topic Re: S32K11x FlexNVM constraints in S32K

S32K11x FlexNVM constraints

Pete66 — Tue, 11 May 2021 15:31:59 GMT

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.

Re: S32K11x FlexNVM constraints

lukaszadrapa — Tue, 11 May 2021 16:54:25 GMT

Hi Pete,

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

Regards,

Lukas

Re: S32K11x FlexNVM constraints

f1_stu — Wed, 12 May 2021 10:38:27 GMT

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

Re: S32K11x FlexNVM constraints

lukaszadrapa — Thu, 13 May 2021 11:17:42 GMT

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

Re: S32K11x FlexNVM constraints

f1_stu — Thu, 13 May 2021 11:26:01 GMT

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

Kind regards,

Stuart