Jon Elson wrote:
> John Kasunich wrote:
>> Its not a scale factor - if it was I would agree with you that you
>> just change the scale.  It literally only counts ONCE per full
>> quadrature cycle.  That represents a hardware change, not just a
>> driver change.  It is up to you whether you want to make that kind
>> of a change - obviously people who already have your board wouldn't
>> be able to benefit without replacing the PROM.
> I really don't think there is a need to change the hardware 
> (EPROM) for this.  I now see why dividing the integer delta by 4 
> won't work.  You need to divide the unscaled integer encoder 
> count by 4, THEN compute the delta from the LAST div-by-4 count, 
> so you aren't computing delta from fractional quadrature cycles.
> This shouldn't be a big deal, however, and I can't see the 
> problem with doing it in the driver.  You also have to be 
> careful to handle the overflows correctly before doing the delta.

I think you are right - I was assuming int->float->scale, where
"scale" is the normal floating point scale factor divided by four.
But if you do int->divby4->float->scale, it should work.

> Is it desired to have both the count AND the delta divided by 4 
> in this mode?

Yes.

> I can't see any flaw in my arithmetic here.

I agree.

Regards,

John Kasunich

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