8101 Datasheet, PDF (133/172 Pages) LSI Computer Systems – Gigabit Ethernet Controller

Table 5.3 SerDes Loopback Procedure
STEP Action
Result
1
Set the REJALL bit in Register 8 Ignore all receive data until the loopback mode is ready
for operation.
2
Set the EWRAP bit in Register 9 Enable the external SerDes loopback mode.
3
Clear the SD_EN bit in Register Ignore the signal detect output from optical transceiver
9
because the receive optical data may be invalid.
4
Set the TBC_DIS bit in Register Stop transmission of data out of 10-bit PHY interface
10
which causes the SerDes and controller to lose sync so
that they properly resync to the new data stream.
5
Wait more than 200 µs
Allow time for the SerDes and controller receivers to lose
sync.
6
Clear the TBC_DIS bit in
Register 10
Turn on the transmitter so that the SerDes and controller
receivers can gain sync.
7
Wait more than 200 µs
Allow time for the SerDes and controller receivers to gain
sync.
8
Clear the REJALL bit in Register Stop ignoring receive data and turn on the receive MAC.
8
9
Do loopback tests
10
Clear the EWRAP bit, and set Turn off the SerDes loopback mode and enable the signal
the SD_EN bit in Register 9 (if detect function (if used).
SD pin is used)
11
Set the ANRST bit in Register 7 Restarts AutoNegotiation. Controller is ready for normal
operation when AutoNegotation is completed.
5.6 AutoNegotiation
AutoNegotiation is a handshake operation between the controller and the
external device (see Section 2.15, “AutoNegotiation”). If the external
device is capable of AutoNegotiation, the procedures described in
Section 5.6.1, “AutoNegotiation at Power Up” should be followed. If the
external device is not capable of AutoNegotiation, refer to Section 5.6.2,
“Negotiating with a Non-AutoNegotiation Capable Device”.
AutoNegotiation
5-7
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