samples: driver: Add LED GPIO sample

This commit provides a new sample which demonstrate
how to use the GPIO LED drivers.

Signed-off-by: Kamil Gawor <Kamil.Gawor@nordicsemi.no>

Author: Kamil Gawor

samples/drivers/led_gpio/CMakeLists.txt

@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.13.1)
+
+include($ENV{ZEPHYR_BASE}/cmake/app/boilerplate.cmake NO_POLICY_SCOPE)
+project(led_gpio)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})

samples/drivers/led_gpio/README.rst

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+.. _gpio-led-sample:
+
+LED GPIO Sample
+###############
+
+Overview
+********
+
+The sample assumes that the LEDs are connected to GPIO lines.
+It is configured to work on boards that have defined the led0 and led1
+aliases and id properties for them in their board devicetree description file.
+The LED id properties are required for the LED GPIO driver.
+The LEDs are controlled, using the
+following pattern:
+
+1. Turn on LEDs
+#. Turn off LEDs
+#. Blink the LEDs
+#. Turn off LEDs
+
+Building and Running
+********************
+
+This sample can be built and flashed to a board as follows:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/driver/led_gpio
+   :board: nrf52840_pca10056
+   :goals: build flash
+   :compact:
+
+After flashing the image to the board, the user LEDs on the board should act according to the given pattern.

samples/drivers/led_gpio/prj.conf

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+CONFIG_GPIO=y
+CONFIG_LED=y
+CONFIG_LED_GPIO=y
+CONFIG_LED_SOFTWARE_BLINK=y

samples/drivers/led_gpio/sample.yaml

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+sample:
+  name: LED GPIO driver sample
+  description: Demonstration of the LED GPIO driver
+tests:
+  sample.drivers.led.gpio:
+    tags: LED gpio
+    depends_on: gpio
+    harness: led
+    platform_whitelist: nrf52840_pca10056

samples/drivers/led_gpio/src/main.c

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+/*
+ * Copyright (c) 2019 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <device.h>
+#include <errno.h>
+#include <drivers/led.h>
+#include <sys/util.h>
+#include <sys/printk.h>
+#include <zephyr.h>
+
+#define LED_DEV_NAME "LED_GPIO_0"
+#define NUM_LEDS 2
+#define BLINK_DELAY_ON 500
+#define BLINK_DELAY_OFF 500
+#define DELAY_TIME 1000
+
+static uint8_t led_id[NUM_LEDS] = {DT_PROP(DT_NODELABEL(led0), id),
+				   DT_PROP(DT_NODELABEL(led1), id)};
+
+void main(void)
+{
+	struct device *led_dev;
+	int i, ret;
+
+	led_dev = device_get_binding(LED_DEV_NAME);
+	if (led_dev) {
+		printk("Found LED device %s\n", LED_DEV_NAME);
+	} else {
+		printk("LED device %s not found\n", LED_DEV_NAME);
+		return;
+	}
+
+	printk("Testing leds");
+
+	while (1) {
+		/* Turn on LEDs one by one */
+		for (i = 0; i < NUM_LEDS; i++) {
+			ret = led_on(led_dev, led_id[i]);
+			if (ret < 0) {
+				return;
+			}
+
+			k_msleep(DELAY_TIME);
+		}
+
+		/* Turn off LEDs one by one */
+		for (i = 0; i < NUM_LEDS; i++) {
+			ret = led_off(led_dev, led_id[i]);
+			if (ret < 0) {
+				return;
+			}
+
+			k_msleep(DELAY_TIME);
+		}
+
+		/* Test the blinking of LEDs one by one */
+		for (i = 0; i < NUM_LEDS; i++) {
+			ret = led_blink(led_dev, led_id[i], BLINK_DELAY_ON,
+					BLINK_DELAY_OFF);
+			if (ret < 0) {
+				return;
+			}
+
+			k_msleep(DELAY_TIME);
+		}
+
+		/* Wait a few blinking before turning off the LEDs */
+		k_msleep(DELAY_TIME * 10);
+
+		/* Turn off LEDs one by one */
+		for (i = 0; i < NUM_LEDS; i++) {
+			ret = led_off(led_dev, led_id[i]);
+			if (ret < 0) {
+				return;
+			}
+
+			k_msleep(DELAY_TIME);
+		}
+	}
+}