Interrupcion por Timer

volatile boolean l;

void TC0_Handler(){

  long status=REG_TC0_SR0;

  l=!l;

}

void setup(){

  pinMode(13,OUTPUT); //LED

  pinMode(2,OUTPUT);   //TIOA0 => Pin B.25

  analogWrite(2,255);//??

  REG_PIOB_PDR=0x2000000;//Pin 25 free from GPIO to peripheral use of timer

  REG_PIOB_ABSR=0x2000000;//Peripheral B free from GPIO to peripheral use of timer

  REG_TC0_WPMR=0x54494d00;  //disable protection of registers

  REG_TC0_CMR0=0x9c403;  //Waveform mode, CLK/128, Mode TIOA

  REG_TC0_RA0=0x0;    //RA start point is 0 

  REG_TC0_RC0=0x9fff6;  //RC stop point is 0x9fff6=1 second???.REVISAR

  REG_TC0_CCR0=0x5;   //Enable Channel 0 and start counting by software

  REG_TC0_IER0=0x10;  //Interrupt when RC is reach.

  REG_TC0_IDR0=0xEF;  //Disable the others interruptions

  NVIC_EnableIRQ(TC0_IRQn);   //Enable TC0 interrupts

}

void loop(){

  digitalWrite(13,l);

}