Circuit Documentation

Summary

This circuit consists of an Arduino UNO microcontroller, a 16x2 I2C LCD display, and a photoresistor (LDR) sensor. The Arduino UNO reads the light intensity from the LDR sensor and displays the status ("Light" or "Dark") on the LCD screen.

Component List

Arduino UNO

• Description: A microcontroller board based on the ATmega328P.
• Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

16x2 I2C LCD

• Description: A 16x2 character LCD display with I2C interface.
• Pins: GND, VCC, SDA, SCL

Photoresistor (LDR) Sensor (Wokwi Compatible)

• Description: A light-dependent resistor sensor.
• Pins: VCC, GND, DO, AO

Wiring Details

Arduino UNO

• 5V: Connected to VCC of the 16x2 I2C LCD and VCC of the Photoresistor (LDR) Sensor.
• GND: Connected to GND of the 16x2 I2C LCD and GND of the Photoresistor (LDR) Sensor.
• SCL: Connected to SCL of the 16x2 I2C LCD.
• SDA: Connected to SDA of the 16x2 I2C LCD.
• D2: Connected to DO of the Photoresistor (LDR) Sensor.

16x2 I2C LCD

• VCC: Connected to 5V of the Arduino UNO.
• GND: Connected to GND of the Arduino UNO.
• SCL: Connected to SCL of the Arduino UNO.
• SDA: Connected to SDA of the Arduino UNO.

Photoresistor (LDR) Sensor (Wokwi Compatible)

• VCC: Connected to 5V of the Arduino UNO.
• GND: Connected to GND of the Arduino UNO.
• DO: Connected to D2 of the Arduino UNO.

Code Documentation

Arduino UNO Code

#include <LiquidCrystal_I2C.h>

#define LDR_PIN 2

LiquidCrystal_I2C lcd(0x27, 20, 4);

void setup() {
  pinMode(LDR_PIN, INPUT);
  lcd.init();
  lcd.backlight();
}

void loop() {
  lcd.setCursor(2, 0);
  lcd.print("Room: ");
  if (digitalRead(LDR_PIN) == LOW) {
    lcd.print("Light!");
  } else {
    lcd.print("Dark  ");
  }
  delay(100);
}

Explanation:

• Libraries: The LiquidCrystal_I2C library is included to control the LCD.
• Pin Definitions: The LDR sensor is connected to digital pin 2 (LDR_PIN).
• LCD Initialization: The LCD is initialized with the I2C address 0x27 and dimensions 20x4.
• Setup Function:
  • The LDR pin is set as an input.
  • The LCD is initialized and the backlight is turned on.
• Loop Function:
  • The cursor is set to column 2, row 0 on the LCD.
  • The text "Room: " is printed.
  • The LDR sensor is read. If the reading is LOW, "Light!" is displayed; otherwise, "Dark" is displayed.
  • A delay of 100 milliseconds is added to avoid rapid updates.