How to setup Zephyr for RTT logging with nRF9160

[Pertti Kasanen]

I'm using a modified at_client program running on an nRF9160. It runs ok as a nonsecure application, under spm. The program can flashed, breakpoints set, single stepped etc. - debugger connection is working ok under SES. 

I've tried different prj.conf parameters as found in Zephyr documentation and e.g. https://devzone.nordicsemi.com/f/nordic-q-a/41742/nrf91-zephyr-enable-lte-logging but never managed to get RTT logging output. The printf/printk functions should write to a RTT channel, right? The following lines have been added to prj.conf

CONFIG_TRUSTED_EXECUTION_NONSECURE=y
#CONFIG_NO_OPTIMIZATIONS=y

CONFIG_PRINTK=y
CONFIG_CONSOLE=y

# UART logging as in devzone.nordicsemi.com/.../nrf91-zephyr-enable-lte-logging
#CONFIG_LOG=y
#CONFIG_SERIAL=y
#CONFIG_STDOUT_CONSOLE=y
#CONFIG_UART_INTERRUPT_DRIVEN=y
# or disable it
#CONFIG_SERIAL=n
CONFIG_STDOUT_CONSOLE=y

#docs.zephyrproject.org/.../nordic_segger.html
#CONFIG_UART_CONSOLE=n
CONFIG_RTT_CONSOLE=y
CONFIG_HAS_SEGGER_RTT=y
CONFIG_USE_SEGGER_RTT=y

#CONFIG_LOG_BACKEND_RTT=y
#CONFIG_SHELL_BACKEND_RTT=y
#CONFIG_LOG_BACKEND_RTT_FORCE_PRINTK=y

and several of the compinations commented out have been tried. Still no output on SES windows or to JLinkRTTClient

Any hints what else needs to be added?

The environment:

• nrf9160_sica on our own PCB. 
  
  • We have our own board .dts. But the same (no RTT output) happens if compiled with zephyr/boards/arm/nrf9160_pca10090ns board definitions
• Latest SDK 0.3.99
• Segger SES 4.16
• SWD 6-pin debugger connector. Segger JLink Ultra+.
  • The connection works, If I compile the SES sample programs for nRF5 and run e.g. the hello_workl, I get the printf / printk output to both SES output window and to JLinkRTTClient
  • Seems that the output does not get sent to UART0 either (but need more testing on that)

Pertti

[Pertti Kasanen]

Now after a few more experiments, RTT logging is working for the first time. Need to test what made the difference.
The working setup had only two lines with changes

CONFIG_SERIAL=y
CONFIG_UART_CONSOLE=n

Here is the conf that is working.

CONFIG_TRUSTED_EXECUTION_NONSECURE=y

#CONFIG_NO_OPTIMIZATIONS=y
CONFIG_PRINTK=y
CONFIG_CONSOLE=y

# UART logging devzone.nordicsemi.com/.../nrf91-zephyr-enable-lte-logging
#CONFIG_LOG=y
#CONFIG_SERIAL=y
#CONFIG_STDOUT_CONSOLE=y
#CONFIG_UART_INTERRUPT_DRIVEN=y
# or disable it
CONFIG_SERIAL=y
CONFIG_STDOUT_CONSOLE=y

#docs.zephyrproject.org/.../nordic_segger.html
CONFIG_UART_CONSOLE=n
CONFIG_RTT_CONSOLE=y
CONFIG_HAS_SEGGER_RTT=y
CONFIG_USE_SEGGER_RTT=y

#CONFIG_LOG_BACKEND_RTT=y
#CONFIG_SHELL_BACKEND_RTT=y
#CONFIG_LOG_BACKEND_RTT_FORCE_PRINTK=y

[Pertti Kasanen]

I have not really figured this out yet. Did not manage to copy the working configuration to another project yet...

[Hakon]

Hello. what project were you running when it worked? And when it didn't? What did the .conf file look like in that case?

[Pertti Kasanen]

Now things have worked properly. When using the "Configure nRF Connect SDK project" editor.

When I was modifying prj.conf directly, something went wrong. I did not have a proper version control set up then for that project so cannot check what was the difference...