Re: [CAD_CAM_EDM_DRO] PIC DRO Revisited

Glen Benson wrote:

> From: "Glen Benson" <benson@...>
>
> Hi,
>
> I have been programming PICs for a few years, and am cosidering
> making a 3 axis DRO. I would be more than glad to share my
> design,code,schematics with all. Having never worked with a DRO, I
> have a couple of questions. How does the DRO know which direction the
> motor is going (so it can increment or decrement). Also what
> properties do the average encoders have (e.g. opto
> using a 5 volt supply, hall effect) do they pulse a signal out or
> need a supply voltage etc.

Most quadrature encoders (both linear and rotary) produce 2 square
waves, with a 90 degree
phase relationship. A state machine is usually used to decode all the
transitions into step and
direction type signals, which can then be counted. Most modern encoders
run off 5 V, and
have either TTL single-ended or differential signals, or open-collector
signals.

>
> I was thinking of using a seperate color of LED diplay for each
> axis. Besides a button to zero each axis are there any other features
> I need to consider?

That would work pretty well, but an (optional) keypad to enter a
coordinate would be
a big plus. Also, the ability to set the X axis to read twice the
movement would be
nice, for lathe work.

Jon