64.6.8 Refresh Sequence

The QSPI uses some analog blocks:

• A DQS delay line
• Pad calibration

Once calibrated at first start of the IP, the product properties (power, voltage, temperature, etc.) continue to change over time, so the analog blocks used by the QSPI require an updated calibration.

The QSPI refresh sequence allows the QSPI to stop transfers on a regular basis to perform a calibration update. A 1 ms refresh interval is a safe value for Refresh register (QSPI_REFRESH).

The following analog blocks are refreshed during the refresh sequence:

• DQS delay
• Pad calibration