Of course, other choices can be made if an application produces smaller maximum duty cycle steps. We’re also interested in the amplitude of the filtered PWM ripple. The filter’s frequency response is: ...

To keep things simple, for now, you just send an 8-bit hex number to set the PWM output duty cycle. For example, if you send an uppercase A (65 decimal or 41 hex), the output will be at 65/256 or ...

This function mixes audio samples and changes the PWM duty cycle of Timer2/OC1. The rates on both of these timers are set up once and never need to change, just the one duty cycle is varied.