Sega Nomad - Add Controller for Player One

Hello people,

I'm looking to add a controller port for player one on the Sega Nomad and have been unable to find a good source of information to accomplish so. The only thing I found online was this diagram which gives me the pinout for (possibly) player one via the Sega 315-5638 chip.

Is this as simple as wiring a 9 pin dsub male to each of the labeled pins in order to get player one working? Has anyone attempted this mod. I would love to have a complete consolized Nomad with a player one controller, that way I don't have to be tethered to the Nomad. Any and all help/guidance is greatly appreciated!

 

I thought the Genesis controllers where 1:1 meaning you could tap directly from test pads on the PCB?

 

Yeah, I'm trying to avoid that since that would be more of a mess of wires that it should be. Anyone else...anybody???

 

Have you looked up the pin out for the Genisis controller?

 

Check this out - http://nfggames.com/forum2/index.php?topic=4831.0

 

Yes, I looked at that but it doesn't really explain how to get it all accomplished hence my reason for asking for guidance. There has to be someone here that got it done.

Could someone chime to n and share their expertise, pleaseeeee!!!

Some magical Sega Nomad wizard that can provide some tech aid to this peasant? LOL

I guess either nobody knows or doesn't want to share this info...

 

You gotta give people more time to respond than this. Not to mention -
http://assemblergames.com/l/threads/rules-as-of-2016.7890/

In the meantime, why not read-up on that nfggames thread and do some research on the chips? Alternatively, you could register there and send a PM to Duo-R and see if he responds.

 

I understand that. Thanks for the suggestions. Yeah, I tried reaching out to that user but it seems he's been off the map for a while (according to active users in that forum).

 

Use an ohms meter and follow the test pad to its respective pins on the chip.

 

Yeah, I have done so an identified the pin outs to map the buttons. However, it seems that onboard controls plus the added player 1 port interfere with each other so I need to find a way (from someone who has done this mod or has worked on mods for the Sega Nomad) to disengage onboard controls when using the player one controller. Maybe a switch may do but wire it to what pin on the pic of the chip I posted...

 

No...I'm pretty sure this is not true. The Genesis has a multiplexed signal with the select line on pin 7. Not only would this approach be messy, it wouldn't even work.

What are you suggesting he trace out? The button inputs go into the input side of the Sega 315-5638 and the multiplexed output comes out the other side. You wouldn't want to add input to the input side of the Sega 315-5638 multiplexer...the signal from your external controller will already be multiplexed.

The only way I see this working is if you just matched up the output side of the existing multiplexer to a D-Sub9 connector. Match the I/O pins on the top of the pinout you posted. Additionally, pin 5 is 5volts and pin 8 is ground. This way, the multiplexed output of the external controller is being fed to the main controller input on the same lines (and in the same format) as the internal controller.

This would probably work, but I've never tried it. I also have no idea if it's a bad idea (from the perspective of an electrical engineer) to merge two outputs like this. Hopefully, some of our more engineering minded members will have a say on this.

If you wanted to have a switch to make only one controller (internal or external) work at a time, you could put a switch on the VCC line. When power is flowing only to the controller port, the internal controls would not be active. When power is flowing only to the internal multiplexer, the external controls would not be active. I'm not sure if this is the best way of going about this, but it's damn simple and would probably work.

 

It says how to do that on the link you were given.


"2nd update - ok lifting pin 24 (VCC) on th 315-5638 chip did the trick! It disabled onboard controls, and the DB9 functioned properly. "

 

Do you think it's sufficient to just toggle the voltage between sources? Or should some diodes be implemented as well to prevent voltage from the other output from coming in contact with the disabled chip? ...or is that just overkill?

 

Yeah, what does he mean by "lift the 24 (VCC) pin"? I know this is 5v but does he mean literally lift the chip pin off the board? That seems a little extreme? But again I may be confused and just want some clarification before attempting this mod and ruin the internal chip or something. What do you guys suggest?

Now, looking at pinout for the dsub for a six button controller like the one onboard the nomad, this is the controller pinout that I found online:
https://www.dropbox.com/s/uimuhgxmjk0varm/File May 20, 3 28 50 AM.jpeg?dl=0
Should I just wire it all the same way as shown above coming from the 315-5836 chip?

 

The chips are surface mount, you need to heat the solder and lift it off the pad (not physically break it, just so it's not making contact)

This disconnects that connection. The alternative is you cut the leg off and that's not what you want to do as it's not reversable.

 

Ok, gotcha! Now, if I want to install a switch to disable onboard controls when player one is running, can I use a spdt switch and have the 5v line (vcc) connected to the middle of the switch and then what leads to the putter tabs? Or how do I go in theory about adding a switch in the middle to go from onboard controls to player 1 external controls. Thanks for everyone's help - I'm very close to starting this mod and report back!

 

@TheRedCrossKnight

Please use the edit button, no need to make a new post for each reply.

 

Ok, so I can't reply by using "reply"? I have to use the edit instead...uh?

 

Press +quote, you can add each post you are replying to and do it in one post.

 

Who would have thunk it!