TNETX15AEPGE Datasheet, PDF (6/79 Pages) Texas Instruments – ADDRESS-LOOKUP DEVICE

TNETX15AE
ADDRESS-LOOKUP DEVICE
SPWS041A – AUGUST 1997 – REVISED OCTOBER 1997
EAM interface
TERMINAL
I/O
NAME NO.
EAM15† 106
EAM14 105
EAM13 104
EAM12 103
EAM11 102
EAM10 101
EAM09 99
EAM08 98
EAM07 97
O
EAM06 96
EAM05 95
EAM04 94
EAM03 93
EAM02 91
EAM01 90
EAM00‡ 89
Terminal Functions
DESCRIPTION
External address match single-/multiple-port routing code select. When EAM15 is high, the EAM-interface terminals
contain a single-port routing code. When EAM15 is low, the EAM-interface terminals contain a multiple-port routing
code.
External address match port routing code select. When EAM15 is high, the EAM14–EAM0 terminals are placed in
the single-port mode. In this mode EAM14–EAM0 terminals encode a single port to which the frame is routed.
EAM14–EAM5 are don’t-care bits and are set to 0. The single-port codes (EAM15–EAM0 terminals) are shown in
the following:
TNETX3150/TNETX3100
Port 00 (uplink)
Port 01
Port 02
Port 03
Port 04
Port 05
Port 06
Port 07
Port 08
Port 09
Port 10
Port 11
Port 12
Port 13
Port 14
Reserved
No-operation code
EAM15–EAM0
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 0 0 0 0 0 0 0 0000 0 0 0 0 b
1 0 0 0 0 0 0 0 0000 0 0 0 1 b
1 0 0 0 0 0 0 0 0000 0 0 1 0 b
1 0 0 0 0 0 0 0 0000 0 0 1 1 b
1 0 0 0 0 0 0 0 0000 0 1 0 0 b
1 0 0 0 0 0 0 0 0000 0 1 0 1 b
1 0 0 0 0 0 0 0 0000 0 1 1 0 b
1 0 0 0 0 0 0 0 0000 0 1 1 1 b
1 0 0 0 0 0 0 0 0000 1 0 0 0 b
1 0 0 0 0 0 0 0 0000 1 0 0 1 b
1 0 0 0 0 0 0 0 0000 1 0 1 0 b
1 0 0 0 0 0 0 0 0000 1 0 1 1 b
1 0 0 0 0 0 0 0 0000 1 1 0 0 b
1 0 0 0 0 0 0 0 0000 1 1 0 1 b
1 0 0 0 0 0 0 0 0000 1 1 1 0 b
1 0 0 0 0 0 0 0 0000 1 1 1 1 b
1 x x x x x x x xxx1 x x x x b
The no-operation code signals that the EAM device does not take part in forwarding decisions on this packet. The
TNETX15AE does not put out this code in normal operations. To successfully disable the TNETX15AE, it is reset and
not started. This causes the EAM interface to float, and external pullup resistors on EAM15 and EAM04 (minimally)
to supply the no-operation code to the TNETX3150/TNETX3150A/TNETX3100 device. Erratic operation occurs if the
TNETX3150/TNETX3150A/TNETX3100 address matching is not enabled when the TNETX15AE is disabled. The
TNETX15AE, when enabled, overrides the operations of the TNETX3150/TNETX3150A/TNETX3100 matching
circuitry; but, it is strongly advised to disable the TNETX3150/TNETX3150A/TNETX3100 address matching if the
TNETX15AE is active. This prevents two logic blocks from attempting to control port suspension and other functions.
When EAM15 is low, the EAM14–EAM0 terminals encode the multiple ports to which the data frame is routed. Each
bit on the EAM14–EAM0 bus is coded as follows:
– 1 on the bit signifies that the data frame is routed to that port.
– 0 on the bit signifies that the data frame is not routed to that port.
Terminal number assignments have a one-to-one correspondence to the port numbers as shown in the following:
EAM Bus Bit 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Port Number 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
† _{Most-significant bit}
‡ _{Least-significant bit}
For example, to multicast a frame to ports 08, 05, 02, and 00 a multiport code of 0000 0001 0010 0101 or 0x0125
is sent.
All multicast packets and unknown unicast packets are forwarded by multiport code (EAM15 = 0) even if only one
bit is set.
To discard a frame, a code of 0x0000 is output (multiple routing code with no ports selected):
TNETX3150/TNETX3100
EAM14–EAM0
Discard frame
000 000000 000 000
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