Custom PCB with MDBT50Q with internal Oscillator

[brandonv]

I developed a custom pcb using the Raytac MDBT50Q-1M module. I tried to minimize the number of components added to the pcb by omitting the external 32K crystal oscillator since the datasheet indicates it as optional.

The software was developed in the nRF Connect SDK 1.2.0 and performs properly on our dev board the MDBT50Q-DB from Raytac which does contain an external crystal.

When I flash the code onto our custom board in debug mode I have observed it goes into an idle state because the clock has not started.

What changes to what files/variables do I need to make in order for the internal RC oscillator to be used and started? I am new to this development platform and have external developers helping write the code but they are being unresponsive to my request.

The project is built with the nrf52840_pca10056 selected as the board in project setup.

[Simonr]

Hi

It should be sufficient to set CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL= n, CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC= y, and make sure that CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC_CALIBRATION= y in your prj.conf file.

Best regards,

Simon

[brandonv]

Simon,

Thank you for the response. Adding this to the prj.conf file enables the board to operate when flashed but if I power cycle the board, no Bluetooth signal is seen.

Is there something else I need to enable in order for the board to initialize on startup?

[Simonr]

Hi

No, once supplied with power, a board should start up and run the program that has been flashed onto it. Are you sure that it is the custom board that is flashed in this case, and not the Development board (which I assume is what you're using to flash the custom board)?

Please also note that you should make a custom board file for custom boards, where you make sure the pins are defined to what you're planning to use them as, and that you don't use unavailable ones for critical functions. 

If you'd like, you could upload schematics and HW files here on DevZone, and we can do a review of your custom board to make sure everything is as it should be.

Best regards,

Simon

[brandonv]

I changed which JTAG connector I was programming with and it seems to work now.

Thank you!