// Author:  Nien Lam
// Date:    09-15-2009
// Title:   Finger Switch Combination Lock
// Descr:   This is a combination lock where the fingers (index, middle, ring) must be
//          pressed down in the correct sequence in order to open the lock.  One of 3 red LEDs will 
//          light when a finger combination is correct.  The master green LED will light once all 
//          3 combinations are entered.


// Digital input pins for finger swtiches.
int indexFinPin  = 2;
int middleFinPin = 3;
int ringFinPin   = 4;

// Digital output pins for the LEDs.
int firstLedPin  = 8;
int secondLedPin = 9;
int thirdLedPin  = 10;
int masterLedPin = 11;

// =========== SET COMBINATION HERE ================================
// Lock combinations for fingers {index, middle, ring)  
int firstComb[]   = { 1, 0, 1 };  
int secondComb[]  = { 1, 1, 0 };
int thirdComb[]   = { 0, 1, 1 };

// Counter to track which how many locks are open.
int lockOpenCount = 1;


void setup() 
{
  // Set finger switches as inputs.
  pinMode(indexFinPin,  INPUT);      
  pinMode(middleFinPin, INPUT);      
  pinMode(ringFinPin,   INPUT);      

  // Set LEDs as output.
  pinMode(firstLedPin,  OUTPUT);      
  pinMode(secondLedPin, OUTPUT);      
  pinMode(thirdLedPin,  OUTPUT);     
  pinMode(masterLedPin, OUTPUT);     
}


void loop() 
{
  // Check first finger combination.
  if (lockOpenCount == 1) {
    if (digitalRead(indexFinPin)  == firstComb[0] && 
        digitalRead(middleFinPin) == firstComb[1] &&
        digitalRead(ringFinPin)   == firstComb[2]) {
      digitalWrite(firstLedPin, HIGH);    
      lockOpenCount++;
      addDelay()
      return;
    }
  }

  // Check second finger combination.
  if (lockOpenCount == 2) {
    if (digitalRead(indexFinPin)  == secondComb[0] && 
        digitalRead(middleFinPin) == secondComb[1] &&
        digitalRead(ringFinPin)   == secondComb[2]) {
      digitalWrite(secondLedPin, HIGH);    
      lockOpenCount++;
      addDelay()
      return;
     }
  }

  // Check third finger combination.
  if (lockOpenCount == 3) {
    if (digitalRead(indexFinPin)  == thirdComb[0] && 
        digitalRead(middleFinPin) == thirdComb[1] &&
        digitalRead(ringFinPin)   == thirdComb[2]) {
      digitalWrite(thirdLedPin, HIGH);    
      lockOpenCount++;
      addDelay()
      return;
    }
  }

  // Turn on Master LED if all locks are open.
  if (lockOpenCount > 3 )
    digitalWrite(masterLedPin, HIGH);    
}


// A common delay function.
void addDelay() 
{
  delay(500);
}