Trigger GPIO interrupt on high pin level

Question

Hi,

I'm modifying the Nodric Developer Academy example for GPIO (https://github.com/NordicDeveloperAcademy/ncs-fund/blob/main/v2.x.x/lesson2/fund_less2_exer2_solution/src/main.c), using the nRF52840DK.

I'm trying to trigger an interrupt based on high pin level, using the following code:

/*
 * Copyright (c) 2016 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/devicetree.h>
#include <zephyr/drivers/gpio.h>

/* 1000 msec = 1 sec */
#define SLEEP_TIME_MS   1000

/* The devicetree node identifier for the "led0" alias. */
#define LED0_NODE 		DT_ALIAS(led0)
#define BUTTON0_NODE	DT_NODELABEL(button0)
#define BUTTON1_NODE	DT_NODELABEL(button1)
#define BUTTON2_NODE	DT_NODELABEL(button2)

//#define BUTTON_PORT DEVICE_DT_GET(DT_GPIO_CTLR(DT_NODELABEL(button0), gpios))

/*
 * A build error on this line means your board is unsupported.
 * See the sample documentation for information on how to fix this.
 */
static const struct gpio_dt_spec led0_spec = GPIO_DT_SPEC_GET(LED0_NODE, gpios);
static const struct gpio_dt_spec button0_spec = GPIO_DT_SPEC_GET(BUTTON0_NODE, gpios);
static const struct gpio_dt_spec button1_spec = GPIO_DT_SPEC_GET(BUTTON1_NODE, gpios);
static const struct gpio_dt_spec button2_spec = GPIO_DT_SPEC_GET(BUTTON2_NODE, gpios);

//Structure for GPIO callback when we define an interrupt
static struct gpio_callback button2_cb;

void button_pressed_callback(const struct device *gpiob, struct gpio_callback *cb, gpio_port_pins_t pins)
{
	gpio_pin_toggle_dt(&led0_spec);
	gpio_pin_set_dt(&button1_spec, 1);
}

void main(void)
{

	gpio_pin_configure_dt(&led0_spec, GPIO_OUTPUT);
	gpio_pin_configure_dt(&button0_spec, GPIO_INPUT | GPIO_ACTIVE_HIGH);
	gpio_pin_configure_dt(&button1_spec, GPIO_OUTPUT);
	gpio_pin_configure_dt(&button2_spec, GPIO_INPUT | GPIO_ACTIVE_HIGH);


	gpio_pin_interrupt_configure_dt(&button2_spec, GPIO_ACTIVE_HIGH);
	gpio_init_callback(&button2_cb, button_pressed_callback, BIT(button2_spec.pin));
	gpio_add_callback(button2_spec.port, &button2_cb);

	while (1) {
		
		k_msleep(SLEEP_TIME_MS);
	}
}

But button 2 (and the interrupt callback) will only work with a low level (triggered when connected to ground). How can I change this to active high (triggers when connected to VDD)?

Thanks in advance.

AHaug · Accepted Answer

Hi, 
 In the devicetree, or rather an overlay to a device tree, you can configure the pin to be active high. 
 
 Build your current project (or something that compiles) for the nRF52840dk 
 Create a new overlay for the file 
 Use the Devicetree helper located at the actions tab in VS Code extension 
 Open the buttons-node 
 Select the button you want to configure 
 Set it to active high instead of active low

You can now see that in the dts you generated in step 2 that the buttons has changed. Every other button than button 2 is active low, while button 2 is active high. 
 
 Recompiling and running your firmware should result in a build where button two is now active high, while the rest is active low. 
 Do note, that the Devicetree helper tool might give the wrong output in some cases, so I recommend that you also consult with the documentation regarding configuring devicetree and overlay here https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/index.html . It is however a tremendously good tool to familiarize yourself with what you can do with nodes and how to change things. 
 Let me know if this resolves your issue 
 Kind regards, Andreas

Trigger GPIO interrupt on high pin level

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