Near-End Pma Loopback; Marginal Conditions And Limitations - Xilinx Virtex-5 RocketIO GTP User Manual

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Near-End PMA Loopback

This mode uses the Near-End source for generating and checking the test data. The
loopback occurs in the serial section of the PMA before the line drivers. The test data can be
generated and checked by the built-in PRBS block inside the PCS or by user logic. The test
data also appears on the package pins.
the built-in PRBS.

Marginal Conditions and Limitations

In the near-end PMA loopback mode, the TXDATA input is routed through the PMA,
serialized, and then looped back in through the RX side of the PMA and back out to
RXDATA. When this mode is in use, there must be nothing driving the RXP/RXN serial
inputs of the channel. The inputs can be left unconnected.
When the device is on a board, the remote transmitter should be 3-stated. If this is not
possible, then the following alternatives are available:
Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
Near-End GTP
Parallel
Parallel
Figure 9-2: Near-End PCS Loopback
Figure 9-3 shows the configuration without using
Near-End GTP
Parallel
Parallel
Figure 9-3: Near-End PMA Loopback
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RX-PMA
RX-PCS
TX-PCS TX-PMA
UG196_c9_02_082906
RX-PMA
RX-PCS
Serial
TX-PCS TX-PMA
Serial
UG196_c9_03_082906
Description
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