For ble central devices on nrf52, there are problems with the internal rc slow clock. When I load the project ble_app_uart_c onto the PCA10040, everything works as expected. The only thing changed is to set the LF source to 0 for internal rc, CTIV = 12 and TEMP_CTIV = 2 as the recommended values. The dev kit works as expected on sdk12 and sdk14. On my custom device which is the same except without the external low frequency crystal, sdk14 crashes on startup with an invalid instruction hard fault that happens within the softdevice. With sdk12, it runs and is able to scan and advertise, but connecting fails every time, which is this issue I reported here devzone.nordicsemi.com/.../
We are going to add the external slow clock to our next revision but this seems like a pretty serious bug that we would like to see fixed soon.
