samples: sensor: hts221

This commit provides sample application for sensor hts221.
By default, it is enabled on board disco_l475_iot1

Change-Id: I535fac8a670fa89cc1cae15ea1abe9cfe4b6c56b
Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>

samples/sensor/hts221/Makefile

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+BOARD ?= disco_l475_iot1
+CONF_FILE = prj.conf
+
+include ${ZEPHYR_BASE}/Makefile.inc

samples/sensor/hts221/README.rst

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+.. _hts221:
+
+HTS221: Temperature and Humidity Monitor
+########################################
+
+Overview
+********
+This sample periodically reads temperature and humidity from the HTS221
+Temperature & Humidity Sensor and displays it on the console
+
+
+Requirements
+************
+
+This sample uses the HTS221 sensor controlled using the I2C interface.
+
+References
+**********
+
+ - HTS211: http://www.st.com/en/mems-and-sensors/hts221.html
+
+Building and Running
+********************
+
+ This project outputs sensor data to the console. It requires an HTS221
+ sensor, which is present on the disco_l475_iot1 board.
+
+ .. code-block:: console
+
+    $ cd samples/sensors/hts221
+    $ make BOARD=disco_l475_iot1
+
+Sample Output
+=============
+
+ .. code-block:: console
+
+    Temperature:25.3 C
+    Relative Humidity:40%
+    Temperature:25.3 C
+    Relative Humidity:40%
+    Temperature:25.3 C
+    Relative Humidity:40%
+    Temperature:25.3 C
+    Relative Humidity:40%
+
+    <repeats endlessly every 2 seconds>

samples/sensor/hts221/prj.conf

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+CONFIG_STDOUT_CONSOLE=y
+CONFIG_I2C=y
+CONFIG_SENSOR=y
+CONFIG_HTS221=y

samples/sensor/hts221/src/Makefile

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+obj-y += main.o

samples/sensor/hts221/src/main.c

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+/*
+ * Copyright (c) 2017 Linaro Limited
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr.h>
+#include <device.h>
+#include <sensor.h>
+#include <stdio.h>
+#include <misc/util.h>
+
+void main(void)
+{
+	struct sensor_value temp, hum;
+	struct device *dev = device_get_binding("HTS221");
+
+	if (dev == NULL) {
+		printf("Could not get HTS221 device\n");
+		return;
+	}
+
+	while (1) {
+		if (sensor_sample_fetch(dev) < 0) {
+			printf("Sensor sample update error\n");
+			return;
+		}
+
+		if (sensor_channel_get(dev, SENSOR_CHAN_TEMP, &temp) < 0) {
+			printf("Cannot read HTS221 temperature channel\n");
+			return;
+		}
+
+		if (sensor_channel_get(dev, SENSOR_CHAN_HUMIDITY, &hum) < 0) {
+			printf("Cannot read HTS221 humidity channel\n");
+			return;
+		}
+
+		/* display temperature */
+		printf("Temperature:%.1f C\n", sensor_value_to_double(&temp));
+
+		/* display humidity (converted from millipercent) */
+		printf("Relative Humidity:%.0f%%\n",
+		       sensor_value_to_double(&hum) / 1000);
+
+		k_sleep(2000);
+	}
+}

samples/sensor/hts221/testcase.ini

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+[test]
+build_only = true
+tags = samples sensor
+platform_whitelist = disco_l475_iot1