S32K324 write DFlash by FEE

[mmyjh_123]

Hello, There is a question about S32K324 write DFlash by FEE:

I plan to write approximately 50 bytes of data into the DFalsh of S32K324 using the FEE method. Since the hardware power supply on the circuit board has a backup time of around 0.743ms, I need to save the critical data within this time frame. Is it feasible to write to the DFlash using the FEE method? If it is not feasible, are there any other options?

Thanks.

[Senlent]

Hi@mmyjh_123

For a power-off backup window of 0.743 milliseconds, FEE is not safe. Even "close to 1 millisecond," the write execution time for a single Fls_MainFunction block already exceeds your available hold time.

You could try using C40_Ip. Using Quad-page (1024 bits) program time， a 50-byte write would theoretically take 450 microseconds. However, within 0.743 milliseconds, any erase operation during an emergency hold is impossible; erasing an 8 KB sector could take up to 30 milliseconds.

Therefore, when implementing this functionality using C40_Ip, always erase the DFLASH address to be programmed during idle periods. Furthermore, if the board can detect input voltage drops before the MCU power failure, commit operations should begin at the earliest possible threshold. Otherwise, add a large capacity capacitor/backup power to ensure the guaranteed window covers the worst-case software path and flash programming margin.

The above is only a theoretical analysis; multiple real-world tests are recommended, ensuring sufficient design margins.