YUVAN SRI S
Published

Automatic Room Temperature Controller Using KiwisIoT

An intelligent IoT-based temperature controller using ESP32 and DHT22 to monitor room conditions, automatically switch cooling fans based on

BeginnerFull instructions provided7
Automatic Room Temperature Controller Using KiwisIoT

Things used in this project

Hardware components

ESP32 Development Board
×1
DHT22 Temperature Sensor
×1
5V Relay Module
×1
DC Cooling Fan
×1
DC Cooling Fan
×1
LED (generic)
LED (generic)
×1
Resistor 10k ohm
Resistor 10k ohm
×1
Breadboard
×1

Software apps and online services

Arduino IDE
Arduino IDE
KiwisIoT
Kiwistron KiwisIoT

Story

Read more

Schematics

Circuit Diagram

Code

Circuit Diagram

C/C++
#include <WiFi.h>
#include <PubSubClient.h>
#include <DHT.h>

// Wi-Fi credentials
const char* ssid = "YOUR_WIFI_NAME";
const char* password = "YOUR_WIFI_PASSWORD";

// KiwisIoT MQTT settings
const char* mqtt_server = "YOUR_MQTT_BROKER";
const int mqtt_port = YOUR_MQTT_PORT;
const char* mqtt_topic = "YOUR_DEVICE_TOPIC";

// Pin configuration
#define DHT_PIN 4
#define RELAY_PIN 18
#define DHT_TYPE DHT22

// Temperature limits
#define TEMP_ON 30.0
#define TEMP_OFF 28.0

// Set according to your relay module
#define RELAY_ON LOW
#define RELAY_OFF HIGH

DHT dht(DHT_PIN, DHT_TYPE);

WiFiClient espClient;
PubSubClient client(espClient);

bool fanState = false;
unsigned long lastRead = 0;

void connectWiFi() {
  WiFi.begin(ssid, password);

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

  Serial.println("WiFi Connected");
}

void reconnectMQTT() {
  while (!client.connected()) {
    if (client.connect("RoomTemperatureController")) {
      Serial.println("MQTT Connected");
    } else {
      delay(2000);
    }
  }
}

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

  pinMode(RELAY_PIN, OUTPUT);
  digitalWrite(RELAY_PIN, RELAY_OFF);

  dht.begin();

  connectWiFi();

  client.setServer(mqtt_server, mqtt_port);
}

void loop() {

  if (WiFi.status() != WL_CONNECTED) {
    connectWiFi();
  }

  if (!client.connected()) {
    reconnectMQTT();
  }

  client.loop();

  if (millis() - lastRead >= 2500) {

    lastRead = millis();

    float temperature = dht.readTemperature();
    float humidity = dht.readHumidity();

    if (isnan(temperature) || isnan(humidity)) {
      Serial.println("Sensor reading failed");

      // Fail-safe: switch fan OFF
      fanState = false;
      digitalWrite(RELAY_PIN, RELAY_OFF);
      return;
    }

    // Automatic fan control
    if (temperature >= TEMP_ON) {
      fanState = true;
    }
    else if (temperature <= TEMP_OFF) {
      fanState = false;
    }

    digitalWrite(
      RELAY_PIN,
      fanState ? RELAY_ON : RELAY_OFF
    );

    Serial.print("Temperature: ");
    Serial.println(temperature);

    Serial.print("Humidity: ");
    Serial.println(humidity);

    Serial.print("Fan Status: ");
    Serial.println(fanState ? "ON" : "OFF");

    char payload[160];

    snprintf(payload, sizeof(payload),
      "{\"temperature\":%.2f,"
      "\"humidity\":%.2f,"
      "\"fan_status\":\"%s\"}",
      temperature,
      humidity,
      fanState ? "ON" : "OFF"
    );

    client.publish(mqtt_topic, payload);
  }
}

Credits

YUVAN SRI S
25 projects • 1 follower

Comments

Related channels and tags
  • Internet of Things
  • Internet of Things
  • Kiwistron