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arduino code for nodemcu/esp8266 for connecting to mqtt broker. It can receive and send messages to MQTT broker
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
// Update these with values suitable for your network.
const char* ssid = "SSID";
const char* password = "passowrd";
const char* mqtt_server = "iot.eclipse.org";
#define mqtt_port 1883
#define MQTT_USER "username"
#define MQTT_PASSWORD "password"
#define MQTT_SERIAL_PUBLISH_CH "/ic/from/nm/sd/"
#define MQTT_SERIAL_RECEIVER_CH "/ic/to/nm/sd/"
WiFiClient wifiClient;
PubSubClient client(wifiClient);
void setup_wifi() {
delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
randomSeed(micros());
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Create a random client ID
String clientId = "NodeMCUClient-";
clientId += String(random(0xffff), HEX);
// Attempt to connect
if (client.connect(clientId.c_str(),MQTT_USER,MQTT_PASSWORD)) {
Serial.println("connected");
//Once connected, publish an announcement...
client.publish("/ic/presence/nm/", "hello world");
// ... and resubscribe
client.subscribe(MQTT_SERIAL_RECEIVER_CH);
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
void callback(char* topic, byte *payload, unsigned int length) {
Serial.println("-------new message from broker-----");
Serial.print("channel:");
Serial.println(topic);
Serial.print("data:");
Serial.write(payload, length);
Serial.println();
}
void setup() {
Serial.begin(115200);
Serial.setTimeout(500);// Set time out for
setup_wifi();
client.setServer(mqtt_server, mqtt_port);
client.setCallback(callback);
reconnect();
}
void publishSerialData(char *serialData){
if (!client.connected()) {
reconnect();
}
client.publish(MQTT_SERIAL_PUBLISH_CH, serialData);
}
void loop() {
client.loop();
if (Serial.available() > 0) {
char bfr[101];
memset(bfr,0, 101);
Serial.readBytesUntil( '\n',bfr,100);
publishSerialData(bfr);
}
}
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