Programming blank nRF52 ic ble issue - crystal issue

[Dajgoro Labinac]

Hi

Last year I got a nRF52 devboard and I modified the ble uart peripheral example to flash a led depending on what it recieves from nRF uart app. It all worked fine(after some forum consulting) so I decided to try making my own version of the devboard (custom pcb) with some extra features. Once the PCB arrived, I got it working, except the ble part. I tried flashing softdevice and did everything as on the devboard, nothing helped. I tried removing the nRF52 mcu from the nRF devboard and soldering a fresh IC that I got from mouser. Same problem, ble now won't work on the devboard either. Then I ordered new devboards, repeated the same flashing process and they work just fine. I can't figure out whats wrong here, can somebody write steps for programming a blank ic from scratch, just in case I'm doing something wrong.

[Dajgoro Labinac]

There are two crystals, the 32.768kHz crystal oscillates constantly once the softdevice is programmed, and the other 32MHz crystal works in bursts. I even had issues with the 32kHz crystal that on the PCB i made i used a jelly bean watch crystal which did not work, but when I soldered a smaller(smd) one it worked. But this other is really strange, since when using the 32MHz crystal seems to work, but it does not. The issue is so sensitive that I can't figure it out by just watching the oscilloscope waveform, I'll have to make a more complex analysis. I have to know how to properly design the crystal section because I am developing a product which will use the nRF52 and I don't want devices mysteriously failing because of some oddity. Maybe I could ask on the eevblog forum.