NR51422 radio not detected

RE: NR51422 radio not detected

Ole Bauck — Mon, 14 Dec 2015 08:37:31 GMT

You cannot use RC oscillator as this has +-1% typical frequency tolerance, +-5% max. The radio needs external crystal.

RE: NR51422 radio not detected

Ole Bauck — Mon, 14 Dec 2015 08:35:34 GMT

The pin capacitance of the XC pins is actually 4 pF (see Product Specifiaction part 8.1), so the ideal capacitor value is 20 pF ( (20+4)/2 = 12).

RE: NR51422 radio not detected

Darshan — Sat, 12 Dec 2015 08:43:40 GMT

Thank You Ole Bauck for your help about the load capacitance.

I rectified the problem and I am able to detect the waves now. I increased the capacitance from 12pF to 24pF across 16Mhz crystal and its working .

RE: NR51422 radio not detected

Darshan — Sat, 12 Dec 2015 07:17:57 GMT

The external 16Mhz crystal accuracy is around 20 PPM and load capacitance used is 12pF 5%. Instead Can we use the internal RC HFCLK oscillator ? So what changes should I make inside the code or its initialised inside soft device ?

please find the crystal data sheet in the question above.

RE: NR51422 radio not detected

Ole Bauck — Fri, 11 Dec 2015 14:29:50 GMT

You said that you used the DK BOM, but I see that you are using a through hole crystal. This may have different load capacitance and hence the capacitors need to be a different value. If these are the wrong value, the frequency of the crystal may be incorrect which will make the radio frequency incorrect. The accuracy of the crystal needs to be +-40 ppm for bluetooth low energy applications. What is the load capacitance (CL) and the accuracy of the crystal?

RE: NR51422 radio not detected

Darshan — Fri, 11 Dec 2015 08:30:30 GMT

Thank You

Like I have already said the code is working and I have debugged all the stages. There is no stuck up. Yes we do use an 32Khz crystal.

I have measured the antenna voltages as well. it seems like its pulsing. but I am not able to detect it

Please find the schematic in my above question.

Pin mappings are all the same from DK to our custom board.

RE: NR51422 radio not detected

Ole Bauck — Thu, 10 Dec 2015 14:40:21 GMT

Is the code running at all? Do you use an external 32 khz crystal? The examples use this and if you don't have it, the code will be stuck in sd_softdevice_enable(...) waiting for the crystal to start. If you don't have external clock change the softdevice init call to this:

SOFTDEVICE_HANDLER_INIT(NRF_CLOCK_LFCLKSRC_RC_250_PPM_TEMP_4000MS_CALIBRATION, NULL);

I see some minor faults in the antenna design since you have not followed the reference design, but these should only degrade antenna performance, dont make it not work.

You may also want to change the pin definitions to match your custom board. Make a new file called custom_board.h with your pin definitions and change preprocessor definition BOARD_PCA10028 to BOARD_CUSTOM (see pca10028.h for how it is done for the DK).

Could you give us some more information like how the application is failing and maybe include the schematic and layout files in the post?