NRF5340 DK Segger J-Link RTT not showing output messages

[Adolfo]

Hi, 

I have this setup:  

MacBook -> iMCU USB (J2) <-> nRF5340 DK <-> P19 Debug Out -> My PCB board

I can currently flash my nRF 5340 successfully and I can connect using the RTT Viewer inside of Visual Studio Code.

My P19 port is using the SWDIO and SWDClk to connect to my board.

I have in my prf.conf the following:

CONFIG_EARLY_CONSOLE=y

CONFIG_CONSOLE=y

CONFIG_RTT_CONSOLE=y

CONFIG_USE_SEGGER_RTT=y

CONFIG_LOG_BACKEND_RTT_MODE_BLOCK=n

CONFIG_PRINTK=y

CONFIG_LOG_PRINTK=n

CONFIG_SERIAL=n

And my src code is:

#include <zephyr/kernel.h>

#include <zephyr/device.h>

#include <zephyr/sys/printk.h>

int main(void)

{

printk("Application started via RTT\n");

while (1) {

printk("application running...\n");

k_sleep(K_SECONDS(1));

}

return 0;

}

My problem is that I cannot get anything to print in the output. I have tried multiple things and nothing works. Any idea to fix this?

[Simonr]

Hi

I believe you initially had a section in your main.c file where you disabled RAM blocks, which are vital to RTT logging since it uses RAM to forward the logging data. Additionally, you seem to be missing the CONFIG_LOG_BACKEND_RTT config which is necessary for enabling the RTT logging backend. See the RTT logging documentation here and refer to the Testing and optimization page for more details.

Best regards,

Simon

[Adolfo]

I've got it to work but not this way only. I had to modify the overlay to disable UART.

[Simonr]

Glad to hear that. Can you share how you disabled the UART for future users as well or what was required for you?

Best regards,

Simon