//Slave Arduino Code:
//SPI SLAVE (ARDUINO)
//SPI COMMUNICATION BETWEEN TWO ARDUINO 
//CIRCUIT DIGEST
//Pramoth.T

#include<SPI.h>
#define LEDpin 7
#define buttonpin 2
volatile boolean received;
volatile byte Slavereceived,Slavesend;
int buttonvalue;
int x = 5;
void setup()

{
  Serial.begin(115200);
  
  pinMode(buttonpin,INPUT);               // Setting pin 2 as INPUT
  pinMode(LEDpin,OUTPUT);                 // Setting pin 7 as OUTPUT
  pinMode(MISO,OUTPUT);                   //Sets MISO as OUTPUT (Have to Send data to Master IN 

  SPCR |= _BV(SPE);                       //Turn on SPI in Slave Mode
  received = false;

  SPI.attachInterrupt();                  //Interuupt ON is set for SPI commnucation
  
}

ISR (SPI_STC_vect)                        //Inerrrput routine function 
{
  Slavereceived = SPDR;         // Value received from master if store in variable slavereceived
  received = true;                        //Sets received as True 
}

void loop()
{ if(received)                            //Logic to SET LED ON OR OFF depending upon the value recerived from master
   {
      if (Slavereceived==8) 
      {
        x+=1;
        
        
        /*
        digitalWrite(LEDpin,HIGH);         //Sets pin 7 as HIGH LED ON
        Serial.println("Slave LED ON");
      }else
      {
        digitalWrite(LEDpin,LOW);          //Sets pin 7 as LOW LED OFF
        Serial.println("Slave LED OFF");
      }
      
      buttonvalue = digitalRead(buttonpin);  // Reads the status of the pin 2
      
      if (buttonvalue == HIGH)               //Logic to set the value of x to send to master
      {
        x=1;
        
      }else
      {
        x=0;*/
   
      }
           if(x == 10){x = 0;}
           
        Slavesend=x;        
        
                          
        SPDR = Slavesend;  
        SPDR = x;//Sends the x value to master via SPDR 
        Serial.println(SPDR);  
        Serial.println(Slavesend);
        delay(500);
      
 
}
}