SPI para DMX

#include <DmxSimple.h>
#include "SPI.h"

char canais [512];
volatile boolean received_flag;
int dmxpin = 5;

void setup() {
  DmxSimple.usePin(dmxpin);

  SPCR |= bit (SPE);

  pinMode(MISO, OUTPUT);

  received_flag = false;

  SPI.attachInterrupt();

}

void loop() {

  if (received_flag){

    for (int i=1;i<513;i++){
    DmxSimple.write(i,canais[i]);
    }


    received_flag = false;
  }
}


ISR (SPI_STC_vect) {

  for (int i=1;i<513;i++){
  canais [i] = SPDR;
  }

  received_flag = true;
}