UART not working under Zephyr samples

[StanislavDimitrov]

I am using bare metal nrf52832 with two quartz crystals - 30 Mhz and 38 kHz for the RTC. When uploading samples - all work from nRF5_SDK_17.0.2. 

When using Zephyr based projects, uart is not working. It shows zeros (when HEX viewer) when print is expected (connecting, disconnecting). Borad that I select for zepyr project is NRF52823 DK. My uart pins are P06 and P08. Using Visual Studio Code with installed nRF connect.

Any idea what is wrong?

[Jared]

Hi,

30 Mhz and 38 kHz for the RTC.

Is the RTC is external or are you thinking of the RTC peripheral on nRF52? The nRF52832 requires a 32MHz crystal for the HFCLK and optionally a 32 kHz crystal for the LFCLK. 

When using Zephyr based projects, uart is not working. It shows zeros (when HEX viewer) when print is expected (connecting, disconnecting). Borad that I select for zepyr project is NRF52823 DK. My uart pins are P06 and P08. Using Visual Studio Code with installed nRF connect.

Are you using a custom board or actually using the nRF52832 devkit? Is the uart initialized successfully, is any error code returned?

regards

Jared 

[StanislavDimitrov]

I have both crystals populated (RTC external). This is a breadboard - only two crystals and corresponding capacitors, as well as all pins exposed. I don't know if the UART is initialized since it does not print proper symbols and I can't see the messages. Still, it can be seen that the program runs, since the led turns on and off when connecting/disconnecting to the Nordic Connect application. 

[Jared]

Hi,

I think you need to use more time to debug your application and see if it asserts somewhere. You can try building your application with the debug optimizations and then start the application with the debugger in VS Code. That should give you more information about what is actually happening when you run your program. 

regards