Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 7/19/2024
Public

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5.5.6.3. Clocking

The list belows describes clocks that are used internally.

  • clk_phy: This is the main clock used by the combo PHY and is generated in the clock manager module. The frequency of this clock must be compliant with the NAND Flash/SD/eMMC device work mode. The maximum frequency for this clock is 200 MHz as this is limited by the pad frequency limit. For SD/eMMC, a 1:1 clock ratio is supported for the clock frequency between PHY clock (clk_phy) and the memory device interface clock for SD/eMMC. The minimum clock frequency in this case is 50 MHz. For lower frequencies, oversampling is required (that is, the clk_phy must be 4 times higher than the SD/eMMC clock period for DDR work modes and 2 times higher for SDR work modes).
  • clk_ctrl: This clock signal's frequency is two times smaller than clk_phy for the NAND Flash controller. For the SD/eMMC controller, the clock frequency is the same as clk_phy. All signals on the DFI interface between the controller and PHY are synchronous with this clock.
  • mem_dqs: This is the read path DQS clock which is driven by the Flash devices to the PHY.
  • delayed_dqs: This is the DLL-delayed and gated version of the read_mem_dqs on the read path.
  • delayed_dqs_cmd: This is the DLL-delayed and gated version of mem_dqs or clk_lpbk (depending on settings) on the read path for command line.
  • clk_wrdqs: This is the DLL-delayed version of clk_phy on the write DQS path.
  • write_dqs: This signal is identical to the clk_phy clock, but it is a generated clock used to create the DQS signal for the write path.
  • clk_wr: This is the DLL-delayed version of clk_phy on the write data path.