Main function starts again after BLE disconnection

[moroboshidan]

Hi,

I'm using nRF51822 to develop our products. I found an interesting problem on our PCB. After I disconnected our PCB from central device, the main function starts from the beginning for every minute. I don't understand what happened. Can anyone explain why? Thank you!

[Einar Thorsrud]

Hi,

The most typical reason for a reset is that an error check has caught an error, and reset the device (which is the default behavior of the error handler when not using a debug build). You should debug the code to see what is going on. I recommend starting with defining DEBUG for your project and seeing if it ends up in an error handler. Another possibility is if you are using a WDT and are not feeding it.

[moroboshidan]

Thanks for the response! Are there any debuggers we can use? For some reasons our PCB cannot print over UART and RTT. 

[moroboshidan]

Also, could you explain a little bit what "feeding WDT"? Thanks!

[moroboshidan]

An update for my problem: we're not using WDT and the system reset happens every several minutes until we connect to the central over BLE. At the same time for some reason our PCB cannot print. Could you suggest other ways to debug? Thanks!

[Einar Thorsrud]

Hi,

You need some way to debug and preferably also get logs from your device. Do you not have that? Since you are able to program it, I assume you have a debugger that you can connect to it?

It is not clear to me whether the issue with not getting any logging is general, or if you only have problems getting logs at the same time when you see the reset? Can you clarify?

If you want to use RTT, you need a J-link debugger. You can, for instance, use the nRF51 DK's debug out port (see DK user guide). No matter what the root cause of this problem is, setting up a proper way to debug is the sensible first step. Then you need to find out why the reset occurs, typically by seeing what happens immediately before it. You can of course also use UART logging.