In SX Microcontrollers, SX/B Compiler and SX-Key Tool, g_daubach wrote:

Hello "State-Engineers"...

I can only agree - state machines can make programming a lot easier. I used them in my SX code as well as in many Windows applications that I wrote.

Jon's sample code shows the typical "state-switcher", like this:

[code]
StateMachine
   mov w, State
   jmp PC+w
   jmp Here
   jmp There
   jmp Elsewhere

Here
  ; some code
  ret

There
  ; some code
  ret

Elsewhere
  ; some code
  ret
[/code]

To select a specific state, the caller, or a routine inside the state machine would have to assign a number from 0 up to the highest allowed state (2 in the example above) to the State variable before calling or re-entering the machine, e.g.:

[code]
   mov w, #1   ; Execute There
   call StateMachine
[/code]

Another version of a "state-switcher" may look like this:

[code]
StateMachine
   mov w, StateAddr
   jmp w

Here
  ; some code
  ret

There
  ; some code
  ret

Elsewhere
  ; some code
  ret
[/code]

Here, the address of the code segment to be executed must be assigned to the StateAddr variable, like this:

[code]
   mov w, #There
   call StateMachine
[/code]

Both methods have thiur pro and cons. The first version makes it easy to sequentially switch from one state to the next by simply inrementing the State variable, where the second version is more self-documenting and shorter.

Have fun with FSMs!

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