20MHZ PWM on 4 pins needed

[SouthernAtHeart]

@MartinL

If you require a PWM signals out of audible range then it's possible to generate 31.25kHz PWM on pins 3, 9, 10 and 11. Just add the following lines to your sketch then use the analogWrite() function as normal:

TCCR1B &= ~_BV(CS11);	// Increase the timer1 PWM frequency to 31.25kHz
TCCR2B &= ~_BV(CS22);	// Increase the timer2 PWM frequency to 31.25kHz
TCCR2B |= _BV(CS20);

I see this from the PWM link mentioned in post 10. So to get it out of audible hearing range, these lines should do the trick it seems. And the data sheet for my motor drivers says it works with PWM up to 100khz, so this should work great for me. Thanks.

//---------------------------------------------- Set PWM frequency for D9 & D10 ------------------------------
//TCCR1B = TCCR1B & B11111000 | B00000001;    // set timer 1 divisor to     1 for PWM frequency of 31372.55 Hz

//---------------------------------------------- Set PWM frequency for D3 & D11 ------------------------------
//TCCR2B = TCCR2B & B11111000 | B00000001;    // set timer 2 divisor to     1 for PWM frequency of 31372.55 Hz