Intel® Cyclone® 10 GX Transceiver PHY User Guide

ID 683054
Date 4/14/2023
Public
Document Table of Contents

7.5.1. ATX PLL Recalibration

When you use the ATX PLL in your application, and it requires a line rate or clock frequency change, you must recalibrate the ATX PLL after you have made the changes.

Follow these steps to recalibrate the ATX PLL:

  1. Request user access to the internal configuration bus by writing 0x2 to offset address 0x0[7:0].
  2. Wait for reconfig_waitrequest to be deasserted (logic low) or wait until capability register of PreSICE Avalon-MM interface control 0x280[2]=0x0.
  3. To calibrate the ATX PLL, perform a Read-Modify-Write of 0x1 to bit[0] of address 0x100 of the ATX PLL.
  4. Release the internal configuration bus to PreSICE to perform recalibration by writing 0x1 to offset address 0x0[7:0].
  5. Periodically check the *cal_busy output signals or read the capability registers 0x280[1] to check *cal_busy status until calibration is complete.
Note:

You should avoid recalibrating the ATX PLL if another TX channel is in transmitting mode (clocked by another ATX PLL in the device). You need to do this to prevent a potential BER on neighboring RX channel placed next to a TX channel clocked by the ATX PLL. You can recalibrate the ATX PLL only if:

  1. The other TX channel that is in transmitting mode is clocked by fPLL or
  2. The other TX channel (clocked by another ATX PLL) must be place under reset condition.