我正在用Arduino编程ESP32,并正在使用标准的pubsubclient库发布MQTT消息。
[在下面的循环中,我注意到我的“内部循环”已发布,但是,变量jsonObjChar
的第二条消息似乎从未发布过该主题?串行监视器中没有任何错误。
void loop(){
String temperature = String(readDHTTemperature());
String humidity = String(readDHTHumidity());
String light = String(readLDRLight());
String jsonObj = "{";
jsonObj.concat("\"deviceId\":\"123456\"");
jsonObj.concat(",");
jsonObj.concat("\"messageType\":\"ambientSensorReading\"");
jsonObj.concat(",");
jsonObj.concat("\"temperature\":\"");
jsonObj.concat(temperature);
jsonObj.concat("\"");
jsonObj.concat(",");
jsonObj.concat("\"humidity\":\"");
jsonObj.concat(humidity);
jsonObj.concat("\"");
jsonObj.concat(",");
jsonObj.concat("\"light\":\"");
jsonObj.concat(light);
jsonObj.concat("\"}");
delay(1000);
int jsonObjCharLength = jsonObj.length() + 1;
char jsonObjChar[jsonObjCharLength];
jsonObj.toCharArray(jsonObjChar, jsonObjCharLength);
Serial.println("PREPARED");
Serial.println(jsonObjChar);
const char topic[13] = "prototype001";
client.publish(topic, "inside loop");
client.publish(topic, jsonObjChar);
// ... and resubscribe
client.subscribe("prototype001");
delay(5000);
}
[jsobObjChar
变量似乎很好,当我将其打印到串行监视器时,它看起来像一个普通的字符串(我已经以JSON格式构造为在服务器端处理)
20:13:41.494 -> PREPARED
20:13:41.494 -> {"deviceId":"123456","messageType":"ambientSensorReading","temperature":"25.10","humidity":"49.90","light":"2592"}
20:13:46.521 ->
如果有帮助,我正在使用cloudmqtt。
任何帮助将不胜感激!!
尝试摆脱字符串,它们会破坏您的堆并导致崩溃。定义全局固定的charBuffers(足够大以容纳最大的消息)和helper(tmp字符)以进行转换和其他操作)不要在循环中定义const字符,而是在设置之前进行操作,因此编译器将它们放置在堆栈中并且不使用堆在运行时。我将您的代码更改为此原则,并在消息之间增加了额外的延迟:
const char topic[13] = "prototype001"; // goes to the stack
char jsonObjChar [256] = '\0'; // set it large enough goes to the stack not heap!
char numBuffer [16] = '\0'; //tmpBuffer for conversion of ints to char
void loop(){
if (!client.connected()) {
reconnect();
}
strcpy (jsonObj, "{"); // Initialize/clear char by using strcpy
strcat(jsonObj, "\"deviceId\":\"123456\""); // strcat append
strcat(jsonObj,",");
strcat(jsonObj,"\"messageType\":\"ambientSensorReading\"");
strcat(jsonObj,",");
strcat(jsonObj,"\"temperature\":\"");
// conversion only needed if temperature is an int, if its char use strcat(jsonObj,readDHTTemperature());
itoa (readDHTTemperature(), numBuffer, 10); // Converts an int to a char array
strcat(jsonObj,numbuffer);
strcat(jsonObj,"\"");
strcat(jsonObj,",");
strcat(jsonObj,"\"humidity\":\"");
// if already char use strcat(jsonObj,readDHTHumidity());
itoa (readDHTHumidity(), numBuffer, 10);
strcat(jsonObj,numbuffer);
strcat(jsonObj,"\"");
strcat(jsonObj,",");
strcat(jsonObj,"\"light\":\"");
// if char strcat(jsonObj,readLDRLight());
itoa (readLDRLight(),numBuffer. 10);
strcat(jsonObj,numbuffer);
strcat(jsonObj,"\"}");
delay(1000);
Serial.println("PREPARED");
Serial.println(jsonObjChar);
client.publish(topic, "inside loop");
delay(1000); // for test onl<
client.publish(topic, jsonObjChar);
// ... and resubscribe
client.subscribe("prototype001");
delay(5000);
client.loop();
}
[如果有效-很好。如果不是,则下一个调试步骤将是查看服务器上收到的内容。