GTS Transceiver PHY User Guide

ID 817660
Date 7/08/2024
Public
Document Table of Contents

2.3.3. PMA Loopback Modes

The PMA channel includes serial and parallel loopback paths. These loopback paths provide support for different debugging options and configurations. Available loopback paths are labeled in the following figure and described below:
  • A: PMA-transmitter-to-receiver internal serial loopback (TX2RXBUF):
    • Loops back the transmitter pre-driver differential I/O signals to the receiver equalizer.
  • B: PMA-transmitter-to-receiver parallel loopback (TX2RXPAR):
    • Parallel loopback from the PMA transmit lane 32 bit data ports to the receive lane 32 bit data ports.
  • C: PMA-receiver-to-transmitter reverse parallel loopback (RX2TXPAR):
    • Parallel loopback from the PMA receive lane 32 bit data ports to the transmit lane 32 bit data ports. This loopback enables the transmitter buffer to transmit data fed directly from the CDR recovered data.
Note: Refer to the GTS PMA/FEC Direct PHY IP Register Map on how to enable and disable various loopback modes supported in the Agilex™ 5 FPGAs.
Figure 19. PMA Loopback Modes