Sumo is a project mainly written in C++ and C, it's free.
Sumo robot firmware
Sumo Robot Software
make sim - compile for SumoSim make avr - compile for ATmega make flash - program microcontroller
|-----------------------|
| G0 G1 |
| |
| |
| E0 E1 |
| |
| |
| G2 G3 |
|-----------------------|G0 <-> G3 G2 <-> G!