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[DPRG] PWM freq

Subject: [DPRG] PWM freq
From: Mohit Taneja mohittaneja at gmail.com
Date: Wed Nov 19 13:43:44 CST 2008

I think it is a bad idea to use something around 15-20Khz because it will
make a painful high pitch whine.


Look up the data sheet on the motor controller you are using, it should list
a typical PWM frequency.



Mohit

On Wed, Nov 19, 2008 at 12:43 PM, Dean Hall <dwhall256 at gmail.com> wrote:

> I'm running PWM at just under 2 KHz.  I did not try to hit some exact magic
> number frequency, I just tried a few frequencies at different orders of
> magnitude and went with the one that seemed to perform.  I remember I
> avoided a higher frequency because the motor whine was annoying.  It still
> has whine, but it's not as annoying.  The Timer2 peripheral in my ATmega103
> running at 8 MHz determines the available frequencies.
>
>    /* Timer2 in non-inverted PWM mode, prescale by div 8 (1953 Hz) */
>    TCCR2 = (_BV(PWM2) | _BV(COM21) | _BV(CS01));
>
> The math works out like this: 8 MHz / 8 prescale / 2^9 for nine bit
> resolution == 1953.125 Hz
>
> !!Dean
>
>
> On Nov 19, 2008, at 12:10 , Duane Brantley wrote:
>
>  If you use PWM to control the speed of your drive wheels, what PWM
>> frequency are you using?    Why did you choose that frequency?
>>
>> Thanks,
>> Duane
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