Problem with System_reset and watchdog

[Nils Minor]

Hi,

i have some trouble with my watchdog in application. If i does a System_reset (no SD Method because i disabled it before) it sometimes top at this point and does nonsense. What reason could it have that this method hangs the application? And i have enabled the watchdog and did a pin reset so it is running, why does the watchdog not kill the running application when its hanging?

Best regards Nils Minor

[Paul]

I have read other watchdog issues on the forum, and I wrote some very simple "blinky" code just to test the watchdog out. Sometime it works and sometime it doesn't.

When it works, it works as expected: when it goes into dead loop, after 1 second, it blinks the LED. When it doesn't work, it hangs.

More strangely, somehow I bricked one of my board. I can still program the board, but won't run even with WDT disabled. I didn't get a chance to debug it.

Did I miss any simple bits here, or there is something about the chip? :)

[Nils Minor]

Hi Paul thank you for your information. This does not sound good to me. Is there maybe an problem when i do an system_reset ( ) and in the same moment the watchdog timer will does a reset?

What else can be a reason for bad working watchdog?

best regards, Nils

[Ole Morten]

With the first revision chip, the watchdog will not run when the debug interface is enabled, so you have to toggle power to the chip to start it. This may therefore appear as the watchdog working intermittently if you're not aware of it. For an example of how the watchdog can be used, you can refer to this project on GitHub: https://github.com/NordicSemiconductor/nrf51-watchdog-resetreas-example

As for bricking a chip, it may be possible to brick a first revision chip if you start the watchdog without first setting the reload register to a non-zero value. In that case, you may end up with a chip that constantly resets. This should however not be a problem on the second revision chip.