simple_on_off.c

// pseudo-ish code for the simple on/off state machine

// define all possible states
enum State {
  ON,
  OFF
};

// define all possible transitions (including NONE)
enum Transition {
  STARTED_PEDALING,
  STOPPED_PEDALING,
  NONE
};

// track current state, starting in the OFF state
State currentState = OFF;

// to detect transitions, we need to know if we ARE pedaling and if we WERE pedaling
boolean isPedaling = false;
boolean wasPedaling = false;

// function to detect transitions based on changes in pedaling state
Transition getTransition(boolean isPedaling, boolean wasPedaling) {
  // if the two states are equal, there was no transition ==> return NONE;
  if(isPedaling == wasPedaling)
    return NONE;
  
  // if the two states are _NOT_ equal, and we are currently pedaling ==> STARTED_PEDALING
  if(isPedaling)
    return STARTED_PEDALING;
  
  // otherwise
  return STOPPED_PEDALING;
}

void loop() {
  // capture previous pedaling state
  wasPedaling = isPedaling;
  
  // update the current pedaling state
  isPedaling = ( digitalRead(magSensor) == HIGH );
  
  Transition transition = getTransition(isPedaling, wasPedaling);
  
  // initalize the _new_ state if there was a transition
  switch(transition) {
  
    case STARTED_PEDALING:
      currentState = ON;
      TurnEverythingOn(); // void function defined elsewhere
      
    case STOPPED_PEDALING:
      currentState = OFF;
      TurnEverythingOff(); // void function defined elsewhere
      
    case NONE:
      // no transition ==> do nothing
      break;
      
    case default:
      break;
  }
  
  // do anything required by the current state
  switch(currentState) {
    case ON:
      updateLights(); // void function defined elsewhere
      updateMusic(); // void function defined elsewhere
      break;
      
    case OFF:
      // everything should have been turned off in the transition
      //   ==> we don't need to do anything here
      break;
      
    case default:
      break;
  }
}

with_winding_down.c

// pseudo-ish code for the state machine with "wind down period"

// define all possible states
enum State {
  ON,
  OFF,
  WINDING_DOWN
};

// define all possible transitions (including NONE)
enum Transition {
  START_PEDALING,
  STOP_PEDALING,
  FINISH_WINDING_DOWN,
  NONE
};

// track current state, starting in the OFF state
State currentState = OFF;

// to detect transitions, now we need to know:
//   * if we ARE pedaling 
boolean isPedaling = false;
//   * if we WERE pedaling 
boolean wasPedaling = false;
//   * AND what the targetWindDownTime
int targetWindDownTime = 0;

// function to detect transitions based on changes in pedaling state or reaching the target windDownTime
Transition getTransition(boolean isPedaling, boolean wasPedaling, int targetWindDownTime) {
  // if winding down, check for winding down finished
  if(currentState == WINDING_DOWN) {
    if(targetWindDownTime > millis();
      return NONE; // still winding down, so no transition
    else
      return WINDING_DOWN_FINISHED;
  }
  // else, check for changes in pedaling
  // if the two pedaling states are equal, there was no pedaling transition ==> return NONE;
  if(isPedaling == wasPedaling)
    return NONE;
  
  // if the two states are _NOT_ equal, and we are currently pedaling
  if(isPedaling)
    return STARTED_PEDALING;
  
  // otherwise
  return STOPPED_PEDALING;
}

void loop() {
  // capture previous pedaling state
  wasPedaling = isPedaling;
  
  // update the current pedaling state
  isPedaling = ( digitalRead(magSensor) == HIGH );
  
  Transition transition = getTransition(isPedaling, wasPedaling, targetWindDownTime);
  
  // initalize the _new_ state if there was a state transition
  switch(transition) {
  
    case STARTED_PEDALING:
      currentState = ON;
      TurnEverythingOn(); // void function defined elsewhere
    
    // stopping pedaling now transitions into WINDING_DOWN state (instead of OFF)
    case STOPPED_PEDALING:
      currentState = WINDING_DOWN;
      targetWindDownTime = millis() + 5000; 
    
    // when winding down finished, transition to OFF state
    case WINDING_DOWN_FINISHED:
      currentState = OFF;
      TurnEverythingOff(); // void function defined elsewhere
      
    case NONE:
      // no transition ==> do nothing
      break;
      
    case default:
      break;
  }
  
  // do anything required by the current state
  switch(currentState) {
    case ON:
      updateLights(); // void function defined elsewhere
      updateMusic(); // void function defined elsewhere
      break;
      
    case OFF:
      // everything should have been turned off in the transition
      //   ==> we don't need to do anything here
      break;
    
    case WINDING_DOWN:
      // need to slowly dim lights?
      // target end time was set in the transition, so nothing else to do here
      break;
      
    case default:
      break;
  }
}