Arduino Knolleary PubSubClient will publish messages but can't receive them - arduino

Question

I am using the Knolleary PubSubClient to make a connection to my MQTT server. I have been able to successfully authenticate and make a connection after not much work. I can even publish messages to topics. However, the issue I am having is that I can subscribe to topics and get no error, but when I publish to that topic (from mosquitto on my Mac) the callback does not get called and the message to the subscribe topic does not appear to be received. I have tried running a mosquitto subscription to the same topic at the same time, and that does receive the published message. Not sure if there is a problem in my callback code or what is going on here. Any help would be appreciated. Arduino code is below:
/*
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] = '\0';
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();
}
Like I said, I can see everything working properly with mosquitto. I have even tried matching up client_ids with no luck. Any help or ideas would be greatly appreciated.

Answer 1

your subscribe topic "testq" must be in an array like
char testq[] = {'t', 'e', 's', 't', 'q', '\0'};
be sure to finisht your array with an ,'\0'
Then you subscribe with:
client.subscribe(testq);