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]

Found the problem! Thanks Wojtek for the support! Since you confirmed that all the steps were right, I went back to the HW. Once when I was fiddling with the devboard I accidentally blasted off the 32MHz crystal with hot air, so I placed some other crystal and checked it works with oscilloscope. And that seems to be the problem. The crystals (hc49 and smd ones) don't work. I have a DS2072A oscillsocope and I compared the waveforms of the original crystal from the new board and the waveform of the replaced crystal and they look identical. I can't figure out what makes the difference (yet), but must be something related to the crystal impendace. I bodged the smaller crystal from the devboard to my PCB and it works! What parameters are different with the crystal from the devboard compared to some other random crystal?