What might cause a HardFault on sd_app_evt_wait()?

[Eliot Stock]

I'm ending up in the HardFault_Handler() on calling sd_app_evt_wait() within a function that reads from the UART. What might cause that? Stack screenshot attached.

I have the SoftDevice enabled at the time but am not advertising (although I'd like to be advertising at the same time at some point, incidentally). The problem's not reliably reproducible, but it happens fairly often.

[Ole Morten]

Normally, my best guess would be that you do this from interrupt priority higher than the SVC interrupt priority, in other words higher than 2. As described in the architecture chapter of the Reference Manual, this is not possible, and will cause a HardFault directly. However, your back trace seems to indicate that you come from main, in which case this sounds strange.

Are you sure there isn't something about your memory setup that's not correct? Are you able to reproduce the problem when running with command line GDB? If so, can you please share an example project?

[Eliot Stock]

I get the same HardFault when using the low priority when init'ing the UART, btw.

Have only been able to debug this using the Eclipse gdb client so far, as I'm still struggling with the command line gdb client (and have posted about that separately).

Happy to post an example project if it would help, but it's a bit too much code for here so would need to go into a case. There could indeed be something wrong with my memory setup but I can't see it yet.