Configure GPIO pin within MCUBoot

RE: Configure GPIO pin within MCUBoot

Hieu — Mon, 28 Jul 2025 11:51:49 GMT

What happened that led you to that conclusion? My test below works just fine.

devzone.nordicsemi.com/.../c348848_5F00_250728_5F00_01.zip

RE: Configure GPIO pin within MCUBoot

Saxman58 — Sat, 26 Jul 2025 06:21:26 GMT

You are right, I didn't have CONFIG_GPIO set in the mcuboot.conf, and once that was included the our_board.c file was compiled. However, it does not get linked with the mcuboot bootloader.

RE: Configure GPIO pin within MCUBoot

Hieu — Fri, 25 Jul 2025 18:19:45 GMT

I think you likely haven't enabled CONFIG_GPIO for MCUboot yet, and so the CMake check failed, and the file wasn't included.

I ran a simple test, and the file is included just fine even for a custom board. You can check it out here, see how the intentional error in our_board.c is going to cause a build failure.

devzone.nordicsemi.com/.../c348848_5F00_250725_5F00_01.zip

Hieu

RE: Configure GPIO pin within MCUBoot

Saxman58 — Thu, 24 Jul 2025 04:15:20 GMT

I was following Sigurd's example to put the above files in the board folder (though his was in the NCS folders). But it may make more sense to put the .c and make file in our project /child_image folder since that's where the mcuboot.conf and mcuboot.overlay files are. And the above code in our board .overlay file would probably make sense to put in mcuboot.overlay since that has all the devicetree info that is needed by the MCUBoot build.

I tried that, but still don't know how to get the build process to compile the our_board.c code and link it in with the rest of the MCUBoot build.

RE: Configure GPIO pin within MCUBoot

Saxman58 — Thu, 24 Jul 2025 03:16:10 GMT

We are using NCS v2.6.1. The relevant code in our board.overlay file (in our project /boards folder) is:

/ {
	hub_reset: hub-reset {
		compatible = "nordic,gpio-pins";
		gpios = <&gpio1 9 GPIO_ACTIVE_HIGH>;
		status = "okay";
	};
};

&gpio1 {
	status = "okay";
};

The build configuration uses nrf7002dk_nrf5340_cpuapp as the board target, and then `boards/our_board.overlay` as the Base Devicetree overlays. The overlay has a lot more customization for our application, but the above is all I need to access from the bootloader.

Here is the our_board.c file with the code we want to add to the MCUBoot bootloader build, but not the main application:

#include <zephyr/init.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/sys/printk.h>

#define HUB_RESET_NODE  DT_ALIAS(hub_reset)

#if DT_NODE_HAS_STATUS(HUB_RESET_NODE, okay)
#define HUB_RESET   DT_GPIO_LABEL(HUB_RESET_NODE, gpios)
#define PIN         DT_GPIO_PIN(HUB_RESET_NODE, gpios)
#define FLAGS       DT_GPIO_FLAGS(HUB_RESET_NODE, gpios)
#else
#error "Board doesn't have a USB Hub Reset"
#define HUB_RESET   ""
#define PIN         0
#define FLAGS       0
#endif

static int board_init(void) {
    int err;
    printk("board_init\n");
    printk("PIN %d\n", PIN);

    static const struct device *hub_rst;
    hub_rst = device_get_binding(HUB_RESET);

    err = gpio_pin_configure(hub_rst, PIN, GPIO_OUTPUT_ACTIVE);
    printk("gpio_pin_configure() returned: %d\n", err);
    if (err < 0) {
        return 1;
    }

    err = gpio_pin_set(hub_rst, PIN, false);
    printk("gpio_pin_set() returned: %d\n", err);
    return 0;
}

SYS_INIT(board_init, APPLICATION, CONFIG_APPLICATION_INIT_PRIORITY);

And here is the CMakeLists file that I hoped would add this to the MCUBoot build:

if(CONFIG_GPIO AND DEFINED CONFIG_MCUBOOT)
    zephyr_library()
    zephyr_library_sources(our_board.c)
endif()

I put both of these in the project /boards folder, but the CMake system isn't finding them. That is the main problem, getting this to be included in the MCUBoot build.

Glen

RE: Configure GPIO pin within MCUBoot

Hieu — Wed, 23 Jul 2025 18:24:04 GMT

Hi Saxman58,

What version of the nRF Connect SDK (NCS) are you working with?

If it is a NCS version with the new board hierarchy (nrf52840dk/nrf52840 vs nrf52840dk_nrf52840), do you have a minimal custom board files to help kickstart me? I don't have one right now.

Hieu