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：

#include<Arduino.h>
#include<SoftwareSerial.h>
#include<ESP8266WiFi.h>
#include<MQTTClient.h>
#include<Adafruit_Sensor.h>
#include<DHT.h>
#include<DHT_U.h>
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：

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：

基于MQTT协议与ESP8266平台的家庭环境监控实现 | 千里

MQTT

硬件

Home Assistant

参考

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