Altera Cyclone IV - Reverse Serial Loopback

1–80 Chapter 1: Cyclone IV Transceivers Architecture
Loopback
Cyclone IV Device Handbook, February 2015 Altera Corporation
Volume 2
1 Serial loopback mode can only be dynamically enabled or disabled during user mode
by performing a dynamic channel reconfiguration.
Reverse Serial Loopback
The reverse serial loopback mode is available for all functional modes except for
XAUI mode. The two reverse serial loopback options from the receiver to the
transmitter are:
■ Pre-CDR mode where data received through the RX input buffer is looped back to
the TX output buffer using the Reverse serial loopback (pre-CDR) option
■ Post-CDR mode where retimed data through the receiver CDR from the RX input
buffer is looped back to the TX output buffer using the Reverse serial loopback
option
The received data is also available to the FPGA logic. In the transmitter channel, only
the transmitter buffer is active.
1 The transmitter pre-emphasis feature is not available in reverse serial loopback (pre-
CDR) mode.
1 Reverse serial loopback modes can only be dynamically enabled or disabled during
user mode by performing a dynamic channel reconfiguration.
Figure 1–71. Serial Loopback Path
(1)
Note to Figure 1–71:
(1) Grayed-Out Blocks are Not Active in this mode.
Tx PCS
Rx PCS
Tx PMA
Serializer
Rx PMA
Serial
loopback
path
Deserializer
To FPGA fabric
for verication
Transceiver
CDR
FPGA
Fabric