基于MQTT协议与ESP8266平台的家庭环境监控实现 | 千里

在智能家居的应用场景中，传感器一直是非常重要的组成部分。比如传感器报告的温度高了可以自动关窗开空调。在一般的使用场景中，众多的传感器和开关会分散在房子中的不同位置，通过布线连接是不现实的，理想的情况当然是通过已有的无线网络进行连接，网络传输就需要特定的协议，MQTT协议就是一个不错的选择。

手头刚好有一些传感器和一个ESP8266芯片的单片机（WeMos D1），做了一个家庭温湿度、光照及空气质量监控器，并通过MQTT协议推送数据到Home Assistant平台。

MQTT

MQTT（Message Queue Telemetry Transport）是一个基于TCP／IP协议的轻量级的发布／订阅消息通讯协议，其最初就是设计来适应嵌入式设备通讯中遇到的硬件计算能力有限，网络带宽低且不可靠等问题，因此它具有开销小（固定长度的头部只有2字节）及异常中断处理等特性。它在IoT领域被大量的应用，尤其在传感器的监测数据推送方面。如Amazon IoT、Microsoft Azure IoT Hub等都把MQTT做为其主要支持的协议。

MQTT需要一个Broker服务器才可以正常工作，我选择了一个开源的MQTT服务器EMQ，可以通过Docker来部署：

1	docker run -d --name=emq -d -p 18083:18083 -p 1883:1883 -p 8083:8083 -p 8443:8443 --restart=always devicexx/emqttd

硬件

下边是硬件的BOM，价格是我购买时的淘宝价：

硬件	价格	说明
WeMos D1	¥16.5	支持Wifi的单片机，可以使用Arduino的IDE进行开发
DHT22	¥13.7	可能是使用最广泛的温湿度模块之一，测量结果准确
Arduino光敏电阻模块	¥3.49	量程较短，弱光测量效果不理想
攀藤科技G5	¥130	淘宝上能找到的比较靠谱的空气质量传感器

装起来就是这个样子的：

下边是代码：

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#include #include #include #include #include #include #include WiFiClient net; MQTTClient client; // DHT22传感器连在Pin D4 DHT_Unifieddht(D4, DHT22); // 攀藤科技G5使用serial连接，这里使用Pin D1与D2做Software Serial SoftwareSerialpmSerial(D1, D2); constcharssid[] ="你的WIFI网络名称"; constcharpass[] ="你的WIFI密码"; #defineLENG 31//0x42 + 31 bytes equal to 32 bytes unsignedcharbuf[LENG]; intPM01Value =0;// PM1值 intPM2_5Value =0;// PM2.5值 intPM10Value =0;// PM10值 unsignedlonglastMillis =0; voidconnect();// <- predefine connect() for setup() voidsetup(){ Serial.begin(115200); pmSerial.begin(9600); pmSerial.setTimeout(1500); dht.begin(); sensor_tsensor; dht.temperature().getSensor(&sensor); Serial.println("------------------------------------"); Serial.println("Temperature"); Serial.print ("Sensor: "); Serial.println(sensor.name); Serial.print ("Driver Ver: "); Serial.println(sensor.version); Serial.print ("Unique ID: "); Serial.println(sensor.sensor_id); Serial.print ("Max Value: "); Serial.print(sensor.max_value); Serial.println(" *C"); Serial.print ("Min Value: "); Serial.print(sensor.min_value); Serial.println(" *C"); Serial.print ("Resolution: "); Serial.print(sensor.resolution); Serial.println(" *C"); Serial.println("------------------------------------"); // Print humidity sensor details. dht.humidity().getSensor(&sensor); Serial.println("------------------------------------"); Serial.println("Humidity"); Serial.print ("Sensor: "); Serial.println(sensor.name); Serial.print ("Driver Ver: "); Serial.println(sensor.version); Serial.print ("Unique ID: "); Serial.println(sensor.sensor_id); Serial.print ("Max Value: "); Serial.print(sensor.max_value); Serial.println("%"); Serial.print ("Min Value: "); Serial.print(sensor.min_value); Serial.println("%"); Serial.print ("Resolution: "); Serial.print(sensor.resolution); Serial.println("%"); Serial.println("------------------------------------"); WiFi.begin(ssid, pass); // Note: Local domain names (e.g. "Computer.local" on OSX) are not supported by Arduino. // You need to set the IP address directly. client.begin("MQTT服务器地址", net); client.onMessage(messageReceived); connect(); } voidconnect(){ Serial.print("checking wifi..."); while(WiFi.status() != WL_CONNECTED) { Serial.print("."); delay(1000); } Serial.print("\nconnecting..."); while(!client.connect("arduino","try","try")) { Serial.print("."); delay(1000); } Serial.println("\nconnected!"); // 这里可以订阅自己发布的消息，调试用 // client.subscribe("/home/livingroom/brightness"); // client.subscribe("/home/livingroom/temperature"); // client.subscribe("/home/livingroom/humidity"); // client.subscribe("/home/livingroom/air"); } voidloop(){ client.loop(); delay(10);// <- fixes some issues with WiFi stability if(!client.connected()) { connect(); } // 每5秒推送一次状态 if(millis() - lastMillis >5000) { lastMillis = millis(); client.publish("/home/livingroom/brightness","{\"value\": "+ String(1024- analogRead(A0)) +"}"); sensors_event_tevent; dht.temperature().getEvent(&event); if(isnan(event.temperature)) { Serial.println("Error reading temperature!"); } else{ client.publish("/home/livingroom/temperature","{\"value\": "+ String(event.temperature) +"}"); } // Get humidity event and print its value. dht.humidity().getEvent(&event); if(isnan(event.relative_humidity)) { Serial.println("Error reading humidity!"); } else{ client.publish("/home/livingroom/humidity","{\"value\": "+ String(event.relative_humidity) +"}"); } if(pmSerial.find(0x42)) {//start to read when detect 0x42 pmSerial.readBytes(buf, LENG); if(buf[0] ==0x4d) { if(checkValue(buf, LENG)) { PM01Value = transmitPM01(buf);//count PM1.0 value of the air detector module PM2_5Value = transmitPM2_5(buf);//count PM2.5 value of the air detector module PM10Value = transmitPM10(buf);//count PM10 value of the air detector module client.publish("/home/livingroom/air","{\"pm1\":"+ String(PM01Value) +", \"pm25\": "+ String(PM2_5Value) +", \"pm10\": "+ String(PM10Value) +"}"); } } } } } voidmessageReceived(String &topic, String &payload){ Serial.println("incoming: "+ topic +" - "+ payload); } charcheckValue(unsignedchar*thebuf,charleng) { charreceiveflag =0; intreceiveSum =0; for(inti =0; i < (leng -2); i++) { receiveSum = receiveSum + thebuf[i]; } receiveSum = receiveSum +0x42; if(receiveSum == ((thebuf[leng -2] <<8) + thebuf[leng -1]))//check the serial data { receiveSum =0; receiveflag =1; } returnreceiveflag; } inttransmitPM01(unsignedchar*thebuf) { intPM01Val; PM01Val = ((thebuf[3] <<8) + thebuf[4]);//count PM1.0 value of the air detector module returnPM01Val; } inttransmitPM2_5(unsignedchar*thebuf) { intPM2_5Val; PM2_5Val = ((thebuf[5] <<8) + thebuf[6]);//count PM2.5 value of the air detector module returnPM2_5Val; } inttransmitPM10(unsignedchar*thebuf) { intPM10Val; PM10Val = ((thebuf[7] <<8) + thebuf[8]);//count PM10 value of the air detector module returnPM10Val; }

编译烧录还需要在Arduino IDE的库管器中安装下边的库：

• Adafruit Unified Sensor
• DHT sensor library
• MQTT

Home Assistant

关于Home Assistant介绍与安装可以参考使用Docker安装Home Bridge与Home Assistant，用Siri控制智能家居。

Home Assistant的配置如下，需要替换“MQTT服务器的IP地址”为真实的服务器地址：

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homeassistant: customize: sensor.brightness_sensor: friendly_name:'光照强度' sensor.temperature_sensor: friendly_name:'室内温度' sensor.humidity_sensor: friendly_name:'室内湿度' sensor.pm1_sensor: friendly_name:'PM1.0' sensor.pm25_sensor: friendly_name:'PM2.5' sensor.pm10_sensor: friendly_name:'PM10' mqtt: broker:MQTT服务器的IP地址 discovery:true discovery_prefix:homeassistant birth_message: topic:'hass/status' payload:'online' will_message: topic:'hass/status' payload:'offline' sensor: - platform:mqtt name:"Brightness Sensor" state_topic:"/home/livingroom/brightness" value_template:"{{ value_json.value }}" - platform:mqtt name:"Temperature Sensor" state_topic:"/home/livingroom/temperature" unit_of_measurement:"°C" value_template:"{{ value_json.value }}" - platform:mqtt name:"Humidity Sensor" state_topic:"/home/livingroom/humidity" unit_of_measurement:"%" value_template:"{{ value_json.value }}" - platform:mqtt name:"PM1 Sensor" state_topic:"/home/livingroom/air" unit_of_measurement:"ug/m3" value_template:"{{ value_json.pm1 }}" - platform:mqtt name:"PM2.5 Sensor" state_topic:"/home/livingroom/air" unit_of_measurement:"ug/m3" value_template:"{{ value_json.pm25 }}" - platform:mqtt name:"PM10 Sensor" state_topic:"/home/livingroom/air" unit_of_measurement:"ug/m3" value_template:"{{ value_json.pm10 }}"

在Home Assistant中看到的效果是这样的：

参考

• MQTT百度百科
• MQTT Wiki Page
• Home Assistant Docs: MQTT
• 攀藤科技G5 数据手册
• Adafruit DHT22 Sensor Library Example
• Arduino MQTT Library ESP8266 Example