so i made a controller with 27 buttons on it and had someone on here help me with some code to assign keystroke commands to the buttons... but when i wired it up, uploaded the code, and tried to use it with the computer i got nothing.
is there something i need to do in order to get the computer to see it as a keyboard plugged into the USB rather than just the arduino???
My understanding (maybe misinterpreted) is that because of the way Arduino uses the USB port it can't emulate a keyboard or other HID directly. As I understand it, that is one of the changes to the Arduino Uno (?).
Having said that the Practical Arduino guys have put together a project to do exactly what you're talking about which you can see here: practicalarduino.com
As your link shows a common Arduino board I know one answer. Different kind of USB devices need different drivers. Arduino uses serial USB chip and drivers.
Usb serial chip on Arduino board uses serial port driver in the computer. You need HID driver for that chip. I dont think it exists. But there may be a chips for USB HID device, but that is an other story. They must of course be adapted to Arduino.
With a little electronics, it is possible to make Arduino work as a non USB keyboard. Again an other long story.
I think you should be able to program the mega2560 to be a USB keyboard, I've done it for the UNO without problems. I've built firmware for the mega2560 that should do the job (i.e. make it appear to be a USB keyboard), please try it out and let me know how it goes.