Breakpoint and reset in SoftDevice addresses 0xA60 and 0xA80

[PRvdO]

Hi,

Our application sometimes hits a breakpoint in SoftDevice at either address 0xA60 or (less often) 0xA80.

Based on this post https://devzone.nordicsemi.com/f/nordic-q-a/9622/application-debug-with-softdevice I believe that it might be an assert in SoftDevice to do with the realtime BLE requirements. Is this correct? Is this maybe caused by an ISR taking too long meaning SoftDevice cannot do it's BLE tasks?

Any help would be great, thanks.

[Vidar Berg]

Hi,

0xA60 is where the hardfault handler is located in the MBR. Please disable the breakpoint on hardfault as shown by the screenshot below (assuming you use SES) and check if the program enters the hardfault handler in your application or if it ends up in the app error handler. 

[PRvdO]

Thanks for the quick response.

Do you know what is at address 0xA80?

The 0xA60 reset only seems to happen after 3 hours so it will take a while to reproduce, in the mean time, the 0xA80 reset happens when multiple BLE devices are connected. Each connected device sends data over BLE which is forwarded via the UART so could it be to do with either of those?

Thanks again.

[Vidar Berg]

I would have to check that. What Softdevice version are you using?

Maybe you can check and see what the ISR number is when you hit the breakpoint at 0xA80. As you can see from the screenshot below, the ISR number is 3 (=hardfault) when the program halts at 0xa60.

[PRvdO]

We are using SoftDevice 7.0.1

This is a screenshot of the problem. As you can see we are stopped at 0xA80 and there is noting on the Call Stack. The ISR register is 0.

Thanks for your help.

[Vidar Berg]

The MBR reset handler starts at 0xA80 so it looks like it just came out of a system reset. I suggest you check RESETREAS register to find out what the reset source was (RESETREAS)

[PRvdO]

So, it seems like the watchdog is the cause of the crash. However, this crash only occurs if the system is left idle for hours and then we connect a phone via BLE. We have repeated the test but with the watchdog disabled and the system runs fine (we were hoping that it would get stuck in a loop and we could find it without the Watchdog but it just keeps running).

Are you aware of anything that might change after a long period of time? We can leave the system for days and it works fine but as soon as we connect a phone it reboots.

[Vidar Berg]

Is the WD being fed during this idle period? Note that Softdevice tasks such as advertisement events are run in the background without waking the application and will cause the WDT counter to be incremented even if you have enabled the pause on sleep option.