nRF52 hangs up when connected to app. With attached debugger it works perfect.

[MaxRPEng]

Hello i have a very strange behaviour of my custom nRF52832 board.

I use the latest SDK16 and at the moment the nRF-DK to flash and debug.

In normal (unconnected) operation everything works fine. But when i connect the device to our app it hangs up after a few seconds.
Only a hard reset will recover it.

The problem, when i attach the debugger to figure out the issue everything works just perfect. That is very strange..

Is that any errata or known problem?

I use the internal lfclock, and use the reset pin as led output.
My project based on the buttonless dfu template example.

I hope there is help for my strange issue.

Thanks a lot.

Max

[Salman]

I am facing the same issue. My custom nRF52832 board restarts. But when I connect rtt viewer it works fine.

[MaxRPEng]

We removed RTT from the project. Then it worked fine.

Nordic is in most ways a mess and we never feel good about the "workarounds" but it works for us!

[Salman]

By remove RTT you mean that disable it form sdk_config.h? If that what you mean I have already done that and it does not helped. Any suggestion how to debug this issue? Also it does not make sense to disable RTT and it work nordic should have a reason why is this happening what how we can resolve it. 

[Vidar Berg]

RTT will *not* become blocking if you use our SDKs default logging configuration. Do you use our NRF_LOG_* macros or printf's to output RTT messages? The latter is blocking.

Also make sure the RTT mode is set to "SKIP":

To debug the issue you can run "nrfjprog --readregs" to find out where the program hangs when you are not in debug mode.