Re: Quadrature for DIY DRO

Scott,

I do not know the answers to all of your questions, but I have a
couple of the US Digital encoders I will loan you to use for
developement on this project. Contact me by email (mazhess at
hotmail.com (of cource use "@" in place of " at ") to work out the
details on shipping.

Mike

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "sshumate" <sshumate@y...>
wrote:

> REMINDER: Please keep all purchase-related inquiries off of the

group

> list and direct them only to me at my private e-mail. Thanks.
>
> I have looked into US Digital quadrature encoders to see if it is
> possible to support them in the DRO and I wanted to get some

feedback

> from people who have used them.
>
> The output of the encoders is 5V common collector with a weak
> pullup. This is good because the DRO circuit already has strong
> pullups on the scale inputs. First question, do other brands of
> quadrature encoders use a different voltage level or different

output

> drivers?
>
> For the 5V output signal the US Digital encoders use, the existing
> PCB could be easily reworked to accept this. It would consist of
> depopulating (or not populating to begin with) the buffer chips

which

> are three 8-pin DIPs. The wires from the connector would then be
> soldered on a couple of the through holes of these DIPS. Second
> question, is there a standard style of connector for these

encoders?

> Would the existing 4 pin mini-DIN work?
>
> I don't think I would be able to support simultaneous reading of

both

> Chinese scales and quadrature encoders. The PIC is very busy while
> triple sampling the Chinese scale serial stream and there is a good
> probability that a quadrature pulse could be missed. Third

question,

> would it be sufficient just to have a setup screen that switched

all

> inputs between Chinese and quadrature mode?
>
> Some of the quadrature encoders have an index pulse. I don't think
> this could be supported in the current design since there are no

free

> pins left on the PIC. Fourth question, is it OK not support this

and

> operate the encoders only in absolute mode?
>
> Lastly, I don't have any quadrature encoders in my home machine

shop

> and I do not really have a need. Would anyone be willing to loan a
> couple to me to develop this feature?
>
> Cheers,
> Scott