S32K314 standby ram usage issues

[SHCHOU]

Hello

I setup 32K standby ram in linker_flash.ld 

SHCHOU_0-1720083170868.png

SHCHOU_1-1720083315646.png

SHCHOU_2-1720083364828.png

The set variable are also in relevant memory section

SHCHOU_3-1720083600339.png

and power on will init...

SHCHOU_4-1720084007026.png

but standby mode exit , these data not save!?

I don't know why?

there is something wrong with my initialzetion? 

or what steps are missing when entering standby mode?

Please help 

Thank you,

[Julián_AragónM]

Hi @SHCHOU,

Modify the linker file to separate the 32KB standby RAM (0x2040 0000 ~ 0x2040 8000) from int_sram memory region, and place standby .bss and .data or .text sections into the new region as well as adjust the link address symbols for customized initialization during startup as such:

Julin_AragnM_2-1720109511030.png

Also, as a note: CM7 CPU D-Cache MUST be disabled to use the Standby RAM area. Or set the standby RAM (0x2040 0000 ~0x2040 8000) as non-cacheable in MPU configuration.

Julin_AragnM_1-1720109465427.png

Keep in mind that the SRAM contents is invalid after Destructive reset.

Best regards,
Julián

[SHCHOU]

Thanks for your reply,

I have setup 32K standby RAM (0x2040 0000 ~ 0x2040 8000) , can you help me confirm that the setting are correct?

and i have also setup standby ram as non-cacheable in MPU configuration.

this setting is ok?

SHCHOU_0-1720142851544.png

[Julián_AragónM]

Hi @SHCHOU,

Yes, it should be correct. Keep in mind that the linker file and startup code does not include initialized data to this section. The linker file explicitly mentions that:

Julin_AragnM_0-1720561360881.png

Best regards,
Julián