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Finite State Machines - Make light work of complex functions

Program your own Finite State Machine using a SPLat Controller for only $29.00.

The EC1 "EasyOne", a 32-bit fully featured SPLat Controller with USB and true multi-tasking is a easy way to learn and a cheap way to build your project.

Finite State diagram

State Diagrams 4, logic short-hand

The most significant feature of the previous diagram, figure 3, is that it condenses the required information into less space than the decision diamonds. The state circle is shorthand for one or more decision diamonds, plus connecting lines. It is a higher level of abstraction.

You will notice, though, that the words On and Off have dropped out. They don't have to - it would be perfectly OK to write "I/P1 = On" or something similar. What I prefer, though, is to let it stand as it is, with the ON condition being implied. If I then want to specify the OFF condition I draw a horizontal bar across the top instead. This convention is borrowed from the Boolean algebra notation used in logic circuits.

If I am describing something in text form it may not be possible to have a bar across the top. In that case the convention is to use either an asterisk or a minus sign directly after it.

In figure 4 I have added a 3rd test condition, namely input 3 turned off, or I/P3*