82503 datasheet(14/45 Pages) INTEL

14 / 45 page

82503

The transmit to receive loopback function is disabled

when the jabber function or link integrity function is

inhibiting transmission

38 SQE Test Function

The 82503 supports the SQE test function when in

TPE mode or in Diagnostic Loopback mode The

82503 will assert its CDT pin within 06 msto1 6 ms

after the end of a transmission and it will remain

asserted for 5- to 15-bit times If the 82503 is in the

TPE mode and is not in diagnostic loopback mode

the link integrity function will disable the SQE test

function when it detects a bad link

39 Port Selection

The 82503 features both manual and automatic port

selection To enable automatic port selection con-

nect APORT to VCC The 82503 then starts in TPE

mode and monitors link integrity If the link is good

the 82503 stays in TPE mode and pulls TPEAUI

high to indicate that the TPE port was selected If

link integrity fails the 82503 switches to AUI mode

and pulls TPEAUI low to indicate that the AUI port

is now active TPEAUI can drive an LED to indicate

port selection (on for AUI off for TPE mode) Note

that LILED will be on if TPE mode is selected and off

if AUI mode is selected If link integrity is disabled

while automatic port selection is enabled the 82503

defaults to TPE mode If the 82503 changes ports

while RTS is active transmission is terminated with

an End of Frame marker on the old port Transmis-

sion of the remaining packet fragment is not allowed

on the new port Transmissions will begin with a

complete data packet

The port can be manually selected by driving

APORT low TPEAUI e 0 selects AUI mode and

TPEAUI e 1 TPE mode When the port is manually

selected the circuitry for the unused port is powered

down Changing ports requires 100 ms to allow the

circuitry for the new port to resume normal opera-

tion

Table 1 Port Selection

Configuration

State

LID APORT TPEAUI

AUI (TPE Port Powered Down)

TPE (AUI Port Powered Down)

Automatic Port Selection

TPE

NOTE

TPEAUI is an output pin when APORT e 1

310 LED Description

The 82503 supports six LED pins to indicate the

status

important

states

TPEAUI

TxLED

POLED LILED RxLED COLED Each pin is capable

of directly driving an LED

3101 TPEAUI

When automatic port selection is enabled (APORT is

high) TPEAUI becomes an LED output and turns

off if TPE mode is selected and on if AUI mode is

selected

3102 TxLED

Transmit status This LED is normally off and flashes

at 25 Hz 5 Hz and 10 Hz to indicate respectively a

low medium and high rate of transmit activity

3103 RxLED

Receive LED This LED is normally off and flashes at

25 Hz 5 Hz and 10 Hz to indicate respectively a

low medium and high rate of receive activity

3104 COLED

Collision LED This LED is normally off and flashes

at 25 Hz 5 Hz and 10 Hz to indicate respectively a

low medium and high rate of collision activity

3105 POLED

Polarity Fault This LED is normally off and turns on

to indicate a polarity fault in the receive pair of the

10BASE-T link Operation of this pin is not affected

by the state of the polarity correction function

(APOLXSQ e X)

3106 LILED

Link Integrity status

When Aport is enabled

(APORT e 1) this LED is normally on (driven low)

to indicate the presence of a valid 10BASE-T link

when the TPE port is active The LED will turn off

(driven high) when the link fails When link integrity is

disabled (LID e 1) while APORT is enabled

(APORT e 1) this LED is turned on (driven low) If

APORT is disabled (APORT e 0) and the AUI port is

manually selected (TPEAUI e 0) the LED output is

tristated

311 Polarity Switching

In TPE mode the 82503 monitors receive link beats

and end-of-frame delimiters for a possible receiver

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