Project 1 - Interfacing a 16*2 LCD with Arduino using I2C protocol
/* Program for “Interfacing a 16*2 LCD with two Arduino’s (one for Master & one for Slave) using Inter-Integrated Circuit (I2C) communication protocol” by sending the message to LCD using I2C communication protocol and display the message on LCD screen*/
//I2C MASTERCODE
//I2C communication between two arduino
#include<Wire.h> //Library for I2C Communication functions
#include<LiquidCrystal.h> //Library for LCD display function
LiquidCrystal lcd(2, 7, 8, 9, 10, 11); //Define LCD Module Pins (RS,EN,D4,D5,D6,D7)
void setup()
{
lcd.begin(16,2); //Initilize LCD display
lcd.setCursor(0,0); //Sets Cursor at first line of Display
lcd.print("CYIENT"); //Prints CIRCUIT DIGEST in LCD
lcd.setCursor(0,1); //Sets Cursor at second line of Display
lcd.print("I2C MASTER ARDUINO"); //Prints I2C ARDUINO in LCD
delay(5000); //Delay for 5 seconds
lcd.clear(); //Clears LCD display
Serial.begin(9600); //Begins Serial Communication at 9600 baud rate
Wire.begin(); //Begins I2C communication at pin (A4,A5)
}
void loop()
{
Wire.requestFrom(8,1); // request 1 byte from slave arduino (8)
byte MasterReceive = Wire.read(); // receive a byte from the slave arduino and store in MasterReceive
int potvalue = analogRead(A0); // Reads analog value from POT (0-5V)
byte MasterSend = map(potvalue,0,1023,0,127); //Convert digital value (0 to 1023) to (0 to 127)
Wire.beginTransmission(8); // start transmit to slave arduino (8)
Wire.write(MasterSend); // sends one byte converted POT value to slave
Wire.endTransmission(); // stop transmitting
lcd.setCursor(0,0); //Sets Currsor at line one of LCD
lcd.print(">> Master <<"); //Prints >> Master << at LCD
lcd.setCursor(0,1); //Sets Cursor at line two of LCD
lcd.print("SlaveVal:"); //Prints SlaveVal: in LCD
lcd.print(MasterReceive); //Prints MasterReceive in LCD received from Slave
Serial.println("Master Received From Slave"); //Prints in Serial Monitor
Serial.println(MasterReceive);
delay(500);
lcd.clear();
}
//I2C SLAVE CODE
//I2C Communication between Two Arduino
#include<Wire.h> //Library for I2C Communication functions
#include<LiquidCrystal.h> //Library for LCD display function
LiquidCrystal lcd(2, 7, 8, 9, 10, 11); //Define LCD Module Pins (RS,EN,D4,D5,D6,D7)
byte SlaveReceived = 0;
void setup()
{
lcd.begin(16,2); //Initilize LCD display
lcd.setCursor(0,0); //Sets Cursor at first line of Display
lcd.print("CYIENT"); //Prints CIRCUIT DIGEST in LCD
lcd.setCursor(0,1); //Sets Cursor at second line of Display
lcd.print("I2C SLAVE ARDUINO"); //Prints I2C ARDUINO in LCD
delay(5000); //Delay for 5 seconds
lcd.clear(); //Clears LCD display
Serial.begin(9600); //Begins Serial Communication at 9600 baud rate
Wire.begin(8); //Begins I2C communication with Slave Address as 8 at pin (A4,A5)
Wire.onReceive(receiveEvent); //Function call when Slave receives value from master
}
void loop(void)
{
lcd.setCursor(0,0); //Sets Currsor at line one of LCD
lcd.print(">> Slave <<"); //Prints >> Slave << at LCD
lcd.setCursor(0,1); //Sets Cursor at line two of LCD
lcd.print("MasterVal:"); //Prints MasterVal: in LCD
lcd.print(SlaveReceived); //Prints SlaveReceived value in LCD received from Master
Serial.println("Slave Received From Master:"); //Prints in Serial Monitor
Serial.println(SlaveReceived);
delay(500);
lcd.clear();
}
void receiveEvent (int howMany) //This Function is called when Slave receives value from master
{
SlaveReceived = Wire.read(); //Used to read value received from master and store in variable SlaveReceived
}

The message passed from master to slave and displayed on the 16*2 LCD:
