Circuit Documentation

Summary

The circuit is designed to control a 220V fan and monitor temperature and humidity using an ESP32 Devkit V1 microcontroller. The system includes a DHT22 sensor for measuring temperature and humidity, a two-channel 5V relay to control the fan, LEDs for status indication, an LCD display for user feedback, a buzzer for alerts, and a power supply to provide the necessary voltages. The ESP32 is programmed to communicate with the Blynk platform for remote monitoring and control.

Component List

ESP32 Devkit V1

• Microcontroller with WiFi capability.
• It has multiple digital I/O pins and supports I2C communication.

Two Channel Relay 5v

• A relay module with two channels that can control high voltage/high current devices.

220V Fan

• A standard fan operating at 220V for air circulation.

LED: Two Pin (red)

• A red LED used for status indication.

LED: Two Pin (green)

• A green LED used for status indication.

DHT22

• A sensor for measuring temperature and humidity.

LCD Display 16x4 I2C

• An LCD display with I2C interface for showing information to the user.

POWER SUPPLY 5V 5AMP

• A power supply unit that provides 5V DC and supports up to 5A current.

Buzzer

• An audible alert device.

Socket

• An AC power socket for connecting the fan and power supply.

Timer

• A timer module for scheduling operations.

Wiring Details

ESP32 Devkit V1

• 3V3 connected to DHT22 VCC and LCD Display VCC.
• GND connected to DHT22 GND, LCD Display GND, both LED cathodes, Buzzer NEGATIVE, and Two Channel Relay GND.
• D4 connected to DHT22 OUT.
• D21 (SDA) and D22 (SCL) connected to LCD Display I2C pins.
• D26 connected to Two Channel Relay IN1.
• D27 connected to Red LED anode.
• D14 connected to Green LED anode.
• D13 connected to Buzzer POSITIVE.
• VIN connected to Two Channel Relay VCC and POWER SUPPLY 12V-24V Output (DC).

Two Channel Relay 5v

• IN1 and IN2 controlled by ESP32.
• VCC connected to ESP32 VIN.
• GND connected to ESP32 GND.
• C1 connected to Timer L1.
• NO1 connected to 220V Fan L, Timer L2, Socket life, and POWER SUPPLY 220V Positive Pole (AC).

220V Fan

• N connected to Socket neutral and POWER SUPPLY 220V Negative Pole (AC).
• L connected to Relay NO1.

LED: Two Pin (red)

• cathode connected to ESP32 GND.
• anode connected to ESP32 D27.

LED: Two Pin (green)

• cathode connected to ESP32 GND.
• anode connected to ESP32 D14.

DHT22

• VCC connected to ESP32 3V3.
• OUT connected to ESP32 D4.
• GND connected to ESP32 GND.

LCD Display 16x4 I2C

• SCL connected to ESP32 D22.
• SDA connected to ESP32 D21.
• VCC connected to ESP32 3V3.
• GND connected to ESP32 GND.

POWER SUPPLY 5V 5AMP

• 220V Positive Pole (AC) connected to Relay NO1.
• 220V Negative Pole (AC) connected to 220V Fan N.
• GND (DC) connected to ESP32 GND.
• 12V-24V Output (DC) connected to ESP32 VIN.

Buzzer

• POSITIVE connected to ESP32 D13.
• NEGATIVE connected to ESP32 GND.

Socket

• earth connected to POWER SUPPLY GND.
• life connected to Relay NO1.
• neutral connected to 220V Fan N.

Timer

• S1 and S2 not connected.
• L1 connected to Relay C1.
• L2 connected to Relay NO1.

Documented Code

ESP32 Devkit V1 Code

#define BLYNK_TEMPLATE_ID "TMPL6-vn2VN_V"
#define BLYNK_TEMPLATE_NAME "Quickstart Template"
#define BLYNK_AUTH_TOKEN "vO02bgbn-43wyzsgJdoY47qDX3Jl8R8y"

/* Comment this out to disable prints and save space */
#define BLYNK_PRINT Serial

#include <DHT.h>
#include <WiFi.h>
#include <BlynkSimpleEsp32.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>  // I2C LCD library

#define DHTPIN 4                 // Pin where the DHT22 data pin is connected
#define DHTTYPE DHT22            // DHT 22 (AM2302)
#define RELAY_PIN 26             // GPIO pin where relay is connected (IN1)
#define RED_LED_PIN 27           // GPIO pin where RED LED is connected
#define GREEN_LED_PIN 14         // GPIO pin where GREEN LED is connected
#define TEMP_MAX_THRESHOLD 65.0  // Maximum temperature threshold in Celsius
#define TEMP_MIN_THRESHOLD 60.0  // Minimum temperature threshold in Celsius

// WiFi credentials
char ssid[] = "haiyaaa";
char pass[] = "430578440";

// Initialize DHT sensor
DHT dht(DHTPIN, DHTTYPE);

// Initialize I2C LCD (address 0x27)
LiquidCrystal_I2C lcd(0x27, 16, 2);

bool blowerState = false;  // Blower state, controlled by Blynk
int blowerbutton;
int countdown = 0;  // Timer countdown (initially 0 seconds)
bool countdownActive = false;
BlynkTimer timer;  // Timer for sensor values and countdown

void setup() {
  Serial.begin(115200);
  dht.begin();  // Start reading the DHT sensor

  // Set relay and LED pins as outputs
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(GREEN_LED_PIN, OUTPUT);

  // Ensure relay and RED LED are off initially, GREEN LED is off
  digitalWrite(RELAY_PIN, HIGH);      // Turn off the relay initially
  digitalWrite(RED_LED_PIN, LOW);     // Turn RED LED off initially
  digitalWrite(GREEN_LED_PIN, LOW);   // Turn GREEN LED off initially

  Serial.println("System initialized...");

  // Initialize LCD
  lcd.init();           // Initialize the LCD with 16 columns and 2 rows
  lcd.backlight();      // Turn on the LCD backlight
  lcd.setCursor(0, 0);
  lcd.print("Connecting to");
  lcd.setCursor(0, 1);
  lcd.print("Wifi");

  // Initialize Blynk connection
  Blynk.begin(BLYNK_AUTH_TOKEN, ssid, pass);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Connected!!");

  delay(3000);

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Cloth Dryer");

  digitalWrite(RELAY_PIN, HIGH);      // Turn blower OFF
  digitalWrite(RED_LED_PIN, LOW);     // Turn RED LED OFF (blower is OFF)
  digitalWrite(GREEN_LED_PIN, LOW);   // Turn GREEN LED OFF

  // Set a timer to read the sensor values every 2 seconds
  timer.setInterval(2000L, readDHTAndSendToBlynk);
}

// Blynk virtual pin to control the blower (relay)
BLYNK_WRITE(V1) {
  blowerbutton = param.asInt();  // Get value from Blynk app (1 or 0)

  if (blowerbutton == 1 && !countdownActive) {
    // If the blower is manually turned on from Blynk, start countdown
    countdownActive = true;
    startBlower();
  } else if (blowerbutton == 0) {
    stopBlower();  // Stop the blower if turned off in Blynk
  }
}

// Function to set the timer duration via Blynk app
BLYNK_WRITE(V2) {
  int timeSelected = param.asInt();  // Get selected time in minutes
  countdown = timeSelected * 60;  // Convert minutes to seconds
  if (countdown > 0) {
    countdownActive = true;
    startBlower();
    timer.setInterval(1000L, countdownFunction);  // Start countdown every second
  }
}

// Function to start the blower
void startBlower() {
  digitalWrite(RELAY_PIN, LOW);     // Turn blower ON
  digitalWrite(RED_LED_PIN, HIGH);  // Turn RED LED ON
  digitalWrite(GREEN_LED_PIN,