engine-software/communication/SPI/v0.5_M_SPI/M_SPI/M_SPI.ino

//Master Arduino Code:
//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 commnuication
  SPI.setClockDivider(SPI_CLOCK_DIV8);    //Sets clock for SPI communication at 8 (16/8=2Mhz)
  digitalWrite(SS,HIGH);                  // Setting SlaveSelect as HIGH (So master doesnt connnect with slave)
}

void loop(void)
{
  byte Mastersend,Mastereceive;          

  buttonvalue = 8;

  digitalWrite(SS, LOW);                  //Starts communication with Slave connected to master
  
  Mastersend = buttonvalue;                            
  Mastereceive=SPI.transfer(Mastersend); //Send the mastersend value to slave also receives value from slave
  Serial.print((int) Mastereceive);
  Serial.print("\t");
  
  Serial.println((char) Mastereceive);
  delay(250);
}