Why mqtt discovery information can't publish to mqtt server

Hardware
1 
#include <PubSubClient.h>
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ArduinoJson.h>
#include <DHTesp.h>




//参数配置
const char* ssid = "******";
const char* password = "*******";
const int mqttPort = 1883;
const char* mqttUser = "***";
const char* mqttPassword = "********";
const char* mqttServer = "********";

// json dht
long lastMsg = 0;
int value = 0;

char msg[300]; //存放json数据
char msg1[300];
char msg2[100];
float humidity;
float temperature;

DHTesp dht;

WiFiClient espClient;
PubSubClient client(espClient);


// mqtt 消息回调
void callback(char *topic, byte* payload, int length) {
  Serial.print("Messageved in topic: ");
  Serial.println(topic);
  Serial.println();
  char receivedChar[100];
  for (int i = 0; i < length; i++) {
    receivedChar[i] = (char)payload[i];
  }

  Serial.print("meaasge: ");
  Serial.println(receivedChar);

  //  if (strcmp(receivedChar, "ON") == 0) {
  //    led_open();
  //  } else if (strcmp(receivedChar, "OFF") == 0) {
  //    led_close();
  //  }
  Serial.println();
}


// 链接mqtt wifi
void connect_wifi_mqtt() {
  // 连接wifi
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.println();
    Serial.println("Connecting WiFi...");
  }
  Serial.println("Connect to the WiFi network success!");

  // 连接mqtt服务器
  // 设置服务器与回调函数
  client.setServer(mqttServer, mqttPort);
  client.setCallback(callback);

  while (!client.connected()) {
    Serial.println("Connecting to MQTT...");
    if (client.connect("ESP8266Client", mqttUser, mqttPassword ))
    {
      Serial.println("Connect to the mqtt server success!");
    } else {
      Serial.println("failed state ");
      Serial.println(client.state());
      delay(2000);
    }
  }
  if (client.connect("ESP8266Client", mqttUser, mqttPassword)) {
    Serial.println("connected");
  } else {
    Serial.print("failed state");
    Serial.print(client.state());
    delay(2000);
  }
}


// mqtt掉线重连
void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect("ESP8266 Client")) {
      Serial.println("connected");
      //      ******************************
      // ... and subscribe to topic
      //    ***************************************

    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println("try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}


// JSON编码
void encodeJson() {
  DynamicJsonBuffer jsonBuffer;
  JsonObject& root1 = jsonBuffer.createObject();
  JsonObject& root2 = jsonBuffer.createObject();
  JsonObject& root3 = jsonBuffer.createObject();

  root1["device_class"] = "sensor";
  root1["name"] = "Temperature";
  root1["state_topic"] = "homeassistant/sensor/sensorBedroom/state";
  root1["unit_of_measurement"] = "°C";
  root1["value_template"] = "{{ value_json.temperature}}";
  //  root1.prettyPrintTo(Serial);
  root1.printTo(msg);

  root2["device_class"] = "sensor";
  root2["name"] = "Humidity";
  root2["state_topic"] = "homeassistant/sensor/sensorBedroom/state";
  root2["unit_of_measurement"] = "%";
  root2["value_template"] = "{{ value_json.humidity}}";
  root2.printTo(msg1);

  root3["humidity"] = humidity;
  root3["temperature"] = temperature;
  //  root3.prettyPrintTo(Serial);
  root3.printTo(msg2);

}

//JSON解码
//void decodeJson(char msg[100]){
//  DynamicJsonBuffer jsonBuffer;
//  JsonObject& root = jsonBuffer.parseObject(msg);
//  float temp = root["Temperature"];
//  float hum = root["Humidity"];
//
//  Serial.println(temp);
//  Serial.println(hum);
//}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  connect_wifi_mqtt();

  dht.setup(4, DHTesp::DHT11);
  // 订阅节点
  //  client.subscribe("LED");
  //  pinMode(pinLED, OUTPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
  delay(dht.getMinimumSamplingPeriod());

  humidity = dht.getHumidity();
  temperature = dht.getTemperature();

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

  encodeJson();

  long now = millis();//记录当前时间
  if (now - lastMsg > 1000) {//每隔1000毫秒秒发一次数据
    encodeJson();
    client.publish("homeassistant/sensor/sensorBedroomT/config", msg);
    client.publish("homeassistant/sensor/sensorBedroomH/config", msg1);
    //    Serial.println(msg);

    if (isnan(humidity)) {
      return;
    } else {

      client.publish("homeassistant/sensor/sensorBedroom/state", msg2);
      client.publish("test", "ttt");
      //      Serial.println(msg2);
      lastMsg = now;
    }
  }
}

but dht data can publish, who can tell me why? thanks

2

FIrst of all, the config message doesn’t need to be sent every time through the loop - only when the MQTT connection is established. I would also add the retain flag, so that HA is configured correctly whenever it restarts.

But I can’t see anything that would stop the data message being published. Does anything get sent?

3

thanks, i try it, but nothing publish to my mqtt server, i can print the msg and msg1 data to my serial

client.publish("homeassistant/sensor/sensorBedroomT/config", msg);
client.publish("homeassistant/sensor/sensorBedroomH/config", msg1);

but the dht meaasge can publish to my server, do you know why?

client.publish("homeassistant/sensor/sensorBedroom/state", msg2);
4

I solved the problem, because the PubSubClient limit the message length, default 128 bytes. Change it in PubSubClient.h can solve this problem. thanks for your advice!

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