Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 7/19/2024
Public

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5.5.6.5.1. DQS Write Signal Generation

The DQS signal is used in the NAND interface to indicate a DQ data valid window which is generated as part of the write data path. The dfi_wrdata_en_p0 and dfi_wrdata_en_p1 signals coming from the NAND memory controller are used for this purpose. These signals also pass through the frequency ratio module to switch from the clk_ctrl clock to the clk_phy clock domain. Once under the clk_phy clock domain, the signals pass through a similar path followed by the write data/command path in the balance module using the clk_wrdqs clock. The DQS signal can also be delayed for an additional 1 clock cycle using the dqs_clkperiod_delay field in the phy_dqs_timing_reg register. As this signal is clock gated by the clk_wrdqs clock, this signal can be adjusted to match the DQ data alignment adding the required delay for this. The control over the clk_wrdqs clock is described in the previous section.

Figure 162. DQS/DQ Alignment in Write Data Path

When working with the NAND controller in SDR mode, the DQS pin is not used, but it is possible to define the state of this using the sdr_dqs_value field in the phy_ctrl_reg register.