adjusting the F_SW and other attempts at silence

[Hummie]

are there any other settings that can be safely changed to make the motor quieter besides the F_SW? Whats the upper limit on the F_SW?

[rew]

When you move F_SW up, the amount of time spent in the "every F_SW" interrupt (ADC interrupt) goes up. Measurements of the "time left" indicate that about 50% of the time is still not spent in the interrupt. So you could double F_SW. But the occasional overrun is probably quite bad. So you want to keep a safe margin. The whine happens at 1/2 F_SW, so you'd need 40kHz, as opposed to the current default of 20kHz to make things silent.