How to enable UART or RTT logging in examples?

[Al Bundy]

I have downloaded nRF5_SDK_12.2.0_f012efa and tried to test logging in examples but without success. Even if I compile an example where NRF_LOG_BACKEND_SERIAL_USES_UART 1 is enabled by default in sdk_config.h I do not get any logs on terminal. I have chmod 666 of /dev/ttyACM0 and set baudrate to default 115200 but still nothing. If I set NRF_LOG_BACKEND_SERIAL_USES_RTT instead of UART I also get nothing on JLinkRRTClient.

Is there anything else that needs to be configured? I compile for pca10028.

[Jørgen Holmefjord]

Hi,

It should be sufficient to set NRF_LOG_ENABLED 1 and either NRF_LOG_BACKEND_SERIAL_USES_UART 1 or NRF_LOG_BACKEND_SERIAL_USES_RTT 1. Note that if NRF_LOG_DEFERRED 1 is set, you also need to process the log buffer using NRF_LOG_PROCESS() or NRF_LOG_FLUSH()

Best regards,

Jørgen

[Al Bundy]

Ok, it works. I though that if NRF_LOG_BACKEND_SERIAL_USES_UART 1 is enabled by default in some examples then NRF_LOG_ENABLED 1 is also enabled by default, but it is not.

[Navin]

Hello Jorgen,

I can't find NRF_LOG_BACKEND_SERIAL_USES_UART.

I get the error: undefined reference to `nrf_log_default_backends_init'

But I have enabled : #ifndef NRF_LOG_BACKEND_UART_ENABLED
                                 #define NRF_LOG_BACKEND_UART_ENABLED 1
                                 #endif

What could I possibly be missing?

[Jørgen Holmefjord]

Did you add the source file components\libraries\log\src\nrf_log_default_backends.c to your project? NRF_LOG_ENABLED also needs to be set.

[ryerye120]

I'm having a similar issue. I'm using SDK16 and developing on the nrf52840 DK. 

I followed the instructions in this video: https://youtu.be/uP8RYgYGRvI?t=179  in addition to the addendums on this thread as well as this other thread: https://devzone.nordicsemi.com/f/nordic-q-a/58414/enabling-nrf_log_enabled-to-log-messages-on-debug-terminal . But I'm still not seeing anything in my debug terminal.

Currently, I have enabled NRF_LOG_BACKEND_RTT_ENABLED as well as the NRF_LOG_ENABLED. I have also disabled NRF_LOG_BACKEND_UART_ENABLED just in case. Have I missed something simple?