使用 ESP8266 进行 mqtt 发布时出现异常

Question

我正在使用其 mqttAPI 将传感器读数发布到 thingSpeak。我已经在 Huzzah esp8266 板上部署了我的项目。在发布一个值之后，我得到了 ESP 异常 9、28。我想我在使用 loop() 函数时遇到了问题。这是我的代码

void loop() {

    if(!mqttCli.connected()){
        reconnectMQTT();  
      }
      mqttCli.loop();

      if(millis()-mqttTimer>mqttInterval){
          taskWiFiCallback();
        }

       }
void taskWiFiCallback(){
   Serial.println("task WiFi Started");
    if(!mqttCli.connected()){
        Serial.println("mqtt not connected");
        reconnectMQTT();
        return;
      }

   Serial.println("mqtt Connection established");
   Serial.println("State:" + mqttCli.connected());

   String topicString ="channels/"+String(channelID)+"/publish/"+String(writeAPIKey);
   int topicLength = topicString.length();
   char topicBuffer[topicLength];
   topicString.toCharArray(topicBuffer,topicLength+1);

   Serial.println(topicBuffer);

   String dataString  = String("field1="+ String(tempC,1) + "&field2=" + String(tempF,1) + "&field3=" + String(humid,1));
   int dataLength = dataString.length();
   char dataBuffer[dataLength];
   dataString.toCharArray(dataBuffer,dataLength+1);
   Serial.println(dataBuffer);
   Serial.println(mqttCli.publish(topicBuffer,dataBuffer) ? "Published" : "Not Published Bawa, Do Something");

   mqttTimer = millis();


 }

void reconnectMQTT(){
 Serial.println("setting up mqtt");
 WiFiClient wifiClient;
 mqttCli.setServer(mqtt_server,1883);
 mqttCli.setClient(wifiClient);
 mqttCli.setCallback(&callback);

 // Creating a random client ID
 String clientId = "ESP8266Client-";
 clientId += String(random(0xffff), HEX);

 while(!mqttCli.connected()){
    if(mqttCli.connect(clientId.c_str())){
    String subTopic = String("channels/"+ String(channelID) + 
    "/subscribe/json/" + String(readAPIKey));
    int subTopicLength = subTopic.length();
    char subTopicBuffer[subTopicLength];
    subTopic.toCharArray(subTopicBuffer,subTopicLength);

    String pubTopic ="channels/" + String( channelID ) + 
    "/publish/"+String(writeAPIKey);
    char pubTopicBuffer[pubTopic.length()];
    pubTopic.toCharArray(pubTopicBuffer,pubTopic.length()+1);

    String message = String("field1=" + String(tempC,1) + "&field2=" + 
    String(tempF,1) + "&field3=" + String(humid,1));
    char messageBuffer[message.length()];
    message.toCharArray(messageBuffer,message.length()+ 1);
    Serial.println(messageBuffer);
    Serial.println(mqttCli.publish(pubTopicBuffer,messageBuffer) ? "Published" : "Unpublished");
    Serial.println(mqttCli.subscribe(subTopicBuffer) ? "Subscribed" : "Unsubscribed"); 

  }else{
       Serial.print("failed, rc=");
      Serial.println(mqttCli.state());
      delay(1000);
    }
}

}

我已经订阅了该主题，它给出了正确的结果，甚至在 reconnectMQTT() 函数中发布。

Answer 1

可能还有其他问题，但要开始：

int topicLength = topicString.length();
char topicBuffer[topicLength];
topicString.toCharArray(topicBuffer,topicLength+1);

您正在声明 topicLength 字节的缓冲区，然后将 topicLength + 1 字节复制到其中。您总是会超出缓冲区一个字节。您需要将其声明为 topicLength + 1 字节长，以便为 C 语言 [=16=] 字符串终止符留出空间。所以：

int topicLength = topicString.length();
char topicBuffer[topicLength+1];
topicString.toCharArray(topicBuffer,topicLength+1);

或者，更好：

int topicLength = topicString.length()+1;
char topicBuffer[topicLength];
topicString.toCharArray(topicBuffer,topicLength);

以后 dataBuffer 以及 pubTopic、messageBuffer 和任何其他将 String 转换为 char 数组的地方也是如此。

此外，请注意您的行

subTopic.toCharArray(subTopicBuffer,subTopicLength);

不会在您在其他地方的长度上加 1 的地方加 1。

使用 ESP8266 进行 mqtt 发布时出现异常

Exception during mqtt publish using ESP8266

arduino

mqtt

esp8266

arduino-esp8266