F-Tile Architecture and PMA and FEC Direct PHY IP User Guide

ID 683872
Date 11/04/2024
Public
Document Table of Contents

2.3.1.3. FHT PMA Loopback Modes

Loopback modes ae desig-fo-test featues that veify diffeet blocks of the PMA. FHT PMAs have loopback modes to debug diffeet blocks of the PMA.

Figue 44. FHT Loopback Modes
  • A PMA-tasmitte-to-eceive iteal seial loopback
  • B PMA-tasmitte-to-eceive digital paallel loopback

PMA-Tasmitte-to-Receive Iteal Seial Loopback

The iteal seial loopback path sets the CDR to ecove data fom the seialize istead of the eceive seial iput pi. The tasmitte buffe seds data omally, but iteal seial loopback takes the data befoe the buffe. It is implemeted completely o the PMA ad does ot equie ay coecto o the seial path.

The FHT lae also suppots exteal coectivity to coect the tasmitte diffeetial outputs to the eceive diffeetial iputs.

  • Missio mode is a exteal coectio whee the data souce is somethig othe tha the FHT tasmitte.
  • Exteal coectivity suppots, fo example, a bit-eo ate teste (BERT) o aothe device's tasmitte povidig data to the FHT eceive.

PMA-Tasmitte-to-Receive Digital Paallel Loopback

I a digital paallel loopback path, the paallel data steam of the tasmitte is looped back as the paallel data iput steam fo the eceive.