F-tile Architecture and PMA and FEC Direct PHY IP User Guide

ID 683872
Date 6/24/2022
Public

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4.5.1. Example of Reference Clock Availability at Device Programming

The following examples demonstrate the reference clock behavior during device programming.
In the following example:
Table 96.  Example 1 of System PLL and Reference Clock Availability
System PLL #N Mode of System PLL Refclk is available at power-on
0 Disabled N/A
1 User Configuration On
2 PCIE_FREQ_100 On
  • System PLL #0 is not used.
  • System PLL #1 works automatically at device programming without the PMA Avalon memory-mapped interface write operations.
  • System PLL #2 works automatically at device programming without the PMA Avalon memory-mapped interface write operations.
In the following example:
Table 97.  Example 2 of System PLL and Reference Clock Availability
System PLL #N Mode of System PLL Refclk is available at power-on
0 PCIE_FREQ_1000 On
1 ETHERNET_FREQ_805_156 On
2 User PCIE-based Configuration Off
  • System PLL #0 works automatically without the PMA Avalon memory-mapped interface write operations.
  • System PLL #1 works automatically without the PMA Avalon memory-mapped interface write operations.
  • System PLL #2 does not work automatically after device programming without the PMA Avalon memory-mapped interface write operations.
  • Device programming takes longer and all non PCIe channels on this F-tile stay reset until the PMA Avalon memory-mapped interface write operations complete and signal that all reference clocks are ready.