What microcontrollers are allowed?

I ran a couple google searches but couldn’t find anything specific. With people now using BeagleBone and Rasberry Pi on their robots, what else is allowed? Are Arduinos and AVRs allowed or just the ARM controllers like RPi?
Thank you!

If it fits within the cost limits, is powered either by the robot’s 12V supply via PDB (custom voltage-reduction circuits, as I recall, are legal within reason, but check the rules on that) or by an integral battery, does not directly control motors/pneumatics, and does not violate any other rules, it is allowed.

At least, under the 2014 rules. Given that there will be a new control system in 2015, I wouldn’t be surprised to see some sort of change.

Oh, that’s great. Thank you.