samples: sensor: mpu6050: convert to devicetree

Add a sample for the MPU6050 that demonstrates on-demand and triggered
display of all sensor data.

Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>

samples/sensor/mpu6050/CMakeLists.txt

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+#
+# Copyright (c) 2019 Nordic Semiconductor ASA
+#
+# 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(mpu6050)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})

samples/sensor/mpu6050/README.rst

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+.. _mpu6050:
+
+MPU6050: Invensense Motion Tracking Device
+##########################################
+
+Description
+***********
+
+This sample application periodically (0.5 Hz) measures the sensor
+temperature, acceleration, and angular velocity, displaying the values
+on the console along with a timestamp since startup.
+
+When triggered mode is enabled the measurements are displayed at the
+rate they are produced by the sensor.
+
+Wiring
+*******
+
+This sample uses an external breakout for the sensor.  A devicetree
+overlay must be provided to identify the I2C bus and GPIO used to
+control the sensor.
+
+Building and Running
+********************
+
+After providing a devicetree overlay that specifies the sensor location,
+build this sample app using:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/sensor/mpu6050
+   :board: nrf52_pca10040
+   :goals: build flash
+
+Sample Output
+=============
+
+.. code-block:: console
+
+   *** Booting Zephyr OS build zephyr-v2.1.0-576-g4b38659b0661  ***
+   [0:00:00.008]:23.6359 Cel
+     accel -5.882554 -6.485893  5.868188 m/s/s
+     gyro   0.014522  0.002264 -0.036905 rad/s
+   [0:00:02.020]:23.6359 Cel
+     accel -5.841853 -6.435615  5.911283 m/s/s
+     gyro   0.017852  0.001199 -0.034640 rad/s
+   [0:00:04.032]:23.6829 Cel
+     accel -5.930438 -6.461951  6.009446 m/s/s
+     gyro   0.012923  0.002131 -0.037171 rad/s
+   [0:00:06.044]:23.6359 Cel
+     accel -5.884948 -6.524200  5.961562 m/s/s
+     gyro   0.012390 -0.001732 -0.045964 rad/s
+   [0:00:08.056]:35.7712 Cel
+     accel -5.863400 -12.872426 -0.154427 m/s/s
+     gyro  -0.034373 -0.034373 -0.034373 rad/s
+   [0:00:10.068]:23.6829 Cel
+     accel -5.906496 -6.461951  5.899312 m/s/s
+     gyro   0.015321 -0.000399 -0.039169 rad/s
+
+<repeats endlessly>

samples/sensor/mpu6050/boards/nrf52_pca10040.overlay

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+/*
+ * Copyright (c) 2019 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&i2c0 {
+	mpu6050@68 {
+		compatible = "invensense,mpu6050";
+		reg = <0x68>;
+		status = "okay";
+		label = "MPU6050";
+		int-gpios = <&gpio0 11 0>;
+	};
+};

samples/sensor/mpu6050/prj.conf

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+#
+# Copyright (c) 2019 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+CONFIG_I2C=y
+CONFIG_SENSOR=y
+CONFIG_MPU6050=y
+CONFIG_MPU6050_TRIGGER_NONE=y

samples/sensor/mpu6050/sample.yaml

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+#
+# Copyright (c) 2019 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+sample:
+  name: MPU6050 Sensor Sample
+tests:
+  sample.sensor.mpu6050:
+    build_only: true
+    platform_whitelist: nrf52_pca10040
+    tags: sensors

samples/sensor/mpu6050/src/main.c

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+/*
+ * Copyright (c) 2019 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr.h>
+#include <device.h>
+#include <drivers/sensor.h>
+#include <stdio.h>
+
+static const char *now_str(void)
+{
+	static char buf[16]; /* ...HH:MM:SS.MMM */
+	u32_t now = k_uptime_get_32();
+	unsigned int ms = now % MSEC_PER_SEC;
+	unsigned int s;
+	unsigned int min;
+	unsigned int h;
+
+	now /= MSEC_PER_SEC;
+	s = now % 60U;
+	now /= 60U;
+	min = now % 60U;
+	now /= 60U;
+	h = now;
+
+	snprintf(buf, sizeof(buf), "%u:%02u:%02u.%03u",
+		 h, min, s, ms);
+	return buf;
+}
+
+static int process_mpu6050(struct device *dev)
+{
+	struct sensor_value temperature;
+	struct sensor_value accel[3];
+	struct sensor_value gyro[3];
+	int rc = sensor_sample_fetch(dev);
+
+	if (rc == 0) {
+		rc = sensor_channel_get(dev, SENSOR_CHAN_ACCEL_XYZ,
+					accel);
+	}
+	if (rc == 0) {
+		rc = sensor_channel_get(dev, SENSOR_CHAN_GYRO_XYZ,
+					gyro);
+	}
+	if (rc == 0) {
+		rc = sensor_channel_get(dev, SENSOR_CHAN_AMBIENT_TEMP,
+					&temperature);
+	}
+	if (rc == 0) {
+		printf("[%s]:%g Cel\n"
+		       "  accel % f % f % f m/s/s\n"
+		       "  gyro  % f % f % f rad/s\n",
+		       now_str(),
+		       sensor_value_to_double(&temperature),
+		       sensor_value_to_double(&accel[0]),
+		       sensor_value_to_double(&accel[1]),
+		       sensor_value_to_double(&accel[2]),
+		       sensor_value_to_double(&gyro[0]),
+		       sensor_value_to_double(&gyro[1]),
+		       sensor_value_to_double(&gyro[2]));
+	} else {
+		printf("sample fetch/get failed: %d\n", rc);
+	}
+
+	return rc;
+}
+
+#ifdef CONFIG_MPU6050_TRIGGER
+static struct sensor_trigger trigger;
+
+static void handle_mpu6050_drdy(struct device *dev,
+				struct sensor_trigger *trig)
+{
+	int rc = process_mpu6050(dev);
+
+	if (rc != 0) {
+		printf("cancelling trigger due to failure: %d\n", rc);
+		(void)sensor_trigger_set(dev, trig, NULL);
+		return;
+	}
+}
+#endif /* CONFIG_MPU6050_TRIGGER */
+
+void main(void)
+{
+	const char *const label = DT_INST_0_INVENSENSE_MPU6050_LABEL;
+	struct device *mpu6050 = device_get_binding(label);
+
+	if (!mpu6050) {
+		printf("Failed to find sensor %s\n", label);
+		return;
+	}
+
+#ifdef CONFIG_MPU6050_TRIGGER
+	trigger = (struct sensor_trigger) {
+		.type = SENSOR_TRIG_DATA_READY,
+		.chan = SENSOR_CHAN_ALL,
+	};
+	if (sensor_trigger_set(mpu6050, &trigger,
+			       handle_mpu6050_drdy) < 0) {
+		printf("Cannot configure trigger\n");
+		return;
+	};
+	printk("Configured for triggered sampling.\n");
+#endif
+
+	while (!IS_ENABLED(CONFIG_MPU6050_TRIGGER)) {
+		int rc = process_mpu6050(mpu6050);
+
+		if (rc != 0) {
+			break;
+		}
+		k_sleep(K_SECONDS(2));
+	}
+
+	/* triggered runs with its own thread after exit */
+}