Genesis Controller --> Colecovision

[Ransom]

See my solution in the second post. Original post follows:

 

I made a Genesis to 7800 controller adapter based on the linked plans. It works great on the 7800. In two-button games, Genesis button B acts like the left Atari button, and button C acts like the right Atari button.

 

Based on the fact that stock 7800 controllers work well as two-button controllers for the Colecovision, I tried to use my project on the CV. But in that case, both Genesis buttons end up acting as the left button, and I can't figure out why.

 

If a stock 7800 controller works on the CV, and if my adapter works on the 7800, then it would seem to follow logically that my adapter would work on the CV. But it doesn't.

 

I've read that the CV demands a separate common for the right button. But A) there doesn't seem to be a second common pin on the CV controller pinout, and B) the 7800 controllers don't use that, so I can't see how that would be the case.

 

What am I missing?

[Ransom]

I gave up on the adapter in frustration, and decided to go back to basics. And the result was, I now have a Genesis controller that works with the CV using two buttons. And the process wasn't that difficult at all!

 

I began with a Genesis 3-button pad, because they're cheap and I have a couple spares. Then I read up on the Colecovision controller and the Genesis controller. I saw that, as expected, the CV controller just uses the standard Atari method for up/down/left/right/button1, but uses a separate ground for button 2. Basically, button 1 grounds pin 6 to pin 8, while button 2 grounds pin 6 to pin 5. Of course you need a diode going from pin 6 in both cases.

 

So I grabbed my Genesis controller, opened it up, and removed all the components other than the wires (that is, I removed the chip, the capacitor, and the resistors). I also snipped wire #7 (+5V), because it isn't needed.

 

Then I followed the instructions in the link above and jumped the vacated holes for pins 3&4, and 6&7 of of the chip so that left and right worked (up and down already are connected as the Genesis doesn't send them through the chip).

 

Button B is naturally hooked to controller pin 8 for ground, so I then just hooked a diode up to the other end of it (see photo). Presto, button B on the Genesis becomes button 1 on the CV.

 

Next I used some existing holes to hook up pin 6 to button A (choosing that button because I judged it to be easier to isolate electrically than button C) and hooked a wire from controller wire 5 to the other side of button A. (Again, see pictures.)

 

I then hooked it up to my Champ keypad adapter, and....everything worked but Button A. What?!

 

I double-checked everything in the controller for continuity problems, and found none. Then I got smart and tried hooking the controller up without the Champ adapter and guess what? Both buttons worked!

 

So I popped the Champ open and found that pin 6 isn't connected to anything in there! So I hooked a diode from pin 6 to the appropriate wire (see pictures), hooked everything back up to the CV, and suddenly it all worked! Woo hoo!

 

Now, I just need to buy one of those nice arcade-style Genesis 3-button joysticks and I'll be one happy gamer!

 

(I apologize for the blurry pictures...I'm not the steadiest photographer as you can tell.)

 

 

 

[jsoper]

I gave up on the adapter in frustration, and decided to go back to basics. And the result was, I now have a Genesis controller that works with the CV using two buttons. And the process wasn't that difficult at all!

I published an adapter circuit a few years ago you might enjoy reading about:

adapter

[Ransom]

I gave up on the adapter in frustration, and decided to go back to basics. And the result was, I now have a Genesis controller that works with the CV using two buttons. And the process wasn't that difficult at all!

I published an adapter circuit a few years ago you might enjoy reading about:

adapter

 

Actually, I did read that. I have it bookmarked. You and so many other people helped me with this project, by providing pieces of my puzzle embedded in your own projects. So thank you!