S32K1xx Software Emulated EEPROM

[ZEROOO]

Hi all,

    When using the S32k118, flexram is configured to emulated EEPROM, which only allows the change from 0 to 1 when erased.However, I found that when I wrote eeprom, the code directly modified the eeprom without first erasing it to 0xFF. I would like to know why this is OK and is there any problem in this way?

[davidtosenovjan]

In this mode FlexRAM acts as access point for EEE memory space, and EEE state machine perform flash erase/program operations to NVM (in this mode assigned to E-flash). From user point of view access to FlexRAM is same as access to ordinary RAM.

For detailed description of EEPROM emulation, I would recommend to study AN11983:
https://www.nxp.com/docs/en/application-note/AN11983.pdf

[ZEROOO]

Hi @davidtosenovjan 

    The issue of eeprom erasable does not seem to be described in detail in AN11983, what I do not quite understand is why the simulation of eeprom can be directly programmed from 0 to 1, but not by the erasable operation? Now I can do this by writing 0xFF.I'm worried about the potential risks.

[davidtosenovjan · Accepted solution]

When using EEE, you do not erase or program the flash directly. This is done by the EEE state machine. You are writing FlexRAM only which is a normal RAM and it doesn't matter if you write 0->1 or 1->0.