Logging over RTT works on nrf52DK but not with BMD350 connected to nrf52DK

[fan_2021]

I have a BMD 350 nrf52832 module connected to nrf52DK board via P20 header.

I am using nrf52DK to flash the firmware onto BMD350.

my code works with nrf52DK and it logs onto the RTT via vscode.


But when I flash BMD350 and open the RTT it doesn't log anything with the same exact firmware.

I am using the same build configuration as both are nrf52832 based.

Am I missing something here? 

#include <stdint.h>

#include <zephyr/kernel.h>

#include <zephyr/device.h>

#include <zephyr/devicetree.h>

#include <zephyr/drivers/i2c.h>

#include <zephyr/sys/printk.h>

#include <zephyr/logging/log.h>

LOG_MODULE_REGISTER(main);

void main(void)

{

LOG_INF("Hello from BMD-350 via RTT!");

while (1) {

k_sleep(K_SECONDS(1));

LOG_INF("Ping");

}

}




Here is my prj.conf



CONFIG_I2C=y

CONFIG_CBPRINTF_FP_SUPPORT=y

CONFIG_LOG=y

# Set default backend to RTT

CONFIG_USE_SEGGER_RTT=y

CONFIG_LOG_BACKEND_RTT=y

CONFIG_LOG=y

CONFIG_LOG_BACKEND_UART=n

CONFIG_LOG_DEFAULT_LEVEL=3

CONFIG_DEBUG_OPTIMIZATIONS=y

CONFIG_DEBUG_THREAD_INFO=y

CONFIG_THREAD_MONITOR=y

CONFIG_NRF_APPROTECT_LOCK=n



BMD 350 is powered externally

| DK Pin | BMD-350 Pin |
| ------ | ----------- |
| VTG | VDD |
| SWDIO | SWDIO |
| SWDCLK | SWDCLK |
| GND | GND |



[Priyanka]

Hi,

Though the nRF52DK and BMD350 use nRF53832 SoC, depending on each device, the pins and connections can change. So please verify whether your connections to the module are proper, according to it's datasheet, so that you can view the RTT logs.

[fan_2021]

RTT works over SWD right?
I have wired the external BMD350 module to P20 header on nrf52DK as follows

VDD to BMD 350 is provided externally. 

| DK Pin     | BMD-350 Pin |
| ------         | -----------         |
| VTG         | VDD              | 
| SWDIO.   | SWDIO         |
| SWDCLK | SWDCLK      |
| GND        | GND              |

I am able to flash the firmware successfully

[fan_2021]

Since my BMD350 module doesn’t have external crystal, setting LFCLK to RC in prj.conf fixed this.