ESP32 Tutorial 48/55 - Remote Temperature Monitoring and LED control MQTT | SunFounder's ESP32 IoT kit

In this video we learn how to monitor temperature and humidity using ESP32 and turn ON/OFF LED over Adafruit IO.

Topics in this lesson

Use Chapters from timeline or click on the time

00:00 Introduction
1:50 Introduction to project
3:16 What is MQTT
6:36 Adafruit IO setup
11:13 wiring
13:38 Arduino code explained
22:03 Selecting ESP32 board and COM port
23:44 Project demonstration
27:05 Updating dashboard

/***********************************************************************
  Adafruit MQTT Basic lesson 1
Watch video instruction for this code on YouTube https://youtu.be/M9BQweAsHJM
Resource page for this lesson and code:
http://robojax.com/course3
Tutoril by https://youTube.com/@robojax

Adafruit MQTT Library ESP32 Adafruit IO SSL/TLS example

Use the latest version of the ESP32 Arduino Core:
    https://github.com/espressif/arduino-esp32

Works great with Adafruit Huzzah32 Feather and Breakout Board:
    https://www.adafruit.com/product/3405
    https://www.adafruit.com/products/4172

Adafruit invests time and resources providing this open source code,
  please support Adafruit and open-source hardware by purchasing
  products from Adafruit!

Written by Tony DiCola for Adafruit Industries.
  Modified by Brent Rubell for Adafruit Industries
  MIT license, all text above must be included in any redistribution
 **********************************************************************/

/// ref: https://www.electronicwings.com/esp32/esp32-mqtt-client

#include <WiFi.h>
#include "WiFiClientSecure.h"
#include "Adafruit_MQTT.h"
#include "Adafruit_MQTT_Client.h"

/************************* WiFi Access Point *********************************/

#define WLAN_SSID "dars"
#define WLAN_PASS "5152535455"

/************************* Adafruit.io Setup *********************************/

#define AIO_SERVER "io.adafruit.com"

// Using port 8883 for MQTTS
#define AIO_SERVERPORT 8883

// Adafruit IO Account Configuration
// (to obtain these values, visit https://io.adafruit.com and click on Active Key)
// #define AIO_USERNAME "YOUR_ADAFRUIT_IO_USERNAME"
// #define AIO_KEY      "YOUR_ADAFRUIT_IO_KEY"

#define AIO_USERNAME "robojax"
#define AIO_KEY "aio_wCyL33EVKLcGoAotGNEQ4dGQYOLZ"

/************ Global State (you don't need to change this!) ******************/

// WiFiFlientSecure for SSL/TLS support
WiFiClientSecure client;

// Setup the MQTT client class by passing in the WiFi client and MQTT server and login details.
Adafruit_MQTT_Client mqtt(&client, AIO_SERVER, AIO_SERVERPORT, AIO_USERNAME, AIO_KEY);

// io.adafruit.com root CA
const char* adafruitio_root_ca =
  "-----BEGIN CERTIFICATE-----\n"
  "MIIDrzCCApegAwIBAgIQCDvgVpBCRrGhdWrJWZHHSjANBgkqhkiG9w0BAQUFADBh\n"
  "MQswCQYDVQQGEwJVUzEVMBMGA1UEChMMRGlnaUNlcnQgSW5jMRkwFwYDVQQLExB3\n"
  "d3cuZGlnaWNlcnQuY29tMSAwHgYDVQQDExdEaWdpQ2VydCBHbG9iYWwgUm9vdCBD\n"
  "QTAeFw0wNjExMTAwMDAwMDBaFw0zMTExMTAwMDAwMDBaMGExCzAJBgNVBAYTAlVT\n"
  "MRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5j\n"
  "b20xIDAeBgNVBAMTF0RpZ2lDZXJ0IEdsb2JhbCBSb290IENBMIIBIjANBgkqhkiG\n"
  "9w0BAQEFAAOCAQ8AMIIBCgKCAQEA4jvhEXLeqKTTo1eqUKKPC3eQyaKl7hLOllsB\n"
  "CSDMAZOnTjC3U/dDxGkAV53ijSLdhwZAAIEJzs4bg7/fzTtxRuLWZscFs3YnFo97\n"
  "nh6Vfe63SKMI2tavegw5BmV/Sl0fvBf4q77uKNd0f3p4mVmFaG5cIzJLv07A6Fpt\n"
  "43C/dxC//AH2hdmoRBBYMql1GNXRor5H4idq9Joz+EkIYIvUX7Q6hL+hqkpMfT7P\n"
  "T19sdl6gSzeRntwi5m3OFBqOasv+zbMUZBfHWymeMr/y7vrTC0LUq7dBMtoM1O/4\n"
  "gdW7jVg/tRvoSSiicNoxBN33shbyTApOB6jtSj1etX+jkMOvJwIDAQABo2MwYTAO\n"
  "BgNVHQ8BAf8EBAMCAYYwDwYDVR0TAQH/BAUwAwEB/zAdBgNVHQ4EFgQUA95QNVbR\n"
  "TLtm8KPiGxvDl7I90VUwHwYDVR0jBBgwFoAUA95QNVbRTLtm8KPiGxvDl7I90VUw\n"
  "DQYJKoZIhvcNAQEFBQADggEBAMucN6pIExIK+t1EnE9SsPTfrgT1eXkIoyQY/Esr\n"
  "hMAtudXH/vTBH1jLuG2cenTnmCmrEbXjcKChzUyImZOMkXDiqw8cvpOp/2PV5Adg\n"
  "06O/nVsJ8dWO41P0jmP6P6fbtGbfYmbW0W5BjfIttep3Sp+dWOIrWcBAI+0tKIJF\n"
  "PnlUkiaY4IBIqDfv8NZ5YBberOgOzW6sRBc4L0na4UU+Krk2U886UAb3LujEV0ls\n"
  "YSEY1QSteDwsOoBrp+uvFRTp2InBuThs4pFsiv9kuXclVzDAGySj4dzp30d8tbQk\n"
  "CAUw7C29C79Fv1C5qfPrmAESrciIxpg0X40KPMbp1ZWVbd4=\n"
  "-----END CERTIFICATE-----\n";

/****************************** Feeds ***************************************/

// Setup a feed called 'test' for publishing and 'test2' for subscription.
// Notice MQTT paths for AIO follow the form: <username>/feeds/<feedname>
Adafruit_MQTT_Subscribe LED = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME "/feeds/LED");
//Adafruit_MQTT_Publish humidity = Adafruit_MQTT_Publish(&mqtt, AIO_USERNAME "/feeds/humidity");
//Adafruit_MQTT_Publish temperature = Adafruit_MQTT_Publish(&mqtt, AIO_USERNAME "/feeds/temperature");

/*************************** Sketch Code ************************************/

// set pin numbers
const int ledPin = 15;  // the number of the led pin

void setup() {
  Serial.begin(115200);
  delay(10);

Serial.println(F("Adafruit IO MQTTS (SSL/TLS) Example"));

// Connect to WiFi access point.
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(WLAN_SSID);

delay(1000);

WiFi.begin(WLAN_SSID, WLAN_PASS);
  delay(2000);

while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println();

Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());

// Set Adafruit IO's root CA
  client.setCACert(adafruitio_root_ca);

// register callback for feed
  LED.setCallback(ledCallback);
  // Setup MQTT subscription for time feed.
  mqtt.subscribe(&LED);

// initialize the LED pin as an output
  pinMode(ledPin, OUTPUT);

}

// uint32_t x=0;

void loop() {

// Ensure the connection to the MQTT server is alive (this will make the first
  // connection and automatically reconnect when disconnected).  See the MQTT_connect
  // function definition further below.
  MQTT_connect();

// indicatorPublish();

// wait 10 seconds for subscription messages
  mqtt.processPackets(10000);

// wait a couple seconds to avoid rate limit
  //delay(2000);
}

void ledCallback(char* message, uint16_t len) {
  char messageBuffer[40];
  snprintf(messageBuffer, sizeof(messageBuffer), "LED status is :: %s, len :: %u", message, len);
  Serial.println(messageBuffer);
  if (strcmp(message, "ON") == 0) {
    Serial.println("Turning ON LED");
    digitalWrite(ledPin, LOW);
  } else {
    Serial.println("Turning OFF LED");
    digitalWrite(ledPin, HIGH);
  }
}

// Function to connect and reconnect as necessary to the MQTT server.
// Should be called in the loop function and it will take care if connecting.
void MQTT_connect() {
  int8_t ret;
  // Stop if already connected.
  if (mqtt.connected()) {
    return;
  }
  Serial.print("Connecting to MQTT... ");
  uint8_t retries = 3;
  while ((ret = mqtt.connect()) != 0) {  // connect will return 0 for connected
    Serial.println(mqtt.connectErrorString(ret));
    Serial.println("Retrying MQTT connection in 5 seconds...");
    mqtt.disconnect();
    delay(5000);  // wait 5 seconds
    retries--;
    if (retries == 0) {
      // basically die and wait for WDT to reset me
      while (1)
        ;
    }
  }
  Serial.println("MQTT Connected!");
}


 /*
Watch video instruction for this code on YouTube https://youtu.be/M9BQweAsHJM
Resource page for this lesson and code:
http://robojax.com/course3
Tutoril by https://youTube.com/@robojax