How to "fake" multitasking on an 8-bit processor?

I have an Arduino with an Adafruit Motor Shield as part of my robot. I want to run the motors at the same time I play a tone on the piezo element.

The problem is that I don't quite know how to fake/simulate multitasking in my code. I tried something like this:

void goForward(int duration) {

    for (int i; i<duration; i++) {
        tl.run(FORWARD);
        tr.run(BACKWARD);
        bl.run(FORWARD);
        br.run(BACKWARD);
        counter++;

        if (counter%4==0) {
            piezo != piezo;
        }

        delay(1);
    }
}

This runs the motors, however it doesn't create a tone on my piezo element. What would be a better way to program this so the piezo could be switched on/off at a frequency of 440 Hz while the motor commands开发者_Go百科 are running?

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I don't know the Arduino board, but most microcontrollers have some timer interrupt. Have you tried to setup such a timer? In the timer interrupt handler you could enable/disable the piezo element, while the main loop could be used for controlling the motor.

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Normal Arduino boards only have 3 timers. This limits "multitask" capability to 3 "threads". Arduino Mega has 16 timers. In other words, the Arduino Mega can be your solution. No?

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Create scheduler to create parallel tasks, and use two timers for your motors, and if you have a third one use it for the buzzer.