@Tom: For the joystick, it didn't really come out as a drop in solution since a lot of the PPM stuff got changed just out of convenience. I'll see if I can put some code together that has the packet types for the pilot controls data. A switch or flag could probably be coded in to switch between PPM or serial controls, but we just turned off the PPM in hard code, so that part might take a little fooling around.
Also, to deal with communication problems (dropping bytes, incorrect bytes, etc) we implemented a checksum at the end of each packet and that pretty much eliminates that problem. I am thinking of switching the code so it follows something similar to the CH robotics protocol (
http://www.chrobotics.com/), which is described in their data sheets for the 6d and 6dm modules. It is like this: 'snp' PT numberDataBytes dataBytes checksum. The point being there are no semicolons so you eliminate lots of excess. The 'snp' means 'start new packet', but you could just start the packet with the 2 letter PT (Pacekt Type) and save more bytes. All but 'snp' and PT are in binary, so you can push a lot more data than with GLuonpilot's current protocol.
@Mitch I'm definitely interested in new radios. I like the XBee for its simplicity, but it is certainly limited. I'd be interested to hear what you find out.