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AR# 31589

Virtex-5 GTP RocketIO - RXELECIDLE usage while in Near-end PMA loopback


This Answer Record describes the limitations of using the electrical idle detection circuit and status signal, RXELECIDLE, while using the loopback functionality of the GTP transceiver.


The electrical idle detection circuits built into the receiver of the GTP are intended to detect when the link partner is either unconnected or not actively driving the data lines. When the differential voltage on the receiver pins (RXN and RXP) drop below a certain threshold, the electrical idle detection circuitry will report this to the user application by asserting RXELECIDLE.

In cases where the GTP has been placed into Near-end PMA loopback (often referred too as internal serial loopback) for testing, RXELECIDLE will no longer reflect the state of the receiver pins and should be ignored.

AR# 31589
Date Created 08/29/2008
Last Updated 12/15/2012
Status Active
Type General Article