82503 Datasheet, PDF (14/45 Pages) Intel Corporation – DUAL SERIAL TRANSCEIVER (DST)

82503
The transmit to receive loopback function is disabled
when the jabber function or link integrity function is
inhibiting transmission
3 8 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 0 6 ms to 1 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
3 9 Port Selection
The 82503 features both manual and automatic port
selection To enable automatic port selection con-
nect APORT to V_CC The 82503 then starts in TPE
mode and monitors link integrity If the link is good
the 82503 stays in TPE mode and pulls TPE AUI
high to indicate that the TPE port was selected If
link integrity fails the 82503 switches to AUI mode
and pulls TPE AUI low to indicate that the AUI port
is now active TPE AUI 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 TPE AUI ^e 0 selects AUI mode and
TPE AUI ^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
LID APORT TPE AUI
State
X0
X0
01
11
0 AUI (TPE Port Powered Down)
1 TPE (AUI Port Powered Down)
X Automatic Port Selection
X TPE
NOTE
TPE AUI is an output pin when APORT e 1
14
3 10 LED Description
The 82503 supports six LED pins to indicate the
status of important states TPE AUI TxLED
POLED LILED RxLED COLED Each pin is capable
of directly driving an LED
3 10 1 TPE AUI
When automatic port selection is enabled (APORT is
high) TPE AUI becomes an LED output and turns
off if TPE mode is selected and on if AUI mode is
selected
3 10 2 TxLED
Transmit status This LED is normally off and flashes
at 2 5 Hz 5 Hz and 10 Hz to indicate respectively a
low medium and high rate of transmit activity
3 10 3 RxLED
Receive LED This LED is normally off and flashes at
2 5 Hz 5 Hz and 10 Hz to indicate respectively a
low medium and high rate of receive activity
3 10 4 COLED
Collision LED This LED is normally off and flashes
at 2 5 Hz 5 Hz and 10 Hz to indicate respectively a
low medium and high rate of collision activity
3 10 5 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
(APOL XSQ ^e X)
3 10 6 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 (TPE AUI ^e 0) the LED output is
tristated
3 11 Polarity Switching
In TPE mode the 82503 monitors receive link beats
and end-of-frame delimiters for a possible receiver