10.1.6.3.1 Maximum QSPI Frequency
The QSPI GCLK frequency must be set to the target frequency fQSCK. The following formulas provide the achievable QSPI frequency in Host Read and Host Write modes. When the result of these formulas exceeds the fQSCK_MAX parameter provided in the tables in QSPI Timings, fQSCK_MAX applies.
- Host Write in Single Data Rate Mode
Where tSU_CLIENT is the input setup time of the client device.
- Host Read in Single Data Rate Mode
Where tVALID is the client time response to output data after detecting a QSCK edge.
- For a QSPI client device with tVALID (or tV) = 12 ns, with QSPI0 = 1.0 ns, fQSCK max = 77 MHz.
- For a QSPI Flash memory device with tVALID (or tV) = 6 ns, and QSPI0 = 1.0 ns, the formula returns a value of 143 MHz, therefore fQSCK = 100 MHz applies in this case.
- Host Write in Dual Data Rate
Mode
Where tSU_CLIENT is the input setup time of the client device.
- Host Read in Dual Data Rate
Mode
Where tVALID is the client time response to output data after detecting a QSCK edge.
- For a QSPI Flash memory device with tVALID (or tV) = 6 ns, and QSPI10 = 0.7 ns, the formula returns a value of 74 MHz, therefore fQSCK = 57.7 MHz applies in this case.