This paper presents a systematic, semi-automated, constructive procedure for designing switching controllers to stabilize pairs of unstable, homogeneous second order systems based on binary sensor measurements. The plant is first approximated by a finite state machine, and a bound on the quality of approximation is established. A control law is then designed to robustly stabilize the nominal finite state machine model in the presence of admissible approximation uncertainty. The resulting controller thus consists of a finite state machine observer and a corresponding full state feedback switching control law. The design procedure is demonstrated on a simple benchmark example.