TNETX3151 datasheet(29/65 Pages) TI1

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TNETX3151

ThunderSWITCH

™ 12/3 ETHERNET™ SWITCH

WITH 12 10-MBIT/S PORTS AND 3 10-/100-MBIT/S PORTS

SPWS048A – MARCH 1998 – REVISED APRIL 1999

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

Table 9. LED Status Bit Definitions and Shift Order

ORDER

NAME

FUNCTION

slast = 0

slast = 1

NAME

FUNCTION

1–7

Zero. Dummy data for first 7 of 48 LEDCLK cycles.

8–19

35–46

SW0–SW11

Software LEDs 0–11. These allow additional software-controlled status to be displayed. These

12 LEDs reflect the values of bits 0–11 of the swled field in LEDControl at the moment that the LED

interface samples them. If this occurs between writes to the most significant and least significant

bytes of LEDControl, these values appear on the LEDs, separated by 1/16th of a second.

20–46

8–34

P00–P26

Port status LEDs 00–26. These 27 LEDs indicate the status of ports 00–26, in this order (port 00

is output first). Note that port 27 (management port) does not have an LED. The transmit multicast

content of these bits can be controlled by the txais bit in LEDControl. Note that IEEE Std 802.3X

pause frames never appear on the LEDs as port activity. The port’s LED toggles each 1/16th of a

second if there was any frame traffic (other than pause frames) on the port during the previous

1/16th of a second.

FLOW

Flow control. LED is on when the internal flow control is enabled and active. Active means that flow

control is asserted during the previous 1/16th of a second.

FAULT

Fault. LED indicates:

– the EEPROM CRC is invalid.

– an external DRAM parity error has occurred.

– the fitled in LEDControl has been set.

The CRC and parity error indications are cleared by hardware reset (terminal or DIO). The CRC

error indication also is cleared by setting load to 1. The parity error indication also is cleared by

setting start to 1.

lamp test

When the device is in the hardware reset state, LEDDATA is driven high and LEDCLK runs continuously. This

causes all LEDs to be illuminated and serves as a lamp test function.

multi-LED display

The LED interface is intended to provide the lowest-cost display with a single multifunction LED per port. In

systems requiring a full-feature display (more than levels of activity) using multiple LEDs per port, this can be

achieved by driving the LEDs directly from the PHY signals.

hardware configurations

10-Mbit/s MAC interfaces (ports 04–15)

One group of eight 10-Mbit/s ports (08–15) and one group of four 10-Mbit/s ports (04–07) interfaces directly with

a TI TNETE2008, which contains eight 10-Mbit/s PHYs. This interface is time multiplexed between the eight

ports, with receive and transmit data being transferred over nibble-wide buses. Any given port needs only to

transfer data at 2.5 MHz (i.e., 2.5 MHz

× 4 bits = 10 Mbit/s), but because TNETE2008 contains eight PHYs, the

frequency of nibble transfers is 20 MHz (i.e., 2.5 MHz

× 8 ports). The remaining control and status signals also

are transferred at this rate.

Table 10 shows how the terminals of a TNETE2008 device are connected to each 10-Mbit/s interface on the

TNETX3151.

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