Answers for "how to use timer register in arduino"

how to use timer register in arduino

/* Arduino 101: timer and interrupts
   1: Timer1 compare match interrupt example 
   more infos: http://www.letmakerobots.com/node/28278
   created by RobotFreak 
*/
#define ledPin 13
void setup()
{
  pinMode(ledPin, OUTPUT);
  
  // initialize timer1 
  noInterrupts();           // disable all interrupts
  TCCR1A = 0;
  TCCR1B = 0;
  TCNT1  = 0;
  OCR1A = 31250;            // compare match register 16MHz/256/2Hz
  TCCR1B |= (1 << WGM12);   // CTC mode
  TCCR1B |= (1 << CS12);    // 256 prescaler 
  TIMSK1 |= (1 << OCIE1A);  // enable timer compare interrupt
  interrupts();             // enable all interrupts
}
ISR(TIMER1_COMPA_vect)          // timer compare interrupt service routine
{
  digitalWrite(ledPin, digitalRead(ledPin) ^ 1);   // toggle LED pin
}
void loop()
{
  // your program here…
}
 Blinking LED with timer overflow interruptsame example like before but now we use the timer overflow interrupt. In this case timer1 is running in normal mode. The timer must be preloaded every time in the interrupt service routine.
/* 
 * Arduino 101: timer and interrupts
 * 2: Timer1 overflow interrupt example 
 * more infos: http://www.letmakerobots.com/node/28278
 * created by RobotFreak 
 */

#define ledPin 13

void setup()
{
  pinMode(ledPin, OUTPUT);

  // initialize timer1 
  noInterrupts();           // disable all interrupts
  TCCR1A = 0;
  TCCR1B = 0;

  TCNT1 = 34286;            // preload timer 65536-16MHz/256/2Hz
  TCCR1B |= (1 << CS12);    // 256 prescaler 
  TIMSK1 |= (1 << TOIE1);   // enable timer overflow interrupt
  interrupts();             // enable all interrupts
}

ISR(TIMER1_OVF_vect)        // interrupt service routine that wraps a user defined function supplied by attachInterrupt
{
  TCNT1 = 34286;            // preload timer
  digitalWrite(ledPin, digitalRead(ledPin) ^ 1);
}

void loop()
{
  // your program here...
}