Conditional UART Activation for Field Debugging in Battery-Operated Matter Project (nRF54L15-DK)

[Bhavya Mathukiya]

Hi Nordic Team,

I’m working on a battery-powered Matter-based project using the nRF54L15-DK. I’ve reviewed the documentation regarding power optimization, which recommends disabling the UART (serial logging) to minimize power consumption during normal operation.

However, for field diagnostics, I would like to retain the ability to access UART logs when needed. Is it possible to keep the UART driver included in the firmware but disable it during regular runtime—and only re-enable it dynamically for debugging purposes in the field?

If this approach is supported, could you please advise on the best way to implement this using NCS? Any relevant examples, configuration tips, or API references would be highly appreciated.

Thank you for your assistance.

Best regards,

Bhavya

[Håkon Alseth]

Hi,

 

Yes, using pm_device, you can dynamically enable/disable the console in a runtime fashion.

Here is a snippet:

/* Using the console here, you can use your chosen device like this:
 * DEVICE_DT_GET(DT_NODELABEL(uart0))
 */
static const struct device *uart_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_console));

...
/* Entering sleep */
	int ret = pm_device_action_run(uart_dev, PM_DEVICE_ACTION_SUSPEND);
	if (ret < 0) {
		/* Failed to resume, add handling here */
	} else {
		/* All OK */
	}
...
/* Resume peripheral again */
	ret = pm_device_action_run(uart_dev, PM_DEVICE_ACTION_RESUME);
	if (ret < 0) {
		/* Failed to resume, add handling here */
	} else {
		/* All OK */
	}

 

Please note that if you only want to send out debug logs, you can disable the uart receiver with this boolean device tree flag:

https://github.com/nrfconnect/sdk-zephyr/blob/v4.0.99-ncs1/tests/boards/nrf/qdec/boards/nrf54l15dk_nrf54l15_cpuapp.overlay#L10

 

Kind regards,

Håkon

[Bhavya Mathukiya]

 Hi Håkon Alseth ,

Thank you for the quick response.

So in this dynamically disabling the console has the same power optimization efficiency similar to disabling through dts file mentioned here?

And when we dynamically disable UART, API used for serial log printing (like LOG_INFO, printk) would cause any issue during regular runtime?

BR,

Bhavya