Last update: 250922 19:23:02
About State Machines.
First litterature then in bottom more nerd c code
Litteratur/links
wikipedia https://en.wikipedia.org/wiki/Finite-state_machine
wiki state diagrams https://en.wikipedia.org/wiki/State_diagram
Moore sm https://en.wikipedia.org/wiki/Moore_machine
interesting part is “fpga” impl
Mealy sm https://en.wikipedia.org/wiki/Mealy_machine
not in same detail as Moore …
impl in fpga https://www.microsemi.com/document-portal/doc_view/130043-state-machine-an
-
looks nice, full example in bottom (Moore)
Two videos (in danish)
how to draw statemachines (in danish)
how to code statemachines (in danish)
State Machines based on function pointers
Three based on function pointers
State Machine based on C case switch construction
Maybe the most readable and therefore simple
The one I use
no more to say
Video
A video and the written code for the case-swicth state machine idea
Designing state machines
A whiteboard or blackboard is very usefull for discussing designs of your SM.
Online tools (based on dot language e.g a->b; b->a; etc) might be what you need.
http://viz-js.com/ is a dynamic that redraw during editing. The state machine can be downloaded as png or other formats.
more to come
fra https://stackoverflow.com/questions/68953216/hierarchical-state-machine-with-graphviz
file [vendingsm here
digraph vendorMachine {
compound=true
graph [color=red]
node [color=red] // yuck style=filled fillcolor=yellow]
edge [color=red]
Entry[shape="point" label=""]
subgraph cluster_cancel {
label = "Cancel"
style = rounded
E2 [shape=rect label="" width=2 style=invis]
E2:sw->C0 [label=cancel]
C0 [label = <
<table cellborder="0" style="rounded">
<tr><td>C0</td></tr>
<hr/>
<tr><td></td></tr>
</table>
> margin=0 shape=none]
C25 [label = <
<table cellborder="0" style="rounded">
<tr><td>C25</td></tr>
<hr/>
<tr><td></td></tr>
</table>
> margin=0 shape=none]
C50 [label = <
<table cellborder="0" style="rounded">
<tr><td>C50</td></tr>
<hr/>
<tr><td></td></tr>
</table>
> margin=0 shape=none]
C75 [label = <
<table cellborder="0" style="rounded">
<tr><td>C75</td></tr>
<hr/>
<tr><td></td></tr>
</table>
> margin=0 shape=none]
subgraph cluster_DispenseC100Drink {
label = "DispenseC100Drink"
style = rounded
C100 [label = <
<table cellborder="0" style="rounded">
<tr><td>C100</td></tr>
<hr/>
<tr><td></td></tr>
</table>
> margin=0 shape=none]
subgraph cluster_DispenseC125Drink {
label = "DispenseC125Drink"
style = rounded
C125 [label = <
<table cellborder="0" style="rounded">
<tr><td>C125</td></tr>
<hr/>
<tr><td></td></tr>
</table>
> margin=0 shape=none]
C150 [label = <
<table cellborder="0" style="rounded">
<tr><td>C150</td></tr>
<hr/>
<tr><td></td></tr>
</table>
> margin=0 shape=none]
C175 [label = <
<table cellborder="0" style="rounded">
<tr><td>C175</td></tr>
<hr/>
<tr><td></td></tr>
</table>
> margin=0 shape=none]
C200 [label = <
<table cellborder="0" style="rounded">
<tr><td>C200</td></tr>
<hr/>
<tr><td></td></tr>
</table>
> margin=0 shape=none]
}
}
}
Entry -> C0
C0 -> C25[label=" Add\n$0.25 "]
C0 -> C50[label=" Add\n$0.50 "]
C25 -> C50[label=" Add\n$0.25 "]
C25 -> C75[label=" Add\n$0.50 "]
C50 -> C75[label=" Add\n$0.25 "]
C50 -> C100[label=" Add\n$0.50 "]
C100 -> C0[label=" Dispense\n $1.00 Drink " ltail="cluster_DispenseC100Drink"]
C75 -> C100[label=" Add\n$0.25 "]
C75 -> C125[label=" Add\n$0.50 "]
C100 -> C125[label=" Add\n$0.25 "]
C100 -> C150[label=" Add\n$0.50 "]
C125 -> C150[label=" Add\n$0.25 "]
C125 -> C175[label=" Add\n$0.50 "]
C125 -> C0[label=" Dispense\n $1.25 Drink " ltail="cluster_DispenseC125Drink"]
C150 -> C175[label=" Add\n$0.25 "]
C150 -> C200[label=" Add\n$0.50 "]
C175 -> C200[label=" Add\n$0.25 "]
C200 -> C0[label=" Dispense\n $2.00 Drink "]
}
ANOTHER FSM IN DOT
digraph finite_state_machine {
fontname="Helvetica,Arial,sans-serif"
node [fontname="Helvetica,Arial,sans-serif"]
edge [fontname="Helvetica,Arial,sans-serif"]
rankdir=LR;
node [shape = doublecircle]; 0 3 4 8;
node [shape = circle];
0 -> 2 [label = "SS(B)"];
0 -> 1 [label = "SS(S)"];
1 -> 3 [label = "S($end)"];
2 -> 6 [label = "SS(b)"];
2 -> 5 [label = "SS(a)"];
2 -> 4 [label = "S(A)"];
5 -> 7 [label = "S(b)"];
5 -> 5 [label = "S(a)"];
6 -> 6 [label = "S(b)"];
6 -> 5 [label = "S(a)"];
7 -> 8 [label = "S(b)"];
7 -> 5 [label = "S(a)"];
8 -> 6 [label = "S(b)"];
8 -> 5 [label = "S(a)"];
}
My own litle system
#include <stdio.h>
#include <unistd.h> // sleep
// States -- you need this forward dcl for the compiler and calling
// define NEXT(next,here,cond)
// |---- condition to be put on the arc in state machine
// |-------- state we are in just now (just for graph)
// |-------------- next state we will jump to
//
// all driven from main (or here setup fct)
typedef void *(*pFct)(void); // for typecast for calling function
#define NEXT(x,y,z) return ((pFct)x)
// my states
pFct led_on(); // as name indicates ...
pFct led_off();
pFct main_state();
pFct led_on() {
printf("on\n");
NEXT(main_state,led_on,back);
}
pFct led_off() {
printf("off\n");
NEXT(main_state,led_off,back);
}
pFct main_state()
{
static int t=0;
// pausefire
if (t==0) {
t = 1;
printf("main1\n");
NEXT(led_on, main_state, toOn);
}
else {
t = 0;
//delay
printf("main2\n");
NEXT(led_off, main_state, toOff);
}
// delay
}
void main() {
while(1) {
sleep(1);
statefunc = (*statefunc)();
}
}
Running the scripts in smdy.zip gives
 |
As long as you retain this notice you can do whatever you want with this stuff on these pages.
If we meet some day, and you think this stuff is worth it, you can buy me a beer in return :-)
(C) Jens Dalsgaard Nielsen
credit for license this goes to phk@FreeBSD.ORG
