S32K311_noinit_ram

[nirmal_masilamani]

I have a project with S32K311 device and I tried to add a variable to the .noinit section, but the variable didn't keep its value after a software reset.

See my linker file below with the definition of the .noinit section.

[Julián_AragónM]

Hi @nirmal_masilamani,

I imagine you are trying to configure the standby RAM to retain its state after low power exit or SW reset, correct?

You can refer to the following community posts, where some example projects where shared for RTC wakeup and Standby RAM configuration:

• S32K3 Low Power Management AN and demos - NXP Community
• S32K3 Low Power Management AN and demos RTD 4.0.0 & 5.0.0 - NXP Community

Best regards,
Julián

[nirmal_masilamani]

Hi,

I have followed the instructions as per the example you provided.

.ld file .

initialization : 

__attribute__ ((section (".sram_standby_bss"))) volatile BootStatus_t g_boot_status;

Still, g_boot_status value resetting after restart.

[Julián_AragónM]

Hi @nirmal_masilamani,

Could you show your project? Also, are you reading the variable by connecting a debugger, or printing it out?

You need to add the Standby RAM section to the memory section:

You also need to initialize the ECC if the reset was destructive, along with disabling the cache. I've sent you a private message through the community for a document explaining these steps.

Best regards,
Julián 

[nirmal_masilamani]

Hello @Junjun ,

Thanks for your reply.

Please find my project in the attachment.

I trying to read the data in debug mode, also whenever i give debug system go to Hardfault

[Julián_AragónM]

Hi @nirmal_masilamani,

I can see in the project you are not going into standby nor performing a reset through SW. Could you share how are you triggering the reset? You can refer to these posts for performing reset through the MC_ME (power) driver: How to invoke software reset in s32k3xx? - NXP Community & S32K344 How to manually trigger one Function Reset - NXP Community.

Also, when connecting with the debugger, please ensure you are selecting the "Attach to running target" to ensure you are not triggering a reset. In PEmicro debugger, this is the option:

Best regards,
Julián

[nirmal_masilamani]

Hello @Julián_AragónM ,

Thanks for the response.

Is it possible to keep the data in noinit ram, even after hardware reset or power off?

[Julián_AragónM]

Hi @nirmal_masilamani,

No, RAM retention is only across functional reset:

Best regards,
Julián

[nirmal_masilamani]

Hello @Julián_AragónM ,

Thanks for your reply, is it possible to use any other memory section for noinit_ram?

Also in the attached project, i am getting hardfault after using int_sram block for standby RAM.

[Julián_AragónM]

Hi @nirmal_masilamani,

No, only SRAM0 has 32KB (depending on the derivative you chose):

Also, where exactly are you entering hard fault? Please use the example provided in the low power community post (S32K3 Low Power Management) firstly as a base, and then you can try to implement it in your project.

Best regards,
Julián