E-Tile Transceiver PHY User Guide

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

7.12.1.3. Changing the refclk[1] Reference Clock Frequency

  1. Device configuration defaults the reference clock to refclk_in_A (refclk[1] in this use case).
  2. Switch PMA Mux to refclk_in_B. Maintain refclk_in_B (refclk[1]) to be stable.
    • Write PMA attribute 0x30 = 0x3 to switch the PMA Mux.
  3. Switch Reference Clock Mux (9:1 mux) from refclk[1] to a stable refclk[0, 2, 3, 4, 5, 6, 7].
  4. Bring up refclk_in_A, and switch PMA Mux to refclk_in_A.
    • Write PMA Attribute 0x30 = 0x0 to switch the PMA Mux.
  5. Change the frequency on refclk[1].
  6. Bring up refclk_in_B, and switch PMA Mux to refclk_in_B.
    • Write PMA attribute 0x30 = 0x3 to switch the PMA Mux.
  7. Switch Reference Clock Mux (9:1 mux) to refclk[1].
  8. Because refclk_in_A is already stable, switch PMA Mux to refclk_in_A.
    • Write PMA Attribute 0x30 = 0x0 to switch the PMA Mux.
  9. Perform a PMA Analog Reset.

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