int buttonPin = 3;
void setup()
{
pinMode(buttonPin, INPUT_PULLUP);
Serial.begin(9600);
Serial.println("ready!");
TCCR2B = 0x07; // clock frequency / 1024
//OCR2B = 0x00; // Output compare
TCNT2 = 0; // Set counter 2 to zero
TIMSK2 = 0x01; // Enable overflow interrupt
attachInterrupt(digitalPinToInterrupt(3), button_ISR, RISING);
}
void loop()
{
}
void button_ISR()
{
Serial.print("button_ISR()");
Serial.print("\n");
}
ISR(TIMER2_OVF_vect) {}