Here is simple program that uses timer overflow interrupt.
import mcujavasource.mcu.*;
/** Tutorial 2: program with timer interrupts.
* Three LEDs flash one after another.
* Default 8-bit timer and its overflow interrupt is used for delay.
* LED's anode is connected to +5V through 330 Ohm resistor,
* cathode - to MCU port.
*/
public class Tutorial2 extends Microcontroller
{
/** Pin of the first LED, PB1 */
private final Pin led1 = getHardware().getPort("B").getPin(1);
/** Pin of the second LED, PB0 */
private final Pin led2 = getHardware().getPort("B").getPin(0);
/** Pin of the third LED, PB2 */
private final Pin led3 = getHardware().getPort("B").getPin(2);
private Timer timer;
private volatile int currentLed = 0;
public void init()
{ //register initialization on startup
getHardware().setAllPortsDirection(Pin.IN);
getHardware().setAllPortsPullUp(true);
led1.setDirection(Pin.OUT);
// led1 is initially turned on
led1.setOutput(Pin.LOW);
led2.setDirection(Pin.OUT);
led2.setOutput(Pin.HIGH);
led3.setDirection(Pin.OUT);
led3.setOutput(Pin.HIGH);
// getting default 8-bit timer
timer = getHardware().getDefaultTimer(8);
timer.setMode(TimerMode.NORMAL);
// prescaling 1024
timer.setPrescaling(1024);
timer.setEnabled(true);
LedSwitcher ledSwitcher = new LedSwitcher();
timer.addTimerListener(ledSwitcher);
timer.setTimerOverflowedFired(true); //this enables interrupt
}
public void start()
{ //main program
getHardware().setInterruptsEnabled(true);
}
private class LedSwitcher implements TimerListener
{
public void timerOverflowed()
{ currentLed++;
if(currentLed >= 3) currentLed = 0;
switch(currentLed)
{ case 0:
led3.setOutput(Pin.HIGH); //turn off led3
led1.setOutput(Pin.LOW); //turn on led1
break;
case 1:
led1.setOutput(Pin.HIGH);
led2.setOutput(Pin.LOW);
break;
case 2:
led2.setOutput(Pin.HIGH);
led3.setOutput(Pin.LOW);
break;
}
}
}
}
Don't forget to activate the listeners! For examples, timer.setTimerOverflowedFired(true); activates TimerListener (in order, this enables interrupt). Listeners cannot be removed in MCU Java source, but can be activated and deactivated.