How to pass bootloader version from bootloader to main application

[Juba Belgaid]

Hi all,

I'd like to pass bootloader version (2bytes) from bootloader_util_reset function (bootloader) to the main of application. can help me to acheive that?

Thank you for your help in advance.

[shibshab]

You could use the retention registers, each of which is one byte.

#import "nrf_power.h"
...
NRF_POWER->GPREGRET  = bootloader_version && 0xff;
NRF_POWER->GPREGRET2 =bootloader_version >> 8 && 0xff; 
...

These are retained when performing a standard soft reset NVIC_SystemReset.

[Aurele]

Hi,

I also want to pass information from my bootloader to my application. Since i know i cannot use UICR register i wanted to use these retention registers. But they are also used to pass information from app to the DFU (to start a DFU update for example). Is it safe enough to use it as you proposed ? Isn't there another solution to pass the bootloader version to my main application ?

Best regards,

Aurélien

[Aurele]

I think it is better to link in both project a dedicated section in RAM that will be shared by app and bootloader