Transceiver Loopback Support; Serial Loopback - Altera Cyclone V Device Handbook

2013.05.06
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The Cyclone V loopback options allow you to verify how different functional blocks work in the transceiver.
Related Information
Cyclone V Device Handbook: Known Issues
Lists the planned updates to the Cyclone V Device Handbook chapters.

Serial Loopback

This section describes the use of serial loopback as a debugging aid to ensure the enabled PCS and PMA
blocks in the transmitter and receiver channels function correctly.
Serial loopback is available for all transceiver configurations except the PIPE mode. You can use serial
loopback as a debugging aid to ensure that the enabled physical coding sublayer (PCS) and physical media
attachment (PMA) blocks in the transmitter and receiver channels are functioning correctly. Furthermore,
you can dynamically enable serial loopback on a channel-by-channel basis.
The data from the FPGA fabric passes through the transmitter channel and is looped back to the receiver
channel, bypassing the receiver buffer. The received data is available to the FPGA logic for verification.
Figure 6-1: Serial Loopback Datapath
Transmitter PMA
Serial
Loopback
can be
Dynamically
Enabled Receiver PMA
When you enable serial loopback, the transmitter channel sends data to both the tx_serial_data output
port and to the receiver channel. The differential output voltage on the tx_serial_data port is based
on the selected differential output voltage (V
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Transceiver Loopback Support

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Transmitter PCS
Receiver PCS
) settings.
OD
6
FPGA
Fabric
ISO
9001:2008
Registered