The main obstacles in promoting IOT applications are cost and energy consumption constraints of the devices and systems. As a step forward in improving the reliability and reducing the cost and energy consumption of IOT devices and systems, we had proposed previously a high-level model for efficient design-space exploration, which is called the symbiotic system (SS) model. In this work, as an example for SS-based design, we show that it is possible to develop symbiotic controllers that achieve higher reliability, thus longer lifetime and lower cost. The proposed approach target FSM-based controllers that are key components in almost all digital systems. The experimental result for a small traffic light controller shows that the reliability is improved by about 1.75 times, assuming only hard faults. If the system encounters more soft errors, the lifetime can be greatly extended, e.g., for 50% soft errors, the reliability improvement is about 8.4 times.