On Mon, 17 Aug 2009, Steve Blackmore wrote:
> Date: Mon, 17 Aug 2009 23:39:06 +0100
> From: Steve Blackmore <[email protected]>
> To: "Enhanced Machine Controller (EMC)" <[email protected]>
> Subject: Re: [Emc-users] Realistic spindle encoder count for parallel port?
>
> On Sun, 16 Aug 2009 21:03:54 -0700 (PDT), you wrote:
>
>
>> Can you use both encoders at once?
>> High resolution for low speed and Low resolution for high speed?
>>
>>
>> You could also do this with the high resolution encoder and a gizmo
>> like the USdigital divider, only with 2 selectable divide ratios run from a
>> single I/O bit, say 1/1 and 1/64. This is easily do-able in a $ 1.20 CPLD
>
> A divider would work well, but I'm no programmer and wouldn't know where
> to start.
If I get a free bit of time I'll cobble together a quadrature divider,
basically:
1. Input digital filter
2. Quadrature decoder (quadrature to up/down)
3. Up down modulo N counter (for divide by N)
4. 2 bit up/down counter
5. 2 bit binary --> quadrature encoder
6. Optional index stretcher
I even think we have some CPLD bds we never used that I can send over for
shipping cost.
>
> If I can't find a simple solution it looks like I'll have to get another
> encoder.
>
>> Would you need the index at high speeds?
>
> My normal working range is 600-1200 rpm. Most of my threading is done at
> 600-1000 rpm, depending on pitch.
>
> Steve Blackmore
> --
>
Peter Wallace
Mesa Electronics
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