How can I get the stack pointer from the program?

[Cyrus Cheung]

After watchdog reset, I want to record the last program counter from the stack. So I want to know how can I get the stack pointer from the program.

[Håkon Alseth]

Hi,

 

The watchdog will not reset the RAM, but it might be corrupted, as per this instance table (see the note):

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/power.html?cp=4_2_0_17_7#unique_832471788

If you are to store the stack, you should store it into a non inited global section from the watchdog event handler.

The watchdog interrupt handler will execute approx. 2 RTC cycles before a reset occurs, so you do not have much time.

If possible, you should also add a simple checksum on the content you're storing, to ensure that it has not been corrupted after wdt reset.

Here's a thread, with an example on dumping the stack:

https://devzone.nordicsemi.com/f/nordic-q-a/30075/saving-the-location-of-watchdog-timeout

Note that the .non_init section is defined by default in SES, so you don't need to add it manually in flash_placement.xml

 

Kind regards,

Håkon