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.