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PRELIMINARY
Am79C985
enhanced Integrated Multiport Repeater Plus (eIMR+TM)
DISTINCTIVE CHARACTERISTICS
s Repeater functions compliant with IEEE 802.3 Repeater Unit specifications s Direct interface with the Am79C987 Hardware Implemented Management Information Base (HIMIBTM) device for building a basic managed multiport repeater s Full software backwards compatibility with existing hub designs using Integrated Multiport Repeater Plus (IMR+TM)/HIMIB devices s Network management and optional feature accessibility through a dedicated serial management port s Four integral 10BASE-T transceivers with onchip filtering eliminating the need for external filter modules on the 10BASE-T transmit-data (TXD) and receive-data (RXD) lines s One Reversible Attachment Unit Interface (RAUITM) port used either as a standard IEEEcompliant AUI port for connection to a Medium Attachment Unit (MAU) or a reversed port for direct connection to a Media Access Controller (MAC) s Low cost suitable for managed multiport repeater designs s Number of repeater ports easily expandable with support for up to seven eIMR+ devices without the need for an external arbiter s All ports capable of being individually isolated (partitioned) in response to excessive collision conditions or fault conditions s Flexible LED support for individual port status and network utilization LEDs s Programmable extended distance mode on RXD lines allowing connection to cables longer than 100 meters s Link Test function and Link Test pulse transmission capable of being disabled through the management port allowing devices that do not implement the Link Test function to work with the eIMR+ device s Programmable automatic polarity detection and correction option permitting automatic recovery from wiring errors s Full amplitude and timing regeneration for retransmitted waveforms s CMOS device with a single +5-V supply
GENERAL DESCRIPTION
The enhanced Integrated Multiport Repeater Plus (eIMR+) device is a VLSI integrated circuit that provides a system-level solution to designing managed multiport repeaters. The device integrates the repeater functions specified in Section 9 of the IEEE 802.3 standard and Twisted Pair Transceiver functions complying with the 10BASE-T standard. The eIMR+ device provides four Twisted Pair (TP) ports and one reversible AUI (RAUI) port for direct connection to a MAC. The total number of ports per repeater unit can be increased by connecting multiple eIMR+ devices through their expansion ports, hence, minimizing the total cost per repeater port. The eIMR+ device also provides a connection to the Am79C987 HIMIB device. The HIMIB device monitors all the necessary counters, attributes, actions, and notifications specified by IEEE 802.3, Section 19 (Layer Management for 10 Megabit per second (Mbps) Baseband Repeaters). When the eIMR+ and HIMIB devices are used together as a chip set, they provide a cost-effective solution to the problem of designing 10BASE-T basic managed multiport repeaters. The device is fabricated in CMOS technology and requires a single +5-V supply.
This document contains information on a product under development at Advanced Micro Devices. The information is intended to help you evaluate this product. AMD reserves the right to change or discontinue work on this proposed product without notice.
Publication# 20651 Rev: B Amendment/0 Issue Date: January 1998
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DI CI FIFO Preamble Phase Lock Loop FIFO CONTROL Jam Sequence TX MUX DO AUI Port RX MUX Manchester Decoder RXD TXD Manchester Encoder TP Port 0 RXD TXD Partitioning Link Test RST Reset LED Interface TP Port 3 eIMR+ Chip Control Expansion Port SELI[1:0] SELO ACK COL DAT JAM LDA[4:0], LDB[4:0] LDGA, LDGB LDC[2:0] ACT[7:0] CLK Clock Gen Timers Test and Management Port STR SI SI_D SO SCLK AMODE CRS_I CRS
BLOCK DIAGRAM
PRELIMINARY
Am79C985
20651B-1
PRELIMINARY
ORDERING INFORMATION Standard Products
AMD standard products are available in several packages and operating ranges. The order number (Valid Combination) is formed by a combination of the elements below. Am79C985 J C \W
ALTERNATE PACKAGING OPTION \W = Trimmed and formed in a tray
TEMPERATURE RANGE C = Commercial (0C to +70C) PACKAGE TYPE J = 84-Pin Plastic Leaded Chip Carrier (PL 084) K = 100-Pin Plastic Quad Flat Pack (PQR100) SPEED OPTION Not Applicable
DEVICE NUMBER/DESCRIPTION Am79C985 enhanced Integrated Multiport Repeater Plus (eIMR+)
Valid Combinations Am79C985 JC, KC\W
Valid Combinations Valid Combinations list configurations planned to be supported in volume for this device. Consult the local AMD sales office to confirm availability of specific valid combinations and to check on newly released combinations.
Am79C985
3
PRELIMINARY
RELATED PRODUCTS
Part No. Am7990 Am7992B Am7996 Am79C90 Am79C98 Am79C100 Am79C981 Am79C982 Am79C983 Am79C984A Am79C987 Am79C988 Am79C900 Am79C940 Am79C960 Am79C961 Am79C961A Am79C965 Am79C970 Am79C970A Am79C974 Serial Interface Adapter (SIA) IEEE 802.3/Ethernet/Cheapernet Transceiver CMOS Local Area Network Controller for Ethernet (C-LANCE) Twisted Pair Ethernet Transceiver (TPEX) Twisted Pair Ethernet Transceiver Plus (TPEX+) Integrated Multiport Repeater Plus (IMR+TM) basic Integrated Multiport Repeater (bIMRTM) Integrated Multiport Repeater 2 (IMR2TM) enhanced Integrated Multiport Repeater (eIMRTM) Hardware Implemented Management Information Base (HIMIBTM) Quad Integrated Ethernet Transceiver (QuIETTM) Integrated Local Area Communications Controller (ILACCTM) Media Access Controller for Ethernet (MACETM) PCnetTM-ISA Single-Chip Ethernet Controller (for ISA bus) PCnetTM-ISA+ Single-Chip Ethernet Controller for ISA (with Microsoft(R) Plug n' Play(R) Support) PCnetTM-ISA II Full Duplex Single-Chip Ethernet Controller for ISA PCnetTM-32 Single-Chip 32-Bit Ethernet Controller PCnetTM-PCI Single-Chip Ethernet Controller (for PCI bus) PCnetTM-PCI II Full Duplex Single-Chip Ethernet Controller (for PCI bus) PCnetTM-SCSI Combination Ethernet and SCSI Controller for PCI Systems Description Local Area Network Controller for Ethernet (LANCE)
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Am79C985
PRELIMINARY
TABLE OF CONTENTS
DISTINCTIVE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 GENERAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 ORDERING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Standard Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 RELATED PRODUCTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 CONNECTION DIAGRAMS (PL 084) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 CONNECTION DIAGRAMS (PQR100) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 LOGIC SYMBOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 LOGIC DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 PIN DESIGNATIONS (PL084) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Listed by Pin Number. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 PIN DESIGNATIONS (PQR100) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Listed by Pin Number. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 PIN DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 AUI Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Twisted Pair Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Expansion Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Management Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 LED Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Miscellaneous Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 FUNCTIONAL DESCRIPTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Basic Repeater Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Repeater Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Signal Regeneration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Jabber Lockup Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Collision Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Fragment Extension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Auto Partitioning/Reconnection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Detailed Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 AUI Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 TP Port Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Twisted Pair Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Connection to Alternate Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Twisted Pair Receivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Link Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Polarity Reversal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Visual Status Monitoring (LED) Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Network Activity Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Expansion Bus Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Internal Arbitration Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 IMR+ Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Management Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 eIMR+ /HIMIB Interconnection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Management Port Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Command/Response Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Port Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Management Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 SET (Write Commands) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Get (Read Commands) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 SYSTEMS APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 eIMR+ to TP Port Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Twisted Pair Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Twisted Pair Receivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 MAC Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Am79C985
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PRELIMINARY AUI Port Interconnections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Internal Arbitration Mode Connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 IMR+ Mode External Arbitration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 eIMR+ Internal Arbitration Mode Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 IMR+ Mode External Arbitration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Visual Status Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 OPERATING RANGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 DC CHARACTERISTICS over Commercial operating ranges unless otherwise specified . . . . . . 35 SWITCHING CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 KEY TO SWITCHING WAVEFORMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 SWITCHING WAVEFORMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 SWITCHING TEST CIRCUIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 PHYSICAL DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 APPENDIX A - SECURITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
6
Am79C985
PRELIMINARY
CONNECTION DIAGRAMS (PL 084)
RXD3- RXD3+ RXD2- RXD2+ RXD1- RXD1+ RXD0- RXD0+ VDD TXD3- TXD3+ AVSS TXD2- TXD2+ VDD
REXT AVSS DI+ DI- VDD CI+ CI- AVSS DO+ DO- AMODE STR DVSS CRS_I SI_D VDD RST CLK DVSS SELI_0 SELI_1
11 10 9 8 7 6 5 4 3 2 1 84 83 82 81 80 79 78 77 76 75 74 12 13 73 72 14 71 15 70 16 17 69 68 18 67 19 66 20 21 65 eIMR+ 64 22 Am79C985 63 23 62 24 61 25 60 26 27 59 58 28 57 29 56 30 55 31 54 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53
SELO COL DVSS ACK DAT VDD JAM CRS DVSS SI SO SCLK VDD ACT0 ACT1 ACT2 DVSS ACT3 ACT4 ACT5 ACT6
TXD1- TXD1+ AVSS
TXD0- TXD0+ VDD
LDC2 LDC1 LDC0 VDD LDGB LDGA LDB4 DVSS LDA4 LDB3 LDA3 DVSS LDB2 LDA2 VDD LDB1 LDA1 DVSS LDB0 LDA0 ACT7
20651B-2
Am79C985
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PRELIMINARY
CONNECTION DIAGRAMS (PQR100)
RXD3+ RXD2- NC RXD2+ RXD1- RXD1+ RXD0- RXD0+ VDD TXD3- TXD3+ AVSS TXD2- TXD2+ VDD TXD1- TXD1+ AVSS TXD0- TXD0+ RXD3- NC NC NC REXT AVSS DI+ DI- VDD CI+ CI- AVSS DO+ DO- AMODE STR DVSS CRS_I SI_D VDD RST NC CLK DVSS SELI_0 SELI_1 NC NC NC SELO 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
eIMR+ Am79C985
80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51
VDD NC NC NC LDC2 LDC1 LDC0 VDD LDGB LDGA LDB4 DVSS LDA4 LDB3 LDA3 DVSS LDB2 LDA2 VDD LDB1 LDA1 NC DVSS LDB0 LDA0 ACT7 NC NC NC ACT6
COL DVSS NC ACK DAT VDD JAM CRS DVSS SI SO SCLK VDD ACT0 ACT1 ACT2 DVSS ACT3 ACT4 ACT5
31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
20651B-3
8
Am79C985
PRELIMINARY
LOGIC SYMBOL
V DD Expansion Port DAT JAM ACK COL SELO SELI[1:0] TXD+ TXD- RXD+ RXD- DO+ DO- DI+ DI- CI+ CI- Twisted Pair Ports (4 Ports)
Test and Management Port
SI Am79C985 SO SCLK AMODE LDA[4:0], LDB[4:0] STR LDGA, LDGB CRS_I LDC[2:0] CRS ACT[7:0] SI_D CLK RST DVSS AVSS
AUI
LED Interface
20651B-4
LOGIC DIAGRAM
AUI LED Port
Control Port
Repeater State Machine
Expansion Port
Twisted Pair Port 0
Twisted Pair Port 3
20651B-5
Am79C985
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PRELIMINARY
PIN DESIGNATIONS (PL 084) Listed by Pin Number
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Pin Name TXD3+ TXD3VDD RXD0+ RXD0RXD1+ RXD1RXD2+ RXD2RXD3+ RXD3REXT AVSS DI+ DIVDD CI+ CIAVSS DO+ DOPin No. 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 Pin Name AMODE STR DVSS CRS_I SI_D VDD RST CLK DVSS SELI_0 SELI_1 SELO COL DVSS ACK DAT VDD JAM CRS DVSS SI Pin No. 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 Pin Name SO SCLK VDD ACT0 ACT1 ACT2 DVSS ACT3 ACT4 ACT5 ACT6 ACT7 LDA0 LDB0 DVSS LDA1 LDB1 VDD LDA2 LDB2 DVSS Pin No. 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 Pin Name LDA3 LDB3 LDA4 DVSS LDB4 LDGA LDGB VDD LDC0 LDC1 LDC2 VDD TXD0+ TXD0AVSS TXD1+ TXD1VDD TXD2+ TXD2AVSS
10
Am79C985
PRELIMINARY
PIN DESIGNATIONS (PQR100) Listed by Pin Number
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Pin Name RXD3NC NC NC REXT AVSS DI+ DIVDD CI+ CIAVSS DO+ DOAMODE STR DVSS CRS_I SI_D VDD RST NC CLK DVSS SELI_0 Pin No. 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 Pin Name SELI_1 NC NC NC SELO COL DVSS NC ACK DAT VDD JAM CRS DVSS SI SO SCLK VDD ACT0 ACT1 ACT2 DVSS ACT3 ACT4 ACT5 Pin No. 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 Pin Name ACT6 NC NC NC ACT7 LDA0 LDB0 DVSS NC LDA1 LDB1 VDD LDA2 LDB2 DVSS LDA3 LDB3 LDA4 DVSS LDB4 LDGA LDGB VDD LDC0 LDC1 Pin No. 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 Pin Name LDC2 NC NC NC VDD TXD0+ TXD0AVSS TXD1+ TXD1VDD TXD2+ TXD2AVSS TXD3+ TXD3VDD RXD0+ RXD0RXD1+ RXD1RXD2+ NC RXD2RXD3+
Note: 1. NC = No Connection.
Am79C985
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PRELIMINARY
PIN DESCRIPTION AUI Port
DI+, DI- Data In Differential Input DI are differential, Manchester receiver pins. The signals comply with IEEE 802.3, Section 7. DO+, DO- Data Out Differential Output DO are differential, Manchester output driver pins. The signals comply with IEEE 802.3, Section 7. CI+, CI- Collision Input Differential Input/Output CI are differential, Manchester I/O signals. As an input, CI is a collision-receive indicator. As an output, CI generates a 10-MHz signal if the eIMR+ device senses a collision.
state of the DAT pin is used in conjunction with JAM to indicate a single port (DAT =1) or multiport (DAT=0) collision. JAM is in the high-impedance state if neither the SEL nor ACK signal is asserted. It is recommended that JAM be pulled up or down via a high value resistor. SELI0-1 Select In Input, Active LOW When the expansion bus is configured for Internal Arbitration mode, these signals indicate that another eIMR+ device is active; SELI0 or SELI1 is driven by SELO from the upstream device. At reset, SELI0 selects between the Internal Arbitration mode and the IMR+ mode of the expansion bus; a HIGH selects the Internal Arbitration mode and a LOW selects the IMR+ mode.
SELI_1 X X SELI_0 1 0 Arbitration Mode Internal IMR+
Twisted Pair Ports
TXD+0-3, TXD-0-3 Transmit Data Differential Output TXD are 10BASE-T port differential drivers (4 ports). RXD+0-3, RXD-0-3 Receive Data Differential Input RXD are 10BASE-T port differential receive inputs (4 ports).
SELO Select Out Output, Active LOW If the expansion bus is configured for Internal Arbitration mode, an eIMR+ device drives this pin LOW when it is active or when either of its SELI0-1 pins is LOW. An active eIMR+ device is defined as having one or more ports receiving or colliding and/or is still transmitting data from the internal FIFO, or extending a packet to the minimum of 96 bit times. When the expansion bus is configured for IMR+ mode, SELO is active when the eIMR+ device is active (acquiring the functionality of the REQ pin on the Am79C981 IMR+ device). ACK Acknowledge Input/Output, Active LOW, Open Drain This signal is asserted to indicate that an eIMR+ device is active. It also signals to the other eIMR+ devices the presence of a valid collision status on the JAM line and valid data on the DAT line. When the eIMR+ device is configured for Internal Arbitration mode, ACK is an I/O, and must be pulled to VDD via a minimum equivalent resistance of 1 k. When the eIMR+ device is configured for IMR+ mode, ACK is an input driven by an external arbiter. COL Collision Input/Output, Active LOW, Open Drain When asserted, COL indicates that more than one eIMR+ device is active. Each eIMR+ device generates the Collision Jam sequence independently. When the eIMR+ device is configured for Internal Arbitration
Expansion Bus
DAT Data Input/Output/3-State If the SELO and ACK pins are asserted during noncollision conditions, the eIMR+ device drives NRZ data onto the DAT line, regenerating the preamble if necessary. During a collision, when JAM is HIGH, DAT is used to differentiate between single-port (DAT=1) and multiport (DAT=0) collisions. DAT is an output when ACK is asserted and the eIMR+ device's ports are active; DAT is an input when ACK is asserted and the ports are inactive. If ACK is not asserted, DAT is in the high-impedance state. It is recommended that DAT be pulled up or down via a high value resistor. JAM Jam Input/Output/3-State The active eIMR+ device drives JAM HIGH, if it detects a collision condition on one or more of its ports. The
12
Am79C985
PRELIMINARY mode, COL is an I/O and must be pulled to VDD via a minimum equivalent resistance of 1 k. When the eIMR+ device expansion port is configured for IMR+ mode, COL is an input driven by an external arbiter. Automatic Polarity Reversal is disabled. If SI is LOW at the rising edge of RST, Automatic Polarity Reversal is enabled. SI_D Serial Input Append Input SI_D is used when two eIMR+ devices share a common HIMIB device. The SO output from the first eIMR+ device should be input to the second eIMR+ chip via this pin. Internally, the second eIMR+ chip appends the SI_D data to its own serial data stream and outputs the result to the HIMIB device via its SO pin. When two eIMR+ devices are connected to a HIMIB device, the HIMIB device has attribute counters for the AUI port on only one of the eIMR+ devices. That eIMR+ device is referred to as the primary eIMR+ device. The other device is referred to as the secondary eIMR+ device. At the rising edge of RST, the combination of CRS_I and SI_D is used to set the eIMR+ device's management mode. If CRS_I is HIGH, the state of SI_D is ignored and the eIMR+ device is configured as a single eIMR+. If CRS_I is LOW, SI_D HIGH indicates that the eIMR+ device is the secondary device. If CRS_I is LOW and SI_D is LOW, the eIMR+ device is configured as the primary device.
Two eIMR+ Devices Primary Secondary eIMR+ eIMR+ Device Device
Management Port
AMODE AUI Mode Input At reset, this pin sets the AUI port to either normal or reversed mode. If AMODE is LOW at the rising edge of RST, the AUI port is set to the normal mode; if AMODE is HIGH, the AUI port is set to the reversed mode. CRS Carrier Sense Output The states of the internal carrier-sense signals for the AUI port and the four twisted-pair ports are output continuously on this pin. The output is a serial bit stream synchronized to CLK. When two eIMR+ devices share a common HIMIB device, CRS on the first device must be connected to the CRS_I (input) of the second eIMR+ device. CRS_I Carrier Sense In Input CRS_I is used when two eIMR+ devices share a common HIMIB device. The CRS output from the first eIMR+ should be input to the second eIMR+ via this pin. Internally, the second eIMR+ appends the information on CRS_I to its own carrier-sense information and outputs the combined result to the HIMIB chip via its CRS pin. At the rising edge of RST, CRS_I is used to set the eIMR+ device's management mode. CRS_I HIGH indicates that only a single eIMR+ device is connected to the HIMIB chip. CRS_I LOW indicates that two eIMR+ devices are connected to a HIMIB chip. SCLK Serial Clock In Input Serial data (input or output) is clocked (in or out) on the rising edge of the signal on this pin. SCLK is asynchronous to CLK and can operate at frequencies up to 10 MHz. SI Serial In Input The SI pin is used as a test/management serial input port. Management commands are clocked in on this pin synchronous to the SCLK input. At reset, SI sets the state of the Automatic Polarity Reversal function. If SI is HIGH at the rising edge of RST,
CRS_I 0 0 1 1
SI_D 0 1 0 1
Single eIMR+ Device
SO Serial Out Output The SO pin is used as a management command serial output port. Responses to management commands are clocked out on this pin synchronous to the SCLK input. STR Store Input The HIMIB device uses this input to communicate with the eIMR+ device. STR connects to an internal pull-up resistor. The resistance value is sufficiently high to allow the STR pins of two eIMR+ devices to be connected together without presenting an excessive load to the HIMIB device.
Am79C985
13
PRELIMINARY
LED Interface
LDA0-4, LDB0-4 LED Drivers Output, Open Drain LDA0-4 and LDB0-4 drive LED Bank A and LED Bank B, respectively. LDA0 and LDB0 indicate the status of the AUI port; LDA1-4 and LDB1-4 indicate the status of the four TP ports. The port attributes monitored by LDA0-4 and LDB0-4 are programmed by three pins, LDC0-2. LDGA Global LED Driver, Bank A Output, Open Drain LDGA is the Global LED driver for LED Bank A. The signal represents global CRS or COL conditions. In a multiple-eIMR+ configuration, LDGA from each of the eIMR+ devices can be tied together to drive a single global LED in Bank A. LDGB Global LED Driver, Bank B Output, Open Drain LDGB is the Global LED driver for LED Bank B. The signal represents global CRS or JAB conditions. In a multiple eIMR+ configuration, LDGB from each of the eIMR+ devices can be tied together to drive a single global LED in Bank B. LDC0-2 LED Control Input These pins select the attributes that will be displayed on LDA0-4, LDB0-4, LDGA, and LDGB. If an LED is programmed to display two attributes, the attribute associated with the periodic blink takes precedence. ACT0-7 Activity Display Output, Open Drain These signals drive the activity LEDs, which indicate the percentage of network utilization. The display is updated every 250 ms.
Miscellaneous Pins
RST Reset Input, Active LOW When RST is LOW, the eIMR+ device resets to its default state. On the rising (trailing) edge of RST, the eIMR+ also monitors the state of the SELI0-1, SI, and AMODE pins, to configure the operating mode of the device. In multiple eIMR+ systems, the falling (leading) edge of the RST signal must be synchronized to CLK. CLK Master Clock In Input This pin is a 20-MHz clock input. REXT External Reference Input This pin is used for an internal current reference. It must be tied to VDD via a 13-k resistor with 1% tolerance. VDD Power Power Pin This pin supplies power to the device. AVSS Analog Ground Ground Pin This pin is the ground reference for the differential receivers and drivers. DVSS Digital Ground Ground Pin This pin is the ground reference for all the digital logic in the eIMR+ device.
14
Am79C985
PRELIMINARY
FUNCTIONAL DESCRIPTION
The Am79C985 eIMR+ device is a single-chip implementation of an IEEE 802.3/Ethernet repeater (or hub). It is offered with four integral 10BASE-T ports plus one RAUI port comprising the basic repeater. The eIMR+ device is also expandable, enabling the implementation of high port count repeaters based on several eIMR+ devices. The eIMR+ device interfaces directly with AMD's Am79C987 HIMIB device. This allows hardware designers to implement a fully managed multiport repeater, as specified by the IEEE 802.3 standard, Section 19, Layer Management for 10 Mbps Baseband Repeaters. When the eIMR+ and HIMIB devices are used as a chip set, the HIMIB device maintains complete repeater and per-port statistics, which can be accessed on demand through an 8-bit parallel interface. The eIMR+ chip complies with the full set of repeater basic functions as defined in Section 9 of ISO 8802.3 (ANSI/IEEE 802.3c). The basic repeater functions are summarized in the paragraphs below.
specification given in Section 9.5.5.1 of the IEEE 802.3 standard. Jabber Lockup Protection The eIMR+ device implements a built-in jabber protection scheme to ensure that the network is not disabled by the transmission of excessively long data packets. This protection scheme causes the eIMR+ device to interrupt transmission for 96 bit-times if the device has been transmitting continuously for more than 65,536 bit times. This is referred to as MAU Jabber Lockup Protection (MJLP). The MJLP status for the eIMR+ device can be read through the Management Port, using the Get MJLP Status command. Collision Handling The eIMR+ device will detect and respond to collision conditions as specified in the IEEE 802.3 specification. Repeater configurations consisting of multiple eIMR+ devices also comply with the IEEE 802.3 specification, using status signals provided by the expansion bus. In particular, a repeater based on one or more eIMR+ devices will handle the transmit collision and one-port-left collision conditions correctly, as specified in Section 9 of the IEEE 802.3 specification. Fragment Extension If the total packet length received is less than 96 bits, including preamble, the eIMR+ device will extend the repeated packet length to 96 bits by appending a Jam sequence to the original fragment. Auto Partitioning/Reconnection Any of the TP ports or the AUI port can be partitioned if the duration or frequency of collisions becomes excessive. The eIMR+ device will continue to transmit data packets to a partitioned port, but will not respond, as a repeater, to activity on the partitioned port's receiver. The eIMR+ device will monitor the port and reconnect it once certain criteria are met. The criteria for reconnection are specified by the IEEE 802.3 standard. In addition to the standard reconnection algorithm, the eIMR+ device implements an alternative reconnection algorithm, which provides a more robust partitioning function for the TP ports and/or AUI port. The eIMR+ device partitions each TP port and the AUI port separately and independently of other network ports. The eIMR+ device will partition an enabled network port if either of the following conditions occurs at that port: 1. A collision condition exists continuously for more than 2048 bit times. (AUI port--SQE signal active; TP port--simultaneous transmit and receive). 2. A collision condition occurs during each of 32 consecutive attempts to transmit to that port. In the AUI port, a collision condition is indicated by an active SQE signal. In a TP port, a collision condition is 15
Basic Repeater Functions
The Am79C985 chip implements the basic repeater functions as defined by Section 9.5 of the ANSI/IEEE 802.3 specification. Repeater Function If any single network port senses the start of a valid packet on its receive lines, the eIMR+ device will retransmit the received data to all other enabled network ports (except when contention exists among any of the ports or when the receive port is partitioned). To allow multiple eIMR+ device configurations, the data will also be repeated on the expansion bus data line (DAT). Signal Regeneration When retransmitting a packet, the eIMR+ device ensures that the outgoing packet complies with the IEEE 802.3 specification in terms of preamble structure and timing characteristics. Specifically, data packets repeated by the eIMR+ device will contain a minimum of 56 preamble bits before the Start-of-Frame Delimiter. In addition, the eIMR+ restores the voltage amplitude of the repeated waveform to levels specified in the IEEE 802.3 specification. Finally, the eIMR+ device restores signal symmetry to repeated data packets, removing jitter and distortion caused by the network cabling. Jitter present at the output of the AUI port will be better than 0.5 ns; jitter at the TP outputs will be better than 1.5 ns. The start-of-packet propagation delay for a repeater set is the time delay between the first edge transition of a data packet on its input port to the first edge transition of the repeated packet on its output ports. The start-ofpacket propagation delay for the eIMR+ is within the
Am79C985
PRELIMINARY indicated when the port is simultaneously attempting to transmit and receive. Once a network port is partitioned, the eIMR+ device will reconnect that port, according to the selected reconnection algorithm, as follows: 1. Standard reconnection algorithm--A data packet longer than 512-bit times (nominal) is transmitted or received by the partitioned port without a collision. 2. Alternative reconnection algorithm--A data packet longer than 512-bit times (nominal) is transmitted by the partitioned port without a collision. A partitioned port can also be reconnected by disabling and re-enabling the port. All TP ports use the same reconnection algorithm; either they must all use the standard algorithm, or they must all use the alternative reconnection algorithm. However, the reconnection algorithm for the AUI port is programmed independently from that of the TP ports. The eIMR+ device also monitors the state of the SELI0-1, SI, CRS_I, SI_D, and AMODE pins on the rising (trailing) edge of RST to configure the operating mode of the device. Table 1 summarizes the state of the eIMR+ chip following reset. AUI Port The AUI Port is fully compatible with the IEEE 802.3, Section 7 requirement for an AUI port. It has the signals associated with an AUI port: DO, DI, and CI. The AUI port has two modes of operation: normal and reverse. When configured for normal operation, the functionality is that of an AUI port on a MAC (CI is an input). When configured for reverse operation, the functionality is that of an AUI on a MAU (CI is an output). The mode of the AUI port is set during the trailing (rising) edge of the reset pulse, by the state of the AMODE pin. A LOW sets the AUI port to its normal mode (CI Input) and a HIGH sets the AUI port to its reverse (CI Output) mode. The eIMR+ device can be connected directly to a MAC through the AUI port. This requires that the AUI port be configured for reverse operation. Refer to the Systems Applications section for more details. TP Port Interface
Detailed Functions
Reset The eIMR+ device enters the reset state when the reset (RST) pin is driven LOW. After the initial application of power, the RST pin must be held LOW for a minimum of 150 s. If the RST pin is subsequently asserted while power is maintained to the eIMR+ device, a reset duration of only 4 s is required. This allows the eIMR+ device to reset its internal logic. During reset, the eIMR+ registers are set to their default values. Also during reset, the eIMR+ device sets the output signals to their inactive state; that is, all analog outputs are placed in their idle state, no bidirectional signals are driven, all active-HIGH signals are driven LOW and all active-LOW signals are driven HIGH. In a multiple eIMR+ system, the reset signal must be synchronized to CLK. See Figure 13 in the Systems Applications section.
Twisted Pair Transmitters
TXD is a differential twisted-pair driver. When properly terminated, TXD will meet the electrical requirements for 10BASE-T transmitters as specified in IEEE 802.3, Section 14.3.1.2. The TXD signal is filtered on the chip to reduce harmonic content per IEEE 802.3, Section 14.3.2.1 (10BASE-T). Since filtering is performed in silicon, TXD can connect directly to a standard transformer, thereby, eliminating the need for external filtering modules. Proper termination is shown in the Systems Applications section.
Table 1. eIMR+ States after Reset Function
Active-LOW Outputs Active-HIGH Outputs SO Output DAT, JAM Transmitters (TP and AUI) Receivers (TP and AUI) AUI Partitioning/Reconnection Algorithm TP Partitioning/Reconnection Algorithm Link Test Functions for TP Ports Automatic Receiver Polarity Reversal Function
State after Reset
HIGH LOW HIGH HIGH IMPEDANCE IDLE ENABLED STANDARD ALGORITHM STANDARD ALGORITHM ENABLED, TP PORTS IN LINK FAIL DISABLED IF SI PIN IS HIGH ENABLED IF SI PIN IS LOW
Pull Up/Pull Down
No No No Either No Terminated N/A N/A N/A N/A
16
Am79C985
PRELIMINARY
Connection to Alternate Media
The eIMR+ device can be connected to the AUI port of any MAU device. Thus, it can support 10BASE-2, 10BASE-5, and 10BASE-FL. To connect to an alternate media type, on-chip filtering should be disabled. This can be achieved by substituting the normal 110- resistor connected across the TXD differential output with a 500- resistor. If on-chip filtering is disabled at a TP port, the Link Pulse must also be disabled. Refer to the section on eIMR+ Management Commands for programming details. Once port filtering is disabled, the TXD output will be a square waveform and can be connected to the AUI port of a transceiver. Some external components are necessary to correctly interface the TXD output to the transceiver.
or has its Link Test function disabled. Separate management commands exist for enabling and disabling the transmission of Link Test pulses on a port-by-port basis. Polarity Reversal The TP ports can be programmed to receive data if a wiring error results in a data packet being received at a TP port with reversed polarity. This function will be enabled upon reception of a negative End Transmit Delimiter (ETD) or negative pulses and allows subsequent packets to be received with the correct polarity. The polarity-reversal function is executed once following reset or link-fail and can be programmed via the management port to be enabled or disabled on a port-by-port basis. The function may be enabled or disabled, following a reset, depending on the level of the SI signal on the rising edge of the RST pulse. Visual Status Monitoring (LED) Support The eIMR+ status port can be connected to LEDs to facilitate the visual monitoring of repeater port status. The status port has twelve output signals, LDA0-4, and LDB0-4, LDGA, and LDGB. LDA0-4 and LDB0-4 represent the four TP ports and AUI port. LDGA and LDGB are global indicators. Attributes that may be monitored are Carrier Sense (CRS), Collision (COL), Partition (PAR), Link Status (LINK), Loopback (LB), Port Disabled (DIS), and Jabber (JAB). Three control bits, LDC0-2, select the particular attributes to be displayed on the LEDs. Table 1 shows how the programming combinations for LDC0-2 control the attributes that will be monitored. Each LED drive pin (LDGA, LDGB, LDA0-4, and LDB0-4) has two states: Off and LOW. When none of the selected attributes are true, the driver is off and the diode is unlit. When an attribute is true, the driver is LOW, and the corresponding LEDs in Bank A or Bank B will be lit. Some of the settings (LDC2 = 1) include a blink function. This allows two attributes to be selected for a given state on the pin. As an example when LDC0-2 = 110, the LDA outputs relating to TP ports will be solidly lit when there is a link established at that port. However, whenever there is activity on a port, the corresponding LDA pin will switch on (LOW) and off at a period of 130 ms. Note that a partition on that port will also cause the pin to go LOW. On LDC settings that have two attributes for a state on a pin (blink or solid-on), the attribute causing the output to blink has priority. (Those attributes are shown in Table 2 with a blink period specified next to it.) If an attribute has no blink period specified, the LED indicates the attribute by being solidly lit.
Twisted Pair Receivers
RXD is a differential twisted-pair receiver. When properly terminated, RXD will meet the electrical requirements for 10BASE-T receivers as specified in IEEE 802.3, Section 14.3.1.3. The receivers do not require external filter modules. Proper termination is shown in the Systems Applications section. The receiver's threshold voltage can be programmed to an extended-distance mode. In this mode, the differential receiver's threshold is reduced to allow a longer cable than the 100 meters specified in the IEEE 802.3 standard. For programming details, refer to the Management Commands section. Link Test The integrated TP ports implement the Link Test function, as specified in the IEEE 802.3 10BASE-T standard. The eIMR+ device will transmit Link Test pulses to any TP port after that port's transmitter has been inactive for more than 8 ms to 17 ms. Conversely, if a TP port does not receive any data packets or Link Test pulses for more than 65 ms to 132 ms and the Link Test function is enabled for that port, then that port will enter the link-fail state. The eIMR+ device will disable a port in link-fail state (i.e., disable repeater transmit and receive functions) until it receives either four consecutive Link Test pulses or a data packet. The Link Test function can be disabled via the eIMR+ management port on a port-by-port basis, to allow the eIMR+ device to operate with pre-10BASE-T networks that do not implement the Link Test function. When the Link Test function is disabled, the eIMR+ device will not allow the TP port to enter link-fail state, even if no Link Test pulses or data packets are being received. Note, however, that the eIMR+ device will always transmit Link Test pulses to all TP ports, regardless of whether or not the port is enabled, partitioned, in link-fail state,
Am79C985
17
PRELIMINARY Table 2. LED Attribute-Monitoring Program Options
LED Control
LDC2 LDC1 LDC0
0 0 0 0 1 1 1 1
0 0 1 1 0 0 1 1
0 1 0 1 0 1 0 1
Global LEDs LDGB LDGA CRS COL CRS COL
CRS 260-ms blk COL CRS CRS
COL 260-ms blk JAB COL COL
TP LEDs LDA1-4 LDB1-4 LINK (Note 2) PAR LINK CRS Reserved (Note 5) Reserved (Note 5) LINK PAR CRS 260-ms blk COL 260-ms blk LINK (Note 3) PAR (Note 3) CRS 512-ms blk LINK PAR or DIS CRS 130-ms blk LINK (Note 4) PAR 1.56-s blk COL (Note 4)
AUI LEDs LDA0 LB LB LDB0 PAR CRS
CRS 260-ms blk (Note 3) CRS 512-ms blk CRS 130-ms blk (Note 4) PAR 1.56-s blk
PAR COL 260-ms blk PAR (Note 3) PAR or DIS PAR (Note 4)
Notes: 1. CRS = Carrier Sense, COL = Collision, JAB = Jabber, LINK = Link, LB = Loop Back, PAR = Partition, DIS = Port Disabled, blk = Blink (Number = period of Blink). 2. For the LDC0-2 setting of 000: If the port is partitioned, the LINK LED is off. 3. All LEDs blink 16 times at 260 ms per blink after reset. 4. All LEDs are on for approximately 4 seconds after reset. 5. LDC0-2 = `010' and `011' are undefined.
The LEDs can also be controlled via the management port. The Enable Software Override commands turn the LEDs on regardless of the attributes selected for display through the LDC setting. Enable Software Override of Bank A LEDs causes the LDA0-4 and LDGA pins to be driven LOW, and Enable Software Override of Bank B LEDs causes the LDB0-4 and LDGB pins to be driven LOW. The blink rate is set by the Software Override LED Blink Rate command. The periods are off, 512 ms, 1560 ms, or solid on. LED software override is executed in two stages, by first issuing the blink rate (Software Override of LED Blink Rate) and then issuing the command to enable the particular port LEDs (Enable Software Override of Bank A/B LEDs). All port combinations selected for software override control will reference the blink rate last issued by the Software Override of the LED Blink Rate command. LDA0-4, LDB0-4, LDGA, and LDGB are open drain output drivers that sink 12 mA of current to turn on the LEDs. In a multiple eIMR+ configuration, the outputs from the global LED drivers (LDGA and LDGB) of each chip can be tied together to drive a single pair of global status LEDs. CRS and COL are extended to make it easier for visual recognition; that is, they will remain active for some time even if the corresponding condition has expired. Once carrier sense is active, CRS will remain active for a minimum of 4 ms. Once a collision is detected, COL is active for at least 4 ms. The exception to this rule is for selection LDC0-2 = 111. For this selection, COL is stretched to 100 s.
When LDC0-2 = 000 or LDC0-2 = 001, the loopback attribute (LB) for the AUI port is displayed on LDA0. LB is true when DO on the MAU is successfully looped back to DI on the AUI port. LB is false (off) if a loopback error is detected, or if the AUI port is disabled or in the reverse mode. Transmit carrier sense is sampled at the end of packet to determine the state of LB. The state of LB remains latched until carrier sense is sampled again for the next packet. The default/power-up state for LB is false (off). Figure 1 shows the recommended connection of LEDs. When LDA0-4, LDB0-4, LDGA, or LDGB are LOW, the LED lights.
VDD eIMR+ LED Interface LDA[4:0] LDB[4:0] LDGA LDGB
R
Typical
20651B-6 20651A-6
Figure 1. Visual Monitoring Application--Direct LED Drive
18
Am79C985
PRELIMINARY Network Activity Display The eIMR+ status port can drive up to eight LEDs to indicate the network-utilization level as a percentage of bandwidth. The status port uses eight dedicated outputs (ACT0-7) to drive a series of LEDs. The number of LEDs in the series that will be lit increases as the amount of network activity increases. ACT0 represents the lowest level of activity; ACT7 represents the highest. ACT0-7 are open-drain outputs that typically sink 12 mA of current to turn on the LEDs. See Figure 2. Table 3 shows ACT0-7 as a function of the percentage of network utilization. The table uses a scale that is more sensitive at low utilization levels. 100% utilization represents the maximum number of events that could occur in a given window of time. The update rate and corresponding internal sampling window for ACT[7:0] is 250 ms. During this sampling window, a counter is used to count the number of times repeater transmit activity is TRUE. The counter uses a free-running clock which has the granularity to detect the minimum packet size of 96 bit times. Figure 3 shows the timing relationship between the sampling window, counting clock, and transmit activity. Table 3. Network Utilization
Number of LEDs Lit by ACT0-7 8 7 6 5 4 3 2 1 Percentage Utilization >80% >64% >32% >16% >8% >4% >2% >1%
VDD
eIMR+ LED Interface
ACT[0] ACT[1] ACT[2] ACT[3] ACT[4] ACT[5] ACT[6] ACT[7]
20651A-7
20651B-7
Figure 2. Network Activity Display
.
latch data; update display; clear counter counter is active Sampling Window Counting Clock Xmit Activity
20651B-8
next counting cycle
Figure 3. Activity Sampling
Am79C985
19
PRELIMINARY Expansion Bus Interface The eIMR+ device expansion bus allows multiple eIMR+ devices to be interconnected. The expansion bus supports two modes of operation: internal arbitration mode and IMR+ mode. The internal arbitration mode uses a modified daisy-chain scheme to eliminate the need for any external arbitration circuitry. The IMR+ mode maintains the full functionality of the IMR+ (Am79C981) expansion bus and benefits from minimum delays. In this mode, the eIMR+ device requires external circuitry to handle arbitration for control of the bus. The eIMR+ arbitration mode is determined at reset. This occurs on the trailing edge of RST according to the state of SELI0-1, as illustrated in Figure 4. The eIMR+ device can be connected to a HIMIB device, as described in the eIMR+/HIMIB Interconnection section. The connection to a HIMIB device is not dependent on the mode of the expansion bus. In other words, the eIMR+ device can be connected to a HIMIB device whether the expansion bus is in internal-arbitration mode or IMR+ mode. where & represents the Boolean AND operation + represents the Boolean OR operation ACK and COL are mutually exclusive. If the eIMR+ device driving ACK senses COL LOW, the device will deassert ACK. DAT and JAM are synchronized to CLK. DAT is the repetition of data from any connected port (either TP or AUI port) encoded in NRZ format. JAM is an internal collision indicator. If JAM is HIGH, the active eIMR+ device has detected an internal collision across one or more of its ports. When this occurs, the DAT signal distinguishes between single-port collisions and multiport collisions. DAT = 1 indicates a single port collision; DAT = 0 indicates a multiport collision. The drive capabilities of the I/O signals on the expansion bus (DAT, JAM, ACK, and COL) are sufficient to allow seven eIMR+ devices to be connected together without the use of external transceivers or buffers. The maximum number of eIMR+ devices that can be daisy chained is limited by the propagation delay of the eIMR+ devices. In practice, the depth of the cascade is limited to three eIMR+ devices, thus allowing a maximum of seven eIMR+ devices connected together via this expansion bus as shown in Figure 5. The active device will not drive the data line, DAT, until one bit time (100 ns) after SELO goes LOW. This is to avoid a situation where two devices drive DAT simultaneously. In Boolean notation, the formula for COL is as follows: COL = (Active port & (SELI1 + SELI0))+ (SELI1 & SELI0)
Internal Arbitration Mode
The internal arbitration mode uses a daisy-chain (cascade) configuration. SELI0-1 are arbitration inputs and SELO is the arbitration output. SELO goes LOW when there is activity on one or more of the eIMR+ ports, or a SELI input is LOW. The SEL lines are connected as shown in Figure 5. This technique allows activity indication to propagate down the chain to the end device. All unused SELI inputs must be tied to VDD. ACK and COL are global activity I/O pins. When the eIMR+ device senses activity, it drives ACK LOW.
IMR+ Mode
In IMR+ mode, the expansion bus requires an external arbiter. The arbiter allows only one eIMR+ device to control the expansion bus. If more than one device attempts to take control, the arbiter terminates all access and signals a collision condition. In IMR+ mode, DAT and JAM retain the same functionality as in internal arbitration mode, but ACK and COL are inputs to the eIMR+ device, driven by the external arbiter. The arbiter should drive ACK LOW when exactly one eIMR+ device is active. It should drive COL when more than one eIMR+ device is active. SELO is an output from the eIMR+ device. It indicates that the eIMR+ device has an active port and is requesting access to the bus. When ACK is HIGH, DAT and JAM are in the high-impedance state. DAT and JAM go active when ACK goes LOW. Refer to the Systems Applications section (Fig.14) for the configuration of IMR+ mode of operation.
RST SELI_0 Mode Selection
SELI_1 X X
SELI_0 1 0
Arbitration Mode Internal IMR+
20651B-9
Figure 4. Expansion Bus Mode Selection An eIMR+ device drives COL LOW when it senses more than one device is active; that is, if the device has an active port AND a SELI input is LOW, OR both SELI inputs are LOW.
Note: The IMR+ mode is recommended when arbitrating between multiple boards.
20
Am79C985
PRELIMINARY
VDD 1k
SELI_0 SELI_1 ACK
SELO SELI_0 SELI_1 ACK COL DAT JAM SELO
SELI_0 SELI_1 ACK
COL SELO
DAT JAM
COL
DAT JAM
SELI_0 SELI_1 ACK
SELO
SELI_0 SELI_1 ACK
SELO SELI_0 SELI_1 ACK COL DAT JAM SELO
SELI_0 SELI_1 ACK
COL
DAT JAM
COL
DAT JAM
SELO
COL
20651B-10
Figure 5. Internal Arbitration--eIMR+ Devices in Cascade
Management Functions
The eIMR+ device receives management commands in the form of byte-length data on the serial input pin, SI. If the eIMR+ device is expected to provide data in response to the command, it will send byte-length data to the serial-output pin, SO. Both the input and output data streams are clocked with the rising edge of the SCLK signal. The byte-length data is in RS232 serialdata format; that is, one start bit followed by eight data bits. The externally generated clock at the SCLK pin
may be either a free-running clock synchronized to the input bit patterns, or a series of individual transitions meeting the setup-and-hold times with respect to the input bit pattern. If the latter method is used, 20 SCLK clock transitions are required for management commands that produce SO data, and 14 SCLK clock transitions are required for management commands that do not produce SO data.
Am79C985
DAT JAM
21
PRELIMINARY eIMR+/HIMIB Interconnection The eIMR+ device interfaces directly to the HIMIB device for full repeater manageability. To this end, the eIMR+ device has a management port and a serial output that allows the HIMIB device to monitor port activity. The eIMR+ device is designed to allow one or two eIMR+ devices to operate with a single HIMIB device. Because the HIMIB device can monitor nine ports (8 TP ports & 1 AUI port), one of the eIMR+ AUI ports is not managed (statistics not kept). When two eIMR+ devices are connected to a HIMIB device, one is designated the primary device and the other is designated the secondary device. This designation serves to identify which device has the managed AUI port. The primary device has the managed AUI port and TP4-7. The secondary device has the unmanaged AUI port and TP0-3. Figure 6 shows how the HIMIB and eIMR+ devices are interconnected. When only one eIMR+ device is connected to a HIMIB device, the AUI port is managed. The HIMIB device treats the twisted-pair ports as TP0-3. Although the HIMIB device does not monitor the AUI port on the secondary eIMR+ device, the AUI port on the secondary device defaults to enabled at reset. The port can be disabled via the Secondary AUI Port Enable command. Management Port Interface The eIMR+ management port is made up of six signals: SI, SI_D, SO, CRS, CRS_I, and SCLK. SI is the serial input from an external management module or the HIMIB device. On the secondary eIMR+ device, SI_D is the response input from the primary eIMR+ device. It is also used at reset to set the eIMR+ device as either a primary or secondary device. CRS transmits the state of the eIMR+ device's internal carrier sense signals.
AUIM Port & TP[3:0]
VDD
CRS_I SI_D
eIMR+
CRS SO
SCLK SI
SCLK SI HIMIB SO CRS a) One eIMR Device Connected to a HIMIB
AUIM Port & TP[7:4] CRS_I eIMR+ CRS (Primary) SI_D SO
DVSS
AUIU Port & TP[3:0] CRS_I eIMR+ CRS (Secondary) SI_D SO SCLK SI
SCLK SI
HIMIB
SCLK SI SO CRS b) Two eIMR Devices Connected to a HIMIB
20651B-11
Figure 6. eIMR-to-HIMIB Connection
22
Am79C985
PRELIMINARY When two eIMR+ devices are connected to one HIMIB device, the secondary device transmits the status of its TP ports, then transmits the status of the primary eIMR+ TP ports and AUI port (CRS and CI). Note that the secondary device does not transmit the status of its AUI port. At Reset, the secondary device (and single eIMR+ device) internally synchronizes the CRS stream to begin with the AUI CI bit. SO is the eIMR+ device response to a Get command. The pins SI_D and CRS_I are multi-purpose pins. Their primary purpose is management input to the primary eIMR+ device. They are also used to set the management mode of the eIMR+ device. The mode is set on the rising edge of RST. The settings are shown in Table 4. Following reset, the eIMR+ devices retain their management designations. However, CRS_I and SI_D return to their management port functions. Command/Response Timing Figure 7 shows the command/response timing. At the end of a GET command, the eIMR+ device waits two SCLK cycles and then transmits the response on SO. The secondary eIMR+ device stores the data received on the SI_D input (from the primary eIMR+ device) in an internal register. When it has transmitted D3 data, it appends the received response to the end of the SO signal. Following reset, after the eIMR+ devices have been assigned their primary and secondary designation, SO and SI_D return to their management-port functions. Port Activity In addition to providing a means for receiving commands and sending data in response to those commands, the management port includes a CRS signal that transmits the state of the eIMR+ device's internal carrier-sense signals. When two eIMR+ devices are connected to one Am79C987 HIMIB device (as shown in the System Applications section), CRS_I of the secondary device receives the following signals from the primary device: the carrier-sense signals of the AUI port, the CI-bit status of the AUI port, and the carrier-sense signals of the TP ports. The secondary device transmits the status of the AUI port (CRS and CI) for the primary device, the status of its own TP ports (TP0-TP3), and then the status of the primary device's TP ports (TP4-TP7). The status of the AUI port of the secondary device is not retransmitted (see Figure 8).
Table 4. eIMR+ Device Management Designations
CRS_I 0 0 1 1 SI_D 0 1 0 1 Single eIMR+ Device Two eIMR+ Devices Primary eIMR+ Device Secondary eIMR+ Device
SCLK
SI SO
ST D0 D1 D2 D3 D4 D5 D6 D7
Primary eIMR+ Device or Single eIMR+ Device SO Secondary eIMR+ Device
ST D0 D1 D2 D3
ST D0 D1 D2 D3 D4 D5 D6 D7
Note: For SO on the Primary device, D[3:0] corresponds to TP[7:4].
20651B-12
Figure 7. Management Get Command/Response
Am79C985
23
PRELIMINARY
CLK TCLK CRS Secondary CRS Primary* CRS One eIMR+ Device
CP A P T0 T1 T2 T3 T4 T5 T6 T7
T4 T5 T6 T7 CP A P
C
A
T0 T1 T2 T3
* Shows actual output stream to secondary device.
20651B-13
Figure 8. Port Activity Signals with Am79C987 HIMIB Device Management Commands The following section details the operation of each management commands available in the eIMR+ device. In all cases, the individual bits in each command are shown with the most-significant bit (bit 7) on the left and the least-significant bit (bit 0) on the right. Table 5 and Table 6 show a summary of default states and a summary of management commands, respectively. Table 5. Summary of Default States after Reset eIMR+ Programmable Option-- CSA AUI Partitioning Algorithm TP Partitioning Algorithm AUI/TP Port Link Test Link Pulse Automatic Receiver Polarity Reversal Extended Distance Mode Blink Rate Software Override of LEDs Off Normal Normal Enabled Enabled Enabled State of SI at reset Disabled Off Disabled
Note: Data is transmitted and received on the serial data lines least-significant bit first and most-significant bit last.
24
Am79C985
PRELIMINARY Table 6. Management Port Command Summary
SO Data Single eIMR+ Device SO Data Primary SO Data Secondary
Commands Set (Write Commands) eIMR+ Chip Programmable Options Alternate AUI Partitioning Algorithm Alternate TP Partitioning Algorithm Primary AUI Port Disable Secondary AUI Port Disable Primary AUI Port Enable Secondary AUI Port Enable TP Port Disable TP Port Enable Disable Link Test Function (per TP port) Enable Link Test Function (per TP port) Disable Link Pulse (per TP port) Enable Link Pulse (per TP port) Disable Automatic Receiver Polarity Reversal (per TP port) Enable Automatic Receiver Polarity Reversal (per TP port) Disable Receiver Extended Distance Mode (Per TP port) Enable Receiver Extended Distance Mode (Per TP port) Disable Software Override of LEDs (Per Port - AUI & TP) Enable Software Override of Bank-A LEDs (Per Port - AUI & TP, Global) Enable Software Override of Bank-B LEDs (Per Port - AUI & TP, Global) Software Override LED Blink Rate Get (Read Commands) AUI Port Status (B, S, and L Cleared) AUI Port Status (B Cleared) AUI Port Status (S, L, Cleared) AUI Port status (None Cleared) TP Port Partitioning Status Bit Rate Error Status of TP Ports Link Test Status of TP Ports Receive Polarity Status of TP Ports MJLP Status Version
SI Data 0000 1CSA 0001 1111 0001 0000 0010 1111 0010 1110 0011 1111 0011 1110 0010 0### 0011 0### 0100 0### 0101 0### 0100 1### 0101 1### 0110 0### 0111 0### 0110 1### 0111 1### 1001 #### 1011 #### 1100 #### 1110 1### 1000 1111 1000 1101 1000 1011 1000 1001 1000 0000 1010 0000 1101 0000 1110 0000 1111 0000 1111 1111
PBSL 0000 PBSL 0000 PBSL 0000 PBSL 0000 0000 C3..C0 0000 E3..E0 0000 L3..L0 0000 P3..P0 M000 0000 0000 0011
0000 PBSL 0000 PBSL 0000 PBSL 0000 PBSL 0000 C7..C4 0000 E7..E4 0000 L7..L4 0000 P7..P4 0000 M000 0000 0011
PBSLP PBSLS PBSLP PBSLS PBSLP PBSLS PBSLP PBSLS C7..C0 E7..E0 L7..L0 P7..P0 MP000 MS000 0011P 0011S
Am79C985
25
PRELIMINARY
SET (Write Commands) Chip Programmable Options
SI Data SO Data (Pri) SO Data (Sec) 0000 1CSA None None
reconnection algorithm. To return the TP ports to the standard (transmit or receive) reconnection algorithm, it is necessary to reset the eIMR+ device. The standard partitioning algorithm is selected on reset.
Primary AUI Port Disable
SI SO Data (Pri) SO Data (Sec) 0010 1111 None None
The eIMR+ chip programmable options can be enabled (or disabled) by setting (or resetting) one or more of the C, S, and A bits in the command string. The three programmable options are C - CI Reporting, S - AUI test mask, and A - Alternate port activity monitor (PAM) function.
C
HIMIB Connection
This bit, when set, indicates to the eIMR+ device that it is connected to a HIMIB device.
S
AUI SQE Test Mask
This command disables the AUI port on the primary eIMR+ device. Subsequently the eIMR+ chip will ignore all inputs to this port and will not transmit a DAT or JAM pattern on the AUI port. Disabling the AUI port also sets the partitioning state machine of the AUI port to the idle state. Therefore, a partitioned port can be reconnected by first disabling the AUI port and then enabling the AUI port. The AUI port on the primary eIMR+ device defaults to enabled on reset.
Setting this bit allows the eIMR+ chip to ignore activity on the CI signal pair, during the SQE test window, following a transmission on the AUI port. Enabling this function does not prevent the reporting of this condition by the eIMR+ device. The two functions operate independently. The SQE Test Window, as defined in IEEE 802.3 (Section 7.2.2.2.4) is from 6 bit times to 34 bit times (0.6 s to 3.4 s). This includes the delay introduced by a 50m AUI. CI activity that occurs outside this window is not ignored and is treated as a true collision.
Secondary AUI Port Disable
SI Data SO Data (Pri) SO Data (Sec) 0010 1110 None None
A
Alternate Port Activity Monitor Function
Setting this bit causes the Port Activity Monitor (PAM) function to be altered such that the CRS data is presented unmodified. In default operation, CRS is masked if the port is either disabled or partitioned. Note that the HIMIB device resets this bit (default operation).
This command disables the AUI port on the eIMR+ device designated as the secondary HIMIB attachment. Subsequently the eIMR+ chip will ignore all inputs to this port and will not transmit a DAT or JAM pattern on the AUI port. Disabling the AUI port also sets the partitioning state machine of the AUI port to the idle state. Therefore, a partitioned port can be reconnected by first disabling the AUI port and then enabling the AUI port. The AUI port on the secondary eIMR+ device defaults to enabled on reset.
Primary AUI Port Enable
SI SO Data (Pri) SO Data (Sec) 0011 1111 None None
Alternate AUI Partitioning Algorithm
SI Data SO Data (Pri) SO Data (Sec) 0001 1111 None None
Invoking this command sets the partition/reconnection scheme for the AUI port to the alternate (transmit-only) reconnection algorithm. To return the AUI port to the standard (transmit or receive) reconnection algorithm, it is necessary to reset the eIMR+ device. The standard partitioning algorithm is selected on reset. If two eIMR+ devices are connected, this command sets both AUI ports.
This command enables the AUI port on the primary eIMR+ device.
Secondary AUI Port Enable
SI Data SO Data (Pri) SO Data (Sec) 0011 1110 None None
Alternate TP Partitioning Algorithm
SI Data SO Data (Pri) SO Data (Sec) 0001 0000 None None
Invoking this command sets the partition/reconnection scheme for the TP ports to the alternate (transmit-only)
This command enables the AUI port on the eIMR+ device designated as the secondary HIMIB attachment. When enabled, the secondary AUI port is fully functional, and can be controlled by the serial/management interface. However, when used with the Am79C987 device, no status is displayed for this port since the HIMIB device does not manage this port. At reset, this port is enabled.
26
Am79C985
PRELIMINARY
TP Port Disable
SI Data SO Data (Pri) SO Data (Sec) 0010 0### None None
eIMR+ device. Designated port values of b011 through b000 in the command data correspond to TP3 through TP0 in the secondary eIMR+ device.
Disable Link Pulse (Per TP Port)
SI Data SO Data (Pri) SO Data (Sec) 0100 1### None None
This command disables the TP port designated by the three least-significant bits of the command byte. Subsequently the eIMR+ chip will ignore all inputs to the designated port and will not transmit a DAT or JAM pattern on that port. Disabling the TP port also sets the partitioning state machine of that port to the idle state. Therefore, a partitioned port can be reconnected by first disabling the port and then enabling it. Designated port values of b111 through b100 in the command byte correspond to TP7 through TP4 in the primary eIMR+ device. Designated port values of b011 through b000 in the command byte correspond to TP3 through TP0 in the secondary eIMR+ device.
This command disables the transmission of the Link pulse on the TP port designated by the three least-significant bits of the command byte. Designated port values of b111 through b100 in the command byte correspond to TP7 through TP4 in the primary eIMR+ device. Designated port values of b011 through b000 in the command data correspond to TP3 through TP0 in the secondary eIMR+ device.
Enable Link Pulse (Per TP Port)
SI Data SO Data (Pri) SO Data (Sec) 0101 1### None None
TP Port Enable
SI Data SO Data (Pri) SO Data (Sec) 0011 0### None None
This command enables the TP port designated by the three least-significant bits of the command byte. Designated port values of b111 through b100 in the command byte correspond to TP7 through TP4 in the primary eIMR+ device. Designated port values of b011 through b000 in the command byte correspond to TP3 through TP0 in the secondary eIMR+ device.
This command enables the transmission of the Link pulse on the TP port designated by the three least-significant bits of the command byte. Designated port values of b111 through b100 in the command byte correspond to TP7 through TP4 in the primary eIMR+ device. Designated port values of b011 through b000 in the command byte correspond to TP3 through TP0 in the secondary eIMR+ device.
Disable Link Test Function (per TP port)
SI Data SO Data (Pri) SO Data (Sec) 0100 0### None None
Disable Automatic Receiver Polarity Reversal (Per TP Port)
SI Data SO Data (Pri) SO Data (Sec) 0110 0### None None
This command disables the Link test function of the TP port designated by the three least-significant bits of the command data. As a consequence of this, the port will no longer be disconnected if it fails the Link Test. If a port has the Link Test disabled, reading the Link Test Status indicates a `Link Pass'. Designated port values of b111 through b100 in the command byte correspond to TP7 through TP4 in the primary eIMR+ device. Designated port values of b011 through b000 in the command data correspond to TP3 through TP0 in the secondary eIMR+ device.
Enable Link Test Function (per TP port)
SI Data SO Data (Pri) SO Data (Sec) 0101 0### None None
This command disables the Automatic Receiver Polarity Reversal function for the TP port designated by the three least-significant bits in the command byte. If this function is disabled on a TP port receiving with reversed polarity (due to a wiring error), the TP port will fail the Link Test due to the incorrect polarity of the received Link pulses. Designated port values of b111 through b100 in the command byte correspond to TP7 through TP4 in the primary eIMR+ device. Designated port values of b011 through b000 in the command byte correspond to TP3 through TP0 in the secondary eIMR+ device. The state of Automatic Polarity Reversal function is set by SI on reset. If SI is HIGH at the rising edge of RST, the eIMR+ device disables Automatic Polarity Reversal. If SI is LOW at the rising edge of RST, the eIMR+ device enables Automatic Polarity Reversal.
This command enables the Link test function of the TP port designated by the three least-significant bits of the command data. As a consequence of this, the port is disconnected if it fails the Link Test. Designated port values of b111 through b100 in the command byte correspond to TP7 through TP4 in the primary
Am79C985
27
PRELIMINARY
Enable Automatic Receiver Polarity Reversal (Per TP Port)
SI Data SO Data (Pri) SO Data (Sec) 0111 0### None None
Disable Software Override of LEDs (Per Port - AUI and TP, Global)
SI Data SO Data (Pri) SO Data (Sec) 1001 #### None None
This command enables the Automatic Receiver Polarity Reversal function for the TP port designated by the three least-significant bits in the command byte. If enabled in a TP port, the eIMR+ chip will automatically invert the polarity of that port's receiver circuitry if the TP port is detected as having reversed polarity (due to wiring error). After reversing the receiver polarity, the TP port could then receive subsequent (reverse polarity) packets correctly. Designated port values of b111 through b100 in the command byte correspond to TP7 through TP4 in the primary eIMR+ device. Designated port values of b011 through b000 in the command byte correspond to TP3 through TP0 in the secondary eIMR+ device.
This command Disables software override of the Port LEDs. Individual LEDs and combinations of LEDs can be selected via the lower four bits of the command byte, as follows:
Disable Receiver Extended Distance Mode (Per TP Port)
SI Data SO Data (Pri) SO Data (Sec) 0110 1### None None
#### 0000-0111 1000 1001 1010 1011 1100 1101 1110 1111
Port(s) affected TP0 - TP7 Primary AUI Secondary AUI Both AUI ports All TP ports All ports Primary Global Secondary Global All Global
Following command execution, the attributes displayed on the LEDs will be determined by LDC0-2. Software override of LEDs is disabled after reset.
This command disables the Receiver Extended Distance Mode and restores the RXD circuit of the transceiver to normal squelch levels for the TP-port driver designated by the three least-significant bits of the command data. Designated port values of b111 through b100 in the command byte correspond to TP7 through TP4 in the primary eIMR+ device. Designated port values of b011 through b000 in the command byte correspond to TP3 through TP0 in the secondary eIMR+ device.
Enable Software Override of Bank-A LEDs (Per Port AUI and TP, Global)
SI Data SO Data (Pri) SO Data (Sec) 1011 #### None None
This command forces the LEDs in Bank A to blink. Individual LEDs and combinations of LEDs can be selected via the lower four bits of the command byte, as follows:
Enable Receiver Extended Distance Mode (Per TP Port)
SI Data SO Data (Pri) SO Data (Sec) 0111 1### None None
This command modifies the RXD circuit of the transceiver for the TP-port driver designated by the three least-significant bits of the command data. The RXD squelch-threshold value is lowered to accommodate signal attenuation associated with lines longer than 100 meters. Designated port values of b111 through b100 in the command byte correspond to TP7 through TP4 in the primary eIMR+ device. Designated port values of b011 through b000 in the command byte correspond to TP3 through TP0 in the secondary eIMR+ device. At reset, Receiver Extended Distance Mode is disabled and the RXD circuit defaults to normal squelch-threshold values.
#### 0000-0111 1000 1001 1010 1011 1100 1101 1110 1111
Port(s) affected TP0 - TP7 Primary AUI Secondary AUI Both AUI ports All TP ports All ports Primary Global Secondary Global All Global
The designated LED drivers(s) will switch between LOW and `off' at the rate set by the Software Override Blink Rate command. Enable Software Override of Bank A LEDs references the blink rate last issued, and overrides any other attribute specified by LDC0-2. Software override of LEDs is disabled after reset.
28
Am79C985
PRELIMINARY
Enable Software Override of Bank-B LEDs (Per Port AUI and TP, Global)
SI Data SO Data (Pri) SO Data (Sec) 1100 #### None None
The four local status bits are:
P
Partitioning Status
This bit is `0' if the AUI port is partitioned and `1' if the AUI port is connected.
This command forces the LEDs in Bank B to blink. Individual LEDs and combinations of LEDs can be selected via the lower four bits of the command byte, as follows. #### 0000-0111 1000 1001 1010 1011 1100 1101 1110 Port(s) affected TP0 - TP7 Primary AUI Secondary AUI Both AUI ports All TP ports All ports Primary Global Secondary Global
B
Bit Rate Error
This bit is set to `1' if there is an instance of FIFO overflow or underflow. The bit is cleared when the eIMR+ device is read.
S
SQE Test Status
This bit is set to `1' if the SQE test error is detected by the eIMR+ chip. The bit is cleared when the status is read.
L
Loopback Error
The designated LED drivers(s) will switch between LOW and `off' at the rate set by the Software Override of LED Blink Rate command. Enable Software Override of Bank B LEDs references the blink rate last issued, and overrides any other attribute specified by LDC0-2. Software override of LEDs is disabled after reset.
The MAU attached to the AUI port is required to loopback data transmitted to DO onto the DI circuit. If the loopback carrier is not detected by the eIMR+ device, this bit is set to `1'. This bit is cleared when the status is read. If a single eIMR+ device is connected to a HIMIB device, SO is PBSL 0000. If two eIMR+ devices are connected to a HIMIB device, SO on the primary device is 0000 PBSLP, and SO on the secondary device is PBSLP PBSLS. The subscript (P) indicates the statistics of the primary eIMR+ device and the subscript (S) indicates the statistics of the secondary eIMR+ device.
Software Override of LED Blink Rate
SI Data SO Data (Pri) SO Data (Sec) 1110 1### None None
Alternate AUI Port(s) Status
There are three further variations of the AUI Port Status Command allowing selective clearing of a combination of B,S, and L bits. These are the following:
This command sets the blink Period of the LEDs with Software Override enabled. The duty cycle is 50%. This command defaults to `off' at reset.
Setting 1110 1000 1110 1001 1110 1010 1110 1011
Blink Period Off 512 ms 1560 ms Solid On
Alternate 1: B is not cleared, S and L are Cleared
SI Data SO Data (Sec) SO Data (Pri) SO Data (Single) 1000 1011 PBSLP PBSLS 0000 PBSL PBSL 0000
These settings apply to the blink rate for both Bank A and Bank B. This command must precede the Enable Software Override of Bank A/B LEDs command. All LED combinations selected for software override will reference the blink rate last issued.
Alternate 2: S and L are not cleared, B is Cleared
SI Data SO Data (Sec) SO Data (Pri) SO Data (Single) 1000 1101 PBSLP PBSLS 0000 PBSL PBSL 0000
Get (Read Commands) AUI Port(s) Status
SI Data SO Data (Sec) SO Data (Pri) SO Data (Single) 1000 1111 PBSLP PBSLS 0000 PBSL PBSL 0000
Alternate 3: None of S, B, and L are Cleared
SI Data SO Data (Sec) SO Data (Pri) SO Data (Single) 1000 1001 PBSLP PBSLS 0000 PBSL PBSL 0000
The combined AUI status of the eIMR+ device(s) allows a single instruction to be used to monitor the AUI port(s).
Am79C985
29
PRELIMINARY
TP Port Partitioning Status
SI Data SO Data (Sec) SO Data (Pri) SO Data (Single) 1000 0000 0000 P3..P0, P7..P0 (output to HIMIB) 0000 P7..P4 0000 P3..P0
Receive Polarity Status of TP Ports
SI Data SO Data (Sec) SO Data (Pri) SO Data (Single) 1110 0000 0000 P3......P0, P7.....P0 (output to HIMIB) 0000 P7......P4 0000 P3......P0
Pn = 0 TP Port Partitioned Pn = 1 TP port Connected where n is a port number in the range 0-7 The response to this command gives the partitioning status of all four TP ports. If a port is disabled, reading its partitioning status will indicate that it is connected. If two eIMR+ devices are connected together, the secondary device indicates the status of all eight TP ports. P7...P4 correspond to the four ports of the primary device. P3..P0 correspond to the four ports of the secondary device.
Pn = 0 TP Port n Polarity Correct Pn = 1 TP port n Polarity Reversed where n is a port number in the range 0-7 The response to this command gives the Received Polarity status of all the TP ports. If the polarity is detected as reversed for a TP port, then the eIMR+ device will set the appropriate bit in this command's result only if the Polarity Reversal Function is enabled for that port. If two eIMR+ devices are connected together, the secondary device indicates the status of all eight TP ports. P7...P4 correspond to the four ports of the primary device. P3..P0 correspond to the four ports of the secondary device.
Bit Rate Error Status of TP Ports
SI Data SO Data (Sec) SO Data (Pri) SO Data (Single) 1010 0000 0000 E3..E0, E7..E0 (output to HIMIB) 0000 E7..E4 0000 E3..E0
MJLP Status
SI Data SO Data (Sec) SO Data (Pri) SO Data (Single) 1111 0000 M000 0000, MP000 MS000 (to HIMIB) 0000 M000 M000 0000
No Error En = 0 FIFO Overflow En = 1 where n is a port number in the range 0-7. The response to this command gives the bit-rate-overflow or underflow (data rate mismatch) condition of all the TP ports. A 1 indicates that the FIFO has overflowed or underflowed due to the amount of data received by the corresponding port. If two eIMR+ devices are connected together, the secondary device indicates the status of all eight TP ports. E7...E4 correspond to the four ports of the primary device. E3...E0 correspond to the four ports of the secondary device.
Each eIMR+ device contains an independent MAU Jabber Lock Up Protection timer. The timer is designed to inhibit the transmit function of the eIMR+ device if it has been transmitting continuously for more than 65536 bit times. This bit remains set and is only cleared when the MJLP status is read using this command. If two eIMR+ devices are connected together, the secondary device will indicate the status of both devices (MP is the status of the primary device; MS is the status of the secondary device).
Link Test Status of TP ports
SI Data SO Data (Sec) SO Data (Pri) SO Data (Single) 1101 0000 0000 L3..L0, L7......L0 (output to HIMIB) 0000 L7..L4 0000 L3..L0
Version
SI Data SO Data (Sec) SO Data (Pri) SO Data (Single) 1111 1111 0000 0011, 0011P 0011S (to HIMIB) 0000 0011 0000 0011
TP Port n in Link Test Failed Ln = 0 Ln = 1 TP port n in Link Test Passed where n is a port number in the range 0-7. The response to this command gives the Link Test status of all the TP ports. A disabled port continues to report Link Test status. Re-enabling the port causes the port to be placed in the Link Test Fail state. If two eIMR+ devices are connected together, the secondary device indicates the status of all eight TP ports. L7..L4 correspond to the four ports of the primary device. L3..L0 correspond to the four ports of the secondary device.
The response to this command gives the version of the eIMR+ device. 0011 was chosen to help distinguish the eIMR+ device from the IMR (Am79C980) and the IMR+ (Am79C981) devices. If two eIMR+ devices are connected together, the secondary device will indicate the version of the primary device in the upper four bits of the SO byte, and its own version number in the lower four bits.
30
Am79C985
PRELIMINARY
SYSTEMS APPLICATIONS eIMR+ to TP Port Connection
The eIMR+ device provides a system solution to designing non-managed multiport repeaters. The eIMR+ device connects directly to AC coupling modules for a 10BASE-T hub. Figure 9 shows the simplified connection.
of a 110- resistor and a 1:1 transformer. The load is a twisted-pair cable that meets IEEE 802.3, Section 14.4 specifications. The cable is terminated at the opposite end by 100 .
Twisted Pair Receivers
RXD signals need to be properly terminated to meet the electrical requirements for 10BASE-T receivers. Proper termination is shown in Figure 11. Note that the receivers do not require external filter modules.
Twisted Pair Transmitters
TXD signals need to be properly terminated to meet the electrical requirement for 10BASE-T transmitters. Proper termination is shown in Figure 10 which consists
eIMR+ TXD0+ TXD0- RXD0+ RXD0- 110 100 1:1
TP Connector
1:1
TP Connector TXD1+ TXD1- RXD1+ RXD1- 110 100 1:1
1:1
TP Connector TXD2+ TXD2- RXD2+ RXD2- 110 100 1:1
1:1
TP Connector TXD3+ TXD3- RXD3+ RXD3- RST CLK
20651B-14
110 100
1:1
1:1
Figure 9.
Simplified 10BASE-T Connection
TXD+ 110 TXD-
1:1 Twisted Pair 100
20650A-13
20651B-15
Figure 10.
TXD Termination
Am79C985
31
PRELIMINARY
RXD+ 1:1 Twisted Pair 100
100
RXD-
20650A-14 20650A-14
20651B-16
Figure 11.
RXD Termination of the MAC and DO is connected to DI of the MAC, because the reverse configuration only affects CI. Where CI is an input in the normal mode, in the reverse mode, CI is an output. Figure 12b shows the normal AUI configuration for reference.
MAC Interface
The eIMR+ device can be connected directly to a MAC through the AUI port. This requires that the AUI port be configured in the reverse mode and connected as shown in Figure 12a. Notice that DI is connected to DO
Am79C940 DO+ DO- 40 DI+ DI- 40 CI+ CI- 40 0.1 F 40 40 40
eIMR+ DI+ DI-
Am7996 DI+ DI- 40 40
1:1
eIMR+ DI+ DI-
DO+ DO-
DO+ DO- 40 40
1:1
DO+ DO- 0.1 F
CI+ CI-
CI+ CI-
1:1
CI+ CI-
40 0.1 F 39 - 150 0.1 F -9 V
40 0.1 F
a) Reverse Mode (with MAC)
b) Normal Mode (with MAU)
20651B-17
20651A-17
Figure 12.
AUI Port Interconnections
Internal Arbitration Mode Connection
The internal arbitration mode uses a modified daisychain scheme to eliminate the need for any external arbiter. In this mode, ACK and COL need to be pulled up through a minimum resistance of 1 k. The DAT and JAM pins also need to be pulled down via a high value resistor. Refer to Figure 13. 32
IMR+ Mode External Arbitration
The IMR+ mode maintains the full functionality of AMD's IMR+ (Am79C981) device's expansion bus. In this mode, the eIMR+ device requires external circuitry to handle arbitration for control of the bus. Figure 14 shows the configuration for the IMR+ mode of operation.
Am79C985
PRELIMINARY
VDD
(Note: In a multiple eIMR+ system, the reset signal must be synchronized to CLK.) 74LS74 RST D
ACK
COL
DAT
JAM
Q
D
Q
SELI_0 SELI_1 RST CLK
eIMR+ SELO SELI_0 SELI_1 RST CLK
DAT JAM
eIMR+ SELO
ACK COL
Q PC
Q PC
20 MHz OSC
VDD
~1 k
SELI_0 SELI_1 RST CLK
JAM DAT
eIMR+ SELO
ACK COL
1 k
VDD
~1 k
20651B-18
Figure 13.
eIMR+ Internal Arbitration Mode Connection
eIMR+ SELI_0 SELO SELI_1 DAT JAM ACK COL
eIMR+ SELI_0 SELO SELI_1 DAT JAM ACK COL
eIMR+ SELI_0 SELO SELI_1 DAT JAM ACK COL
1 k
COL ACK SEL1 SEL2 SEL3 Arbiter
GCOL
20651B-19
Figure 14. IMR+ Mode External Arbitration
Am79C985
33
PRELIMINARY
Visual Status Display
LDA/B[4:0] and LDGA/B provide visual status indicators for the eIMR+. LDA/B[4:0] displays Link, Carrier Sense, Collision, and Partition information for the TP and AUI ports. LDGA/B display global Carrier Sense, Collision, and Jabber information. In a multiple eIMR+ configuration, the global LED drivers (LDGA/B) from each chip can be tied together to drive a single pair of global status LEDs. The open drain output of these drivers facilitate this configuration. Refer to Figure 15.
VDD
LDA[4:0] eIMR+ LDB[4:0]
LDGA LDGB
LDA[4:0] eIMR+ LDB[4:0]
LDGA LDGB
20651B-20
Figure 15.
Visual Status Display Connection
34
Am79C985
PRELIMINARY
ABSOLUTE MAXIMUM RATINGS
Storage Temperature . . . . . . . . . . -65 C to +150 C Ambient Temperature Under Bias . . . . 0 C to +70 C Supply Voltage referenced to AVSS or DVSS (AVDD, DVDD) . . . . . . . -0.3 V to +6.0 V
OPERATING RANGES Commercial (C) Devices
Temperature (TA) . . . . . . . . . . . . . . . . . 0 C to +70 C Supply Voltages (VDD) . . . . . . . . . . . . . . . . .+5 V 5%
Stresses above those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent device failure. Functionality at or above these limits is not implied. Exposure to Absolute Maximum Ratings for extended periods may affect reliability. Programming conditions may differ.
Operating ranges define those limits between which the functionality of the device is guaranteed.
DC CHARACTERISTICS over Commercial operating ranges unless otherwise specified
Parameter Symbol Digital I/O VIL VIH VOL VOH IIL IILSTR VOLOD AUI Ports IIAXD VAICM VAIDV VASQ VATH VAOD VAOC VAODI VAODOFF IAODOFF VAOCM IIRXD RRXD VTIVB VTID Input Current at DI and CI Pairs DI, CI Open Circuit Input Voltage Range Differential Mode Input Voltage Range (DI, CI) DI, CI Squelch Threshold DI Switching Threshold Differential Output Voltage (DO+) - (DO) Differential Output Voltage (CI+) - (CI-) (Reverse Mode) DO Differential Output Voltage Imbalance DO Differential Idle Output Voltage DO Differential Idle Output Current DO+, DO- Common Mode Output Voltage Input Current at RXD and CI Pairs RXD Differential Input RXD+, RXD- Open Circuit Input Voltage (bias) Differential Mode Input Range (RXD) VDD = 5.0 V VSSParameter Description
Test Conditions
Min
Max
Unit
Twisted Pair Ports AVSSAm79C985
35
PRELIMINARY
DC CHARACTERISTICS (continued)
Parameter Symbol
Parameter Description RXD Positive Squelch Threshold (peak) RXD Negative Squelch Threshold (peak) RXD Post-Squelch Positive Threshold (peak) RXD Post-Squelch Negative Threshold (peak) RXD Positive Squelch Threshold (peak) - Extended Distance Mode RXD Negative Squelch Threshold (peak) - Extended Distance Mode RXD Post-Squelch Positive Threshold - Extended Distance Mode RXD Post-Squelch Negative Threshold - Extended Distance Mode RXD Switching Threshold Power Supply Current (Idle) (Note 2) Power Supply Current (Transmitting)
Test Conditions Sinusoid 5 MHzMin
Max
Unit
Twisted Pair Ports (Continued) VTSQ+ VTSQ- VTHS+ VTHS- VLTSQ+ VLTSQ- VLTHS+ VLTHS- VRXDTH IDD 300 -520 150 -293 180 -365 90 -175 -60 520 -300 293 -150 365 -180 175 -90 60 mV mV mV mV mV mV mV mV mV
Power Supply Current - - 100 350 mA mA
Notes: 1. Parameter not tested. 2. LED current not included. Maximum current rating on LED drivers is 12 mA.
36
Am79C985
PRELIMINARY
SWITCHING CHARACTERISTICS
Parameter Symbol tCLK tCLKH tCLKL tCLKR tCLKF tPRST tRST tRSTSET tRSTHLD tXRS tXRH
Parameter Description CLK Clock Period CLK Clock High CLK Clock Low CLK Rise Time CLK Fall Time Reset Pulse Width after Power On Reset Pulse Width Reset HIGH Setup Time with respect to CLK Reset LOW Hold Time AMODE, SELI0, CRS_I, and SI_D Setup Time to Rising Edge of RST AMODE,SELI0, CRS_I and SI_D Hold Time from Rising Edge of RST CLK Rising Edge to DO Toggle DO+, DO- Rise Time (10% to 90%) DO+, DO- Fall Time (90% to 10%) DO+, DO- Rise and Fall Time Mismatch DO End of Transmission DI Pulse Width Accept/Reject Threshold DI Pulse Width Not to Turn-off Internal Carrier Sense CI Pulse Width Accept/Reject Threshold CI Pulse Width Not to Turn-off Threshold CI Rise Time (In Reverse Mode) CI Fall Time (In Reverse Mode) CI+, CI- Rise and Fall Time Mismatch (AUI in Reverse Mode) CLK HIGH to SELO Driven LOW CLK HIGH to SELO Driven HIGH CLK HIGH to DAT/JAM Driven CLK HIGH to DAT/JAM Not Driven DAT/JAM Setup Time to CLK DAT/JAM Hold Time from CLK COL/ACK Setup Time to CLK COL/ACK Hold Time from CLK SI, SCLK Hold Time
Test Conditions
Min 49.995 20 20 - - 150 4 15 0 0 400
Max 50.005 30 30 10 10 - - - - - -
Unit ns ns ns ns ns
Clock and Reset Timing
s s
ns ns ns ns
AUI Port Timing tDOTD tDOTR tDOTF tDORM tDOETD tPWODI tPWKDI tPWOCI tPWKCI tCITR tCITF tCIRM - - - - 275 |VIN|>|VASQ| (Note 2) |VIN|>|VASQ| (Note 3) |VIN|>|VASQ| (Note 4) |VIN|>|VASQ| (Note 5) 15 136 10 75 - - - 30 7.0 7.0 1.0 375 45 200 26 160 7.0 7.0 1.0 ns ns ns ns ns ns ns ns ns ns ns ns
Expansion Bus Timing tCLKHRL tCLKHRH tCLKHDR tCLKHDZ tDJSET tDJHOLD tCASET tCAHLD tSCLKHLD CL = 50 pF CL = 50 pF CL = 100 pF CL = 100 pF 15 15 14 14 10 9 10 9 50 30 30 30 30 - - - - - ns ns ns ns ns ns ns ns ns
Am79C985
37
PRELIMINARY
SWITCHING CHARACTERISTICS (continued)
Parameter Symbol tTXTD tTETD tPWKRD tPERLP tPWLP tSCLK tSCLKH tSCLKL tSCLKR tSCLKF tSISET tSIHLD tSODLY tCLKHCRS tSTRSET tSTRHLD
Parameter Description CLK Rising Edge to TXD Transition Delay Transmit End of Transmission RXD Pulse Width Maintain/Turn-off Threshold Idle Signal Period Idle Link Test Pulse Width SCLK Clock Period SCLK Clock HIGH SCLK Clock LOW SCLK Clock Rise Time SCLK Clock Fall Time SI Input Setup Time to SCLK Rising Edge SI Input Hold Time from SCLK Rising Edge SO Output Delay from SCLK Rising Edge CLK Rising Edge to CRS valid STR Setup Time STR Hold Time
Test Conditions
Min - 250
Max 50 375 200 24 120 - - - 10 10 - - 40 40 - -
Unit ns ns ns ms ns ns ns ns ns ns ns ns ns ns ns ns
Twisted Pair Port Timing
|VIN|>|VTHS| (Note 6)
136 8 75 100 30 30 - - 10 10
Management Port Timing
CL = 100 pF CL = 100 pF
- 5 5 9
Notes: 1. Parameter not tested. 2. DI pulses narrower than tPWODI (min) will be rejected; pulses wider than tPWODI (max) will turn internal DI carrier sense on. 3. DI pulses narrower than tPWKDI (min) will maintain internal DI carrier on; pulses wider than tPWKDI (max) will turn internal DI carrier sense off. 4. CI pulses narrower than tPWOCI (min) will be rejected; pulses wider than tPWOCI (max) will turn internal CI carrier sense on. 5. CI pulses narrower than tPWKCI (min) will maintain internal CI carrier on; pulses wider than tPWKCI (max) will turn internal CI carrier sense off. 6. RXD pulses narrower than tPWKRD (min) will maintain internal RXD carrier sense on; a pulse wider than tPWKRD (max) will turn RXD carrier sense off.
38
Am79C985
PRELIMINARY
KEY TO SWITCHING WAVEFORMS
WAVEFORM INPUTS Must be Steady May Change from H to L May Change from L to H Don't Care, Any Change Permitted Does Not Apply OUTPUTS Will be Steady Will be Changing from H to L Will be Changing from L to H Changing, State Unknown Center Line is HighImpedance "Off" State
KS000010-PAL
SWITCHING WAVEFORMS
t CLK t CLKH t CLKL
CLK
t CLKR
t CLKF
20650A-20
20651B-21
Figure 16.
Clock Timing
Am79C985
39
PRELIMINARY
SWITCHING WAVEFORMS (continued)
t SCLKR t SCLK tSCLKF
SCLK tSCLKH t SCLKL
SI/SI_D tSODLY t SISET tSIHLD
SO
20651B-22
Figure 17.
Management Port Timing
CLK tRSTHLD RST tRST or tPRST tRSTSET
TCLK
Note: TCLK represents internal eIMR+ timing
20651B-23
Figure 18.
Reset Timing
AMODE, SELI[0], SI_D, CRS_I
tXRS
tXRH
RST
20651B-24
Figure 19.
Mode Initialization
40
Am79C985
PRELIMINARY
SWITCHING WAVEFORMS (continued)
CLK
TCLK SELO
ACK
COL
tDJSET IN
tDJHOLD
DAT/JAM
Note: TCLK represents internal eIMR+ timing
20651B-25
Figure 20. Expansion Bus Input Timing
CLK
TCLK tCLKHRL SELO tCASET ACK tCAHLD COL tCLKHDR DAT/JAM OUT tCLKHDZ tCASET tCLKHRH
Note: TCLK represents internal eIMR+ timing
20651B-26
Figure 21. Expansion Bus Output Timing
Am79C985
41
PRELIMINARY
SWITCHING WAVEFORMS (continued)
CLK
TCLK tCLKHRH SELO tCLKHRL ACK tCASET COL tCAHLD DAT/JAM IN IN tCASET
Note: TCLK represents internal eIMR+ timing
20651A-27
20651A-27
20651B-27
Figure 22.
Expansion Bus Collision Timing
CLK tDOTD D0+ D0tDOTR tDOTF tDOETD
20651B-28
Figure 23.
AUI Timing Diagram
tPWKDI (tPWKCI)
tPWKDI (tPWKCI)
DI+ (CI)
VASQ
tPWODI (tPWOCI)
20650A-28
20651B-29
Figure 24.
AUI Receive Diagram
42
Am79C985
PRELIMINARY
SWITCHING WAVEFORMS (continued)
1 CLK tTXTD TXD+ tTETD 0 1 0 1 1 1 0 1 0 ETD
TXD-
20651B-30
Figure 25.
TP Ports Output Timing Diagram
tPWLP
tPERLP
20651B-31
Figure 26.
TP Idle Link Test Pulse
VTSQ+ RXD+/- VTSQ-
tPWKRD
VTHS+ VTHS-
20560A-31
tPWKRD
tPWKRD
20651B-32
Figure 27. TP Receive Timing Diagram
Am79C985
43
PRELIMINARY
SWITCHING TEST CIRCUIT
VDD
Pin
Test Point
VSS
20650A-32
20651B-33
Figure 28.
Switching Test Circuit
44
Am79C985
PRELIMINARY
PHYSICAL DIMENSIONS PL 084 84-Pin Plastic Leaded Chip Carrier (measured in inches)
.062 .083
1.185 1.195
1.150 1.156
.042 .056
1.185 1.195 1.150 1.156
Pin 1 I.D.
1.090 1.130 1.000 REF
.013 .021
.026 .032
.050 REF
.007 .013
.090 .130 .165 .180
SEATING PLANE
TOP VIEW
SIDE VIEW
16-038-SQ PL 084 DF79 8-1-95 ae
Am79C985
45
PRELIMINARY
PQR100 100-Pin Plastic Quad Flat Pack
17.00 17.40
Pin 100
12.35 REF
13.90 14.10
Pin 80
Pin 1 I.D.
18.85 REF 19.90 20.10 23.00 23.40
Pin 30 Pin 50
2.70 2.90 0.25 MIN
0.65 BASIC
3.35 MAX
SEATING PLANE
16-038-PQR-1_AH PQR100 DP92 6-20-96 lv
46
Am79C985
Appendix A
Security
EAVESDROP PROTECTION
The eIMR+/HIMIB devices are capable of providing network eavesdrop protection. This feature is protected by a software key. An application note containing the necessary software key and implementation details is available from AMD. A brief description of eavesdrop protection is given below. For more information, contact your local AMD sales representative.
packet's destination address with the two address registers associated with each repeater port: Last Source Address Register and Preferred Source Address Register. Eavesdrop protection can be masked on a portby-port basis. Disruption of multicast packets can also be masked on a port-by-port basis. If the destination address is a broadcast address, the packet is transmitted unmodified on all ports. In many instances, a station targeted with a specific destination address will not reside within the same repeater as the originating station. To ensure that packets arrive at the intended destination, eIMR+/HIMIB ports can be programmed to pass packets with an invalid destination address undisturbed if no other port on the repeater has a valid address that matches the destination address. The eIMR+/HIMIB devices can determine if there is a match on the repeater by monitoring its ports and by monitoring signals on the eIMR+/HIMIB expansion bus.
FEATURES SUMMARY
Eavesdrop protection is based on the concept that confidential data should only be received by specified secure stations. The eIMR+/HIMIB devices are capable of repeating packets only to ports considered secure for a packet's destination address. On all other ports, transmission can be disrupted by transmitting a pattern of alternating 1s and 0s. The eIMR+/HIMIB can disrupt packet transmission, as described above, on ports not having a valid address. Valid addresses are determined by comparing a
CLK
TCLK
STR
AUI
TP0
TP1
TP2
TP3
TP4
TP5
TP6
TP7
Note: TCLK illustrates internal eIMR+ chip clock phase relationship.
20651B-34
Figure A1.
STR Input Signal from Am79C987 HIMIB Device
Am79C985
A-1
Trademarks Copyright (c) 1997 Advanced Micro Devices, Inc. All rights reserved. AMD, the AMD logo, and combinations thereof are trademarks of Advanced Micro Devices, Inc. Hardware Implemented Management Information Base (HIMIB), Integrated Multiport Repeater (IMR) Integrated Multiport Repeater Plus (IMR+), Basic Integrated Multiport Repeater (bIMR), and enhanced Multiport Repeater Plus (eIMR+) are trademarks of Advanced Micro Devices, Inc. Product names used in this publication are for identification purposes only and may be trademarks of their respective companies.
A-2
Am79C985

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