🚀 go-pugleaf

I sent this Email to the person asking, but it seems that more than one
person is interested in how to do this, so here is my two bits on the 
mouse.

Note that these are the pinouts of the amiga and the mouse, as they 
have the same numbering scheme on the male and female connectors.

pin #       NAME              function

1           FORWARD*          Quadrature output back-forward  

2    	    BACK*             Quadrature output forward-back

3     	    LEFT*             Quadrature output left-right

4	    RIGHT* 	      Quadrature output right-left

5	    No connection

6	    FIRE0*	      left mouse button.

7           +5      	      +5 power into the mouse. 

8           GND  	      Ground into the mouse.           

9 	    POT0Y 	      right mouse button.





Quadrature outputs look like this: (See page E-14 of hardware man v1.1)

 LEFT*  ___     ___     ___     ___     ___     ___
           \___/   \___/   \___/   \___/   \___/
          ___     ___     ___     ___     ___     ___
RIGHT*  _/   \___/   \___/   \___/   \___/   \___/
 
As you can see, these are out of phase 90 degrees. The phase angle 
will change from +90 degrees to -90 degress when then direction
the mouse is moving changes from left to right. A neat little
circuit to take advantage of this fact is as follows:

			
		 _________     Q0 out		    _________
		|	  |    |     _______       |	     |	
LEFT* ----------| D     Q |----|   \ \      \	   |	   Q |--- Q1 out
		|         |    |----| |	     \_____|	     |
		|	  |	|---| |      /	   | D 	     |
		|      Q* |	|  / /______/	   |	     |
		|_________|     |		   |_________|
 				|
			      RIGHT*

These are edge triggered d flip flops. This circuit acts like a counter
which will keep track of the position of the mouse at all times. This
particular circuit is only able to count up to 3, then it rolls over to 
0 again, (outputs at Q0 and Q1), but it will count up when the mouse
is rolling left, and count down when it is rolling right (I may have 
these reversed). If you want to add more resolution, just repeat the part
of the circuit on the right, extending it out to as many bits as 
you might need. You may also be able to use a binary counter that has 
a up/down input (like the 74ls193 I think), and implement the circuit
in fewer gates.  Just repeat this same circuit for the forward/back
part of the mouse, and presto chango, you have a mouse driven 
position sensing device.  

   Adding a little clarity here, the RIGHT* input to the above
circuit is just a up/down select. When it is hi, the circuit counts
down, and when it is lo, the circuit counts up (may be backwards).
It works because the quadrature output RIGHT* will always be hi
on the falling edge of the LEFT* input, causing the EOR gate 
to flip the Q1 output to Q1*, which makes the counter count down.
If the thing reverses direction, the RIGHT* input will now always
be lo on the falling edge of LEFT*, causing the EOR to do nothing
to the output pulse Q1, therefore makeing the counter count up.   

 The two mouse buttons are just normally open switches that are 
shorted to ground when the button is pushed. These do not have 
internal pullup resistors, so you need to supply some. 
A good value I like to use is 1K to +5. The switches will then
supply you with +5 when open, and ground when closed.

Finally, make sure you use a good +5 supply for the mouse, as it 
has 4 comparators internally that generate the quadrature pulses
from the led/photosensor pairs.  I can't think of anything else
that might help you, but if you have more questions you think
I might be able to answer, mail me or call and ask! Drop me
some Email and let me know what your project is about and how
well the mouse works for you. Good luck!

   Greg Garner
   gmg@hcx.uucp   path:  ...!uunet!harris.cis.ksu.edu!hcx!gmg
   501-442-4847