Re: [CAD_CAM_EDM_DRO] Re: Black box

Actually, thats how master control works. It creates a bit stream and then
streams it out. The problem is to interupt windows to do it in the
background. I think I have found a way and am working on it now. The sound
card in most computers has a DSP chip which can be programmed from 1hz to
100khz and will interrput the processor at
that rate. My thought now is to have an application create the bit stream
and then use the DSP interrupt to send it out. I don't see why it can't work
just like real audio, instead of the speaker send it to the printer port.

I'll let you know after a few experiments.
Art

----- Original Message -----
From: "Jon Elson" <jmelson@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: Friday, October 13, 2000 4:37 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Black box


>
>
> Art Fenerty wrote:
>
> > Definitely nice Tom, but the holy grail, I think, is to do it
> > without any hardware added to your computer at all.
> > It's what keeps me interested anyway.
>
> And, it is totally clear to me that you CAN'T do this, with any
> processor
> at all, from a DSP, to a 1 GHz Pentium, whatever, your choice!
>
> Actually, I DO know a way to do it, and there might be hardware that is
> already on the PC that can be used. What you need is to compose a
> huge bit stream, and put 1's in there where you want steps, and 0's
> where there should be no step. Then, you send this stream out to
> the stepper drive. I can think of the sound port as a device that does
> something like this, already. The video data coming out to the video
> monitor also does this, but I don't see much of a practical way to
> subvert that, without losing your screen display. Possibly the floppy
> port could also be used to generate the bit stream.
>
> But, most computers now have an ECP port, and it can do DMA to
> the data port. SO, you compose a chunk of the bit stream, and then
> just need a timer out on the parallel port to handshake the bytes
> out to the data port. When the stream is done, another stream
> is already ready to be sent. This should actually work, shouldn't
> cause too much overhead if the byte rate is set low enough, and
> the stuff added to the parallel port sounds like a one shot and a
> gate or two, to be quick and dirty, or a crystal oscillator and
> a counter chip if you want to precisely control the rate.
>
> Anyone want to try implementing this? (Or will it be OK to wait a
> couple of weeks for my stepper timing chip, which should give
> better control with less overhead.)
>
> Jon
>
>
>
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