samples: sensor: Add sample for MH-Z19B

Add sample for MH-Z19B CO2
sensor.

Signed-off-by: Yong Cong Sin <[email protected]>

Author: ycsin

samples/sensor/mhz19b/CMakeLists.txt

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+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(mhz19b)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})

samples/sensor/mhz19b/README.rst

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+.. _mhz19b-sample:
+
+MH-Z19B: CO2 Sensor Sample
+##########################
+
+Description
+***********
+
+This sample application demonstrate the configurations of the MH-Z19B CO2
+sensor, then periodically reads CO2 data from the sensor. The driver
+currently only support uart interrupt APIs.
+
+Requirements
+************
+
+The baudrate of the UART must be configured to 9600, and must support
+interrupt driven API.
+
+Building and Running
+********************
+
+To build the application, a board with UART interface
+has to be chosen, or a custom devicetree overlay has to be provided.
+Here Nucleo G0B1RE board is used.
+Then, connect the RX and TX from your Zephyr target board to the
+MH-Z19B CO2 sensor and power the sensor according to the datasheet.
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/sensor/mhz19b
+   :board: nucleo_g0b1re
+   :goals: build
+   :compact:
+
+Sample Output
+=============
+
+The application will perform runtime configuration of the sensor, then
+read back the sensor configuration data. After that it will read the CO2
+data every 2 seconds.
+
+.. code-block:: console
+
+   Winsen MH-Z19B CO2 sensor application
+   Configuring sensor - OK
+   Reading configurations from sensor:
+   Sensor range is set to 5000ppm
+   Sensor ABC is enabled
+   sensor: co2 reading: 758
+   sensor: co2 reading: 759
+   sensor: co2 reading: 762
+
+   <repeats endlessly every 2 seconds>

samples/sensor/mhz19b/boards/nucleo_g0b1re.overlay

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+/*
+ * Copyright (c) 2021, G-Technologies Sdn. Bhd.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&usart1 {
+	current-speed = <9600>;
+	mhz19b {
+		compatible = "winsen,mhz19b";
+		maximum-range = <10000>;
+		abc-on;
+		label = "MHZ19B_2";
+	};
+};

samples/sensor/mhz19b/prj.conf

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+CONFIG_STDOUT_CONSOLE=y
+CONFIG_SERIAL=y
+CONFIG_UART_INTERRUPT_DRIVEN=y
+CONFIG_SENSOR=y
+CONFIG_MHZ19B=y

samples/sensor/mhz19b/sample.yaml

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+#
+# Copyright (c) 2021 G-Technologies Sdn. Bhd.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+sample:
+  name: MH-Z19B CO2 sensor
+tests:
+  sample.sensor.mhz19b:
+    build_only: true
+    harness: sensor
+    tags: sensors
+    depends_on: serial
+    filter: dt_compat_enabled("winsen,mhz19b")

samples/sensor/mhz19b/src/main.c

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+/*
+ * Copyright (c) 2021 G-Technologies Sdn. Bhd.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr.h>
+#include <sys/printk.h>
+#include <drivers/sensor.h>
+#include <drivers/sensor/mhz19b.h>
+
+void main(void)
+{
+	const struct device *dev;
+	struct sensor_value val;
+	int ret;
+
+	printk("Winsen MH-Z19B CO2 sensor application\n");
+
+	dev = DEVICE_DT_GET_ONE(winsen_mhz19b);
+	if (!device_is_ready(dev)) {
+		printk("sensor: device not found.\n");
+		return;
+	}
+
+	printk("Configuring sensor - ");
+
+	val.val1 = 5000;
+	ret = sensor_attr_set(dev, SENSOR_CHAN_CO2, SENSOR_ATTR_FULL_SCALE, &val);
+	if (ret != 0) {
+		printk("failed to set range to %d\n", val.val1);
+		return;
+	}
+
+	val.val1 = 1;
+	ret = sensor_attr_set(dev, SENSOR_CHAN_CO2, SENSOR_ATTR_MHZ19B_ABC, &val);
+	if (ret != 0) {
+		printk("failed to set ABC to %d\n", val.val1);
+		return;
+	}
+
+	printk("OK\n");
+
+	printk("Reading configurations from sensor:\n");
+
+	ret = sensor_attr_get(dev, SENSOR_CHAN_CO2, SENSOR_ATTR_FULL_SCALE, &val);
+	if (ret != 0) {
+		printk("failed to get range\n");
+		return;
+	}
+
+	printk("Sensor range is set to %dppm\n", val.val1);
+
+	ret = sensor_attr_get(dev, SENSOR_CHAN_CO2, SENSOR_ATTR_MHZ19B_ABC, &val);
+	if (ret != 0) {
+		printk("failed to get ABC\n");
+		return;
+	}
+
+	printk("Sensor ABC is %s\n", val.val1 == 1 ? "enabled" : "disabled");
+
+	while (1) {
+		if (sensor_sample_fetch(dev) != 0) {
+			printk("sensor: sample fetch fail.\n");
+			return;
+		}
+
+		if (sensor_channel_get(dev, SENSOR_CHAN_CO2, &val) != 0) {
+			printk("sensor: channel get fail.\n");
+			return;
+		}
+
+		printk("sensor: co2 reading: %d\n", val.val1);
+
+		k_msleep(2000);
+	}
+}