#include <Wire.h>           // includes the I2C library                                           
//String readString;          // this variable will be used to store on or off commands given in the serial monitor.                                                           
byte I2C_OnOff;             // a byte variable with which we will send information to the slave via I2C                                               
void setup()
{
  Wire.begin();             // start the I2C communication                                               
  Serial.begin(9600);       // start the Serial communication
  Serial.println("Type On to turn on the LED and Off to shut it down!");   // write on the monitor for note for a user
}a
void loop()
{
  while (Serial.available()) // check if the user has inserted anything in the serial monitor and read it
  {
    delay(2);                                                               
    char c = Serial.read();  // store this information through char c variable letter by letter                                               
    readString += c;         // and move these characters inside a readString string                                              
  }
  if (readString == "BlueOn" or readString == "BLUEON" or readString == "blueon") // an if statement which will determine the value of a I2C_OnOff variable depending on the users input
  {
    I2C_OnOff = 1; // If the user inserts "BlueOn", "BLUEON" or "blueon" the I2C_OnOff variable will store number 1
  }
  else if (readString == "BlueOff" or readString == "BLUEOFF" or readString == "blueoff")
  {
    I2C_OnOff = 0; // If the user inserts "BlueOff", "BLUEOFF" or "blueoff" the I2C_OnOff variable will store 0.
  }
  if (readString.length() > 0)                                            
  {
    Serial.println(readString);  // displaying the users input on the Serial Monitor                                          
    readString = "";             // If the readString string has any value display this value and empty the string                                          
  }
  Wire.beginTransmission(1);    // open the transmission with the student that has an address 1                                            
  Wire.write(I2C_OnOff);        // send it a byte I2C_OnOff value                                           
  Wire.endTransmission();       // end the transmission.                                            
}