Mqtt subscribe example that i cobbled together. Flashing led
Posted: Sun Apr 26, 2015 10:12 amHi, so i was looking for an example on another thread, i couldn't find exactly what i was looking for so i pasted something together and thought i would contribute what i managed to get working.
Please feel free to comment or correct as needed.
This example actuates a LED / Relay or whatever when the correct string is received.
Have fun, let me know if you make something from it! i totally cannot take credit but i would still like to know what can be done.!
Gambit
Please feel free to comment or correct as needed.
This example actuates a LED / Relay or whatever when the correct string is received.
Code: Select all
#include <PubSubClient.h>
#include <ESP8266WiFi.h>
//////////////////////////Added toggling led with any topic publish "1" /////
const char* ssid = "............";
const char* password = "............";
char* topic = "#"; // using wildcard to monitor all traffic from mqtt server
char* server = "192.168.0.7"; // Address of my server on my network, substitute yours!
char message_buff[100]; // initialise storage buffer (i haven't tested to this capacity.)
WiFiClient wifiClient;
PubSubClient client(server, 1883, callback, wifiClient);
String macToStr(const uint8_t* mac)
{
String result;
for (int i = 0; i < 6; ++i) {
result += String(mac[i], 16);
if (i < 5)
result += ':';
}
return result;
}
void setup() {
Serial.begin(115200);
delay(10);
// prepare GPIO2 *********************************************************************
pinMode(2, OUTPUT); // i am using gpio2 as output to toggle an LED
digitalWrite(2, 0); //*****************************************************************
Serial.println();
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
// connection to broker script.
if (client.connect("arduinoClient")) {
client.publish("outTopic","hello world");
client.subscribe("#"); // i should probably just point this to the varialbe above.
}
}
void loop() {
client.loop();
}
void callback(char* topic, byte* payload, unsigned int length) {
// Here is what i have been using to handle subscriptions. I took it as a snippet from elsewhere but i cannot credit author as i dont have reference!
int i = 0;
Serial.println("Message arrived: topic: " + String(topic));
Serial.println("Length: " + String(length,DEC));
// create character buffer with ending null terminator (string)
for(i=0; i<length; i++) {
message_buff[i] = payload[i];
}
message_buff[i] = '\0';
String msgString = String(message_buff);
Serial.println("Payload: " + msgString);
int state = digitalRead(2); // get the current state of GPIO1 pin
if (msgString == "1"){ // if there is a "1" published to any topic (#) on the broker then:
digitalWrite(2, !state); // set pin to the opposite state
Serial.println("Switching LED");
}
}
Have fun, let me know if you make something from it! i totally cannot take credit but i would still like to know what can be done.!
Gambit
So I guess some kind of automatic publishing would be needed from the broker or another client.