app: initial application skeleton

initial application skeleton demonstrating:

- custom boards
- custom DT bindings
- Out-of-tree drivers

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

.gitignore

@@ -0,0 +1,10 @@
+# editors
+.vscode
+*.swp
+*~
+
+# python
+.venv
+
+# build
+/build*

CMakeLists.txt

@@ -0,0 +1,7 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+#
+# This CMake file is picked by the Zephyr build system because it is defined
+# as the module CMake entry point (see zephyr/module.yml).
+
+add_subdirectory(drivers)

Kconfig

@@ -0,0 +1,8 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+#
+# This Kconfig file is picked by the Zephyr build system because it is defined
+# as the module Kconfig entry point (see zephyr/module.yml). You can browse
+# module options by going to Zephyr -> Modules in Kconfig.
+
+rsource "drivers/Kconfig"

README.md

@@ -1,2 +1,58 @@
-# example-application
+# Zephyr Example Application
-Example out-of-tree application that is also a module
+
+This repository contains a Zephyr example application. The main purpose of this
+repository is to serve as a reference on how to structure Zephyr based
+applications. Some of the features demonstrated in this example are:
+
+- Basic application skeleton
+- [Custom boards][board_porting]
+- Custom [devicetree bindings][bindings]
+- Out-of-tree [drivers][drivers]
+- Documentation using Doxygen and Sphinx
+- Example CI configuration (using Github Actions)
+
+[board_porting]: https://docs.zephyrproject.org/latest/guides/porting/board_porting.html
+[bindings]: https://docs.zephyrproject.org/latest/guides/dts/bindings.html
+[drivers]: https://docs.zephyrproject.org/latest/reference/drivers/index.html
+
+## Getting Started
+
+Before getting started, make sure you have a proper Zephyr development
+environment. You can follow the official
+[Zephyr Getting Started Guide](https://docs.zephyrproject.org/latest/getting_started/index.html).
+
+### Initialization
+
+The first step is to initialize the workspace folder (``my-workspace``) where
+the ``example-application`` and all Zephyr modules will be cloned. You can do
+that by running:
+
+```shell
+# initialize my-workspace for the example-application (main branch)
+west init -m https://github.com/zephyrproject-rtos/example-application --mr main my-workspace
+# update Zephyr modules
+cd my-workspace
+west update
+```
+
+### Build & Run
+
+The application can be built by running:
+
+```shell
+west build -b $BOARD -s app
+```
+
+where `$BOARD` is the target board. A sample debug configuration is also
+provided. You can apply it by running:
+
+```shell
+west build -b $BOARD -s app -- -DOVERLAY_CONFIG=debug.conf
+```
+
+Note that you may also use it together with `rtt.conf` if using Segger RTT. Once
+you have built the application you can flash it by running:
+
+```shell
+west flash
+```

app/CMakeLists.txt

@@ -0,0 +1,15 @@
+#-------------------------------------------------------------------------------
+# Zephyr Example Application
+#
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.13.1)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+
+project(app LANGUAGES C VERSION 1.0.0)
+
+configure_file(app_version.h.in ${CMAKE_BINARY_DIR}/app/include/app_version.h)
+target_include_directories(app PRIVATE ${CMAKE_BINARY_DIR}/app/include src)
+
+target_sources(app PRIVATE src/main.c src/foo.c)

app/Kconfig

@@ -0,0 +1,15 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+#
+# This file is the application Kconfig entry point. All application Kconfig
+# options can be defined here or included via other application Kconfig files.
+# You can browse these options using the west targets menuconfig (terminal) or
+# guiconfig (GUI).
+
+menu "Zephyr"
+source "Kconfig.zephyr"
+endmenu
+
+module = APP
+module-str = APP
+source "subsys/logging/Kconfig.template.log_config"

app/app_version.h.in

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+/**
+ * @file app_version.h
+ *
+ * Application version information.
+ *
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef APP_VERSION_H_
+#define APP_VERSION_H_
+
+/** Application major version. */
+#define APP_VERSION_MAJOR ${PROJECT_VERSION_MAJOR}
+/** Application minor version. */
+#define APP_VERSION_MINOR ${PROJECT_VERSION_MINOR}
+/** Application patch version. */
+#define APP_VERSION_PATCH ${PROJECT_VERSION_PATCH}
+
+/** Application version. */
+#define APP_VERSION \
+	((APP_VERSION_MAJOR << 16) + \
+	 (APP_VERSION_MINOR << 8) + \
+	  APP_VERSION_PATCH)
+
+/** Application version (string). */
+#define APP_VERSION_STR "${PROJECT_VERSION}"
+
+#endif /* APP_VERSION_H_ */

app/debug.conf

@@ -0,0 +1,19 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+#
+# This is a Kconfig fragment which can be used to enable debug-related options
+# in the application. See the README for more details.
+
+# compiler
+CONFIG_DEBUG_OPTIMIZATIONS=y
+
+# console
+CONFIG_CONSOLE=y
+
+# UART console
+CONFIG_SERIAL=y
+CONFIG_UART_CONSOLE=y
+
+# logging
+CONFIG_LOG=y
+CONFIG_APP_LOG_LEVEL_DBG=y

app/prj.conf

@@ -0,0 +1,7 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+#
+# This file contains selected Kconfig options for the application.
+
+CONFIG_SENSOR=y
+CONFIG_EXAMPLESENSOR=y

app/rtt.conf

@@ -0,0 +1,9 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+#
+# This is a Kconfig fragment which can be used to enable Segger RTT options.
+# It should be used in conjunction with debug.conf.
+
+# segger RTT console
+CONFIG_USE_SEGGER_RTT=y
+CONFIG_RTT_CONSOLE=y

app/src/foo.c

@@ -0,0 +1,11 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "foo.h"
+
+int app_foo_bar(void)
+{
+	return 0;
+}

app/src/foo.h

@@ -0,0 +1,30 @@
+/**
+ * @file foo.h
+ *
+ * Foo API.
+ *
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef _FOO_H_
+#define _FOO_H_
+
+/**
+ * @defgroup app_foo Foo API
+ *
+ * A detailed description of the foo API.
+ *
+ * @{
+ */
+
+/**
+ * @brief An example foo API call.
+ *
+ * @return 0 on success, negative errno otherwise.
+ */
+int app_foo_bar(void);
+
+/** @} */
+
+#endif /* _FOO_H_ */

app/src/main.c

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr.h>
+#include <drivers/sensor.h>
+
+#include "app_version.h"
+#include "foo.h"
+
+#include <logging/log.h>
+LOG_MODULE_REGISTER(main, CONFIG_APP_LOG_LEVEL);
+
+void main(void)
+{
+	int ret;
+	const struct device *sensor;
+
+	printk("Zephyr Example Application %s\n", APP_VERSION_STR);
+
+	ret = app_foo_bar();
+	if (ret < 0) {
+		LOG_ERR("app_foo_bar failed (%d)", ret);
+		return;
+	}
+
+	sensor = DEVICE_DT_GET(DT_NODELABEL(examplesensor0));
+	if (!device_is_ready(sensor)) {
+		LOG_ERR("Sensor not ready");
+		return;
+	}
+
+	while (1) {
+		struct sensor_value val;
+
+		ret = sensor_sample_fetch(sensor);
+		if (ret < 0) {
+			LOG_ERR("Could not fetch sample (%d)", ret);
+			return;
+		}
+
+		ret = sensor_channel_get(sensor, SENSOR_CHAN_PROX, &val);
+		if (ret < 0) {
+			LOG_ERR("Could not get sample (%d)", ret);
+			return;
+		}
+
+		printk("Sensor value: %d\n", val.val1);
+
+		k_sleep(K_MSEC(1000));
+	}
+}
+

boards/arm/custom_plank/Kconfig

@@ -0,0 +1,8 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_ENABLE_DCDC
+	bool "Enable DCDC mode"
+	select SOC_DCDC_NRF52X
+	default y
+	depends on BOARD_CUSTOM_PLANK

boards/arm/custom_plank/Kconfig.board

@@ -0,0 +1,6 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_CUSTOM_PLANK
+	bool "Custom Plank Board"
+	depends on SOC_NRF52840_QIAA

boards/arm/custom_plank/Kconfig.defconfig

@@ -0,0 +1,9 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+if BOARD_CUSTOM_PLANK
+
+config BOARD
+	default "custom_plank"
+
+endif # BOARD_CUSTOM_PLANK

boards/arm/custom_plank/README.md

@@ -0,0 +1,6 @@
+# Custom Plank Board
+
+`custom_plank` board is used to demonstrate how to create custom boards. It is
+in fact a simplified version of the nRF52840-DK board, so the
+`example-application` can be run on that development kit when using
+`custom_plank`.

boards/arm/custom_plank/board.cmake

@@ -0,0 +1,12 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+board_runner_args(jlink "--device=nrf52" "--speed=4000")
+board_runner_args(pyocd "--target=nrf52840" "--frequency=4000000")
+
+set(OPENOCD_NRF5_SUBFAMILY "nrf52")
+
+include(${ZEPHYR_BASE}/boards/common/nrfjprog.board.cmake)
+include(${ZEPHYR_BASE}/boards/common/jlink.board.cmake)
+include(${ZEPHYR_BASE}/boards/common/pyocd.board.cmake)
+include(${ZEPHYR_BASE}/boards/common/openocd-nrf5.board.cmake)

boards/arm/custom_plank/custom_plank.dts

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/dts-v1/;
+#include <nordic/nrf52840_qiaa.dtsi>
+
+/ {
+	model = "Custom Plank Board";
+	compatible = "vendor,custom-plank";
+
+	chosen {
+		zephyr,console = &uart0;
+		zephyr,sram = &sram0;
+		zephyr,flash = &flash0;
+	};
+
+	examplesensor0: examplesensor_0 {
+		compatible = "zephyr,examplesensor";
+		label = "EXAMPLESENSOR_0";
+		input-gpios = <&gpio0 11 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
+	};
+};
+
+&gpio0 {
+	status = "okay";
+};
+
+&uart0 {
+	compatible = "nordic,nrf-uarte";
+	status = "okay";
+
+	current-speed = <115200>;
+	tx-pin = <6>;
+	rx-pin = <8>;
+	rts-pin = <5>;
+	cts-pin = <7>;
+};

boards/arm/custom_plank/custom_plank.yaml

@@ -0,0 +1,15 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+identifier: custom_plank
+name: Custom-Plank
+type: mcu
+arch: arm
+ram: 256
+flash: 1024
+toolchain:
+  - zephyr
+  - gnuarmemb
+  - xtools
+supported:
+  - gpio

boards/arm/custom_plank/custom_plank_defconfig

@@ -0,0 +1,12 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_SOC_SERIES_NRF52X=y
+CONFIG_SOC_NRF52840_QIAA=y
+CONFIG_BOARD_CUSTOM_PLANK=y
+
+CONFIG_ARM_MPU=y
+CONFIG_HW_STACK_PROTECTION=y
+
+CONFIG_GPIO=y
+CONFIG_GPIO_AS_PINRESET=y

drivers/CMakeLists.txt

@@ -0,0 +1,4 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+add_subdirectory_ifdef(CONFIG_SENSOR sensor)

drivers/Kconfig

@@ -0,0 +1,6 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+menu "Drivers"
+rsource "sensor/Kconfig"
+endmenu

drivers/sensor/CMakeLists.txt

@@ -0,0 +1,4 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+add_subdirectory_ifdef(CONFIG_EXAMPLESENSOR examplesensor)

drivers/sensor/Kconfig

@@ -0,0 +1,6 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+if SENSOR
+rsource "examplesensor/Kconfig"
+endif # SENSOR

drivers/sensor/examplesensor/CMakeLists.txt

@@ -0,0 +1,5 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+zephyr_library_sources(examplesensor.c)

drivers/sensor/examplesensor/Kconfig

@@ -0,0 +1,8 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+config EXAMPLESENSOR
+	bool "Example sensor"
+	depends on GPIO
+	help
+	  Enable example sensor

drivers/sensor/examplesensor/examplesensor.c

@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT zephyr_examplesensor
+
+#include <device.h>
+#include <drivers/gpio.h>
+#include <drivers/sensor.h>
+
+#include <logging/log.h>
+LOG_MODULE_REGISTER(examplesensor, CONFIG_SENSOR_LOG_LEVEL);
+
+struct examplesensor_data {
+	int state;
+};
+
+struct examplesensor_config {
+	struct gpio_dt_spec input;
+};
+
+static int examplesensor_sample_fetch(const struct device *dev,
+				      enum sensor_channel chan)
+{
+	const struct examplesensor_config *config = dev->config;
+	struct examplesensor_data *data = dev->data;
+
+	data->state = gpio_pin_get(config->input.port, config->input.pin);
+
+	return 0;
+}
+
+static int examplesensor_channel_get(const struct device *dev,
+				     enum sensor_channel chan,
+				     struct sensor_value *val)
+{
+	struct examplesensor_data *data = dev->data;
+
+	if (chan != SENSOR_CHAN_PROX) {
+		return -ENOTSUP;
+	}
+
+	val->val1 = data->state;
+
+	return 0;
+}
+
+static const struct sensor_driver_api examplesensor_api = {
+	.sample_fetch = &examplesensor_sample_fetch,
+	.channel_get = &examplesensor_channel_get,
+};
+
+static int examplesensor_init(const struct device *dev)
+{
+	const struct examplesensor_config *config = dev->config;
+
+	int ret;
+
+	if (!device_is_ready(config->input.port)) {
+		LOG_ERR("Input GPIO not ready");
+		return -ENODEV;
+	}
+
+	ret = gpio_pin_configure_dt(&config->input, GPIO_INPUT);
+	if (ret < 0) {
+		LOG_ERR("Could not configure input GPIO (%d)", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+#define EXAMPLESENSOR_INIT(i)						       \
+	static struct examplesensor_data examplesensor_data_##i;	       \
+									       \
+	static const struct examplesensor_config examplesensor_config_##i = {  \
+		.input = GPIO_DT_SPEC_GET(DT_DRV_INST(i), input_gpios),	       \
+	};								       \
+									       \
+	DEVICE_DT_INST_DEFINE(i, examplesensor_init, NULL,		       \
+			      &examplesensor_data_##i,			       \
+			      &examplesensor_config_##i, POST_KERNEL,	       \
+			      CONFIG_SENSOR_INIT_PRIORITY, &examplesensor_api);
+
+DT_INST_FOREACH_STATUS_OKAY(EXAMPLESENSOR_INIT)

dts/bindings/sensor/zephyr,examplesensor.yaml

@@ -0,0 +1,24 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  An example sensor that reads the GPIO level defined in input-gpios. The
+  purpose of this sensor is to demonstrate how to create out-of-tree drivers.
+
+  Example definition in devicetree:
+
+    examplesensor {
+        compatible = "zephyr,examplesensor";
+        label = "EXAMPLESENSOR";
+        input-gpios = <&gpio0 0 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
+    };
+
+compatible: "zephyr,examplesensor"
+
+include: base.yaml
+
+properties:
+  input-gpios:
+    type: phandle-array
+    required: true
+    description: Input GPIO to be sensed.

west.yml

@@ -0,0 +1,16 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+manifest:
+  self:
+    path: example-application
+
+  remotes:
+    - name: zephyrproject-rtos
+      url-base: https://github.com/zephyrproject-rtos
+
+  projects:
+    - name: zephyr
+      remote: zephyrproject-rtos
+      revision: master
+      import: true

zephyr/module.yml

@@ -0,0 +1,20 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+build:
+  # Path to the Kconfig file that will be sourced into Zephyr Kconfig tree under
+  # Zephyr > Modules > example-application. Path is relative from root of this
+  # repository.
+  kconfig: Kconfig
+  # Path to the folder that contains the CMakeLists.txt file to be included by
+  # Zephyr build system. The `.` is the root of this repository.
+  cmake: .
+  settings:
+    # Additional roots for boards and DTS files. Zephyr will use the
+    # `<board_root>/boards` for additional boards. The `.` is the root of this
+    # repository.
+    board_root: .
+    # Zephyr will use the `<dts_root>/dts` for additional dts files and
+    # `<dts_root>/dts/bindings` for additional dts binding files. The `.` is
+    # the root of this repository.
+    dts_root: .