Re: [CAD_CAM_EDM_DRO] Re: home switches

>--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Peter Homann"
><peter.homann@a...> wrote:
>
>
>>Hi,
>>
>>The technique I use on my TurboTaig board is to combine the home switch
>>input with the 'home' (phase 0) signal from the stepper driver. I
>>
>>
>checked
>
>
>>the datasheet for the 5804 and it doesn't have this output. The 3977
>>
>>
>or the
>
>
>>ST L297 does though. This output on these components is there to solve
>>exactly your problem.
>>
>>
>>

One other way to do this is attach a slotted disc to the motor. Put an
optical
break detector (one of those things in old floppy drives that has an emitter
and detector across a gap, that will detect something blocking the light
path)
across the disc, and it will give one pulse every revolution. This is
essentially
the same as the index pulse on an encoder. it can be set up to qualify the
home switch position to a pretty fine tolerance. However, many people
have reported repeatability from .003" down to .0005" with standard
microswitches. I'm guessing these are the "big" type, about 3/4" square by
1.5" long.

Jon