 ns

T16 MRD, MWR Deasserted before Next BALE Asserted 20 ns

T17 CHRDY Asserted to SD0 –15 I/O Read

Data Valid (Notes 2, 3, 6)

T18 IORD, IOWR Deasserted before AEN Invalid 25 25 ns

T19 AEN Valid before BALE Deasserted 50 50 ns

T20 IORD Asserted to SD0 –15 Read Data Valid (Notes 3 and 7) 150 90 ns

T21 LA17 – 23 Valid before BALE Deasserted 40 ns

8-Bit 16-Bit

Min Max Min Max

50 ns

60 60 ns

Page 74

8.0 Preliminary Switching Characteristics (Continued)

ISA Slave Accesses

Symbol Description Transfers Transfers Units

T22 BALE Deasserted before LA17 –23 Invalid 0 ns

T23 LA17 – 23 Valid before MRD, MWR Asserted 40 ns

T24 Read Data Valid on MSD0 –15 to Valid on SD0 –15 70 70 ns

T25 MSRD Deasserted to MSD0 –15 Read Data Invalid (Note 3) 0 0 ns

T26 Write Data Valid on SD0 –15 to Valid on MSD0 –15 65 65 ns

T27 SA0 – 19 Valid to RCS or BPCS Asserted (Note 11) 55 55 ns

T28a MRD Asserted to MSRD Asserted 60 60 ns

T28b MWR Asserted to MSWR Asserted 120 120 ns

T29 SA0 – 19 Valid to MSA1–15 Valid 60 60 ns

T30 SA0 – 19 Invalid to RCS or BPCS Deasserted (Note 11) 0 0 ns

T31 MRD, SMRD Deasserted to MSRD Deasserted 0 0 ns

T32 MSWR Deasserted to MA1b15 Invalid 10 10 ns

T33 MSWR Deasserted to MSD0 –15 Invalid (Note 3) 0 0 ns

T34 MSA1 – 15 valid before MSWR Asserted 20 20 ns

T35a RCS Asserted to CHRDY Asserted (Note 11, 12) 80 80 ns

T35b BPCS Asserted to CHRDY Asserted (Note 13) 175 175 ns

T36a MSRD, MSWR Asserted to CHRDY Asserted (Note 11) 15 15 ns

T36b MSRD, MSWR Asserted to CHRDY Asserted (Note 13) 150 150 ns

T37 MSA1 – 15 Valid to CHRDY Asserted (Note 11) 75 75 ns

T38a Driving Data from SD0 –15 on to MSD0 –15

to CHRDY Asserted (Note 11)

T38b Driving Data from SD0–15 on to MSD0–15

to CHRDY Asserted (Note 13)

Note 1: M16, IO16 are only asserted for 16-bit transfers.

Note 2: CHRDY is only deasserted if the NIC core can not service the access immediately. It is held deasserted until the NIC core is ready, causing the system to

insert wait states.

Note 3: On 8-bit transfers only 8 bits of MSD0– 15 and D0– 7 are driven.

Note 4: This is the early CHRDY timing, required by some machines, where CHRDY is referenced to BALE. In this mode of operation, under certain circumstances,

CHRDY will be asserted for cycles which are not for this device, i.e. memory cycles or I/O cycles where SA0 –9 match our address before reaching their valid state. In such a case the time to assert CHRDY, from MRD

Note 5: This is the standard CHRDY timing where CHRDY is asserted after IORD

Note 6: Read data valid is referenced to CHRDY when wait states have been inserted.

Note 7: If no wait states are inserted read data valid can be measured from IORD

Note 8: This is a minimum timing with no additional wait states.

Note 9: This is the standard IO16

Note 10: This is the late IO16

Note 11: This is a timing for a RAM access.

Note 12: RCS refers to RCS1

explanation.

Note 13: This is a timing for a Boot PROM access.

timing where IO16 is asserted after a valid address decode.

timing, required by some machines, where IO16 is asserted after a valid address decode and IORD or IOWR going active.

and RCS2. Depending on the mode of operation either or both can be asserted. See the Functional Bus Timing section for a further

, MWR or SA0 –9 invalid, will be the same as the deassertion time specified.

or IOWR.

8-Bit 16-Bit

Min Max Min Max

60 60 ns

260 260 ns

Page 75

8.0 Preliminary Switching Characteristics (Continued)

RESET Timing

TL/F/11498– 55

Symbol Description Min Max Units

T1 RESET Asserted Until IO Inactive Asserted (Note 1) 400 ns

T2 RESET Asserted Until RegLoad State Entered (Note 2) 415 ms

T3 RESET Deasserted Until RegLoad Deasserted (Note 3) 100 ns

T4 RESET Deasserted Until EELOAD State Entered (Note 4) 0 ms

TS EELoad Width (Note 4) 320 ms

Note 1: I/O inactive is not an external signal. It is used here to indicate the length of time RESET must be active before the AT/LANTIC Controller recognizes it, begins to drive the ISA outputs to their inactive state and ignores ISA inputs except RESET.

Note 2: RegLoad is not an external signal. It is used here to indicate the length of time RESET must be active before the AT/LANTIC Controller begins contiguring. When IOinactive goes active the internal pull-down resistors on the memory support buses are enabled.

Note 3: If RegLoad is high the values on the memory support buses are Iatched into the configuration registers when RESET is deasserted. The pull-down resistors on this bus are enabled until RegLoad is deasserted.

Note 4: EELoad is not an extemal signal, it is used here to indicate when the EEPROM store is loading.

Serial EEPROM Timing

Symbol Description Min Max Units

T1 EECS Setup to SK 150 ns

T2 EECS Hold after SK 250 ns

T3 MSD2 Low Time 450 ns

T4 MSD2 High Time 450 ns

T5 MSD2 Clock Period (Note 1) 1 ms

T6 Data In Setup to MSD2 High 100 ns

T7 Data In Hold from MSD2 High 100 ns

T8 Data Out Valid from MSD2 High 500 ns

Note 1: Derived from Crystal Oscillator Tolerance

0.01%.

TL/F/11498– 56

Page 76

8.0 Preliminary Switching Characteristics (Continued)

AUI Transmit Timing (End of Packet)

TL/F/11498– 57

Symbol Description Min Max Units

TOh

TOI

AUI/TPI Receive Timing (End of Packet)

Transmit Output High before Idle 200 ns

Transmit Output Idle Time 8000 ns

TL/F/11498– 58

Symbol Description Min Max Units

eop1

eop0

Note 1: This parameter is guaranteed by design and is not tested.

Receive End of Packet Hold Time after Logic ‘‘1’’ (Note 1) 225 ns

Receive End of Packet Hold Time after Logic ‘‘0’’ (Note 1) 225 ns

Page 77

8.0 Preliminary Switching Characteristics (Continued)

Link Pulse Timing

Symbol Description Min Max Units

Ipw

Time between Link Output Pulses 8 24 ns

Link Integrity Output Pulse Width 80 130 ns

TL/F/11498– 59

Page 78

8.0 Preliminary Switching Characteristics (Continued)

TPI Transmit Timing (End of Packet)

TL/F/11498– 60

Symbol Description Min Max Units

del

Off

Offd

Note 1: This parameter is guaranteed by design and is not tested.

Pre-Emphasis Output Delay (TXOgto TXOdg) (Note 1) 46 54 ns

Transmit Hold Time at End of Packet (TXOg) (Note 1) 250 ns

Transmit Hold Time at End of Packet (TXOdg) (Note 1) 200 ns

Page 79

9.0 AC Timing Test Conditions

Input Pulse Levels (TTL/CMOS) GND to 3.0V

Input Rise and Fall Times (TTL/CMOS) 5 ns

Input and Output Reference Levels 1.3V

(TTL/CMOS)

Input Pulse Levels (Diff.)

Input and Output 50% Point of

Reference Levels (Diff.) the Differential

TRI-STATE Reference Levels Float (DV)

Output Load (See Figure Below)

All specifications are valid only if the mandatory isolation is employed and all differential signals are taken to be at the AUI side of the pulse transformer.

Output Load (See Figure Below)

350 mV tob1315 mV

0.5V

Pin Capacitance T

25§C, fe1 MHz

Symbol Parameter Typ Units

OUT

Input Capacitance 7 pF

Output Capacitance 10 pF

DERATING FACTOR

Output timing is measured with a purely capacitive load of 50 pF, or 240 pF. The following correction factor can be used for other loads (Note: This factor is preliminary):

Derating for 3SL, MOS Derating for 3SH, OCL, TPI

e E

0.05 ns/pF

e E

0.03 ns/pF

AUI Transmit Test Load

Note 1: Load Capacitance used depends on output type (includes scope

and jig capacitance):

For 3SL, MOS, TPI, AUI: C For 3SH, OCH: C

Note 2: Specifications which measure delays from an active state to a high impedance state are not guaranteed by production test, but are characterized using 70 pF, and are correlated to determine true driver turn-off time by eliminating inherent R-C delay times in measurements.

Note 3: S1

Note 4: Pull-up load for CHRDY

Open for timing test for push pull outputs.

VCCfor VOLtest.

GND for VOHtest.

VCCfor High Impedance to active low and

active low to High Impedance measurements.

GND for High Impedance to active high and

active high to High Impedance measurements.

50 pF.

240 pF.

1kX.

IO16

300X.

M16

300X.

TL/F/11498– 61

Note: In the above diagram, the TXaand TXbsignals are taken from the AUI side of the isolation (pulse transformer). The pulse transformer used for all testing is a 100 mH

0.1% Pulse Engineering PE64103.

TL/F/11498– 62

Page 80

Physical Dimensions inches (millimeters)

Plastic Quad Flat Package (VUL)

Order Number DP83905AVQB

NS Package Number VUL160A

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NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or 2. A critical component is any component of a life systems which, (a) are intended for surgical implant support device or system whose failure to perform can

DP83905 AT/LANTIC AT Local Area Network Twisted-Pair Interface Controller

into the body, or (b) support or sustain life, and whose be reasonably expected to cause the failure of the life failure to perform, when properly used in accordance support device or system, or to affect its safety or with instructions for use provided in the labeling, can effectiveness. be reasonably expected to result in a significant injury to the user.

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Datasheet DP83905AVQB Datasheet (NSC)

Specifications and Main Features

Frequently Asked Questions

User Manual