Intel® MAX® 10 Clocking and PLL User Guide

ID 683047
Date 12/26/2023
Public
Document Table of Contents

4.2.4.2. Dynamic Phase Configuration with Advanced Parameters

The finest phase shift step resolution you can get in the Avalon ALTPLL Intel® FPGA IP is 1/8 of the VCO period. If the VCO frequency is at the lower end of the supported VCO range, the phase shift step resolution might be larger than preferred for your design.

You can modify your phase shift resolution using the dynamic phase reconfiguration feature of the PLL. If you want to modify the phase shift resolution without the dynamic phase reconfiguration feature enabled, perform the following steps:

  1. Create an Avalon ALTPLL instance. Make sure you specify the speed grade of your target device and the PLL type.
  2. On the PLL Reconfiguration page, turn on Create optional inputs for dynamic phase reconfiguration and Enable phase shift step resolution.
  3. On the Output Clocks page, set your desired phase shift for each required output clock. Note all the internal PLL settings shown.
  4. On the Bandwidth/SS page, click More Details to see the internal PLL settings. Note all of the settings shown.
  5. On the Inputs/Lock page, turn on Create output file(s) using the ‘Advanced’ PLL Parameters.
  6. Return to the PLL Reconfiguration page and turn off Create Optional Inputs for Dynamic Phase Reconfiguration.
  7. Click Finish to generate the PLL instantiation file(s).
    When using Advanced Parameters, the PLL wrapper file (< Avalon ALTPLL_instantiation_name >.v or < Avalon ALTPLL_instantiation_name >.vhd) is written in a format that allows you to identify the PLL parameters. The parameters are listed in the Generic Map section of the VHDL file, or in the defparam section of the Verilog file.
  8. Open your PLL instantiation wrapper file and locate either the Generic Map or the defparam section.
  9. Modify the settings to match the settings that you noted in steps 3 and 4.
  10. Save the PLL instantiation wrapper file and compile your design.
  11. Verify that the output clock frequencies and phases are correct in the PLL Usage report located under the Resource section of the Fitter folder in the Compilation Report.

By using this technique, you can apply valid PLL parameters as provided by the Avalon ALTPLL Intel® FPGA IP parameter editor to optimize the settings for your design.

Alternatively, you can leave the dynamic phase reconfiguration option enabled and tie the relevant input ports—phasecounterselect[3..0], phaseupdown, phasestep, and scanclk—to constants, if you prefer not to manually edit the PLL wrapper file using the Advanced PLL Parameters option.