[Rickertsen2]

I don't see any reason you need a coprocessor for these tasks. The processor built into the controller is more than adequite for basic robot controlling. The only reason for a coprocessor is if you are doing very sophisicated navigation, feedback control loops etc. Last year we had a coprocessor to handle all of our navigation. We chose to use another PIC because we were already familiar with them and so that code snippets could be interchanged between the RC and our coprocssor. Specifically we used a PIC18F252. Again unless you are doing something very special and have some sort of experience with embedded design and programming i would strongly caution against a second procssor.