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Conference hydra::amiga_v1

Title:AMIGA NOTES
Notice:Join us in the *NEW* conference - HYDRA::AMIGA_V2
Moderator:HYDRA::MOORE
Created:Sat Apr 26 1986
Last Modified:Wed Feb 05 1992
Last Successful Update:Fri Jun 06 1997
Number of topics:5378
Total number of notes:38326

1771.0. "Digitizing tablets." by SPIDER::BUSCH () Wed Oct 12 1988 17:20

I would like to build what amounts to an X-Y digitizing tablet. My idea is to
generate signals which emulate the Amiga mouse, but which have an absolute
positional reference rather than a relative reference, as the normal mouse has.
Can anybody tell me what the signals on the mouse connector look like (voltages,
waveforms, etc.) or where I can look these things up?  If this works, my next 
step would be to add a third sensor to make it an X-Y-Z digitizer. 

Actually, my idea would be to measure the position of a point with respect to
it's distance from three fixed points and then do a coordinate transformation to
convert to X-Y-Z space. 

Dave
T.RTitleUserPersonal
Name		DateLines
1771.1ELWOOD::PETERSWed Oct 12 1988 18:1911
    
    	You might try a software solution. It is possible to write a
    program ( driver ) that creates very low level mouse messages that
    fools AMIGA Dos into thinking they came from the mouse.
    
    	There is a PD program that can record and play back mouse 
    sequences this way. Also the commercial tablets work this way.
    
    
    		Steve Peters
1771.2Trying to emulate a mouse.OPUS::BUSCHThu Oct 13 1988 00:0712
>	You might try a software solution. It is possible to write a
>	program ( driver ) that creates very low level mouse messages that
>	fools AMIGA Dos into thinking they came from the mouse.
    
That's not exactly what I had in mind. What I'm looking for is what the input 
signal requirements are so that I can build a piece of hardware to do my
measuring and then send it's signals to the Amiga as if it were coming from a 
mouse. 

Dave
1771.3ClarificationBARDIC::RAVANFri Oct 14 1988 18:525
    Re: .0

    Three fixed points in 3-space or 2-space?

    -jim
1771.4Quadrature mouse tutorialPRNSYS::LOMICKAJJeff LomickaMon Oct 17 1988 16:0629
I can't speak for the Amiga, but most inexpensive computers use
quadurature encoded mice.  Each axis get's two signal wires, and they
are encoded as follows:

For motion in one direction:
               _____       _____       _____       _____
Phase 1	|_____|     |_____|     |_____|     |_____|     
        ___       _____       _____       _____       __
Phase 2	   |_____|     |_____|     |_____|     |_____|     

For motion in the other direction:
               _____       _____       _____       _____
Phase 1	|_____|     |_____|     |_____|     |_____|     
            _____       _____       _____       _____
Phase 2	___|     |_____|     |_____|     |_____|     |__

You might note that this can be generated directly by a slotted disk
that has two photo-detectors on it.  Levels are usually TTL compatible. 
(Careful, some mice are CMOS.)

You can use this method to simulate mice just fine, and you can
therefore generate "precise" relative motion between two points, without
concern about "slip" that takes place with real mechanical mice.

The gotcha in all this is that some software systems perform mouse
speed detection, and scale the motion of the mouse as some function of
the speed.  If the Amiga is such a system, the resulting motion that
gets reported to your program will no longer be linear!
1771.5Mouse AcceleratorsTLE::RMEYERSRandy MeyersMon Oct 17 1988 23:2810
Re: .4

>The gotcha in all this is that some software systems perform mouse
>speed detection, and scale the motion of the mouse as some function of
>the speed.  If the Amiga is such a system, the resulting motion that
>gets reported to your program will no longer be linear!

The Amiga doesn't do mouse speed scaling out of the box.  However, some
of the combination mouse accelerator-screen blanker-hot key programs
do scale the mouse moves by the speed of the mouse.
1771.6SUBSYS::BUSCHDave Busch at NKS1-2Tue Oct 18 1988 13:336
If I have MachII running in the background while I run a BASIC program which 
reads the mouse position, will MachII still accellerate the mouse, or will BASIC
give a true reading of where the mouse is? I guess that it's an easy enough 
experiment to run.

Dave