Understanding state machine example

Projects Programming
13

The addition of time to NextAction is problematic too. Here's a refactor that should be better:

// States are named for ease of use
#define START   0  
#define SCANNING   1
#define RESULTS  2
#define RESET 3

// Timing variables
const int StartTime = 2500;
const int ScanTime = 1500;
const int RESULTSTime = 1500;
const int ResetTime = 2000;

int state=START;  // initial state
unsigned long StateStartTime=0L;
unsigned long StateDuration=0L;

void setup() 
{
Serial.begin(9600);    // initialize serial communication for debugging
state=START; 
StateStartTime=millis();
StateDuration=StartTime; 
}

void loop()
{
if(millis()-StateStartTime > StateDuration)
  ChangeState();  
 }

void ChangeState()  // Function declared outside of the main loop, for managing the state
{
StateStartTime=millis();
switch (state)
  {
  case START:
    Serial.println("case START");
    StateDuration=StartTime; 
    state=SCANNING;
    break;
  case SCANNING:
    Serial.println("case SCANNING");
    StateDuration=ScanTime; 
    state=RESULTS;
    break;
  case RESULTS:
    Serial.println("case RESULTS");
    StateDuration=RESULTSTime;  
    state=RESET;
    break;
  case RESET:
    Serial.println("case RESET");  
    StateDuration=ResetTime; 
    state=START;
    break;
  }
}