Since moving to FreeRTOS Renoster's control system lost the use of Timer1 thus the ability to control 4 servos using PWM. After some scouring on the net using a 4017 decade counter seem to be the solution to get that functionality back.

Renoster requires a fairly integrate control system, with several tasks required to run almost simultaneously, e.g. position calculation, way point tracking, mapping etc. and others need to be able to interrupt those in the event of possible danger, e.g. collision detection, tilt detection etc. A preemptive multitasking OS such as FreeRTOS provides all these features.