Running the code below, when I send any character in the Serial arduino is not printing "a" back. I think it's something wrong with the timer1 code but it should work cause this code was given by my teacher in C class.
ISR(TIMER1_COMPA_vect){
}
void setup() {
Serial.begin(115200);
//http://www.instructables.com/id/Arduino-Timer-Interrupts/?ALLSTEPS
noInterrupts();
TCCR1A = 0;// set entire TCCR1A register to 0
TCCR1B = 0;// same for TCCR1B
TCNT1 = 0;//initialize counter value to 0
// set compare match register for 1000000hz increments with 8 bits prescaler
OCR1A = 1;// = (16*10^6) / (1000000*8) - 1 (must be <65536)
// turn on CTC mode
TCCR1B |= (1 << WGM12);
// Set CS11 bit for 8 prescaler. Each timer has a different bit code to each prescaler
TCCR1B |= (1 << CS11);
// enable timer compare interrupt
TIMSK1 |= (1 << OCIE1A);
interrupts();
}
void loop() {
if (Serial.available()) {
Serial.println("a");
}
}
OCR1A = 1is a really really low value. This will mean almost all the time is spend inside the ISR routine (called once every 16 clock cycles). Try with something higher first (e.g. 255). – Gerben Mar 5 '15 at 20:37