Simple Genesis/Megadrive gamepad button jump mod.

[Mrs Beanbag]

Wouldn't it be better just to make a little in-line adapter to do this?  Then you wouldn't have to do the same mod for every new controller you bought.

I use a Sega Megadrive pad on my Amiga, one thing I mean to do one day is to make an adapter that allows me to program for all the buttons.  Some of the buttons are multiplexed.  The Amiga can output a control bit on one of the pins, but the Megadrive pads use a different one.  A little dongle that swaps two pins over should suffice.

[Mrs Beanbag]

There is an "impossible" combination of joystick outputs that I'm surprised nobody ever made use of, namely up+down+left+right.  In fact any combination that involves two opposite directions together wouldn't usually be possible (7 in total).  Someone clever could have used this to give us a start/select button and maybe some others, without the need for extra pins or multiplexing.

Also one thing I have in mind now is an adapter for a playstation pad that connects to both the controller ports, so the analogue stick can be used as the mouse.

[Mrs Beanbag]

You can't just wire the analogue stick into the mouse port, a mouse actually sends digital serial data.  If you have the joystick plugged into Port 0 you can actually move the mouse pointer by wiggling the joystick around in a circular motion.  I found this useful sometimes!

I've no idea how a PSX analogue stick works, but the serial data stream that comes out is published somewhere (at least I found this documented for the PS1 controller).  Such an adapter would require some kind of PIC.

[Mrs Beanbag]

If you want to use PSX joypad as a mouse just get the PSX-Amiga converter from kipper2k http://kipper2k.com/amigaforsale/
Works great, just press "Select", mouse mode, press "Select" again, Joystick mode.

Neat enough!  But you can't use both at once... and you would have to swap it from Port 1 to Port 0 as well.

[Mrs Beanbag]

You can get Playstation adapters which emulate the CD32 pad and the mouse at the same time, let you program combos, use one analogue stick as a digital joystick and the other as a mouse, there's not much they can't do (except magically emulate a keyboard). AmigaManiac sells the adapters with Paul Willingham's code here - http://www.amigamaniac.com/psx2db9.html

So this has two 9-pin outputs, right?  There isn't a picture and the page doesn't seem to indicate that.

I have the Amiga light gun, sadly it isn't any use on my LCD screen I have wondered if it would be possible to do something clever with a web cam.  I programmed a little light gun target practice app back in the day, it's very simple, but it's based on timing so any adapter would need access to the video signal too, because it needs to trigger when the beam position passes in front of the gun.

[Mrs Beanbag]

Yeah but sadly almost all joysticks you could buy had only one button... or they were all wired to the same pin, in any case.  Obviously it has the capability because the mouse has two buttons!

I wanted to mod a joystick to have two buttons once, only to realise that it didn't even have the corresponding pin in the plug.  The whole wire was missing from the lead.

[Mrs Beanbag]

When you check the schematics, you will notice that there is also a pin 5 on Amiga ports for a third button or middle mouse button.

Indeed.  The interesting thing about buttons 2 & 3 is that these pins are writable as well as readable, so they can be used for multiplexing to give you even more buttons.  Presumably this is how the CD32 pad works.  The Sega Megadrive pads also work this way, but unfortunately they use pin 7 as the select line, which on the Amiga is +5V.  On the Sega pads, +5V is on pin 5.  So if you swapped pins 5 & 7 in theory you could use all of the buttons.  But it doesn't work the same way as the CD32 pad, which apparently has some sort of state machine inside it.

I have wanted to make myself an adapter for some time to get the use of those extra buttons.  Having only one button to play with is really frustrating from a game design point of view.  (It's one reason Mr Beanbag's only move is jump!)