sample: sensor: mpr: Add MPR sample application

The sample reads pressure data from an MPR sensor and prints it to the
console.

Signed-off-by: Sven Herrmann <[email protected]>

Author: sven-hm

samples/sensor/mpr/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(mpr)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})

samples/sensor/mpr/README.rst

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+.. _mpr-sample:
+
+MPR Pressure Sensor
+###################
+
+Overview
+********
+
+This sample application periodically (1Hz) measures atmospheric pressure in
+kilopascal. The result is written to the console.
+
+References
+**********
+
+- MPR: https://sensing.honeywell.com/micropressure-mpr-series
+
+Wiring
+******
+
+This sample uses an MPRLS0025PA00001A sensor controlled using the i2c
+interface. Connect **VIN**, **GND** and Interface: **SDA**, **SCL**.
+
+Building and Running
+********************
+
+This project outputs sensor data to the console. It requires a sensor from the
+MPR series.
+It does not work on QEMU.
+In the sample below the :ref:`arduino_due` board is used.
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/sensor/mpr
+   :board: arduino_due
+   :goals: build flash
+
+Sample Output
+*************
+
+.. code-block:: console
+
+   pressure value: 101.976303 kPa
+   pressure value: 101.986024 kPa
+   pressure value: 101.989736 kPa
+   pressure value: 101.987424 kPa
+   pressure value: 101.992099 kPa
+   pressure value: 101.989171 kPa
+   pressure value: 101.984226 kPa
+
+   <repeats endlessly>

samples/sensor/mpr/boards/arduino_due.overlay

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+/*
+ * Copyright (c) 2020, Sven Herrmann
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&twi0 {
+    mpr@18 {
+        compatible = "honeywell,mpr";
+        reg = <0x18>;
+        label = "MPR";
+    };
+};

samples/sensor/mpr/prj.conf

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+CONFIG_STDOUT_CONSOLE=y
+CONFIG_I2C=y
+CONFIG_SENSOR=y
+CONFIG_MPR=y

samples/sensor/mpr/sample.yaml

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+sample:
+  name: MPR Pressure Sensor
+tests:
+  sample.sensor.mpr:
+    harness: sensor
+    tags: sensors
+    depends_on: i2c
+    platform_whitelist: arduino_due

samples/sensor/mpr/src/main.c

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+/*
+ * Copyright (c) 2020 Sven Herrmann
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr.h>
+#include <device.h>
+#include <drivers/sensor.h>
+#include <stdio.h>
+
+void main(void)
+{
+	const char *const devname = DT_INST_0_HONEYWELL_MPR_LABEL;
+	struct device *dev = device_get_binding(devname);
+	int rc;
+
+	if (dev == NULL) {
+		printf("Device %s not found.\n", devname);
+		return;
+	}
+
+	while (1) {
+		struct sensor_value pressure;
+
+		rc = sensor_sample_fetch(dev);
+		if (rc != 0) {
+			printf("sensor_sample_fetch error: %d\n", rc);
+			break;
+		}
+
+		rc = sensor_channel_get(dev, SENSOR_CHAN_PRESS, &pressure);
+		if (rc != 0) {
+			printf("sensor_channel_get error: %d\n", rc);
+			break;
+		}
+
+		printf("pressure: %u.%u kPa\n", pressure.val1, pressure.val2);
+
+		k_sleep(K_SECONDS(1));
+	}
+}