samples: sensors: add sample for i3g4250d gyro

Adds a sample for the ST I3G4250D gyroscope.

Signed-off-by: Jonathan Hahn <Jonathan.Hahn@t-online.de>

samples/sensor/i3g4250d/CMakeLists.txt

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+#
+# Copyright (c) 2021, Jonathan Hahn
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(i3g4250)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})

samples/sensor/i3g4250d/README.rst

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+.. _i3g4250d:
+
+I3G4250D: 3-axis digital output gyroscope
+#########################################
+
+Description
+***********
+
+This sample application configures the gyroscope with a fixed
+sampling rate and polls the measurements with the same rate and
+displays the measurements along with a timestamp since startup.
+
+Requirements
+************
+
+This sample application uses the I3G4250D sensor connected via
+SPI interface. This is the case for example for stm32f3_disco@E
+board devicetree.
+
+Building and Running
+********************
+
+To build the application a board with I3G4250D on SPI interface
+has to be chosen, or a custom devicetree overlay has to be provided.
+Here STM32F3 discovery board is used.
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/sensor/i3g4250d
+   :board: stm32f3_disco@E
+   :goals: build flash
+
+Sample Output
+*************
+
+.. code-block:: console
+
+   *** Booting Zephyr OS build zephyr-v2.6.0-1897-ga09838064f26  ***
+   Set sensor sampling frequency to 200.000000 Hz.
+   Polling at 200.000000 Hz
+   12 ms: x 2454.031430 , y 2336.015410 , z -1800.030108
+   22 ms: x -248.003106 , y -268.979704 , z 6.018390
+   32 ms: x -214.989906 , y -237.023468 , z 6.013926
+   41 ms: x -193.978308 , y -205.032232 , z 2.000356
+   51 ms: x -158.986716 , y -171.014568 , z 3.969998
+   60 ms: x -138.979582 , y -153.003326 , z 3.978748
+   70 ms: x -120.981554 , y -129.982800 , z -13.971422
+   80 ms: x -106.984060 , y -112.967272 , z -80.006572

samples/sensor/i3g4250d/prj.conf

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+CONFIG_SPI=y
+CONFIG_SENSOR=y
+CONFIG_I3G4250D=y

samples/sensor/i3g4250d/sample.yaml

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+#
+# Copyright (c) 2021 Jonathan Hahn
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+sample:
+  name: I3G4250D Sensor Sample
+tests:
+  sample.sensor.i3g4250d:
+    platform_allow: stm32f3_disco@E
+    tags: sensors

samples/sensor/i3g4250d/src/main.c

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+/*
+ * Copyright (c) 2021 Jonathan Hahn
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdio.h>
+#include <zephyr.h>
+#include <device.h>
+#include <drivers/sensor.h>
+
+#define SAMPLING_INTERVAL_MS 10
+#define DISPLAY_INTERVAL_MS 50
+
+static int set_sampling_frequency(const struct device *sensor, double sampling_frequency)
+{
+	struct sensor_value setting;
+
+	sensor_value_from_double(&setting, sampling_frequency);
+
+	return sensor_attr_set(sensor,
+			       SENSOR_CHAN_GYRO_XYZ, SENSOR_ATTR_SAMPLING_FREQUENCY, &setting);
+}
+
+static void fetch_and_display(const struct device *sensor)
+{
+	struct sensor_value gyro[3];
+
+	int rc = sensor_sample_fetch(sensor);
+
+	if (rc != 0) {
+		printf("ERROR: Failed fetching gyro values: %d.\n", rc);
+		return;
+	}
+
+	rc = sensor_channel_get(sensor,
+				SENSOR_CHAN_GYRO_XYZ,
+				gyro);
+
+	if (rc != 0) {
+		printf("ERROR: Failed getting gyro values: %d\n", rc);
+		return;
+	}
+
+	printf("%u ms: x %f , y %f , z %f\n",
+	       k_uptime_get_32(),
+	       sensor_value_to_double(&gyro[0]),
+	       sensor_value_to_double(&gyro[1]),
+	       sensor_value_to_double(&gyro[2]));
+}
+
+void main(void)
+{
+	const double sampling_frequency = 1000.0 / SAMPLING_INTERVAL_MS;
+	const struct device *sensor = DEVICE_DT_GET_ONE(st_i3g4250d);
+
+	if (!device_is_ready(sensor)) {
+		printf("Sensor %s is not ready\n", sensor->name);
+		return;
+	}
+
+	printf("Set sensor sampling frequency to %f Hz.\n", sampling_frequency);
+	set_sampling_frequency(sensor, sampling_frequency);
+
+	printf("Start polling with an interval of %d ms\n", DISPLAY_INTERVAL_MS);
+	while (true) {
+		fetch_and_display(sensor);
+
+		/* Wait some time before printing the next value */
+		k_sleep(K_MSEC(DISPLAY_INTERVAL_MS));
+	}
+}