#include <SPI.h>
//globals
int receivedValue;

void setup(){
  pinMode(SS, OUTPUT); // set the chip Select pin to be an output, 
  //so that this board knows it is the master device
  SPI.begin(); 
  SPI.setBitOrder(MSBFIRST); // send the most significant bit first
  SPI.setDataMode(SPI_MODE0); // have data be collected by each device on the falling clock edge
}

void loop(){
  digitalWrite(SS, LOW);
  receivedValue = SPI.transfer(0b11111111); // send eight 1's
  digitalWrite(SS, HIGH);
  
  delay(1);
  
  digitalWrite(SS, LOW);
  receivedValue = SPI.transfer(0b00000000); // send eight 0's
  digitalWrite(SS, HIGH);
  
  delay(1);
}