Peter
Like steve im having much the same problem if you have a circuit for I index
stretcher it would be well handy 


Kind Regards 
Steve Beale 
Skype steve.beale

-----Original Message-----
From: Peter C. Wallace [mailto:[email protected]] 
Sent: 18 August 2009 00:55
To: [email protected]; Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] Realistic spindle encoder count for parallel port?

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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