samples: sensor: dht_polling: Add generic dht sample application

This simple application periodically prints the temperature and humidity
measured by one or more digital humidity/temperature sensors.

Signed-off-by: Ian Morris <[email protected]>

samples/sensor/dht_polling/CMakeLists.txt

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+# Copyright (c) 2023 Ian Morris
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(dht_polling)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})

samples/sensor/dht_polling/README.rst

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+.. _dht_polling:
+
+Generic Digital Humidity Temperature sensor polling sample
+##########################################################
+
+Overview
+********
+
+This sample application demonstrates how to use digital humidity temperature
+sensors.
+
+Building and Running
+********************
+
+This sample supports up to 10 humidity/temperature sensors. Each sensor needs to
+be aliased as ``dhtN`` where ``N`` goes from ``0`` to ``9``. For example:
+
+.. code-block:: devicetree
+
+  / {
+	aliases {
+			dht0 = &hs300x;
+		};
+	};
+
+Make sure the aliases are in devicetree, then build and run with:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/sensor/dht_polling
+   :board: <board to use>
+   :goals: build flash
+   :compact:
+
+Sample Output
+=============
+
+.. code-block:: console
+
+       hs300x@44: temp is 25.31129 oC humidity is 30.391259 %RH
+       hs300x@44: temp is 25.51272 oC humidity is 30.446194 %RH
+       hs300x@44: temp is 25.51272 oC humidity is 30.372947 %RH
+       hs300x@44: temp is 25.51272 oC humidity is 30.391259 %RH
+       hs300x@44: temp is 25.31129 oC humidity is 30.372947 %RH
+       hs300x@44: temp is 25.31129 oC humidity is 30.354635 %RH
+       hs300x@44: temp is 25.51272 oC humidity is 30.372947 %RH
+       hs300x@44: temp is 25.51272 oC humidity is 30.372947 %RH
+       hs300x@44: temp is 25.51272 oC humidity is 30.391259 %RH
+       hs300x@44: temp is 25.51272 oC humidity is 30.446194 %RH
+       hs300x@44: temp is 25.51272 oC humidity is 30.531648 %RH

samples/sensor/dht_polling/boards/nucleo_f401re.overlay

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+/*
+ * Copyright (c) 2023 Ian Morris
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	aliases {
+		dht0 = &hs300x;
+	};
+};
+
+ &i2c1 {
+	status = "okay";
+
+	hs300x: hs300x@44 {
+		compatible = "renesas,hs300x";
+		reg = <0x44>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+	};
+};

samples/sensor/dht_polling/prj.conf

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+CONFIG_STDOUT_CONSOLE=y
+CONFIG_SENSOR=y

samples/sensor/dht_polling/sample.yaml

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+#
+# Copyright (c) 2023 Ian Morris
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+sample:
+  description: Digital Humidity Temperature polling sample
+  name: DHT polling sample
+tests:
+  sample.sensor.dht_polling:
+    tags: sensors
+    filter: dt_alias_exists("dht0")
+    integration_platforms:
+      - nucleo_f401re
+    harness: console
+    harness_config:
+      type: one_line
+      regex:
+        - "[0-9A-Za-z_,+-.]*@[0-9A-Fa-f]*: temp is (.*) oC humidity is (.*) %RH"

samples/sensor/dht_polling/src/main.c

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+/*
+ * Copyright (c) 2023 Ian Morris
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <zephyr/device.h>
+#include <zephyr/drivers/sensor.h>
+#include <zephyr/sys/util_macro.h>
+#include <zephyr/kernel.h>
+
+#define DHT_ALIAS(i) DT_ALIAS(_CONCAT(dht, i))
+#define DHT_DEVICE(i, _)                                                                 \
+	IF_ENABLED(DT_NODE_EXISTS(DHT_ALIAS(i)), (DEVICE_DT_GET(DHT_ALIAS(i)),))
+
+/* Support up to 10 temperature/humidity sensors */
+static const struct device *const sensors[] = {LISTIFY(10, DHT_DEVICE, ())};
+
+int main(void)
+{
+	int rc;
+
+	for (size_t i = 0; i < ARRAY_SIZE(sensors); i++) {
+		if (!device_is_ready(sensors[i])) {
+			printk("sensor: device %s not ready.\n", sensors[i]->name);
+			return 0;
+		}
+	}
+
+	while (1) {
+		for (size_t i = 0; i < ARRAY_SIZE(sensors); i++) {
+			struct device *dev = (struct device *)sensors[i];
+
+			rc = sensor_sample_fetch(dev);
+			if (rc < 0) {
+				printk("%s: sensor_sample_fetch() failed: %d\n", dev->name, rc);
+				return rc;
+			}
+
+			struct sensor_value temp;
+			struct sensor_value hum;
+
+			rc = sensor_channel_get(dev, SENSOR_CHAN_AMBIENT_TEMP, &temp);
+			if (rc == 0) {
+				rc = sensor_channel_get(dev, SENSOR_CHAN_HUMIDITY, &hum);
+			}
+			if (rc != 0) {
+				printf("get failed: %d\n", rc);
+				break;
+			}
+
+			printk("%16s: temp is %d.%d oC humidity is %d.%d %%RH\n", dev->name,
+							temp.val1, temp.val2, hum.val1, hum.val2);
+		}
+		k_msleep(1000);
+	}
+	return 0;
+}