UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 41799

Virtex-4 Aurora - Core reports "Channel-up" even though receive pins (RXN/RXP) are not connected

Description

The core reports "Channel up" and I seem to receive data, even though I disconnect the signal from the receiver pins (RXN/RXP). This happens in hardware and can also be reproduced in simulation.

How is this possible?

Solution

The Virtex-4 MGT requires a calibration circuit to be active when no input signal is present to prevent the MGT from getting damaged. The calibration circuit gets enabled through the "RX_Signal_detect" signal.

Once the calibration circuit is activated, by pulling the "RX_signal_detect" signal Low, it puts the MGT in serial loopback to keep the receiver circuit active.

Data that is sent on TX of that MGT is therefore also received on the RX side.

The data that seems to be received is really the data that is sent on the TX side of the same MGT.

AR# 41799
Date Created 06/15/2011
Last Updated 12/15/2012
Status Active
Type General Article
IP
  • Aurora 8B/10B Virtex-4 FX