RTT from external module on nRF52-DK

[suricat]

I'm trying to connect external nrf52832 module to nrf52-dk (PCA10040). I use wiring scheme from this picture:

And it works fine for programming. But I can't get RTT messages from my external module - only from onboard chip.

I suppose this may require some electonic or programm configuration to switch RTT source. But I can't find any information about it.

I use PlatformIO as IDE and ZephyrRTOS as Framework. Just for testing I use primitive code like this:

void main (void)
{
    while (1) {
        k_sleep (K_MSEC (500));
        printk ("Hello \n");
    }
}

May be I missed something or did wrong? How to get RTT from external module correctly?

[Jared]

Hi there,

what voltage do you measure on VTG? Is it equal to VDD? The onboard debugger should bypass the onboard nRF if it sense svoltage on the VTG pin.

regards

Jared 

[suricat]

VTG is connected direct to VDD and has the same voltage is 2.832 volts.

With this wiring scheme I can programm external module correctly. But RTT data allways comes from internal chip.

[suricat]

So, finally I figured out. As I said before I use PlatformIO as IDE and Zephyr as framework. For printing debug messages I used printk() function and wathced results in PlatformIO terminal. But I missed that terminal shows data as serial monitor and it get this data from uart link between nrf-chip and jlink-programmer chip. When I tried connect to J-Link RTT Viewer I've see nothing and this moment I suspect that my debug messages has transferred not through SWD but through uart.

Problem was fixed after adding

CONFIG_USE_SEGGER_RTT=y
CONFIG_RTT_CONSOLE=y
CONFIG_UART_CONSOLE=n

in prj.conf