Schematic and BOM are at the bottom of this page.
Firmware is provided on github
The firmware is tested with a number of Sony brand controllers, but be aware that it has received NO TESTING with second party controllers which may not work. The hardware and firmware will work with every Sony controller, including the old Dual Analog monster of a controller which does not work with most commercial controllers.
Also, a larger / hand assembly version of this hardware is available on the github page. This version was designed to allow high school student to create custom interfaces for their FIRST robots and is simple enough for most any novice to assemble.