S32K11x FlexNVM constraints

[Pete66]

We are using an S32K114 with FlexNVM in EEPROM mode with 2K RAM and D-FLASH.

We are not using CSEc but may in the future.

I am trying to understand AN12003

(1) Operation

I believe that AN12003 informs me that we may run a program with interrupts enabled from P-FLASH whilst the FlexNVM state machine in erasing and writing to D-FLASH.

We may not however; read from or execute code from D-FLASH whilst the FlexNVM state machine is active.

Please confirm. 

[lukaszadrapa]

Hi Pete,

yes, your understanding is correct. There's also similar description in the reference manual:

Regards,

Lukas

[f1_stu]

Hi Lukas,

So just to clarify, as I've been working with the S32K116 and its EEEPROM implementation; for a system that is partitioned so that it has a region of FlexRAM and FlexNVM, with the FlexNVM area existing in a separate block (D/E) of flash i.e. distinct from P-Flash. If a write is made to the FlexRAM (which initiates the EEEPROM internal state machine), interrupts do not have to be disabled, as long as the code that is executed concurrently doesn’t perform any operations on the E-Flash/FlexNVM region of flash memory - is that correct? It’s just that when I did some initial work on this, the software seemed to enter a trap if interrupts weren’t disabled when the EEE state machine initialised, so just wanted to check.

Best regards,

Stuart

[lukaszadrapa]

Hi Stuart,

yes, that's correct.

Are you sure that your interrupt handlers or functions called by interrupt handlers do not access FlexNVM/EEE?

Regards,

Lukas

[f1_stu]

Thanks for confirming. I'll go over the code again to check what could be causing it.

Kind regards,

Stuart