Prerequisites:
Make sure you completed The Maze level. I also use KV diagrams later on, so you might check out this guide before: K-map
The idea - what is a state machine?
Imagine you have to build a circuit to control some kind of device. You don't have a full computer - only basic gates, and need to come up with a solution, so that your device behave the way you want it to.
The idea is, that we go over all possible things that our device can do step-by-step. We draw a circle for each of those steps and call it a state. Usually every possible output that our device can have has at least one state. We then connect this circles by arrows that have a certain condition assigned to it (called transitions). These conditions are usually a specific configuration of input signals (What shall the device do when certain inputs arrive).
This means something like that:
We go from state A to state B, when the condition on the arrow from A to B is met.
By doing so, we can construct a picture where the complete behaviour is visible for us and we can understand it easily (= state machine). The cool thing is: There is a completely deterministic way to convert this pictures to circuits by following a few steps, and your device will do exactly what you specified in the picture. It is so straight forward, that you can technically write a program that converts state machines to circuits.
Tables
 |
 |
means |
|---|---|---|
 |
|
Free |
|
 |
Wall |
|
|
Door |
 |
|
Always (we don't care about the value of the input) |
|
|
means | |
|---|---|---|---|
|
|
Free | |
|
|
Wall | |
|
|
Door | |
|
|
Always (we don't care about the value of the input) | |