nrf54 wakeup using uart pins as gpio.

RE: nrf54 wakeup using uart pins as gpio.

Håkon Alseth — Wed, 17 Dec 2025 12:26:30 GMT

Hi!

[quote user="narfster"]

I confirmed this works as I needed.

I suspend uart, then configure rx pin as interrupt and it work.

after interrupt fires, i disable it and re enable uart.

thanks.

[/quote]

That is great to hear, and thank you so much for sharing your proposed code. Hope you have a wonderful day!

Kind regards,

Håkon

RE: nrf54 wakeup using uart pins as gpio.

narfster — Wed, 17 Dec 2025 11:34:27 GMT

I confirmed this works as I needed.

I suspend uart, then configure rx pin as interrupt and it work.

after interrupt fires, i disable it and re enable uart.

thanks.

static int configure_uart_rx_wakeup(void)
{
    if (!device_is_ready(uart_rx_pin.port)) {
        return -ENODEV;
    }

    int ret = gpio_pin_configure_dt(&uart_rx_pin,
                                    GPIO_INPUT | GPIO_PULL_UP);
    if (ret) {
        return ret;
    }

    ret = gpio_pin_interrupt_configure(uart_rx_pin.port,
                                       uart_rx_pin.pin,
                                       GPIO_INT_EDGE_BOTH);
    if (ret) {
        return ret;
    }

    k_work_init_delayable(&work, work_thread);

    gpio_init_callback(&gpio_cb,
                       gpio_isr,
                       BIT(uart_rx_pin.pin));

    ret = gpio_add_callback(uart_rx_pin.port, &gpio_cb);
    if (ret) {
        return ret;
    }

    return 0;
}

RE: nrf54 wakeup using uart pins as gpio.

Håkon Alseth — Tue, 16 Dec 2025 18:20:43 GMT

Hi,

This topic comes into play when using PM runtime API:

button with "gpio-keys" not fired when CONFIG_PM_DEVICE_RUNTIME=y

SHELL will also be a consumer of your uart, so it will keep it on. Try instead of using serial backend for shell, to use RTT instead.

This function call will create issues:

    gpio_init_callback(&uart_rx_pin,
                       gpio_isr,
                       BIT(uart_rx_pin.pin));

Should point to "gpio_cb", not "uart_rx_pin".

If you choose to go with PM runtime API, you should enable the "uart_rx_pin.port" via pm_device_runtime_get() when disabling the uart.

If you choose to use PM without runtime, you should suspend the uart, then setup your gpio callback.

Kind regards,

Håkon

RE: nrf54 wakeup using uart pins as gpio.

narfster — Mon, 15 Dec 2025 12:37:03 GMT

for clarity - I am expecting characters sent from PC connected to uart to fire the ISR and waking the uart.

in the ISR or main context configure the uart to run again.

in the past - On nrf5 SDK we have done this manipulation and it work wonderful.