The MKUSB is an interface to connect the MikroKopter with an Computer via the USB port. Its used for configuration, telemtry and firmware update of the MikroKopter.
This version V3 is for the use with our new Flight-Ctrl V3.0.
By placing a jumper, the target board can be supplied with 5V if needed.( do not supply a complete MikroKopter!)