Project Documentation

Arduino-Controlled Incubator with Temperature Regulation and LCD Display

Circuit Documentation

Summary

This circuit is designed to control an incubator's temperature using a DHT22 temperature and humidity sensor, a 5V relay to switch an AC bulb (used as a heater), and a 120mm 12V fan for air circulation. The system is controlled by an Arduino UNO microcontroller, which interfaces with an LCD display for user feedback and three pushbuttons for user input to set the desired temperature. The relay controls the power to the AC bulb, and the fan is connected to a 12V power supply. The circuit includes resistors for current limiting and pull-up configurations.

Component List

DHT22

Temperature and Humidity Sensor
Pins: + (Power), Out (Signal), - (Ground)

5V Relay

Electromechanical switch
Pins: Normally Open, Common terminal, Normally Closed, In (Control), GND, VCC

LCD 16x2 (Wokwi Compatible)

Alphanumeric Liquid Crystal Display
Pins: VSS, VDD, V0, RS, RW, E, D0-D7, A (Anode), K (Cathode)

LCM1602 IIC

I2C Interface for LCD
Pins: GND, VCC, SDA, SCL, D6-D7, A, K, VSS, VDD, V0, RS, D2-D5, RW, E, D0-D1, LED_A, LED_B

Pushbutton (x3)

Momentary tactile switch
Pins: Pin 1, Pin 2, Pin 3, Pin 4

Resistor (x3)

Electrical passive component
Resistance: 10 Ohms, 200 Ohms, 200 Ohms

AC Bulb

Incandescent light bulb
Pins: P (Phase), N (Neutral)

POWER SUPPLY 12V 5AMP

DC Power Supply
Pins: 220V Positive Pole (AC), 220V Negative Pole (AC), GND, GND (DC), 12V-24V Output (DC)

120mm Fan 12V

Cooling fan
Pins: 12V+, GND

Arduino UNO

Microcontroller Board
Pins: Digital I/O, Analog Inputs, Power, Ground, and other control pins

Wiring Details

DHT22

- to 5V
Out to Arduino UNO D5
- to GND

5V Relay

In to Arduino UNO D6
VCC to 5V
GND to GND
Normally Open to AC Bulb P
Common terminal to 220V Positive Pole (AC)

LCD 16x2 (Wokwi Compatible) & LCM1602 IIC

VSS to VSS
VDD to VDD
V0 to V0
RS to RS
RW to RW
E to E
D0 to D0
D1 to D1
D2 to D2
D3 to D3
D4 to D4
D5 to D5
D6 to D6
D7 to D7
A to A
K to K

Pushbuttons (x3)

Pin 4 to Arduino UNO D4, D3, D2 (respectively for each button)
Pin 2 to GND
Pin 3 to Resistor (10 Ohms, 200 Ohms, 200 Ohms respectively for each button)

Resistor (x3)

One side to Pushbutton Pin 3
Other side to 5V

AC Bulb

P to 5V Relay Normally Open
N to 220V Negative Pole (AC)

POWER SUPPLY 12V 5AMP

220V Positive Pole (AC) to 5V Relay Common terminal
220V Negative Pole (AC) to AC Bulb N and 120mm Fan 12V+
GND to GND (DC)
12V-24V Output (DC) to 120mm Fan 12V+

120mm Fan 12V

12V+ to 220V Negative Pole (AC)
GND to GND

Arduino UNO

D6 to 5V Relay In
D5 to DHT22 Out
D4, D3, D2 to Pushbuttons Pin 4
A4 to LCM1602 IIC SDA
A5 to LCM1602 IIC SCL
5V to DHT22 +, 5V Relay VCC, LCM1602 IIC VCC, and Resistor (10 Ohms, 200 Ohms, 200 Ohms)
GND to DHT22 -, 5V Relay GND, LCM1602 IIC GND, Pushbuttons Pin 2

Documented Code

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <DHT.h>

// Configuration of pins
#define DHTPIN 4           // Data pin for DHT22 sensor
#define DHTTYPE DHT22      // DHT sensor type
#define RELAY_PIN 7        // Relay pin for the heater
#define BUTTON_INC 8       // Pushbutton 1: Increase target temperature
#define BUTTON_DEC 9       // Pushbutton 2: Decrease target temperature
#define BUTTON_TOGGLE 10   // Pushbutton 3: Toggle heater on/off

DHT dht(DHTPIN, DHTTYPE);
LiquidCrystal_I2C lcd(0x27, 16, 2);

float targetTemp = 37.5;    // Initial target temperature
bool heating = false;       // Heater status

void setup() {
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(BUTTON_INC, INPUT_PULLUP);
  pinMode(BUTTON_DEC, INPUT_PULLUP);
  pinMode(BUTTON_TOGGLE, INPUT_PULLUP);

  lcd.begin(16, 2); // Initialize the LCD
  lcd.backlight();
  dht.begin();

  Serial.begin(9600);
  lcd.setCursor(0, 0);
  lcd.print("Incubator Ready");
  delay(2000);
  lcd.clear();
}

void loop() {
  // Read temperature from the sensor
  float temperature = dht.readTemperature();
  if (isnan(temperature)) {
    Serial.println("Failed to read temperature");
    return;
  }

  // Target temperature control with pushbuttons
  if (digitalRead(BUTTON_INC) == LOW) {
    targetTemp += 0.5;
    delay(300);
  }
  if (digitalRead(BUTTON_DEC) == LOW) {
    targetTemp -= 0.5;
    delay(300);
  }

  // Manual heater control
  if (digitalRead(BUTTON_TOGGLE) == LOW) {
    heating = !heating; // Toggle heater status
    delay(300);
  }

  // Automatic heater control based on temperature
  if (temperature < targetTemp) {
    heating = true;
  } else if (temperature >= targetTemp) {
    heating = false;
  }

  // Heater relay control
  digitalWrite(RELAY_PIN, heating ? HIGH : LOW);

  // Display temperature, target, and heater status on LCD
  lcd.setCursor(0, 0);
  lcd.print("Temp: ");
  lcd.print(temperature);
  lcd.print(" C");

  lcd.setCursor(0, 1);
  lcd.print("Target: ");
  lcd.print(targetTemp);
  lcd.print(" C ");
  lcd.print(heating ? "ON" : "OFF");

  // Delay for the next reading
  delay(2000);
}

This code is responsible for reading the temperature from the DHT22 sensor, controlling the relay based on the temperature and user input, and displaying the current temperature, target temperature, and heater status on the LCD. The pushbuttons allow the user to adjust the target temperature and toggle the heater on or off.