weesiang_loke:
thanks for the replies but i need to use only the microcontroller to generate the sinusoidal wave, because later i will need to program it to the lilypad. therefore i need to figure out how to do this by using the fast pwm mode. besides, in future i may need to make a remote control device to control the amplitude and make change of some of the variable in the pwm. so what i am thinking is to use only one timer to do it.
Then it will not be possible for you to create a sine wave as none of the arduino compatible AVR chips contain a true D/A output, you will always have to have external circuitry (low-pass filtering and amplification or external D/A device) to create sine waves. A PWM output is fundamentally a digital output signal, the voltage is always either 0 or +5vdc and any specific point of time, where a sine wave is a smoothly changing analog voltage.
Lefty