In our paper we propose an original method of entropy evaluation and variation in process of finite state machine (FSM) state assignment. As have been shown in [1] Power consumption in FSM combinational part depends on entropy of inputs and outputs of FSM combinational circuit. Our work is continuation of this result. We consider higher design level and propose a method of entropy evaluation during FSM state assignment. It gives opportunity to control switching frequency inside a future combinational circuit. The basic attention we concentrate at practical implementation of state assignment method for changing entropy value in designed FSM.