topic Re: FlexRAM not writable during Flash erase (FTFE_FCNFG->RAMRDY becomes 0) in Kinetis Microcontrollers

FlexRAM not writable during Flash erase (FTFE_FCNFG->RAMRDY becomes 0)

noperator — Fri, 15 Apr 2022 10:35:02 GMT

Hello,

I would like to use FlexRAM on K24FN1M0V as general purpose RAM, but I noticed that after initiating a Flash mass erase, attempting to write to the FlexRAM leads to a hard fault. After the mass erase is finished, the RAM is accessible again, but it is erased to 0xFF.

I found in K24P144M120SF5RM Section 29.4.10.9:

The EEERDY and RAMRDY bits are clear during the Read 1s All Blocks operation and
are restored at the end of the Read 1s All Blocks operation

Is the same true for the 'Erase All Blocks' command? It is not documented.

Is there any way to prevent this so that FlexRAM can be used as general purpose RAM?

Thanks,

Ivan

Re: FlexRAM not writable during Flash erase (FTFE_FCNFG->RAMRDY becomes 0)

jay_heng — Mon, 18 Apr 2022 06:46:06 GMT

From RM: The Erase All Blocks operation erases all flash memory, initializes the FlexRAM, verifies all memory contents, and releases MCU security.

so it is the same true for the 'Erase All Blocks' command.

FlexRAM is part of FTF flash controller, it will always be effected by FTF operation.

Re: FlexRAM not writable during Flash erase (FTFE_FCNFG->RAMRDY becomes 0)

noperator — Mon, 18 Apr 2022 07:48:34 GMT

Thanks for the confirmation, Jay. It would have been nice if the FTF left this RAM alone except for the 'Program Section' operation, but I understand it's a hardware limitation. I will stick to using the main RAM only.