gauauu

This is the exact issue I had with most iterations of my design. I tried adding various caps and didn't have any luck.

Yeah, I had used conceptually 2 separate 1-to-2 splitters, but kept a single select line going through a single inverter just to simplify the circuit.

Is there any similar type of thing but for diodes? I tried doing some searching but didn't find anything, but it didn't help that I didn't know what search terms to look for :-)

Another question for you smart people. The last method I tried (switching the grounds and using diodes for isolation) works great for actual Atari joysticks, but during testing, we ran into trouble with Genesis pads. Apparently the internal circuitry in these causes them to actually hold the outputs high when a button isn't pressed, even if the ground pin isn't low. Which means that if you plug in a Genesis pad into one of the two ports, the other controller never registers. So the current design works wonderfully for original sticks, but doesn't let you use Genesis pads at all. The only solutions I can think of for this are: 1. Add a ton of diodes, one for each output pin for each controller, so that each controller can only drive a pin low, but can't hold it high. (This would require adding 20-24 diodes to the design, ugh) 2. Completely redesign the circuit again Before I go down either of those routes, I wondered if any of you might have suggestions of simple solutions that I may have missed? You can see the schematic I was using at https://www.dropbox.com/s/42wj6c96hu93fup/319x2.zip?dl=0

I've never owned one, so unless one suddenly appears for cheap at a garage sale, an intellivision version won't be coming soon. The most likely next port will be original Gameboy or Apple II

Just FYI if anyone is interested, I'm finishing up a Sega Dreamcast port of this game right now. It's a lot shinier, but fundamentally the same game (once again, reusing most of the game logic code, because C is so ridiculously portable). If you're interested, you can grab it from http://www.bitethechili.com/roboninja-climb/ alongside the other versions.

No idea. I'm pretty sure that the guy that brought it is planning on bringing a bunch of stuff again, but don't know if he's bringing punch-out or not.

I'll be there, demoing some of my homebrew NES projects in the NintendoAge room. Come say hi!

Thanks for the help, all. The design of running them parallel with an inverter on the ground, and using diodes for isolation, is working perfectly. No signs of interference. I've got it all on a messy breadboard right now (I don't know how you hardware people stay sign, the mess of wires drives me crazy!), but it's time to make some prototype PCBs!

Just did a proof-of-concept today, wiring it up with the general idea you guys suggested (2 sticks wired in parallel, other than the ground switched from the RIOT output pins). It's just in parallel right now (so other hardware, so I depend on software turning the alternate pins back to input to prevent short-circuits!), but the general concept works so far. I'll do some more tests with adding the diodes, and whatnot, but it appears promising so far.

2600 is currently the only target.

You guys rock. I'm going to try some experiments with putting the sticks in parallel, switching the grounds (with diodes as suggested) I'm having trouble finding info about the 1N1414, is there a different part that would be similar? (I'm not very knowledgeable about the difference between diode types) I'll have to double check this later tonight.

This is how my original design worked. I used the player 2 port, 2 pins as output to drive 4:1 multiplexers. Then read everything as normal on the RIOT on the player 1 port. It still had the same flicker/interference issues :-(

Thanks for all the replies. Yeah, I tried, but I'm not very experienced with this sort of thing, and wasn't able to see it. I imagine that's because I don't really know what I'm doing with a scope though :-) Also, I don't think it's the L/R pins into the TIA causing trouble -- my first design had everything going into the normal pins on the 2nd controller port, and it had the same issue. I tried caps across the ICs, but they may have been too high. I can try again with 0.1uF. I like these ideas, I may give them a try. Thanks for the suggestions, all. Yeah, the different designs we tested all have a bit of delay. We've been switching the pins, waiting a bit, then reading.

Hey all, as some of you know, I've been slowly working on a design to do 4 joysticks on the Atari 2600, using a simple multiplexer scheme -- using one or two of the controller lines as output to drive a multiplexer, allowing multiple joysticks in a joystick port. It's mostly worked really well, BUT on consoles that are still using RF (ie haven't been modded for A/V out), there's a bit of flicker on the screen whenever you wiggle one of the joysticks. Apparently, there's something that happens while switching the joystick that causes a spike or surge or something that shows up in the video. After asking around, and trying a number of designs to fix this, I'm running out of ideas. I've been working with John Champeau to hopefully use this in his upcoming Wizard of Wor game, but we're wanting to get these issues worked out to make it possible. If any of you hardware gurus are interested in helping, and have any suggestions, we'd be really interested to hear it. I'm posting a link to the Eagle schematic and board files of one variation of it. I've tried quite a few slight variations, and they all exhibit the same behavior. At the advice of a knowledgeable friend, I also tried piggybacking 10 microFarad caps over the pull-up resistors, but that didn't resolve the issue. https://www.dropbox.com/s/2ufezgdjs733lot/2mux.zip?dl=0 Please let me know if you have any suggestions, or ideas for us. Thanks!