ep1agx50d Altera Corporation, ep1agx50d Datasheet - Page 34

• Manufacturer Part Number: ep1agx50d
• Description: Arria Gx Device Data Sheet
• Manufacturer: Altera Corporation

Transceivers
Figure 2–18. Transceiver Data Path in Serial Loopback
2–26
Arria GX Device Handbook, Volume 1
PLD
Logic
Array
RX Phase
Compen-
sation
FIFO
TX Phase
Compen-
sation
FIFO
Serial Loopback
Figure 2–18
In GIGE and Serial RapidIO modes, you can dynamically put each
transceiver channel individually in serial loopback by controlling the
rx_seriallpbken port. A high on the rx_seriallpbken port puts
the transceiver into serial loopback and a low takes the transceiver out of
serial loopback.
As seen in
serializer is looped back to the receiver CRU in serial loopback. The
transmitter data path from the PLD interface to the serializer in serial
loopback is the same as in non-loopback mode. The receiver data path
from the clock recovery unit to the PLD interface in serial loopback is the
same as in non-loopback mode. Since the entire transceiver data path is
available in serial loopback, this option is often used to diagnose the data
path as a probable cause of link errors.
1
Reverse Serial Loopback
Reverse serial loopback mode uses the analog portion of the transceiver.
An external source (pattern generator or transceiver) generates the source
data. The high-speed serial source data arrives at the high-speed
differential receiver input buffer, passes through the CRU unit and the
retimed serial data is looped back, and is transmitted though the
high-speed differential transmitter output buffer.
Figure 2–19
Serializer
Byte
De-
When serial loopback is enabled, the transmitter output buffer is
still active and drives the serial data out on the tx_dataout
port.
Serializer
Figure
Byte
shows the transceiver data path in serial loopback.
shows the data path in reverse serial loopback mode.
Decoder
8B/10B
2–18, the serial data output from the transmitter
Encoder
8B/10B
Match
FIFO
Rate
Transmitter PCS
Receiver PCS
Aligner
Word
Receiver PMA
Serializer
De-
Transmitter PMA
Serial Loopback
Altera Corporation
Serializer
Recovery
Clock
Unit
May 2008