// From https://randomnerdtutorials.com/esp32-mqtt-publish-subscribe-arduino-ide
// https://randomnerdtutorials.com/esp32-adc-analog-read-arduino-ide
// Compatible with https://github.com/pixavier/mqtt4snap request/response and request reporter blocks
#include <WiFi.h>
#include "PubSubClient.h"
const char* ssid = "Wokwi-GUEST";
const char* password = "";
const char* mqttServer = "broker.emqx.io";
int port = 1883;
String stMac;
char mac[50];
char clientId[50];
WiFiClient espClient;
PubSubClient client(espClient);
const int ldrPin = 35;
void setup() {
Serial.begin(115200);
randomSeed(analogRead(0));
delay(10);
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
wifiConnect();
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
Serial.println(WiFi.macAddress());
stMac = WiFi.macAddress();
stMac.replace(":", "_");
Serial.println(stMac);
client.setServer(mqttServer, port);
client.setCallback(callback);
pinMode(ldrPin, INPUT);
}
void wifiConnect() {
WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
}
void mqttReconnect() {
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
long r = random(1000);
sprintf(clientId, "clientId-%ld", r);
if (client.connect(clientId)) {
Serial.print(clientId);
Serial.println(" connected");
client.subscribe("name/ldr/#");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
delay(5000);
}
}
}
void callback(char* topic, byte* payload, unsigned int length) {
String stPayload;
char topicBuf[50];
char payloadBuf[20];
for (int i = 0; i < length; i++) {
stPayload += (char)payload[i];
}
String strTopic = String(topic); // topic example: topicName/ldr/lux/idCall-1032.3
Serial.print("topic: ");
Serial.println(strTopic);
int lastPos = strTopic.lastIndexOf("@"); // callbackTopic (cback): Last subtopic
if (lastPos > 0) {
String topic = strTopic.substring(0, lastPos - 1); // cback example: idCall-1032.3
String cback = strTopic.substring(lastPos + 1); // cback example: idCall-1032.3
Serial.print("cack: ");
Serial.println(cback);
int len = cback.length() + 1;
cback.toCharArray(topicBuf, len);
if (topic.equals("name/ldr/get/lux")) {
int lux = analogRead(ldrPin);
sprintf(payloadBuf, "%d", lux);
Serial.println(payloadBuf);
client.publish(topicBuf, payloadBuf, len);
}
}
}
void loop() {
delay(10);
if (!client.connected()) {
mqttReconnect();
}
client.loop();
}