Blink Led using MQTT in arduino - arduino

Question

I have to implement a prototyping scenario that blink LED in the arduino with MQTT protocol. I already tried with several MQTT libraries but non of them not work perfectly. Connection to the MQTT broker working successfully but when I publish the message with topic which I set in arduino not blink the LED. Arduno have to publish a message when it successfully connect but this publishing part also not working
this is my code
#include <SPI.h>
#include <Ethernet.h>
#include <PubSubClient.h>
// Set the MAC address
byte mac[] = { 0xDE, 0xED, 0xBA, 0xFE, 0xFE, 0xED };
IPAddress ip(192, 168, 1, 100);
IPAddress server(192, 168, 1, 20);
// Set what PINs our Led's are connected to
int redPin = 13;
//int greenPin = 6;
//int bluePin = 7;
// Set a generic code that will trigger our Blue Led
// think of this as a set of codes for automation you might write
byte triggerRed[13] = "12345";
// handles messages that are returned from the broker on our subscribed channel
void callback(char* topic, byte* payload, unsigned int length) {
Serial.print("New message from broker on topic:");
Serial.println(topic);
Serial.print("Payload:");
Serial.write(payload, length);
// Check and see if our payload matches our simple trigger test
if ((length == 5) & (memcmp(payload, triggerRed, 5) == 0) )
{
//blink(redPin);
}
}
EthernetClient ethClient;
PubSubClient client(ethClient);
// Fire up our PubSub client
//PubSubClient client(server, 1883, callback);
void setup()
{
// Open serial communications
Serial.begin(9600);
client.setServer(server, 1883);
client.setCallback(callback);
// Setup our Leds
pinMode(redPin, OUTPUT);
// pinMode(greenPin, OUTPUT);
// pinMode(bluePin, OUTPUT);
// attempt a DHCP connection
Serial.println("Attempting to get an IP address using DHCP:");
if (!Ethernet.begin(mac))
{
// if DHCP fails, start with a hard-coded address:
Serial.println("failed to get an IP address using DHCP, trying manually");
Ethernet.begin(mac, ip);
}
Serial.print("My address:");
Serial.println(Ethernet.localIP());
// Connect to Broker, give it arduino as the name
if (client.connect("arduino")) {
// Good, we connected turn on the red led
digitalWrite(redPin, HIGH);
// Publish a message to the status topic
client.publish("status","Arduino is now online");
// Listen for messages on the control topic
client.subscribe("ultra");
}
}
void loop()
{
client.loop();
}
// Anything with flashing lights.
void blink(int targetLed)
{
digitalWrite(redPin, HIGH);
}
how can I fix this ?

Answer 1

Put connection routine in a loop and try with test.mosquitto.org first.
Here is code that works for me (Ethernet shield hardware):
definitions:
#define CLIENT_NAME "myclientname"
#define TOPIC "mytopic"
byte mac[] = { 0xDE, 0xED, 0xBA, 0xFE, 0xFE, 0xED };
IPAddress ip(192, 168, 1, 105);
IPAddress server(85, 119, 83, 194);// test.mosquitto.org
#define MQTT_PORT 1883
IPAddress myDns(8, 8, 8, 8);
EthernetClient ethClient;
PubSubClient client(ethClient);
setup:
client.setServer(server, MQTT_PORT);
client.setCallback(callback);
Ethernet.begin(mac);
loop:
if (!client.connected()) {
reconnect();
}
client.loop();
reconnect routine
void reconnect() {
if (millis() - reconnectionTimer >reconnection_period){// Loop until we're reconnected
reconnectionTimer = millis();
if (!client.connected()) {
// Attempt to connect
if (client.connect(CLIENT_NAME)) {
client.subscribe(TOPIC);
}
else {
Serial.print(client.state());
Serial3.print(client.state());
}
}
}
}
update for blink:
void blink(){
digitalWrite(led, LOW);
delay(500);
digitalWrite(led, HIGH);
}

Answer 2

I lost a lot of time because i had the problem with the mqtt server. ensure that your server is using mqtt protocol, because i was using ws protocol and any library that I tried doesn't works with this protocol