TNETX15AE datasheet(25/78 Pages) TI

25 / 78 page

TNETX15AE

ADDRESS-LOOKUP DEVICE

SPWS041A – AUGUST 1997 – REVISED OCTOBER 1997

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

statistics registers at 0x17–0x1D (DIO)

BYTE 3

BYTE 2

BYTE 1

BYTE 0

DIO ADDRESS

Secvioctr

0x14

Unkmultictr

Unkunictr

0x18

Numnodes

0x1C

All registers in this field are read only and their default value after reset is 0. The 16-bit counters in this section

must be read by bytes. It is recommended that the bytes be read least-significant byte through most-significant

byte (last). An additional stimulus can cause a carry between these two reads.

security violation counter, secvioctr at 0x17 (DIO)

The secvioctr field contains the number of times that a secured address attempts to move ports. This register

generates a stat interrupt (statistics overflow interrupt) when it is one-half full (most-significant bit in the field is

a 1). Reading this register automatically clears it and the default value of this register is 0x00.

unknown unicasts counter, unkunictr at 0x18–0x19 (DIO)

The unkunictr register counts the number of times that the TNETX15AE device floods a frame that has a unicast

destination address. These frames are used when the TNETX15AE cannot find the destination address in its

lookup table. This register generates a stat interrupt (statistic overflow interrupt) when it is one-half full

(most-significant bit in the field is a 1). Reading the most-significant byte of this register automatically clears it

and the default value of this register is 0x0000.

unknown multicasts counter, unkmultictr at 0x1A–0x1B (DIO)

The unkmultictr register counts the number of times that the TNETX15AE device floods a frame that has a

multicast destination address. Multicast destination addresses are flooded when the TNETX15AE cannot find

the destination address in its lookup table. This register generates a stat interrupt (statistics overflow interrupt)

when it is one-half full (most-significant bit in the field is a 1). Reading the most-significant byte of this register

automatically clears it and the default value of this register is 0x0000.

lookup table node count, numnodes at 0x1C–0x1D (DIO)

The numnodes counter register contains the number of addresses currently in the lookup table. This register

is read only and its value at reset is 0x0000.

SRAM address register, RAMaddr at 0x20–0x22 (DIO)

The RAMaddr register is used with the RAMdata (at 0x24, 0x25) register to access the TNETX15AE

external SRAM.

BYTE 2

BYTE 1

BYTE 0

BIT

INC

Reserved

RAM ADD

Initial values after reset

BIT

NAME

FUNCTION

INC

Address auto-increment. When INC is 1, this increments the RAM ADD field to access the next location in the SRAM.

The address is incremented by one after every read or write is performed on the most-significant byte of the RAMdata

22–21

Reserved

Writes to this location are ignored and read as 0.

20–0

RAM ADD

RAM address. This 21-bit field holds the address of the SRAM location, which is read or written. The data that is to

be read or written is placed in the RAMdata register. This interface is read/write at all times except during reset.

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