Path: utzoo!attcan!uunet!ncrlnk!ncr-sd!hp-sdd!ucsdhub!ucsd!sdcc6!sdcc10!cs161agc
From: cs161agc@sdcc10.ucsd.EDU (John Schultz)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Analog Joysticks
Keywords: Analog, Joystick, Full-range
Message-ID: <10@sdcc10.ucsd.EDU>
Date: 11 Nov 88 05:00:53 GMT
References: <12539@steinmetz.ge.com> <8@sdcc10.ucsd.EDU> <5204@cbmvax.UUCP>
Reply-To: cs161agc@sdcc10.ucsd.edu.UUCP (John Schultz)
Distribution: na
Organization: University of California, San Diego
Lines: 61

In article <5204@cbmvax.UUCP> grr@cbmvax.UUCP (George Robbins) writes:
>1) The pinout for the analog joysticks is supposed to compatible with
>   traditional game machine game paddles / analog joysticks - you
>   shouldn't need any sort of adapter for these.

    Apple compatible joysticks have a DB-9 _male_ connector, and are
not pin to pin compatible.  IBM compatible joysticks have a DB-15 male
connector...(We don't know of any other analog joysticks currently
available).

>2) Most of these things seem to come in around 470K - give or take
>   a factor of two.  You can diddle the pot values or add some more
>   timing capacitance, but there are some trade-offs.  Increasing
>   resistance increase noise level, increasing capacitance may
>   decrease repetability.

    We have tried both methods: Higher resistance pots (1 meg) work
fine (but who wants to rip apart their joystick, let alone find a
pot that will fit).  Adding capacitors in parallel (.22 uF - .32 uF)
will generate the full range.  We've used the joystick (with a
little scaling) to drag windows, etc., under intuition.

>3) Noise level varies from machine to machine.  The A500 is not so
>   good, others somewhat better.  Much depends on where the timing
>   capacitor are located.  If they are near the Paula chip, they
>   tend to filter out noise spikes, if far away induced noise tends
>   to randomly trip the comparators.  I don't know the effect of
>   locating them in the joystick assembly itself.

    We put the caps on the Amiga end of our adaptatron; works well.
We performed preliminary tests by placing the caps on the pots
inside the joystick; worked either way.  Early test code on A500's
(using no caps) produced very limited range and spurious readings.
The A2000 had better results, and the A1000 the best.

>7) Somone mentioned external hardware to get more accuracy repeatability -
>   it's been done before, though I don't know what the results were.  I'm
>   not sure how much that will really help...  You can probably do about
>   as well by moving the timing caps and/or messing with RC values...

   What we need is a major joystick manufacturer to make joysticks
for the Amiga with the correct connectors and caps wired inside the
joystick.  Less hassle for the end user and encouragement for
developers to write software to support such devices;  Advance the
state of the art...

>George Robbins - now working for,	uucp: {uunet|pyramid|rutgers}!cbmvax!grr
>but no way officially representing	arpa: cbmvax!grr@uunet.uu.net
>Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)

  George, the hardware manual states to use pins 3 and 4 for the
buttons.  We would also like to support button 3 (available on some
IBM joysticks).  We are currently using pin 2; could we also use
pin 1, to support 4 buttons? (Pin 6 is also available, but X-Specs
3D uses pin 6 to toggle the shutters).  Our ajoystick.library will
contain these user functions: OpenAJoystick, CloseAJoystick, and
ReadAJoystick(potx,poty,button1,button2,button3).

  Any input would be appreciated,

    John