Help me incorporate a paddle controller into a 7800 arcade stick

[+GoldenWheels]

I've been having a fun making 7800 arcade sticks lately.

 

I'd like to build one which incorporates a paddle controller. I simply have no idea how to wire it.

 

I'd also like to avoid cannibalizing a pair of paddle controllers to do this, so if anyone can show me where to get parts for the paddle bit, that would be awesome. I don't even really know what the things are actually called...a potentiometer I think?

 

Ideally I'd like this to use one of the two existing buttons on the stick....though I could add a third "paddle" button if need be.

 

I'm not experienced at this stuff but am willing to learn.

[PacManPlus]

I don't think that's going to be possible, unless you use the 2nd port for the paddles. Reason being that the 7800 left and right fire buttons use the paddle signal lines. That's part of the reason I use the 2nd player port for the paddles in my games (the other reason is for the High Score Cart).

Also, the paddle buttons map to left and right on the joystick (one for each paddle).

 

[+GoldenWheels]

I don't think that's going to be possible, unless you use the 2nd port for the paddles. Reason being that the 7800 left and right fire buttons use the paddle signal lines. That's part of the reason I use the 2nd player port for the paddles in my games (the other reason is for the High Score Cart).

Also, the paddle buttons map to left and right on the joystick (one for each paddle).

 

Jeez...I had not even thought of that. I've been looking at 2600 diagrams and how people have made their own combo controller for it, not even realizing that those lines are already used for the 7800. D'oh. Well, thank for pointing out the obvious to me PMP, someone had to!

 

I could make it a 2600 controller only I guess, but that's not how I roll. 7800 two button or bust.

[toiletunes]

you'd have to include a selector switch to go between joystick mode and paddle mode.

[+GoldenWheels]

you'd have to include a selector switch to go between joystick mode and paddle mode.

Would that still only work on a 2600? I was looking at this diagram which does include a switch:

 

[toiletunes]

I don't know schematics, but the selector would have to go on the paddle signal/fire button lines- then you'd be ok for 7800 mode.

I'd like to own something like this, less controllers means less clutter, less wear on the controller port.

[Andromeda Stardust]

I don't think that's going to be possible, unless you use the 2nd port for the paddles. Reason being that the 7800 left and right fire buttons use the paddle signal lines. That's part of the reason I use the 2nd player port for the paddles in my games (the other reason is for the High Score Cart).

Also, the paddle buttons map to left and right on the joystick (one for each paddle).

 

 

you'd have to include a selector switch to go between joystick mode and paddle mode.

 

It can be done with a common DPDT switch. My custom Atari controller has paddles and internal 7800 wiring.

 

Paddles connect one 1M pot between pin 9 and VCC (pin 7) and another 1M pot between pin 5 and VCC (I used 470kohm pots in my custom build because most games only use about a quarter of the range anyway, and the 1M pots were just too twitchy for my liking).

 

7800 controllers also use pins 5 and 9 by pulling them high when a strong high signal is sent to pin 6. Normally a weak high logic signal sent to pin 6 will drain into the 620 ohm resistor (a more common 560 or 680 can be substituted if a 620 cannot be found) when either button is pressed, but when the 7800 is operating in twin button mode, pressing a button pulls up one of the paddle pins instead.

 

In order to create a 7800 controller with paddles, a toggle switch must be utilized. Disconnecting pins 5 and 9 from the 7800 controller will prevent proper function in twin button games, but single button or 2600 mode games will still detect a low when either button is pressed.

 

Likewise most 2600 joystick games ignore paddle input, however homebrew games that read the paddle lines for alternate controller configuration or detection of Genesis controllers for "extra button" may misbehave. One notable application is the Harmony menu can be navigated with a paddle controller, although joystick is much easier to use.

 

So either the paddles or the twin button specific portion of the 7800 must be removed from the circuit by employing a double pole double throw switch. The center taps on both sides connect to pins 5 and 9. The taps on one side of the switch go to the 7800 Fire buttons on the resistor side, and the taps on the other side of the switch go to the 2600 paddle pots.

 

With this arrangement, all 2600 joystick games will work with the toggle switch in 7800 mode, most 2600 joystick games will work with the toggle switch in paddle mode, and games that specifically use paddles or two button 7800 sticks should use the corresponding setting, or they will not function properly. Active paddles in a twin stick 7800 game behave as though both fire buttons are always pressed, and obviously paddle games won't respond to movement with the pots disconnected.

 

Here is a demo of the joystick. It is quite literally a jack of all trades:

 

I mainly created this video to show of my ingenious 4-way/8-way joystick switch, but it also shows off the 7800 resistors and paddle pots built into the same joystick. I hope this helps. I can draw you a schematic if you need one but I need to go to bed atm.

 

Happy New Year!

 

EDIT: My paddles are installed on either side of my joystick. Not in an ergonomic position for two player use, but each button corresponds to the right and left joystick inputs, except right paddle is joyleft and left paddle is joyright (the side buttons I installed also make excellent pinball paddles for Midnight Magic and Bumper Bash). Using the 7800 fire buttons for paddle fires in a manner similar to that shown in this diagram

is not possible because the 7800 fire buttons do not share a common ground connection with the other inputs. The controller in that diagram (Gemini?) will also likely not behave well with homebrews that scan for Genesis controller "extra button" since they use pin 5 to detect the presence of a Genesis controller. The "extra button" feature is always active as long as pin 9 is low. Back to the point, if you use a DPDT switch to select between paddle or 7800 mode of operation, you will need additional fire buttons for the paddles. These would be wired in parallel with joyleft and joyright.