Arduino – blinky with Timer1 OVF

Yet another Arduino blinky project. This version of “blinky” example is using Timer1 Overflow interrupt to make an onboard LED blink for roughly one second. The code is on Github, click here.

Parts Required

• Arduino board (i.e. Arduino/Genuino UNO)

Software

This code is written in C++ and can be compiled using an Arduino IDE. All information about how to compile this project is here.

/**
 * Copyright (c) 2019, Łukasz Marcin Podkalicki <lpodkalicki@gmail.com>
 * Arduino/002
 * Blinky with Timer1 OVF.
 */

#define LED_PIN     (13)
#define TIMER_TCNT  (57723) // 65536 - 16MHz/1024/2

void setup() {
  pinMode(LED_PIN, OUTPUT); // set LED pin as output
  TCCR1A = 0; // clear register
  TCCR1B = _BV(CS12)|_BV(CS10); // set Timer1 prescaler to 1024
  TIMSK1 |= _BV(TOIE1); // enable Timer1 overflow interrupt
  TCNT1 = TIMER_TCNT; // reload timer counter
  interrupts(); // enable global interrupts
}

void loop() {
  // do nothing
}

ISR(TIMER1_OVF_vect) {
  TCNT1 = TIMER_TCNT; // reload timer counter
  digitalWrite(LED_PIN, !digitalRead(LED_PIN)); // Toggle LED pin
}