Getting started with gpio overlay

[garrettb]

Hi

I am really struggling to get started with overlay files. I have read through a lot of documentation, watched a few hours of YouTube tutorials, and yet I can’t even get going with one gpio.

I have an existing project for the nRF5340_DK, based I think on Nordic’s BLE UART Peripheral example.
I had to change the pins used for the i2c bus, so I managed to hack an overlay fiel for that, which works – but probably isn’t correct.
So now I want to try using one of the GPIO, as an output.

The examples I found were here and here.

I couldn't get either to build.

Any help / guidance / pointers would be appreciated, thank you.

DETAILS

I decided to pick gpio0.25, and then gpio0.26, since they seem to be free.

Here is my overlay file – you will see both attempts at the end of the file – one commented out:

/*
 * Copyright (c) 2022 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
 */

/ {
	chosen {
		nordic,nus-uart = &uart0;
	};
};


&pinctrl {
	i2c2_default: i2c2_default {
		group1 {
			psels = <NRF_PSEL(TWIM_SCL, 0, 6)>, <NRF_PSEL(TWIM_SDA, 0, 7)>;
		};
	};

	i2c2_sleep: i2c2_sleep {
		group1 {
			psels = <NRF_PSEL(TWIM_SDA, 0, 7)>,
				<NRF_PSEL(TWIM_SCL, 0, 6)>;
			low-power-enable;
		};
	};
};

&i2c2 {
	compatible = "nordic,nrf-twim";
	status = "okay";


	pinctrl-0 = <&i2c2_default>;
	pinctrl-1 = <&i2c2_default>;
	pinctrl-names = "default", "sleep";
};


&uart0_default {
	group2 {
		psels = <NRF_PSEL(UART_RX, 0, 22)>, <NRF_PSEL(UART_CTS, 0, 21)>;
	};
};

&uart0_default {
	group1 {
		psels = <NRF_PSEL(UART_RTS, 0, 19)>;
	};
};

// !gpio! - start
// From example here: https://devzone.nordicsemi.com/f/nordic-q-a/94963/need-simple-devicetree-overlay-example-for-gpio
/*
/{

	custom_gpios {
 
	   compatible = "gpio-keys";
 
	   cusgpio0: cusgpio_0 {
 
		  gpios = <&gpio0 25 GPIO_ACTIVE_HIGH>;
 
		  label = "My custom GPIO";
 
	   };
 
	};
 
	aliases {
 
	mycusgpio = &cusgpio0;
	};
 
 };

// From example here: https://devzone.nordicsemi.com/f/nordic-q-a/72618/extra-gpios-in-board-overlay-for-nrf9160dk
*/
/ {
    gpiocustom {
        compatible = "gpio-keys";
        gpiocus0: gpiocus_0 {
            gpios = <&gpio0 25 GPIO_ACTIVE_LOW>;
            label = "Custom gpio 25";
        };
        gpiocus1: gpiocus_1 {
            gpios = <&gpio0 26 GPIO_ACTIVE_LOW>;
            label = "Custom gpio 26";
        };
    };
    aliases {
        gpiocus0 = &gpiocus0;
        gpiocus1 = &gpiocus1;
    };
};
// !gpio! – end

And in main.c, again – two attempts, one commented out:

// !gpio! - start
//#define GPIO025_NODE  DT_ALIAS(mycusgpio)
//#define GPIO025           DT_GPIO_LABEL(GPIO025_NODE, gpios)
#define GPIO025_NODE    DT_ALIAS(gpiocus0)
#define GPIO025         DT_GPIO_LABEL(GPIO025_NODE, gpios)
// !gpio! - end

And in main():

    const struct device *dev_gpio0;                 // !gpio!

    dev_gpio0 = device_get_binding(GPIO025);        // !gpio!

Here are the warnings and errors I get for the first build (for gpio0.25 only – which is the attempt commented out above):

src\main.c:213:13: warning: Macro is deprecated
  213 |  dev_gpio0 = device_get_binding(GPIO025);
      |             ^~~~~~~~~~~~~~~~~~~~~
 build\zephyr\include\generated\devicetree_unfixed.h:1749:58: error: 'DT_N_S_soc_S_peripheral_40000000_S_gpio_842500_P_label' undeclared (first use in this function); did you mean 'DT_N_S_soc_S_peripheral_40000000_S_gpio_842500_P_reg'?
 1749 | #define DT_N_S_custom_gpios_S_cusgpio_0_P_gpios_IDX_0_PH DT_N_S_soc_S_peripheral_40000000_S_gpio_842500
      |                                                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:3068:24: note: in definition of macro 'DT_CAT'
 3068 | #define DT_CAT(a1, a2) a1 ## a2
      |                        ^~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:106:2: note: in expansion of macro 'DT_PROP'
  106 |  DT_PROP(DT_GPIO_CTLR_BY_IDX(node_id, gpio_pha, idx), label) __DEPRECATED_MACRO
      |  ^~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:3076:41: note: in expansion of macro 'DT_N_S_custom_gpios_S_cusgpio_0_P_gpios_IDX_0_PH'
 3076 | #define DT_CAT6(a1, a2, a3, a4, a5, a6) a1 ## a2 ## a3 ## a4 ## a5 ## a6
      |                                         ^~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:1247:2: note: in expansion of macro 'DT_CAT6'
 1247 |  DT_CAT6(node_id, _P_, prop, _IDX_, idx, _PH)
      |  ^~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:54:2: note: in expansion of macro 'DT_PHANDLE_BY_IDX'
   54 |  DT_PHANDLE_BY_IDX(node_id, gpio_pha, idx)
      |  ^~~~~~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:106:10: note: in expansion of macro 'DT_GPIO_CTLR_BY_IDX'
  106 |  DT_PROP(DT_GPIO_CTLR_BY_IDX(node_id, gpio_pha, idx), label) __DEPRECATED_MACRO
      |          ^~~~~~~~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:120:2: note: in expansion of macro 'DT_GPIO_LABEL_BY_IDX'
  120 |  DT_GPIO_LABEL_BY_IDX(node_id, gpio_pha, 0) __DEPRECATED_MACRO
      |  ^~~~~~~~~~~~~~~~~~~~
 src\main.c:64:19: note: in expansion of macro 'DT_GPIO_LABEL'
   64 | #define GPIO025   DT_GPIO_LABEL(GPIO025_NODE, gpios)
      |                   ^~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:3068:24: note: in expansion of macro 'DT_N_ALIAS_mycusgpio'
 3068 | #define DT_CAT(a1, a2) a1 ## a2
      |                        ^~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:213:25: note: in expansion of macro 'DT_CAT'
  213 | #define DT_ALIAS(alias) DT_CAT(DT_N_ALIAS_, alias)
      |                         ^~~~~~
 src\main.c:63:22: note: in expansion of macro 'DT_ALIAS'
   63 | #define GPIO025_NODE DT_ALIAS(mycusgpio)
      |                      ^~~~~~~~
 src\main.c:64:33: note: in expansion of macro 'GPIO025_NODE'
   64 | #define GPIO025   DT_GPIO_LABEL(GPIO025_NODE, gpios)
      |                                 ^~~~~~~~~~~~
 src\main.c:213:33: note: in expansion of macro 'GPIO025'
  213 |  dev_gpio0 = device_get_binding(GPIO025);   
      |                                 ^~~~~~~
 build\zephyr\include\generated\devicetree_unfixed.h:1749:58: note: each undeclared identifier is reported only once for each function it appears in
 1749 | #define DT_N_S_custom_gpios_S_cusgpio_0_P_gpios_IDX_0_PH DT_N_S_soc_S_peripheral_40000000_S_gpio_842500
      |                                                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:3068:24: note: in definition of macro 'DT_CAT'
 3068 | #define DT_CAT(a1, a2) a1 ## a2
      |                        ^~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:106:2: note: in expansion of macro 'DT_PROP'
  106 |  DT_PROP(DT_GPIO_CTLR_BY_IDX(node_id, gpio_pha, idx), label) __DEPRECATED_MACRO
      |  ^~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:3076:41: note: in expansion of macro 'DT_N_S_custom_gpios_S_cusgpio_0_P_gpios_IDX_0_PH'
 3076 | #define DT_CAT6(a1, a2, a3, a4, a5, a6) a1 ## a2 ## a3 ## a4 ## a5 ## a6
      |                                         ^~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:1247:2: note: in expansion of macro 'DT_CAT6'
 1247 |  DT_CAT6(node_id, _P_, prop, _IDX_, idx, _PH)
      |  ^~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:54:2: note: in expansion of macro 'DT_PHANDLE_BY_IDX'
   54 |  DT_PHANDLE_BY_IDX(node_id, gpio_pha, idx)
      |  ^~~~~~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:106:10: note: in expansion of macro 'DT_GPIO_CTLR_BY_IDX'
  106 |  DT_PROP(DT_GPIO_CTLR_BY_IDX(node_id, gpio_pha, idx), label) __DEPRECATED_MACRO
      |          ^~~~~~~~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:120:2: note: in expansion of macro 'DT_GPIO_LABEL_BY_IDX'
  120 |  DT_GPIO_LABEL_BY_IDX(node_id, gpio_pha, 0) __DEPRECATED_MACRO
      |  ^~~~~~~~~~~~~~~~~~~~
 src\main.c:64:19: note: in expansion of macro 'DT_GPIO_LABEL'
   64 | #define GPIO025   DT_GPIO_LABEL(GPIO025_NODE, gpios)
      |                   ^~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:3068:24: note: in expansion of macro 'DT_N_ALIAS_mycusgpio'
 3068 | #define DT_CAT(a1, a2) a1 ## a2
      |                        ^~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:213:25: note: in expansion of macro 'DT_CAT'
  213 | #define DT_ALIAS(alias) DT_CAT(DT_N_ALIAS_, alias)
      |                         ^~~~~~
 src\main.c:63:22: note: in expansion of macro 'DT_ALIAS'
   63 | #define GPIO025_NODE DT_ALIAS(mycusgpio)
      |                      ^~~~~~~~
 src\main.c:64:33: note: in expansion of macro 'GPIO025_NODE'
   64 | #define GPIO025   DT_GPIO_LABEL(GPIO025_NODE, gpios)
      |                                 ^~~~~~~~~~~~
 src\main.c:213:33: note: in expansion of macro 'GPIO025'
  213 |  dev_gpio0 = device_get_binding(GPIO025);   
      |                                 ^~~~~~~
[27/221] Building C object zephyr/drivers/mbox/CMakeFiles/drivers__mbox.dir/mbox_nrfx_ipc.c.obj
[29/219] Building C object modules/nrf/lib/dk_buttons_and_leds/CMakeFiles/..__nrf__lib__dk_buttons_and_leds.dir/dk_buttons_and_leds.c.obj
ninja: build stopped: subcommand failed.
FATAL ERROR: command exited with status 1

And the error and warning for my second attempt:

../src/main.c: In function 'main':
src\main.c:215:13: warning: Macro is deprecated
  215 |  dev_gpio0 = device_get_binding(GPIO025);  // !gpio!
      |             ^~~~~~~~~~~~~~~~~~~~~
build\zephyr\include\generated\devicetree_unfixed.h:1752:56: error: 'DT_N_S_soc_S_peripheral_40000000_S_gpio_842500_P_label' undeclared (first use in this function); did you mean 'DT_N_S_soc_S_peripheral_40000000_S_gpio_842500_P_reg'?
 1752 | #define DT_N_S_gpiocustom_S_gpiocus_0_P_gpios_IDX_0_PH DT_N_S_soc_S_peripheral_40000000_S_gpio_842500
      |                                                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:3068:24: note: in definition of macro 'DT_CAT'
 3068 | #define DT_CAT(a1, a2) a1 ## a2
      |                        ^~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:106:2: note: in expansion of macro 'DT_PROP'
  106 |  DT_PROP(DT_GPIO_CTLR_BY_IDX(node_id, gpio_pha, idx), label) __DEPRECATED_MACRO
      |  ^~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:3076:41: note: in expansion of macro 'DT_N_S_gpiocustom_S_gpiocus_0_P_gpios_IDX_0_PH'
 3076 | #define DT_CAT6(a1, a2, a3, a4, a5, a6) a1 ## a2 ## a3 ## a4 ## a5 ## a6
      |                                         ^~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:1247:2: note: in expansion of macro 'DT_CAT6'
 1247 |  DT_CAT6(node_id, _P_, prop, _IDX_, idx, _PH)
      |  ^~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:54:2: note: in expansion of macro 'DT_PHANDLE_BY_IDX'
   54 |  DT_PHANDLE_BY_IDX(node_id, gpio_pha, idx)
      |  ^~~~~~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:106:10: note: in expansion of macro 'DT_GPIO_CTLR_BY_IDX'
  106 |  DT_PROP(DT_GPIO_CTLR_BY_IDX(node_id, gpio_pha, idx), label) __DEPRECATED_MACRO
      |          ^~~~~~~~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:120:2: note: in expansion of macro 'DT_GPIO_LABEL_BY_IDX'
  120 |  DT_GPIO_LABEL_BY_IDX(node_id, gpio_pha, 0) __DEPRECATED_MACRO
      |  ^~~~~~~~~~~~~~~~~~~~
src\main.c:66:19: note: in expansion of macro 'DT_GPIO_LABEL'
   66 | #define GPIO025   DT_GPIO_LABEL(GPIO025_NODE, gpios)
      |                   ^~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:3068:24: note: in expansion of macro 'DT_N_ALIAS_gpiocus0'
 3068 | #define DT_CAT(a1, a2) a1 ## a2
      |                        ^~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:213:25: note: in expansion of macro 'DT_CAT'
  213 | #define DT_ALIAS(alias) DT_CAT(DT_N_ALIAS_, alias)
      |                         ^~~~~~
src\main.c:65:22: note: in expansion of macro 'DT_ALIAS'
   65 | #define GPIO025_NODE DT_ALIAS(gpiocus0)
      |                      ^~~~~~~~
src\main.c:66:33: note: in expansion of macro 'GPIO025_NODE'
   66 | #define GPIO025   DT_GPIO_LABEL(GPIO025_NODE, gpios)
      |                                 ^~~~~~~~~~~~
src\main.c:215:33: note: in expansion of macro 'GPIO025'
  215 |  dev_gpio0 = device_get_binding(GPIO025);  // !gpio!
      |                                 ^~~~~~~
build\zephyr\include\generated\devicetree_unfixed.h:1752:56: note: each undeclared identifier is reported only once for each function it appears in
 1752 | #define DT_N_S_gpiocustom_S_gpiocus_0_P_gpios_IDX_0_PH DT_N_S_soc_S_peripheral_40000000_S_gpio_842500
      |                                                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:3068:24: note: in definition of macro 'DT_CAT'
 3068 | #define DT_CAT(a1, a2) a1 ## a2
      |                        ^~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:106:2: note: in expansion of macro 'DT_PROP'
  106 |  DT_PROP(DT_GPIO_CTLR_BY_IDX(node_id, gpio_pha, idx), label) __DEPRECATED_MACRO
      |  ^~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:3076:41: note: in expansion of macro 'DT_N_S_gpiocustom_S_gpiocus_0_P_gpios_IDX_0_PH'
 3076 | #define DT_CAT6(a1, a2, a3, a4, a5, a6) a1 ## a2 ## a3 ## a4 ## a5 ## a6
      |                                         ^~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:1247:2: note: in expansion of macro 'DT_CAT6'
 1247 |  DT_CAT6(node_id, _P_, prop, _IDX_, idx, _PH)
      |  ^~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:54:2: note: in expansion of macro 'DT_PHANDLE_BY_IDX'
   54 |  DT_PHANDLE_BY_IDX(node_id, gpio_pha, idx)
      |  ^~~~~~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:106:10: note: in expansion of macro 'DT_GPIO_CTLR_BY_IDX'
  106 |  DT_PROP(DT_GPIO_CTLR_BY_IDX(node_id, gpio_pha, idx), label) __DEPRECATED_MACRO
      |          ^~~~~~~~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree\gpio.h:120:2: note: in expansion of macro 'DT_GPIO_LABEL_BY_IDX'
  120 |  DT_GPIO_LABEL_BY_IDX(node_id, gpio_pha, 0) __DEPRECATED_MACRO
      |  ^~~~~~~~~~~~~~~~~~~~
src\main.c:66:19: note: in expansion of macro 'DT_GPIO_LABEL'
   66 | #define GPIO025   DT_GPIO_LABEL(GPIO025_NODE, gpios)
      |                   ^~~~~~~~~~~~~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:3068:24: note: in expansion of macro 'DT_N_ALIAS_gpiocus0'
 3068 | #define DT_CAT(a1, a2) a1 ## a2
      |                        ^~
C:\Users\me\ncs\v2.1.0\zephyr\include\zephyr\devicetree.h:213:25: note: in expansion of macro 'DT_CAT'
  213 | #define DT_ALIAS(alias) DT_CAT(DT_N_ALIAS_, alias)
      |                         ^~~~~~
src\main.c:65:22: note: in expansion of macro 'DT_ALIAS'
   65 | #define GPIO025_NODE DT_ALIAS(gpiocus0)
      |                      ^~~~~~~~
src\main.c:66:33: note: in expansion of macro 'GPIO025_NODE'
   66 | #define GPIO025   DT_GPIO_LABEL(GPIO025_NODE, gpios)
      |                                 ^~~~~~~~~~~~
src\main.c:215:33: note: in expansion of macro 'GPIO025'
  215 |  dev_gpio0 = device_get_binding(GPIO025);  // !gpio!
      |                                 ^~~~~~~
[27/222] Building C object zephyr/drivers/pinctrl/CMakeFiles/drivers__pinctrl.dir/pinctrl_nrf.c.obj
[29/220] Building C object zephyr/drivers/mbox/CMakeFiles/drivers__mbox.dir/mbox_nrfx_ipc.c.obj
[30/220] Building C object zephyr/drivers/entropy/CMakeFiles/drivers__entropy.dir/C_/Users/garrett/ncs/v2.1.0/nrf/drivers/entropy/entropy_cc3xx.c.obj
[31/220] Building C object modules/nrf/lib/dk_buttons_and_leds/CMakeFiles/..__nrf__lib__dk_buttons_and_leds.dir/dk_buttons_and_leds.c.obj
ninja: build stopped: subcommand failed.
FATAL ERROR: command exited with status 1

By the way, I don’t know where this came from, in the overlay file – I suspect is was from when I was playing with the Device Tree GUI:

&uart0_default {
	group2 {
		psels = <NRF_PSEL(UART_RX, 0, 22)>, <NRF_PSEL(UART_CTS, 0, 21)>;
	};
};

&uart0_default {
	group1 {
		psels = <NRF_PSEL(UART_RTS, 0, 19)>;
	};
};

[garrettb]

Hi

I feel like I am getting closer to a solution, but…

So here’s the code from my overlay:

/ {
    gpiocustom {
        compatible = "gpio-keys";
        gpiocus0: gpiocus_0 {
            gpios = <&gpio0 25 GPIO_ACTIVE_LOW>;
            label = "Custom gpio 28";
        };
        gpiocus1: gpiocus_1 {
            gpios = <&gpio0 26 GPIO_ACTIVE_LOW>;
            label = "Custom gpio 29";
        };
    };
    aliases {
        gpiocus0 = &gpiocus0;
        gpiocus1 = &gpiocus1;
    };
};

My defines:

#define CUS_PIN0_NODE	DT_NODELABEL(gpiocus0)
#define CUS_PIN0		DT_GPIO_PIN(CUS_PIN0_NODE, gpios)

And the code in main()

	const struct device *dev_gpio0;

	dev_gpio0 = DEVICE_DT_GET(DT_NODELABEL(gpiocus0));
	if (!device_is_ready(dev_gpio0)) {
		printk("main: gpio not ready\n");
	}
	gpio_pin_configure(dev_gpio0, CUS_PIN0,  GPIO_OUTPUT);
	gpio_pin_set(dev_gpio0, CUS_PIN0, 0);

Resulting in this error:

C:\dev\myapp\src\main.c:296: undefined reference to `__device_dts_ord_19'

[Priyanka]

Hello,
I am sorry, but we are short staffed this week due to Public Holidays in Norway. We will be back on Monday 22nd and hope to be able to answer all incoming requests within a couple of days, depending on the backlog. I am sorry for the inconvenience.

Best regards,
Priyanka

[Priyanka]

Hi Garrett,

This is how I placed the snippet and was able to get away with the error:

	for (;;) {
		dk_set_led(RUN_STATUS_LED, (++blink_status) % 2);
		k_sleep(K_MSEC(RUN_LED_BLINK_INTERVAL));
	}
	
		if (!device_is_ready(my_dev)) {										// !io!
	  /* Not ready, do not use */
	  return;

	}

It's also strange that the nrf52840dk_nrf52840.overlay is not being recognize for you. Because I placed it inside the peripheral_uart project folder directly and it detects for me.

I will cross check your project zip file once again.

-Priyanka

[garrettb]

When I do the same, the projects build successfully.

However, I don't see the point in putting the code there, as it will never be run, because of the forever loop. Which is why it probably builds - because the compiler probably recognises that it is redundant, so omits it.

[garrettb]

I can't believe it is proving so difficult (and so far impossible) for me just to use one i/o pin. Can someone else help out on this please?

[Johnny Nguyen]

Hey Garrett,

I pulled a fresh peripheral_uart sample and built it on the nRF52840DK.

I added your overlay for adding the gpiocustom node to re-use port 0 pin 28 from the ARD header.

/ {
    gpiocustom {
        compatible = "gpio-keys";
        gpiocus0: gpiocus_0 {
            gpios = <&gpio0 28 GPIO_ACTIVE_LOW>;
            label = "Custom gpio 28";
        };
    };
    aliases {
        gpiocus0 = &gpiocus0;
    };
};

I then added that i/o pin as an input that triggers an interrupt callback that prints "MODE button pressed" when the pin is driven low from high. (Tested with my logic analyzer)

All changes I used for being able to use that pin as an input are highlighted here in this PR.

Custom gpio by droidecahedron · Pull Request #1 · droidecahedron/nrf_peripheral_uart_custom_gpio (github.com)

I hope this sheds some light on how to use that I/O pin within peripheral UART sample. (I added the interrupt callback because I assumed since you named it button that would have been the intention. If not, let me know and we can sync up.)

Best regards,

[garrettb]

Hi Johnny

Thanks for the reply.

I will look in to this further on Monday.

Right now, I created a new project again, from the peripheral uart application.

I pasted in your changes.

And when I build, I get this error:

undefined reference to `gpio_is_ready_dt'

This is for the line in main:

	if(!gpio_is_ready_dt(&modebutton))

I did find this post here, which I assume is the (new) issue.

Is there a way around using gpio_is_ready_dt()?

[Johnny Nguyen]

Hello Garrett,

My apologies, I'm on NCS v2.4.0 and I just noticed you are on 2.1.0.

I switched to 2.1.0 and had to replace gpio_is_ready_dt(&modebutton) with device_is_ready(modebutton.port)

Functions as intended. (Tested again with my logic analyzer acting as a button)

Diff can be found here in the 2_1_0 branch of the repo I linked earlier: need to do this for it to work in v2.1.0 · droidecahedron/nrf_peripheral_uart_custom_gpio@8c69678 (github.com)

Let me know how it goes for you when you get around to testing.

(If you decide to uprev to v2.4.0, you can swap it back to gpio_is_ready_dt)

[garrettb]

I presume it's because I am using SDK v2.1.0.

I will install the latest nrF Connect SDK and try it out and let you know how I get in.

Thanks

[garrettb]

Hi Johnny, the code above built & worked etc., once I updated to the latest nRF Connect SDK (v2.4.1)  - which presumably updated my version of zephyr etc. Thank you,