topic Re: Does BIST damage Standby RAM data? in S32K

Does BIST damage Standby RAM data?

Pusoy — Tue, 16 Jan 2024 07:18:36 GMT

Hi,

We have allocated a Standby RAM segment in linker_flash_s32k344.ld file in our project (as shown in the figure below) to store relevant data during Standby mode and for use in the next run mode. However, recently I discovered that the content of the Standby RAM region gets corrupted after our project completes the BIST self-test.

Does the BIST self-test corrupt the content of the Standby RAM region?

This is crucial for our project as we need to use the Standby RAM to save data.

Re: Does BIST damage Standby RAM data?

petervlna — Tue, 16 Jan 2024 08:55:58 GMT

Hello,

I assume you are talking about Online BIST execution.

Here you can define which part of RAM will be tested. So it depends on your configuration of the BIST.

If you are using any driver for it, refer to driver documentation for BIST configuration in order to exclude RAM block from BIST.

StandbyRAM is part of SRAM0, so you have to exclude SRAM0 from your tests in order to prevent its content to be destroyed:

This was a common use case in past when customers were defining their BIST sequences in code.

Best regards,

Peter

Re: Does BIST damage Standby RAM data?

Pusoy — Tue, 16 Jan 2024 09:29:26 GMT

Hello,

Thank you very much for your response.

Our project currently uses the S32K314 chip, so it only supports online mode.

At the same time, we are using the SPD 1.0.0 library to run BIST. Since SPD only provides two online configurations (BIST_SAFETYBOOT_CFG and BIST_DIAGNOSTIC_CFG), both of these configurations include MBIST0, which is SRAM0 (the area where StandbyRAM is located).

Therefore, we cannot directly call the SPD library to preserve the data in the StandbyRAM area.

How can I modify the program to preserve the data in the StandbyRAM area?

I am looking forward to your reply. Thank you very much!

Re: Does BIST damage Standby RAM data?

petervlna — Wed, 17 Jan 2024 12:02:01 GMT

Hello,

How can I modify the program to preserve the data in the StandbyRAM area?

I was talking to the SW team. SPD driver do not offer such possibility.

However they had already such questions and the recommendation is to store that content in NVM in order to preserve it.

best regards,

Peter