GTS Transceiver PHY User Guide: Agilex™ 3 FPGAs and SoCs

ID 848344
Date 8/04/2025
Public
Document Table of Contents

3.14.2.1. GTS Attribute Access Method Example 1: Enable or Disable Internal Serial Loopback Mode (RX Auto Adaptation Mode)

The following example describes the steps to enable and disable serial loopback for the GTS PMA during RX auto adaptation mode.
  1. To enable serial loopback:
    1. Assert RX reset.
    2. Wait for RX reset ACK.
    3. Write 0x6A040 to address 0xA403C.

      6: data field for serial loopback enable.

      A: option field to request service, not set in reset and set parameters.

      0: lane number field for physical lane 0.

      40: opcode field for serial loopback.

    4. Poll address 0xA4040 until bit 14 = 0 and bit 15 = 1.
    5. Write 0x62040 to address 0xA403C.

      6: data field for serial loopback enable.

      2: option field to de-assert service request, not set in reset and set parameters.

      0: lane number field for physical lane 0.

      40: opcode field for serial loopback.

    6. Poll address 0xA4040 until bit 14 = 0 and bit 15 = 0.
    7. Deassert RX reset.
    8. Wait for RX reset ACK deassert.
  2. To disable serial loopback:
    1. Assert RX reset.
    2. Wait for RX reset ACK.
    3. Write 0x0A040 to address 0xA403C.

      0: data field for serial loopback disable.

      A: option field to request service, not set in reset and set parameters.

      0: lane number field for physical lane 0.

      40: opcode field for serial loopback.

    4. Poll address 0xA4040 until bit 14 = 0 and bit 15 = 1.
    5. Write 0x02040 to address 0xA403C.

      0: data field for serial loopback disable.

      2: option field to de-assert service request, not set in reset and set parameters.

      0: lane number field for physical lane 0.

      40: opcode field for serial loopback.

    6. Poll address 0xA4040 until bit 14 = 0 and bit 15 = 0.
    7. Deassert RX reset.
    8. Wait for RX reset ACK deassert.