Project 1 - Interfacing a 16*2 LCD with Arduino using I2C protocol

Interfacing a 16x2 LCD with Two Arduinos Using I2C Communication Protocol.

Requirements:

• 2 Arduino boards (e.g., Arduino Uno)
• 16x2 LCD with I2C module
• Jumper wires
• Breadboard
• Pull-up resistors (optional, if not included in your I2C module)
  
  Circuit Connections:

1. Master Arduino:

   • Connect SDA (A4 for Uno) and SCL (A5 for Uno) to corresponding pins on the Slave Arduino.
   • Connect GND and VCC to common ground and power.

2. Slave Arduino:

   • Connect SDA and SCL to the LCD module’s SDA and SCL pins.
   • Connect the LCD module’s VCC and GND to the Arduino's 5V and GND.

3. Ensure all GND pins are connected together for a common ground.
   
   PROGRAM:

   #include <Wire.h>

   #include <LiquidCrystal_I2C.h>

   // LCD Setup

   LiquidCrystal_I2C lcd(0x27, 16, 2); // LCD address (0x27), 16 columns, 2 rows

   // Variables

   String receivedMessage = ""; // To store the message received by the Slave

   // Role Selection (Uncomment one line based on the role)

   // #define MASTER

   #define SLAVE

   void setup() {

   #ifdef MASTER

   // Master setup

   Wire.begin(); // Initialize I2C as Master

   Serial.begin(9600);

   Serial.println("Master Ready");

   #endif

   #ifdef SLAVE

   // Slave setup

   Wire.begin(8); // Initialize I2C as Slave with address 8

   Wire.onReceive(receiveEvent); // Register receive event

   lcd.init(); // Initialize the LCD

   lcd.backlight(); // Turn on backlight

   lcd.setCursor(0, 0);

   lcd.print("Waiting...");

   #endif

   }

   void loop() {

   #ifdef MASTER

   // Master logic: Send a message to the Slave

   Wire.beginTransmission(8); // Start communication with Slave (address 8)

   Wire.write("Hello, Slave!"); // Send the message

   Wire.endTransmission(); // Stop communication

   Serial.println("Message sent to Slave");

   delay(1000); // Wait 1 second

   #endif

   #ifdef SLAVE

   // Slave logic: Display the received message on the LCD

   if (receivedMessage != "") {

   lcd.clear();

   lcd.setCursor(0, 0);

   lcd.print(receivedMessage);

   receivedMessage = ""; // Clear the message after displaying

   }

   #endif

   }

   // Slave Event Handler

   void receiveEvent(int bytes) {

   #ifdef SLAVE

   receivedMessage = ""; // Clear the buffer

   while (Wire.available()) {

   char c = Wire.read(); // Read each character

   receivedMessage += c;

   }

   #endif

   }
   
   OUTPUT:
   Master Arduino
   
   Master Ready
   Message sent to Slave
   Message sent to Slave
   Message sent to Slave
   .......
   
   slave Arduino
   
   Hello, Slave!