Arduino Knolleary PubSubClient 将发布消息，但无法接收它们

Question

我正在使用 Knolleary PubSubClient 连接到我的 MQTT 服务器。经过不多的工作，我已经能够成功进行身份验证并建立连接。我甚至可以向主题发布消息。但是，我遇到的问题是我可以订阅主题并且没有错误，但是当我发布到该主题时（从 Mac 上的 mosquitto），不会调用回调，并且似乎没有收到订阅主题的消息。我尝试同时运行同一主题的 mosquitto 订阅，并且确实会收到已发布的消息。不确定我的回调代码是否有问题或这里发生了什么。任何帮助将不胜感激。Arduino代码如下：

/*
 Basic MQTT example 
  - connects to an MQTT server
  - publishes "hello world" to the topic "outTopic"
  - subscribes to the topic "inTopic"
*/
#include <SPI.h>
#include <Ethernet.h>
#include <PubSubClient.h>
// Update these with values suitable for your network.
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte server[] = { 10, 2, 63, 123 };
byte ip[]     = { 192, 168, 1, 10 };

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.println(topic);
  //convert byte to char
  payload[length] = '';
  String strPayload = String((char*)payload);
  Serial.println(strPayload);
  //int valoc = strPayload.lastIndexOf(',');
  //String val = strPayload.substring(valoc+1);
  //Serial.println(val);

}
EthernetClient ethClient;
PubSubClient client(server, 1883, callback, ethClient);
void setup()
{
  Serial.begin(19200);
  Serial.println("==STARTING==");
  // start the Ethernet connection:
  if (Ethernet.begin(mac) == 0) {
    Serial.println("Failed to configure Ethernet using DHCP");
    // no point in carrying on, so do nothing forevermore:
    // try to congifure using IP address instead of DHCP:
    Ethernet.begin(mac, ip);
  }
  // give the Ethernet shield a second to initialize:
  delay(1000);
  Serial.println("connecting...");
  for (byte thisByte = 0; thisByte < 4; thisByte++) {
    // print the value of each byte of the IP address:
    Serial.print(Ethernet.localIP()[thisByte], DEC);
    Serial.print("."); 
  }
  //delay(500);
  boolean con = client.connect("1", "3snzzon5dyade:abc", "OBSCURED_FOR_SEC");
  while(con != 1){
    Serial.println("no con-while");
     con = client.connect("1", "3snzzon5dyade:abc", "OBSCURED_FOR_SEC");
  }
  //Serial.println(con);
  if(con){
    Serial.println("got con");
    client.publish("testq","hello world");
    client.subscribe("testq");
  }else Serial.println("no con");
}
void loop()
{
  client.loop();
}

就像我说的，我可以看到mosquitto一切正常。我什至尝试过匹配client_ids但没有运气。任何帮助或想法将不胜感激。

Answer 1

您的订阅主题"testq"必须在类似

char testq[] = {'t', 'e', 's', 't', 'q', ''};

确保以 ，'\0' 完成数组

然后您订阅：

client.subscribe(testq);