Example of Timer Interrupt on Arduino

It's example to use Timer Interrupt of Arduino Esplora, to toggle RGB LED when timer interrupt reached.



testTimer.ino

#include <Esplora.h>

volatile boolean ledon;
volatile unsigned long lasttime;
volatile unsigned long now;
 
void setup() {
    ledon = true;
    Esplora.writeRGB(100, 100, 100);

    lasttime = millis();
    
    // 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
    
}
 
void loop() {
 
}

ISR(TIMER1_OVF_vect)
{
    TCNT1 = 34286; // preload timer
    
    ledon = !ledon;
    if(ledon){
        Esplora.writeRGB(0, 0, 1);
    }else{
        Esplora.writeRGB(0, 0, 0);
    }
    
    now = millis();
    Serial.println(now - lasttime);
    lasttime = now;
}

reference: http://blog.oscarliang.net/arduino-timer-and-interrupt-tutorial/