I have finally managed to get serial communication between the MultiWii board and the Raspberry PI working through use of a level shiftier Admittedly this did took a few attempts likely due to back connections when soldering. This also involved disabling the serial console on the Raspberry PI so I could take over the UART on the GPIO without the system closing the port after a certain time.
In addition I have been working on adjusting the MultiWii code to allow for dual control input via serial and an RC receiver and have managed to successfully control the quadcopter through serial but still need to implement a way of switch between control methods. Also with help from the MultiWii community I managed to connect a HC-SR04 ultrasonic sonar sensor, allowing for more accurate distance from ground readings then from the Barometor.
Unfortunately the quadcopter is currently unusable due to not one but two ESC’s catching fire. This occurred after a very minor crash and is likely due to age and overuse of the ESC coupled with poor quality. To this end I have ordered four new ESC’s which should arrive sometime in January. So until then my focus is going to be at getting the software components working perfectly ready for a series of flight tests.