AR# 39756

12.4/13.x ChipScope IBERT - How do I set the Virtex-6 GTH Transceivers in various loopback modes?


ChipScope tool IBERT for GTH Transceivers supports near-end PCS loopback under the "Loopback Mode" pull-down menu, but does not support the near-end PMA loopback (unlike the IBERT for GTX Transceivers). The other type of supported loopback is the Far-end PMA loopback (labeled incorrectly as Far-end PCS loopback)for the GTH transceiver.

This Answer Record explains how to select the variousloopback modes for GTH Transceivers in IBERT.


Near-end PMA Loopback:

The near-end PMA loopback for GTH Transceivers is currently not supported by the IBERT tool, but it can be selected by setting the followingattributes manually through the "DRP Settings" tabin IBERT:

Attribute Value
PMA_LPBK_CTRL_LANE<n>[1:0] 2'b10

It is important to note here thatthough PMA_LPBK_CTRL_LANE<n>[1:0] attributeis perGTH lane,the SLICE_CFG and LANE_AMON_SEL are not lane specific attributes,but affect all four lanes in a Quad. Therefore, all four transceivers in aQuadare placed in near-end PMA loopback mode when these attributes are set to these values. This feature is to be addressed in a future version of the IBERT tool.

Near-end PCS Loopback:

The near-end PCS loopback can be selected from the pull-down menu in the IBERT tool. IBERT sets the following bit to enable the near-end PCS loopback when selected from the menu.

Attribute Value
PCS_MODE_LANE<n>[14] 1'b1

Far-end PMA Loopback:

Far-end PMA loopback is supported in GTH Transceivers, but far-end PCS loopback is not supported. The"Far-end PCS" in the IBERT tool is incorrectly labeled (it is actually far-end PMA loopback), and selecting this option only sets the PCS_MODE<n>[15] bit to 1'b1. The other attribute PCS_RESET<n>[1] is not set correctly either.This feature is to be addressed in a future revision of the IBERT tool.

Attribute Value
PCS_MODE_LANE<n>[15] 1'b1
PCS_RESET_LANE<n>[1] 1'b0

The far-end PMA loopback can be selected correctly by setting the above attributes manually through the "DRP Settings" tab in IBERT.

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
40485 13.x ChipScope Pro - Known Issues for the ChipScope Pro 13.x Software N/A N/A

Associated Answer Records

AR# 39756
Date 01/02/2013
Status Active
Type General Article