Clocking and PLL User Guide: Agilex™ 5 FPGAs and SoCs

ID 813671
Date 9/17/2025
Public
Document Table of Contents

6.2.3. Design Example for HVIO I/O PLL Reconfiguration

The design example consists of the following device and IPs:

  • Uses Agilex™ 5 device to demonstrate the implementation of the following two different HVIO I/O PLL reconfiguration options:
    • I/O PLL divide settings reconfiguration
    • Clock gating reconfiguration
  • Includes the following IPs:
    • IOPLL FPGA IP
    • In-System Sources & Probes IP
    • Agilex™ Reset Release IP

    You must install Quartus® Prime software version 25.1.1 or later on a Windows* or Linux* computer that meets the minimum requirements.

    Before reconfiguration, the I/O PLLs configurations are as follows:

    • HVIO Bank I/O PLL 1:
      1. 50 MHz with 0 ps phase shift on counter C0 output
      2. 50 MHz with 0 ps phase shift on counter C1 output

    The input reference clock is 100 MHz. The reconfiguration ports are connected to a state machine to perform I/O PLL reconfiguration operations. Assert reconfig_startsignal to trigger the operation. You can select the desired reconfiguration mode through the mode_0 and mode_1 inputs, controlled through the In-System Sources & Probes IP core.

    Table 20.  Reconfiguration Mode Selection for the Design Example
    Reconfiguration Mode mode_1 mode_0
    Direct PLL reconfiguration 0 1
    Clock gating reconfiguration 1 0

    Follow these steps to recompile the design example:

    1. Download and restore the Design Example file.
    2. Change the device and pin assignments to match your hardware.
    3. Recompile the design example and ensure that it does not contain any timing violation after reconfiguration.