Re: Re: G320s, New and Improved!

On 7 Sep, CAD_CAM_EDM_DRO@yahoogroups.com wrote:

> Message: 6
> Date: Fri, 07 Sep 2001 00:57:21 -0000
> From: mariss92705@...
> Subject: Re: G320s, New and Improved!
>
> Jon,
>
> Good afternoon! The only way illegal transitions can occur are if (1)
> the channel A and B lines are shorted together or (2) a non-
> quadrature encoder is used such as using the least 2 bits of an
> absolute encoder.

OR if a tiny spec of dust, or perhaps even finger oil, gets into one of
the slits of the encoder.

In building my own DRO readout, I used a small PIC programmed to accept
quadrature input and output three signals ..

Direction, set high or low
Step, a 1us pulse, used to trigger an interrupt on another PIC
Error, when an illegal state was detected.

When the "main" PIC got an error signal, the LCD display would blink
ERROR.

I was quite dismayed to see how often I saw the word ERROR when testing
with a variety of rotary encoders, some robbed from those little
Electronics Goldmine motors, some robbed from HP ink printers, some
robbed from I don't know where.

Alan

--

Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta