Add a controller port to a handheld?

Trying to get homebrew running on your PSP? Want to add a screen light to your Game Boy? Trying to figure out how to work your GP2X? By popular demand, discuss it in here! (This forum is for pre-built handhelds, NOT custom made portables!)

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Joined: Tue Feb 21, 2012 5:19 pm

Add a controller port to a handheld?

Post by jimmimak » Tue Feb 21, 2012 5:59 pm


I am planning to make a GGTV (Sega Game Gear that connects to a TV) and want to add a control pad port. I've found most people hack a normal control pad to act as basic switches and wire a port to the original button pressure pad contacts. I want to do it properly and decode the original control pad signals from a Mega Drive control pad and have logic gates simulating button presses on the Game Gear. This allows me to still use the control pad on my other consoles, and it won't matter which controller is used. I have an arcade stick and normal pads, so I'd like it to be able to use all of them.

I found the pinouts online, and made a simple logic circuit design using a NAND gate, a NOR gate, 2 inverters and a 555, that I think will work. The MD controller is normally sent a 5v pulse at 30-60hz from the console, and alternates its messages to the console between A+START buttons and B+C buttons. I was wondering whether anyone else had done anything like this before?

This is the info source I am using for the MD control pad protocol:

I am concerned that the Game Gear might interpret the 30-60hz pulses from the simulated buttons as multiple button presses (like turbo fire) rather than holding down a button. If nobody else has done this, I'll just have to dive in myself, but any advice/tips are welcome. Also, I still haven't decided what the case should look like, or what to make it from. I like the idea of using varnished/stained wood, for vintage-ness..

Here is an impressive example of a Game Gear TV I saw online recently, there are 9 pages showing how it was made: ... %2Fgg.html

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Joined: Sun Aug 14, 2011 5:38 am

Re: Add a controller port to a handheld?

Post by pasc » Wed Dec 25, 2013 5:23 am

Check this out:" onclick=";return false;

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