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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Hodgkinson on February 11, 2008, 08:20:44 PM

Title: Amiga Joysticks - Where are the pots and buttons fed from?
Post by: Hodgkinson on February 11, 2008, 08:20:44 PM

As the title says, I can see from the A1200 manual where to connect potentiometers and buttons to on the mouse/joystick port, but where are the buttons and potentiometers fed from? +5v or ground?

I’m just in the process of knocking together two joystick adaptors…I’ve just been and bought some cable from Maplins in Sheffield this evening and I already have the D connectors and shells from Rapid Electronics (*OMG* Maplins are getting expensive for electronic parts…)

Thanks,
Hodgkinson.

Title: Re: Amiga Joysticks - Where are the pots and buttons fed from?
Post by: delshay on February 12, 2008, 12:26:55 AM

why two joysticks?

i have a single joystick in my project with four fire buttons. works great with FREESPACE.

Title: Re: Amiga Joysticks - Where are the pots and buttons fed from?
Post by: AMC258 on February 12, 2008, 02:29:13 AM

Granted this particular memory is 20 years old but I think the buttons sink to ground.  Never messed with the pots though.

Title: Re: Amiga Joysticks - Where are the pots and buttons fed from?
Post by: on February 12, 2008, 05:28:07 AM

I don't know about pots but I can assure you the buttons on joysticks aren't "fed" at all.

They simply signal by shorting between the signal line (up/down/left/right/fire) and the ground.

Title: Re: Amiga Joysticks - Where are the pots and buttons fed from?
Post by: Hodgkinson on February 12, 2008, 12:26:43 PM

Thanks for the replies.
So the buttons and pots sink to ground?

Im making two adaptors cos' I can :-D Mainly so that if I want to swap the mouse for a joystick, say using a autoswitcher, then I've got enough adaptors to do it.

I've also got a box full of 20 brand new mini joystick X/Y units with contacts for up/down/left/right that I bought from Greenweld as a pack for £5; so they might get pressed into use on somthing one day.

Regards,
Hodgkinson.

Title: Re: Amiga Joysticks - Where are the pots and buttons fed from?
Post by: banzai on February 12, 2008, 01:21:27 PM

Actually, those pots will have one lead at +5V, the opposite at GND, and the middle (called the "wiper") connected to the port. This allows the analog input to run from 0-5V. Commodore used a 500K pot in their controllers, IIRC.

So, for a fully wired port:

1 -> UP Switch (other lead to GND)
2 -> DOWN Switch (other lead to GND)
3 -> LEFT Switch (other lead to GND)
4 -> RIGHT Switch (other lead to GND)
5 -> X-axis pot center lead (other leads to +5 & GND)
6 -> FIRE Switch (other lead to GND)
7 -> +5VDC (to pots, 100mA max.)
8 -> GND
9 -> Y-axis pot center lead (other leads to +5 & GND)

Note: X-axis is the left-right, and Y-axis is up/down. Also, depending on the orientation of the pots, you may have to reverse the +5 and Gnd leads to get the proper behavior.
Pin numbers are typically molded on the back of most DBx connectors, but are really hard to see. Double-check with an LED or VOM before wiring up the +5.

Good Luck...

banzai

Title: Re: Amiga Joysticks - Where are the pots and buttons fed from?
Post by: Hodgkinson on February 12, 2008, 08:31:49 PM

Ah ha. Thanks for the info!

I was thinking that it might be more like a PC gameport where the potentiometer is wired as a variable resistor and connected up to +5v.
Having said that the Commodore method makes much more sense!

Thanks,
Hodgkinson.

EDIT: Do the up/down/left/right buttons work at the same time? Or are they mutually exclusive with the pots?