I finally got around to building up the MDM board. I populated 1 motor driver IC and the rs485 driver. I had a problem where the package I used from Kicad for my Atxmega was too small so I had to create another Atxmega break out PCB and wire that to the original MDM board. Long story short I have lab view on the PC sending messages via rs485 to the xmega which is driving PWM to the motor driver that drives the motor with a propeller attached. The motor draw less than an amp at full speed when unloaded and about 3 amps when submerged in water.