//SPI MASTER (ARDUINO)
//SPI COMMUNICATION BETWEEN TWO ARDUINO CIRCUIT DIGEST
#include<SPI.h> //Library for SPI 
#define LED 7
#define ipbutton 2
int buttonvalue;
int x;
void setup (void){
 Serial.begin(115200); //Starts Serial Communication at Baud Rate 115200
 pinMode(ipbutton,INPUT); //Sets pin 2 as input 
 pinMode(LED,OUTPUT); //Sets pin 7 as Output
 SPI.begin(); //Begins the SPI communication
 SPI.setClockDivider(SPI_CLOCK_DIV8); //Sets clock for SPI communication at 
// 8 (16/8 = 2 MHz)
 digitalWrite(SS,HIGH); //Setting SS to HIGH do disconnect master from slave
}
void loop(void){
 byte Mastersend, Mastereceive;
 buttonvalue = digitalRead(ipbutton); //Reads the status of the pin 2
 if(buttonvalue == HIGH) //Setting x for the slave based on input at pin 2
 {
 x = 1;
 }
 else
 {
 x = 0;
 }
 digitalWrite(SS, LOW); //Starts communication with Slave from the Master
 Mastersend = x;
 Mastereceive = SPI.transfer(Mastersend); //Sends the Mastersend value to 
//the slave and also receives value from the slave
 if(Mastereceive == 1) //To set the LED based on value received from slaveu
 {
 digitalWrite(LED,HIGH); //Sets pin 7 HIGH
 Serial.println("Master LED is ON");
 }
 else
 {
 digitalWrite(LED,LOW); //Sets pin 7 LOW
 Serial.println("Master LED is OFF");
 }
 delay(1000);
}