CD32 reset from joypad?

[Amiga1992]

Would it be possible to add a little something inside the CD32, probably a very small PCB, that somehow piggybacks on the joystick port signal, so when we keep pressed all four circle buttons plus L and R for more than 2 seconds the CD32 resets itself?

This is for lazy asses like me who hate to get up from the couch to reset and choose another game from the CD32-XXX compilation he is currently using :P I don't think it'd be too difficult but I am not sure how you could patch onto tehse signals without soldering stuff to the PCB.

[s2325]

You can use this:

[Jope]

Or one of those remote control power sockets. :-)

[fryguy]

Yep Im using a nexa remote controlled socket for my ever drive equiped NES.

[TomCrazy]

@Akira
I think it's perfectly doable, but it might be a bit complicated considering that the CD32 joypad is (as far as I can understand it - haven't opened one up myself) using some kind of multiplexing / data encoding scheme for the trigger buttons, while using a direct signal connection to the directionals (just like a joystick). You would need to find a way to decode the encoded signals or find a place on the CD32 motherboard where these signals are already decoded. However, I think you cannot find these signals on board since according to the schematics, it looks like this decoding is happening inside Akiko.

So what you need to do is to analyze what happens with the signals coming out from the joypad when pressing the buttons that you wish would trigger a reset, then build a circuit that extracts a single hi/low signal from that, then add in an RC time constant and configure it according to what you desire (a 555 comes to mind), then convert the output of that signal to an open collector output.
You can then take that signal and (since it's of open collector type) make a wired-AND connection to the _RESET line on the motherboard to have it reset the whole thing when you press the chosen buttons on the joypad for a certain amount of time set by the RC time constant.

So the answer is yes, it should definitely be possible. But it's not something you do in just 10 minutes. You have to design a circuit that behaves in the way I mentioned here to make it work.

The most difficult part is to decode the signal coming out from the CD32 joypad. I am not sure whether the joypad is using multiplexed signals or serial data, but for ordinary multiplexing, I guess you can find a demux chip that does the job pretty well. But if you find it to be serial data, then things are getting a bit more complicated. You would probably have to use a logic analyzer to capture the data on the serial and clock line an see how it looks like, then try to decode it into a single output which listens to and changes state only on a specific data word, like I mentioned before. I don't really know if there is any easy was to do this without getting into PIC programming or something along those lines.

Note that I'm writing this without any knowledge of how the CD32 encodes the signals before sending them off to the Amiga. The decoding process might be easier than expected, depending on how the encoded data looks like. Or it might be more complicated.

Also, if I were to do this mod, I would probably add in that you also have to press down e.g left/down (diagonal) on the directional in order for the reset to trigger. This will significantly reduce the risk of a reset being triggered by mistake when you're pounding the buttons like crazy while playing your favorite shoot em up.

In the end, it all comes down to how far you are willing to go and how much time you're willing to spend to perform this modification.

[TomCrazy]

I just realized now that you wrote "without soldering on the PCB".
Well, without soldering I guess the answer is no. You cannot do a modification like this without soldering. :P

[xArtx]

Lol, it's likely not happening.
I think it might be that the first fire button is directly connected like other Amiga joysticks,
but don't quite remember.

[Amiga1992]

What I thought is something that piggybacks on the joystick port assembly somehow, the pins re exposed and maybe there's a chance. Otherwise yeah, it would be kinda complicated.

I thought about the special way the CD32 works with buttons after posting. Perhaps teh solution is just to use some of the signals. It doesn't have to be 4 buttons + LR, it could maybe be red, blue plus a direction, or something like that, as I think red is button 1 and blue is button 2 and they are probably wired straight.
The circuit would have to check for this signal being pressed for X ammount of time to not get confused with normal combinations (although I doubt you'd ever use red+blue+up).

But yeah, I threw it out here for either someone to actually come up with an idea or for the rest to make fun of it. I remember when I was told an Amiga mod turntable software was impossible...

[Retro1234]

WHDload games you can set the quit key as any button on the CD32 pad.

[TomCrazy]

@Akira
I googled some info on the CD32 joypad. None of the buttons is wired straight, but the red one is wired slightly differently and is buffered through a tri-state gate before going to pin 6 on the joyport. However, I do not know whether this tri-state driver is set up strictly as an input follower, or if it sometimes goes into high Z mode as well. As far as I can see it, that depends on what kind of signal the Amiga is providing at pin 5.

An 8 bit PISO shift register (74LS165N) is used to encode the states of the 7 buttons on the joypad into a serial data signal which is then going to pin 9 on the Amiga joyport, which corresponds to "button 2" on a normal Amiga pinout scheme for the joyports. (Pin 6 is "button 1".)

On the CD32 side, pin 6 is going to Akiko as a signal labeled "_FIRE", and pin 9 is going to Paula as "POTY".

Here is some info that might help you in your modification:

http://gerdkautzmann.de/cd32gamepad/a100schematic.png
http://www.amiga.org/forums/showthread.php?t=35768
http://old.pinouts.ru/Inputs/AmigaMouseJoy_pinout.shtml
https://www1.elfa.se/data1/wwwroot/a...ko645634_e.pdf

Using these links, you should be able to design a circuit that fulfills your needs.