nRF COMP driver prevents Zephyr from booting on nRF54L15

Question

Hi,
I'm trying to use the nRF COMP peripheral in Zephyr.
My application boots and runs normally until I enable the DeviceTree overlay for the COMP.
As soon as the overlay is added, the device stops booting (no logs appear).

If I remove the overlay entirely, the system boots as expected.

/ {
    aliases {
        comp0 = &comp;
    };
};

#include <zephyr/dt-bindings/comparator/nrf-comp.h>

/* Based on:
 * https://docs.zephyrproject.org/latest/build/dts/api/bindings/comparator/nordic%2Cnrf-comp.html
 */

&comp {
    status = "okay";
    main-mode = "SE";
    psel = <NRF_COMP_AIN0>;  // P1.04
    refsel = "VDD";
    sp-mode = "NORMAL";
    th-up = <29>;            // ≈ 1.70 V
    th-down = <27>;          // ≈ 1.60 V
    isource = "DISABLED";
    enable-hyst;
};

my config

CONFIG_COMPARATOR=y
CONFIG_PRINTK=y
CONFIG_LOG=y

my main.c

#include <zephyr/sys/printk.h>
#include <zephyr/drivers/comparator.h>
#include <zephyr/kernel.h>

#define COMP_NODE DT_ALIAS(comp0)

static const struct device *comp = DEVICE_DT_GET(COMP_NODE);

static void handle_comparator_event(const struct device *dev, void *user_data)
{
    bool output = comparator_get_output(dev);
    printk("Comparator event: output is %s\n", output ? "HIGH" : "LOW");
}

int main(void)
{
    printk("Starting main\n");

    if (!device_is_ready(comp)) {
        printk("Comparator device not ready\n");
        return 0;
    }

    comparator_set_trigger(comp, COMPARATOR_TRIGGER_BOTH_EDGES);
    comparator_set_trigger_callback(comp, handle_comparator_event, NULL);

    printk("Comparator device is ready\n");

    while (1) {
        printk("Main running ...");
        k_sleep(K_MSEC(1000));
    }

    return 0;
}

- No log output at all

- never reaches printk("Starting main")

I'm using nRF54L15dk with Zephyr 4.3.0

Benjamin · Accepted Answer

Hi,
I reproduced your issue. You are setting the comparator input to AIN0 which on the nRF54L15 is P1.04. See pin assignments. This is the same pin that is used for UART and causes a conflict here. You will have to change the analog input pin or the UART pin arrangement. I changed the input to AIN5 and then your code worked fine.

Best regards,
Benjamin

nRF COMP driver prevents Zephyr from booting on nRF54L15

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