ESP8266智能家居（3）——单片机数据发送到mqtt服务器

news2024/11/21 0:27:39

1.主要思想

前期已学习如何用ESP8266连接WIFI，并发送数据到服务器。现在只需要在单片机与nodeMCU之间建立起串口通信，这样单片机就可以将传感器测到的数据：光照，温度，湿度等等传递给8266了，然后8266再对数据进行打包，发送到服务器。

51单片机和nodeMCU的连线方式如下

它们串口的两根线交叉连接，二者的USB供电端一起接在电脑的USB口上。如果它们不是用的同一套供电系统，就需要注意共地的问题！

2.代码设计

51单片机的主体代码大致如下;

主要就是测量一些数据，然后通过串口发送到nodeMCU

nodeMCU的代码如下：

#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <ArduinoJson.h>
const char* ssid = "iPhone";          //WIFI名称   自己补上你的WIFI
const char* password = "12345678";      //WIFI密码    自己补上你的密码
const char* mqtt_server = "broker-cn.emqx.io";      //mqtt服务器地址 （IP/域名）  不改
const char *pubTopic="my_pubtopic";
const char *subTopic="my_subtopic";


WiFiClient espClient;
PubSubClient client(espClient);

char information[80]="";
int value = 0;

void setup_wifi() {

  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

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

  randomSeed(micros());

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

void callback(char* topic, byte* payload, unsigned int length) {
  String cmd="";
  for (int i = 0; i < length; i++) {
    cmd+=(char)payload[i];
  }
  const size_t capacity = JSON_OBJECT_SIZE(1) + 10;   //计算buffer的大小   ...SIZE（1）表明buffer中只有一个对象
  DynamicJsonBuffer jsonBuffer(capacity);           //创建动态的jsonbuffer
 JsonObject& root = jsonBuffer.parseObject(cmd);     //解析Json对象字符串
 Serial.println("get");
 if(root.containsKey("led"))      //判断是否包含某个键
 {
  int led = root["led"]; 
  if(led==1)
  {
     Serial.println("1");
   }
  else
    Serial.println("2");
 }
 if(root.containsKey("beep"))      //判断是否包含某个键
 {
  int beep = root["beep"]; 
  if(beep==1)
  {
     Serial.println("3");
   }
  else
    Serial.println("4");
 }
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Create a random client ID
    String clientId = "ESP8266Client-";
    clientId += String(random(0xffff), HEX);
    // Attempt to connect
    if (client.connect(clientId.c_str())) {
      Serial.println("connected");
      // Once connected, publish an announcement...
      client.publish(pubTopic, "hello world");
      // ... and resubscribe
      client.subscribe(subTopic);
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}



void setup() {
  Serial.begin(9600);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

void loop() {

  if (!client.connected()) {
    reconnect();
  }
  client.loop();
  value=0;
  while(!Serial.available());    //等待数据传送过来，若没有数据，一直等待，即执行到本行不向下执行
  while(Serial.available())
  {    
    information[value]=(char)Serial.read();  
    value++;  
    delay(3);
  }
    client.publish(pubTopic, information); 
    Serial.print(information);
 // }
}