使用ESP8266快速开发一个物联网应用

MQTT模板

一个好的模板将极大的提高编程效率

传感器 发送数据

以超声波为例

#include 
#include 
#include 
#include 
#include 
#include  // Only needed for Arduino 1.6.5 and earlier

//Wifi Configuration
#define MQTT_VERSION MQTT_VERSION_3_1_1
const char* WIFI_SSID = "wifi ssid";
const char* WIFI_PASSWORD = "wifi password";
const PROGMEM char* MQTT_PUBLISH_TOPIC = "topic";
const PROGMEM char* MQTT_CLIENT_ID = "client id";
const PROGMEM char* MQTT_SERVER_IP = "IP";
const PROGMEM uint16_t MQTT_SERVER_PORT = port;
const PROGMEM char* MQTT_USER = "user";
const PROGMEM char* MQTT_PASSWORD = "password";

unsigned int HighLen = 0;
unsigned int LowLen  = 0;
unsigned int Len_mm  = 0;

SoftwareSerial us100(D1,D2);//Rx,Tx
WiFiClient wifiClient;
PubSubClient client(wifiClient);

void callback(char* p_topic, byte* p_payload, unsigned int p_length) {

  // concat the payload into a string
  String payload;
  for (uint8_t i = 0; i < p_length; i++) {
    payload.concat((char)p_payload[i]);
  }

}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("INFO: Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect(MQTT_CLIENT_ID, MQTT_USER, MQTT_PASSWORD)) {
      Serial.println("INFO: connected");
      // Once connected, publish an announcement...
    } else {
      Serial.print("ERROR: failed, rc=");
      Serial.print(client.state());
      Serial.println("DEBUG: try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}
void publishData(float dist) {
  // create a JSON object
  // doc : https://github.com/bblanchon/ArduinoJson/wiki/API%20Reference
  StaticJsonBuffer<200> jsonBuffer;
  JsonObject& root = jsonBuffer.createObject();
  // INFO: the data must be converted into a string; a problem occurs when using floats...
  root["distance"] = (String)dist;
  root.prettyPrintTo(Serial);
  /*
     {
        "temperature": "23.20" ,
        "humidity": "43.70"
     }
  */
  char data[200];
  root.printTo(data, root.measureLength() + 1);
  client.publish(MQTT_PUBLISH_TOPIC, data, true);
}

void setup() {
  // set baudrate as 9600bps.
  us100.begin(9600);
  Serial.begin(9600);
  // init the WiFi connection
  Serial.println();
  Serial.println();
  Serial.print("INFO: Connecting to ");
  WiFi.mode(WIFI_STA);
  Serial.println(WIFI_SSID);
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("INFO: WiFi connected");
  Serial.print("INFO: IP address: ");
  Serial.println(WiFi.localIP());

  // init the MQTT connection
  client.setServer(MQTT_SERVER_IP, MQTT_SERVER_PORT);
  client.setCallback(callback);

}

void loop() {
  
  if (!client.connected()) {
    reconnect();
  }
    
  us100.flush();     // clear receive buffer of serial port
  us100.write(0X55); // trig US-100 begin to measure the distance
  delay(500);          //delay 500ms to wait result
  
  if(us100.available() >= 2) {                    //when receive 2 bytes 
    HighLen = us100.read();                   //High byte of distance
    LowLen  = us100.read();                   //Low byte of distance
    Len_mm  = HighLen*256 + LowLen;             //Calculate the distance
    
    Serial.print("Distance is: ");   //output the result to serial monitor
    Serial.print(Len_mm);             //output the result to serial monitor
    Serial.println("mm");  
    publishData((float)Len_mm);
  }

  delay(500);  
  client.loop();
}

仅需通过修改头部配置信息 publishData()函数 与 loop循环即可. esp8266将以JSON的数据格式向Broker发送数据

执行器 接收数据

以继电器为例

#include 
#include 
#include 
#define MQTT_VERSION MQTT_VERSION_3_1_1

//Wifi Configuration
const char* WIFI_SSID = "wifi ssid";
const char* WIFI_PASSWORD = "wifi password";
const PROGMEM char* MQTT_SUBSCRIBE_TOPIC = "relay";
const PROGMEM char* MQTT_CLIENT_ID = "relay";
const PROGMEM char* MQTT_SERVER_IP = "mqtt server ip";
const PROGMEM uint16_t MQTT_SERVER_PORT = 1883;
const PROGMEM char* MQTT_USER = "mqtt user";
const PROGMEM char* MQTT_PASSWORD = "mqtt password";

//relay

int relay = D0;

WiFiClient wifiClient;
PubSubClient client(wifiClient);

void callback(char* p_topic, byte* p_payload, unsigned int p_length) {

  String payload;
  
  for (uint8_t i = 0; i < p_length; i++) {
    payload.concat((char)p_payload[i]);
  }

  StaticJsonBuffer<200> jsonBuffer;
  // doc : https://github.com/bblanchon/ArduinoJson/wiki/API%20Reference

  JsonObject& mBuffer = jsonBuffer.parseObject(payload);

  const char* state = mBuffer["state"];

  if(state == "on"){
    digitalWrite(relay, HIGH);
  }else if(state == "off"){
    digitalWrite(relay, LOW);
  }

}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("INFO: Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect(MQTT_CLIENT_ID, MQTT_USER, MQTT_PASSWORD)) {
      Serial.println("INFO: connected");
      client.subscribe(MQTT_SUBSCRIBE_TOPIC);
    } else {
      Serial.print("ERROR: failed, rc=");
      Serial.print(client.state());
      Serial.println("DEBUG: try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void setup() {
  Serial.begin(115200);
  Serial.println();
  Serial.println();
  Serial.print("INFO: Connecting to ");
  WiFi.mode(WIFI_STA);
  Serial.println(WIFI_SSID);
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("INFO: WiFi connected");
  Serial.print("INFO: IP address: ");
  Serial.println(WiFi.localIP());

  // init the MQTT connection
  client.setServer(MQTT_SERVER_IP, MQTT_SERVER_PORT);
  client.setCallback(callback);

  pinMode(relay, OUTPUT);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
}

仅修改callback()函数即可 通过mBuffer["键"]取值
上位机数据发送示例

{"sensor":"gps","time":1351824120,"data":[48.756080,2.302038]}

注意防转义 两边的双引号