E-Tile Transceiver PHY User Guide

ID 683723
Date 9/30/2022
Public
Document Table of Contents

6.4. PMA Analog Reset

The transceiver has internal logic that is clocked by the transceiver's reference clock. There is only one PMA reset, and it affects both TX and RX PMAs.
Table 61.  When to Perform a PMA Analog Reset
Event Reason to Reset
Device configuration Initial adaptation does not help bring up the device in a good state.
Correcting a loose cable connection and bringing up a link Initial adaptation does not help bring up the device in a good state.
Changing the reference clock frequency or reference clock source Dynamic reconfiguration does not operate properly. See Dynamic Reconfiguration for details.
Changing data rates (both transceiver and link) Dynamic reconfiguration does not operate properly. See Dynamic Reconfiguration for details.
Changing channel physical connections (for example, going from cable to backplane) Initial adaptation does not help bring up the device in a good state.
Changing or interrupting the transceiver power supply Initial adaptation does not help bring up the device in a good state.

To reset the internal controller, use the transceiver’s Avalon® memory-mapped interface bus to:

  1. Write 0x200[7:0] = 0x00.
  2. Write 0x201[7:0] = 0x00.
  3. Write 0x202[7:0] = 0x00.
  4. Write 0x203[7:0] = 0x81.
  5. Read 0x207 until it becomes 0x80. This indicates that the operation completed successfully.
  6. Read-modify-write 0x95[5] = 0x1 to enable PMA calibration when loading the new PMA settings.
  7. Resetting the internal logic causes the transceiver to lose its settings for the data rate and serialization/deserialization values. Write 0x91[0] = 1 to load the initial settings in the programming file (when the embedded MIF streamer is not used), or go to the last profile (when the embedded MIF streamer is used).

Alternatively, you can load in a new profile using the MIF streamer or by loading in the PMA settings by sending the individual attributes. See Reconfiguring the Duplex PMA Using the Reset Controller in Automatic Mode for an example. Loading the PMA settings using register 0x91[0] or the MIF streamer enables the PMA.

Table 62.  Alternatives to a PMA Analog Reset
Use Case Description Solution
Link fault management or fault handling of a link-down

Systems relying on IEEE link fault handling are impacted by a PMA analog reset bringing down both the transmitter and receiver.

The transmitter is turned off after a PMA analog reset which triggers a local fault on the link partner.

The receiver needs to recover from the loss of a lock without a PMA analog reset.

Turning on or off transmitter and receiver buffers and recalibrating the receiver helps narrow down the issue during link-down scenarios.

Enable or disable the TX and RX buffers (see 0x0001: PMA Enable/Disable).

Use Initializing an RX and "Initial Adaptation" in PMA Receiver Equalization Adaptation Usage Model to recalibrate the receiver.

Turning on internal serial loopback from mission mode A PMA analog reset can be avoided by resetting the receiver equalization. Use Resetting the RX Equalization.
Changing the loss profile for a given medium Changing media from short reach to long reach may require a PMA analog reset. Use Initializing an RX and "Initial Adaptation" in PMA Receiver Equalization Adaptation Usage Model to recalibrate the receiver.
Handling different link partners for the transmitter and receiver of a given channel This requires independent receiver adaptation without a PMA analog reset so that the transmitter is not disrupted. Use Initializing an RX and "Initial Adaptation" in PMA Receiver Equalization Adaptation Usage Model to recalibrate the receiver.
Speed training for CPRI Turning off the transmitter buffer during link training avoids the need for a transmitter reset or PMA analog reset. Enable or disable the TX and RX buffers (see 0x0001: PMA Enable/Disable).

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