grr@cbmvax.UUCP (02/08/87)
Per request, I am reposting the original article on converting WICO and
perhaps Atari 2600 trackballs to mouse-compatible devices. While I have
not tried the conversion, what the original author describes seems to
be quite reasonable.
One other approach that might be easier would be to obtain a spare mouse,
extract the little logic board and attach it to the various LEDs, photo-
sensors and switches...
The original article in comp.sys.amiga describes how to convert WICO
and Atari 2600 track balls to work with the Amiga. Converting for the
Atari ST is essentially the same, except for some disagreement between
Atari and CBM on which quadrature signals go to which "joystick" lines.
Pin Amiga Atari
=== ===== =====
1 Vertical X-B
2 Horizontal X-A
3 Vertical-Quatrature Y-A
4 Horizontal-Quadrature Y-B
5 Pot X N.C.
6 Left Button Left Button
7 +5V +5V
8 Ground Ground
9 Pot Y-Right Button Right Button
As you can see, the pin-outs are compatible enough that no harm will result
if the two are interchanged, however since the quadrature outputs don't
match up you will get pointless twitching instead of useful motion. Simply
switch the wires going to pins 1 thru 4 until you get it right.
A minor problem is that the WICO trackballs are discontinued, so unless you
already know where to find one, you may have problems.
Original (corrected) article from blgardne@esunix.UUCP (Blaine Gardner):
Title: Wico trackball mouse VERSION 2.0 (BUG FIX & ATARI NOTE)
Ok, here it is, sorry I took so long to post it. I have tried to make this
understandable, if you don't know what an LM 339 or a DB9 is, maybe you
shouldn't try this.
---------------------------------------------------------------------------
Wico track ball modification.
Converting the Wico track ball into an Amiga mouse compatible track ball
is a fairly simple procedure. But if you are uncomfortable with a soldering
iron, get some competent help.
You could damage your Amiga if you make a mistake when
assembling this project! You could also void your Amiga
warranty! You will definitly void your trackball warranty!
YOU HAVE BEEN WARNED!!!
Ok, now that that's out of the way here are the gory details.
The stock trackball contains a small pc board, this will be removed and
replaced with one containing an LM 339 quad comparator.
The comparator simply converts the output of the opto-coupler to a TTL
level pulse. Both the X and Y axis use two emitter-detector pairs. The
output of each of these detectors is fed through one of the comparators.
The output of the comparator is then fed to the Amiga's mouse port. Since
the output of the trackball will be identical to the mouse's output, the
modified trackball will work with ALL software that uses the mouse.
Here we go!
Remove the 6 (six) screws from the bottom of the trackball case and
open it (right-side-up please). In the lower-right corner there is a small
pc board with two connectors. Remove the board & connectors. You can toss
the board, and the cable that has the joystick connector. (The cable only
has 7 wires and we need 8. You can scrounge the 11 pin male header off of
the board.)
Cut a piece of perf board the same size as the original board. Just
make sure it fits in the same place as the original. The plastic grooves
will hold it perfectly.
Two cautions here: make sure the top can be screwed down without hanging
up on the new board, and make sure all your components will clear the
standoff near the board!
Using the (crude) schematics below, wire up the circuit. You will need to
drill a hole in the case to mount a second switch (for the right button).
Make sure the second switch will clear all existing hardware! Wire the second
switch between ground and pin 9 on the DB 9 connector.
It is a good idea to place a medium sized capacitor (10-20 uf) across +5 and
ground where power enters the perf board.
Parts List:
Wico Trackball #72-4545
Wico Corporation
Consumer Division
6400 W. Gross Point Road
Niles, Illinois 60648
800-323-4014
Joystick Extension Cord Radio Shack #276-1978
LM 339 Quad Comparator Radio Shack #276-1712
14 pin DIP Socket Radio Shack #276-1999
Soft-Touch Switch Radio Shack #275-1566
Perf Board
11 pin Male Header (can be removed from Wico)
10 - 20 microfarad capacitor (12V or higher)
Resistors (1/4 or 1/8 Watt, 5% tolerance)
280 Ohm (4 each)
3.3K Ohm (4 each)
6.8K Ohm (4 each)
100K Ohm (4 each)
---------------------------------------
Wico TrackBall Internal Connector
(Color code assumes Wico is consistent in their wiring.)
1 Pushbutton White
2 +5 (Y-axis) Red
3 +5 (X-axis) Red
4 Ground (Pushbutton) White
5 Ground (X-axis) Black
6 Ground (Y-axis) Black
7 N/C ---
8 Y-axis output Violet
9 Y-axis output Blue
10 X-axis output Green
11 X-axis output Yellow
---------------------------------------
Pinouts for LM 339
------------------------
| 14 13 12 11 10 9 8 |
) |
|. 1 2 3 4 5 6 7 |
------------------------
1 Output 2
2 Output 1
3 +5 Volts
4 Input 1-
5 Input 1+
6 Input 2-
7 Input 2+
8 Input 3-
9 Input 3+
10 Input 4-
11 Input 4+
12 Ground
13 Output 4
14 Output 3
---------------------------------------
Amiga Mouse Connector (DB 9 Female)
-------------
\ 5 4 3 2 1 /
\ 9 8 7 6 /
---------
1 V pulse
2 H pulse
3 VQ pulse
4 HQ pulse
5 N/C
6 Button 1 (Left)
7 + 5 Volts
8 Ground
9 Button 2 (Right)
----------------------------------------------
Connections from Wico | Connections from LM 339
11 pin socket to LM 339 | to DB9 (Mouse port connector)
|
Wico -> LM 339 | LM 339 --> DB9
---- ------ | ------ ---
1 (to pin 6 on DB9) | 2 1
2 3 \__+5 Volts | 13 2
3 3 / | 1 3
4 12 \ | 14 4
5 12 >--Ground | N/C 5
6 12 / | (pin 1 on Wico) 6
7 N/C | +5 Volts 7
8 4 | Ground 8
9 6 | 9
10 10 |
11 8 |
---------------------------------------
O +5 Volts O +5 Volts
| |
\ \
3.3K Ohm / / 6.8 K Ohm
\ 100K Ohm \
| |
+-----/\/\/\/-------+ |
| /| | |
| / +|---+------+ (Pins 5,7,9,11)
| /1/4 | |
Output to /__|________/ LM | |
Amiga \ \ 339 | \
(Pins 1,2,13,14) \ | / 280 Ohm
\ -|--+ \
\| | |
| |
| |
Input from ball >-------+ -----
(Pins 4,6,8,10) | ---
| -
\
3.3K Ohm /
\
|
|
|
-----
---
-
-------------------------------------------------------
There it is! The above information was obtained from the Amiga Hardware
Reference Manual, and from tearing apart my mouse & trackball and trace-
ing out the schematics myself. (Mostly from tearing my hardware apart!)
Any errors in the above information are mine (but for a few hours work
they can be yours too! |^) ), not Evans & Sutherland's. They are kind
enough to pay me to play with their computers, they have no control over
my ramblings here on usenet.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
The above infomation is the correct version. In my first posting + 5 volts
and button 2 were switched on the DB9 pinouts.
There have been a lot of inquiries about doing the same modification on
the Atari 2600 trackball. I hadn't seen the Atari untill two days ago, but
I can now tell you that the same procedure will work for it. In fact it is
a little easier on the Atari trackball because the LM339 is already present.
Just remove all the components from the board except the 339, the supply
voltage filter (inductor + electrolytic cap near the 6 pin header), and
resistors R9 - R18. Actually you'll have to remove those too because they
are the wrong values, and the 339 socket blocks several traces that need
to be cut. (As I remember 430K and 10K should be swapped for 100K and 3.3K
respectively.)
The biggest problem is that Atari wired the 339 as a non-inverting
comparator, and Amiga uses an inverting comparator. So you'll have to CUT
AND JUMPER (those that flinched may leave the room) to get the inverted
configuration (see above data for the correct circuit).
I don't plan to do a detailed plan for the Atari trackball, if the above
information doesn't mean much, don't try it yourself.
This general plan should work for all trackballs that use a pair of opto-
couplers on each axis. The old TG trackball for the Apple II (and probably
other computers) will NOT work since it uses a pair of pots.
I hope this helps all you hardware hackers that can't live without a real
trackball. Have fun, and don't blow up your Amiga!
--
George Robbins - now working for, uucp: {ihnp4|seismo|rutgers}!cbmvax!grr
but no way officially representing arpa: cbmvax!grr@seismo.css.GOV
Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)