Programming the keyboard functions on the Teensy is surprisingly simple. There are great instructions on the Teensy development board page for sending keystrokes to your computer and because the board identifies itself as a USB keyboard it works when plugged into a PC or Mac with no additional software! One note: to use the USB keyboard mode you must use the “Teensyduino” software which allows you to program the Teensy using the Arduino programming language and IDE rather than the native Teensy language. I’ve included the code in full at the bottom of the post, but to give a brief overview, when the upvote button is pressed the key combination “CTRL + SHIFT + A” is sent to the computer over USB, likewise if downvote is pressed “CTRL + SHIFT + Z” is sent to the computer. I defined these keystrokes in the Reddit Enhancement Suite manually because they seemed like a key combination that wouldn’t conflict with other programs (default is “a” and “z”).



Above is a drawing of the circuit I put together for the buttons. As you can see it’s really simple and basically an exact copy of the “Button” example on the Arduino website. I moved the circuit from my breadboard to a scrap of circuit board I had left over from my Arc Reactor project and soldered everything down. Since I was looking to fit this into a pretty small space my tolerances (wire length, etc) were also small. Much to my surprise everything worked on my first attempt to move it to a finished board. The only thing left to do was reconnect the USB cord I snipped in half to fit into my project box and put a couple dabs of hot glue on the lid to keep it closed.

