State machine programming ideas for single-chip microcomputer

The essence of this processing method is to insert some meaningful work at intervals while the program is waiting for events, so that the CPU does not wait needlessly all the time.

(2) Logical completeness

I think logical completeness is the biggest advantage of state machine programming.

I don’t know if you have ever written a small calculator program in C language. I wrote it a long time ago, and when I tested it, it was terrible! When I input calculations in a disciplined manner, the program can get correct calculation results, but if I deliberately input random combinations of numbers and operation symbols, the program always gets inexplicable results.

Later, I tried to simulate the working process of the program. The correct calculation formula was clear and the process was smooth. But when I encountered an irregular formula, I felt dizzy while walking. There were so many flags, so many The variables kept changing, and finally the analysis could no longer be carried out.

After a long time, I got to know the state machine, and then I suddenly realized that the program at that time had logical loopholes. If this calculator program is regarded as a reactive system, then a number or operator can be regarded as an event, and a calculation is a set of event combinations.

For a reactive system with complete logic, the system can handle events correctly no matter what combination of events, and the working status of the system itself is always in a knowable and controllable state. On the other hand, if the logical function of a system is incomplete, driven by certain combinations of specific events, the system will enter an unknowable and uncontrollable state, contrary to the designer's intention.

State machines can solve the problem of logical completeness.

State machine is a design method that centers on the system state and uses events as variables. It focuses on the characteristics of each state and the mutual conversion relationship between states. State transitions are precisely caused by events, so when studying a specific state, we will naturally consider the impact of any event on this state. In this way, every event that occurs in every state will be considered by us, and there will be no logical loopholes left.

Maybe everyone will think that this is empty, but practice will bring true knowledge. One day, if you really want to design a program with complex logic, I guarantee you will say: wow! State machines are really useful!