samples: boards: nrf91: add nrfx sample

Adds a sample that shows how to use nrfx drivers in Zephyr.

Signed-off-by: Marcin Szymczyk <marcin.szymczyk@nordicsemi.no>

samples/boards/nrf91/nrfx/CMakeLists.txt

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+# 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(nrfx_sample)
+
+target_sources(app PRIVATE src/main.c)

samples/boards/nrf91/nrfx/README.rst

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+.. _nrf91_nrfx:
+
+nRF91 nrfx example
+##################
+
+Overview
+********
+
+This sample demonstrates the usage of nrfx library in Zephyr.
+GPIOTE and DPPI are used as examples of nrfx drivers.
+
+The code shows how to initialize the GPIOTE interrupt in Zephyr
+so that the nrfx_gpiote driver can use it. Additionally, it shows
+how the DPPI subsystem can be used to connect tasks and events of
+nRF peripherals, enabling those peripherals to interact with each
+other without any intervention from the CPU.
+
+Zephyr GPIO driver is disabled to prevent it from registering its own handler
+for the GPIOTE interrupt. Button 1 is configured to create an event when pushed.
+This calls the ``button_handler()`` callback and triggers the LED 1 pin OUT task.
+LED is then toggled.
+
+Requirements
+************
+
+This sample has been tested on the NordicSemiconductor nRF9160 DK (nrf9160_pca10090) board.
+
+Building and Running
+********************
+
+The code can be found in :zephyr_file:`samples/boards/nrf91/nrfx`.
+
+To build and flash the application:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/boards/nrf91/nrfx
+   :board: nrf9160_pca10090
+   :goals: build flash
+   :compact:
+
+Push Button 1 to toggle the LED 1.
+
+Connect to the serial port - notice that each time the button is pressed,
+the ``button_handler()`` function is called.
+
+See nrfx_repository_ for more information about nrfx.
+
+.. _nrfx_repository: https://github.com/NordicSemiconductor/nrfx

samples/boards/nrf91/nrfx/prj.conf

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+CONFIG_GPIO=n
+CONFIG_NRFX_GPIOTE=y
+CONFIG_NRFX_DPPI=y
+CONFIG_LOG=y
+CONFIG_LOG_PROCESS_THREAD_SLEEP_MS=100

samples/boards/nrf91/nrfx/sample.yaml

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+sample:
+  name: nrfx usage sample
+tests:
+  sample.board.nrf91.nrfx:
+    platform_whitelist: nrf9160_pca10090
+    tags: board

samples/boards/nrf91/nrfx/src/main.c

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+/*
+ * Copyright (c) 2019 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr.h>
+
+#include <nrfx_gpiote.h>
+#include <nrfx_dppi.h>
+
+#include <logging/log.h>
+LOG_MODULE_REGISTER(nrfx_sample, LOG_LEVEL_INF);
+
+#define INPUT_PIN	DT_ALIAS_SW0_GPIOS_PIN
+#define OUTPUT_PIN	DT_ALIAS_LED0_GPIOS_PIN
+
+static void button_handler(nrfx_gpiote_pin_t pin, nrf_gpiote_polarity_t action)
+{
+	LOG_INF("GPIO input event callback");
+}
+
+void main(void)
+{
+	LOG_INF("nrfx_gpiote sample on %s", CONFIG_BOARD);
+
+	nrfx_err_t err;
+
+	/* Connect GPIOTE_0 IRQ to nrfx_gpiote_irq_handler */
+	IRQ_CONNECT(DT_NORDIC_NRF_GPIOTE_GPIOTE_0_IRQ_0,
+		    DT_NORDIC_NRF_GPIOTE_GPIOTE_0_IRQ_0_PRIORITY,
+		    nrfx_isr, nrfx_gpiote_irq_handler, 0);
+
+	/* Initialize GPIOTE */
+	err = nrfx_gpiote_init();
+	if (err != NRFX_SUCCESS) {
+		LOG_ERR("nrfx_gpiote_init error: %08x", err);
+		return;
+	}
+
+	nrfx_gpiote_in_config_t const in_config = {
+		.sense = NRF_GPIOTE_POLARITY_HITOLO,
+		.pull = NRF_GPIO_PIN_PULLUP,
+		.is_watcher = false,
+		.hi_accuracy = true,
+		.skip_gpio_setup = false,
+	};
+
+	/* Initialize input pin to generate event on high to low transition
+	 * (falling edge) and call button_handler()
+	 */
+	err = nrfx_gpiote_in_init(INPUT_PIN, &in_config, button_handler);
+	if (err != NRFX_SUCCESS) {
+		LOG_ERR("nrfx_gpiote_in_init error: %08x", err);
+		return;
+	}
+
+	nrfx_gpiote_out_config_t const out_config = {
+		.action = NRF_GPIOTE_POLARITY_TOGGLE,
+		.init_state = 1,
+		.task_pin = true,
+	};
+
+	/* Initialize output pin. SET task will turn the LED on,
+	 * CLR will turn it off and OUT will toggle it.
+	 */
+	err = nrfx_gpiote_out_init(OUTPUT_PIN, &out_config);
+	if (err != NRFX_SUCCESS) {
+		LOG_ERR("nrfx_gpiote_out_init error: %08x", err);
+		return;
+	}
+
+	nrfx_gpiote_in_event_enable(INPUT_PIN, true);
+	nrfx_gpiote_out_task_enable(OUTPUT_PIN);
+
+	LOG_INF("nrfx_gpiote initialized");
+
+	/* Initialize DPPI channel */
+	u8_t channel;
+
+	err = nrfx_dppi_channel_alloc(&channel);
+	if (err != NRFX_SUCCESS) {
+		LOG_ERR("nrfx_dppi_channel_alloc error: %08x", err);
+		return;
+	}
+
+	/* Configure input pin to publish to the DPPI channel and output pin to
+	 * receive events from the DPPI channel. Note that output pin is
+	 * subscribed using the OUT task. This means that each time the button
+	 * is pressed, the LED pin will be toggled.
+	 */
+	nrf_gpiote_publish_set(
+		nrfx_gpiote_in_event_get(INPUT_PIN),
+		channel);
+	nrf_gpiote_subscribe_set(
+		nrfx_gpiote_out_task_get(OUTPUT_PIN),
+		channel);
+
+	/* Enable DPPI channel */
+	err = nrfx_dppi_channel_enable(channel);
+	if (err != NRFX_SUCCESS) {
+		LOG_ERR("nrfx_dppi_channel_enable error: %08x", err);
+		return;
+	}
+
+	LOG_INF("DPPI configured, leaving main()");
+}