Soo.. I ordered a couple of Atari 2600 joysticks from Ebay (all genuine and Atari sanctioned I'm sure :)), so I could use them with the FPGA VCS project. I thought it would be cool to retrofit the other one with a microcontroller that acts as like a USB keyboard, sending arrow key and space presses when when wiggling the stick and hitting that fire so I can use the joystick with the plethora of emulators out there.
After a bit of googling I found Teensy which is a small footprint USB capable AVR microcontroller board. The small bootloader on the AVR lets you program the flash memory inside the chip using the USB if you press the small button on the board and during normal operation the microcontroller acts as a USB device. A perfect fit for our task.
So in all it's glory the story is pretty much such that the conductive pads (part of the actual stick assembly) press down on the squiggly patterns and short the circuit connecting one of the colored wires to the black one (the left most pad). We will be connecting the black wire to the ground and the rest of the wires to the I/O pins of the micro controller. The pins have internal pull-ups which means that they will sense '1' (the operating voltage) when the circuit connected to the pin is open. When the squiggly thing is shorted the pin gets shorted to the ground and it senses '0'. The internal pull-up resistor limits the current so things don't fry. Awesome.
Liberate the wires from the opression of the DB-9 connector, strip, twist and prepare to solder them to the F port pins of the AVR.
Also now would be a perfect time to flash the firmware on the chip, because you need to be able to press that tiny button to do so.
Turns out the strain relief on the random USB cable I picked is a snug fit with the hole in the casing of the joystick. Perfect.
