GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Menon — Tue, 24 Mar 2026 09:33:44 GMT

Hello,

Just letting you know that you can always request a hardware review with us. Please create a new case and share your design files there, one of our engineers will review them and suggest any necessary requirements (if needed).

Kind Regards,

Abhijith

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Jishnu K J — Tue, 24 Mar 2026 06:19:47 GMT

Hello Abhijith,

Thank you for the clarification and for your support. We will review the hardware changes you suggested.

Best regards,
Jishnu K J

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Menon — Mon, 23 Mar 2026 12:28:23 GMT

Hello,
In that case, I believe there is no way to achieve this through software alone. You would probably need some hardware customization.

One possible suggestion is to add a pull-up on Q1 by connecting R9 to VDD instead of GND, and use P1.06 in an open-drain configuration. The default behavior for GPIOs is high-impedance, so during reset, SYS_EN would also be pulled high.

If possible, you could also redesign this part of the circuit so that it turns off on a high input instead of a low input.

Kind Regards,

Abhijith

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Jishnu K J — Thu, 19 Mar 2026 05:46:27 GMT

Hello Abhijith,

Yes, we observe the same behavior not only during DFU (FOTA), but also during a normal reboot.

In all these cases, the GPIO pin P1.06 (SYS_EN) returns to its default state after reset, causing the system to power off before the bootloader or application can reconfigure it.

Best regards,
Jishnu K J

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Menon — Wed, 18 Mar 2026 14:21:34 GMT

Hello,

I believe you only need to configure the mcuboot.overlay to initialize the pin in the bootloader. Regarding the issue you raised, does it occur only during DFU (FOTA)? Based on your description, the same behavior should also be observed during a normal reboot, such as after an assertion or a watchdog reset.

Kind Regards,

Abhijith

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Jishnu K J — Wed, 18 Mar 2026 12:25:20 GMT

Hi Abhijith,

I followed your suggestion and configured the bootloader using the sysbuild approach. I created a sysbuild folder and added both mcuboot.overlay and mcuboot.conf, similar to the sample you shared.

After building, I can confirm that the overlay is being applied correctly. I verified this in build/mcuboot/zephyr/zephyr.dts, where the GPIO hog is present:

gpio1: gpio@d8200 {
    compatible = "nordic,nrf-gpio";
    gpio-controller;
    reg = < 0xd8200 0x300 >;
    #gpio-cells = < 0x2 >;
    ngpios = < 0x10 >;
    status = "okay";
    port = < 0x1 >;
    gpiote-instance = < &gpiote20 >;
    phandle = < 0x11 >;

    load_cell_en_hog: load-cell-en-hog {
        gpio-hog;
        gpios = < 0x6 0x0 >;
        output-high;
        line-name = "load-cell-enable";
    };
};

However, in our case, it still does not work. After the firmware update, the GPIO pin P1.06 is cleared, and the device powers off.

Best regards,

Jishnu K J

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Menon — Tue, 17 Mar 2026 13:47:57 GMT

hello,

Since you are using NCS v3.0.2, I assume you are working with sysbuild. In that case, creating a child_image folder is not the correct approach for configuring MCUboot. Instead, you should create a sysbuild folder and include an mcuboot.overlay file there. Please refer to this sample, which demonstrates how to configure the bootloader.

Kind Regards,

Abhijith

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Jishnu K J — Tue, 17 Mar 2026 13:27:08 GMT

Hello Abhijith,

I tried configuring the GPIO pin in the bootloader, but it did not work. I suspect that the overlay file I created (mcuboot.overlay) is not being applied during the boot process.

The overlay file I used is shown below:

&gpio1 {
    status = "okay";

    /* Ensure P1.06 stays HIGH during MCUboot */
    load_cell_en_hog: load-cell-en-hog {
        gpio-hog;
        gpios = <&gpio1 6 GPIO_ACTIVE_HIGH>;
        output-high;
        line-name = "load-cell-enable";
    };
};

The file is placed at:

my_project/
 └── child_image/
      └── mcuboot.overlay

I have also added CONFIG_BOOTLOADER_MCUBOOT=y in sysbuild.conf.

Is there anything I might be missing? Also, is there any documentation available for properly applying overlays to MCUboot?

Best regards,

Jishnu K J

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Menon — Tue, 17 Mar 2026 10:36:15 GMT

Hello,

In this case, I don’t think GPIO retention is the right approach.

Instead, it’s worth trying to initialize the pin as early as possible in the bootloader. I’m not 100% sure this will work though, since it depends on how the GPIO behaves during reset. If the pin goes high-Z, it won’t actively drive the line low, so it may stay on long enough for the bootloader to re-assert it.

Kind Regards,

Abhijith

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Jishnu K J — Mon, 16 Mar 2026 10:26:14 GMT

Hello Abhijith,

Thank you for the clarification.

In our design, P1.06 (SYS_EN) is used as the power enable pin. It is initially set high to keep the system powered on. If this pin goes low, the system powers off.

We also have a power button in the circuit. The firmware detects the button press by reading P1.05 (SYS_OUT) and then toggles P1.06 (SYS_EN) to control the system power.

However, after performing FOTA, the device reboots and the state of P1.06 returns to its default value. As a result, SYS_EN becomes low and the system powers off. The device can only power on again when the button is pressed manually to power up the controller.

I have attached the relevant part of the schematic for reference.

Best regards,
Jishnu K J

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Menon — Fri, 13 Mar 2026 14:16:39 GMT

Hello,

GPIO configs are only retained through a system off reset. For other reset sources they are cleared. So after the OTA update and reboot, the GPIO returning to its default/reset state is the expected behavior. Could you give some more context on what exactly is the use case here? See the section reset behavior.

Kind Regards,

Abhijith

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Jishnu K J — Fri, 13 Mar 2026 13:27:42 GMT

Hello Abhijith,

Okay, noted. I will wait for your update.

In the meantime, I checked the API you mentioned (nrf_gpio_pin_retain_enable), but it does not appear to be defined in SDK v3.0.2.

Best regards,

Jishnu K J

RE: GPIO state not retained after FOTA reboot on nRF54L15 (Zephyr SDK 3.0.2)

Menon — Thu, 12 Mar 2026 14:30:04 GMT

Hello,

nRF54L15 does support GPIO retention, but you need to enable it using the retention API, see nrf_gpio_pin_retain_enable.

That said, I’m not sure if the GPIO state will survive the reset that happens during FOTA, since that process involves a system reset and the behavior can depend on the reset type. I’ll double-check this and get back to you.

Kind Regards,

Abhijith