TNETX3100PGC datasheet(45/80 Pages) TI1

45 / 80 page

TNETX3100

ThunderSWITCH™ 10-PORT 10-/100-MBIT/S ETHERNET™ SWITCH

SPWS031D – JUNE 1997 – REVISED OCTOBER 1997

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

LED interface

An LED interface allows a visual status for each port to be displayed. Each port has a single LED; the LED

display conveys information about the port state.

PORT STATE

LED DISPLAY

No link

Off

Link, but no activity

Occasional activity

On, with occasional off periods (1/16th second)

High activity

Fast flashing (8 Hz)

Partitioned

On for 0.5 seconds, then off for 1.5 seconds

In addition to the port status information, the LED interface also enables the state of the internal flow control and

fault functions to be displayed along with four software-controllable LEDs. The display can be configured in a

mode that displays only the partitioned status by setting the PONLY bit in the LED register. The LEDDATA signal

is active low since TTL is more efficient at driving low than high (see Figure 10).

TNETX3100

74ACT374

Shift Register

74ACT373

Latch

74ACT374

Shift Register

74ACT373

Latch

LED Matrix

LEDCLK

LEDDATA

LEDSTR

Figure 10. LED Interface

Sixteen status bits are shifted serially out and then LEDSTR is pulsed to latch the data; this process is repeated

every 1/16th of a second. The shift register can be shortened if a system is not required to display all of the LEDs;

a very low-cost system that implements only the FAULT LED can be readily implemented by using LEDSTR to

clock a single external latch.

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