Joystick Ports and Front Panel

These have got the be the easiest parts of the entire project. The JAMMA connector provides a pin for every button on the control panel, including the four cardinal directions of the joysticks. Controls are triggered by connecting the approriate pin to ground. This is exactly what a stand-alone Neo-Geo joystick does too, so we can simply match up the pins:

[TABLE: Neo-Geo controller pinout]

Don't forget the +5V feed which some later joysticks require. The other buttons on the front panel (coins, test, service) work in the same way: simply connect one end of a button to the signal and the other to ground.

It's also very handy to be able to use a button on your joystick to trigger the "insert coin" signal. This is just a matter of providing two electrical paths between the coin signal and ground: one is the front panel button, the other goes trough the joystick. The "select" button is good for this, but should you ever want to use this as a fifth button, it's easy to fit a switch to allow both possibilities:

[IMG: schematic of coin/B5 switch]

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