So, how do I use this with the Arduino environment?
I downloaded the source, but am not sure where to put it.
Sorry if this is extremely n00bish.
download arduino-18 from arduino.cc and you have all you need to program it. You can install the pins file I posted else where if you want to address the extra pins only on the Seeed version, as an extension of the standard pin space. The rest is just like an standard arduino mega, with a slightly different/larger number of pins. Most people do not use all the pins but get the mega for the additional memory/program space and flash. (A few of us a fiends for pins, but we are the abnormal ones.) Try to put a FAT-32 file system in the small arduino and it is hard get it to fit with any other code on less than a mega.