Arduino Project 12

// import the library
 #include <Servo.h>
 // create an instance of the servo library
 Servo myServo;
 const int piezo = A0;
 const int switchPin = 2;
 const int yellowLed = 3;
 const int greenLed = 4;
 const int redLed = 5;             
//defines LED's and piezo's pins.
// variable for the piezo value
 int knockVal;
 // variable for the switch value
 int switchVal;
// variables for the high and low limits of the knock value
 const int quietKnock = 10;
 const int loudKnock = 100;
// variable to indicate if locked or not
 boolean locked = false;
 // how many valid knocks you've received
 int numberOfKnocks = 0;
void setup(){
 // attach the servo to pin 9
 myServo.attach(9);
// make the LED pins outputs
 pinMode(yellowLed, OUTPUT);
 pinMode(redLed, OUTPUT);
 pinMode(greenLed, OUTPUT);
// set the switch pin as an input
 pinMode(switchPin, INPUT);
// start serial communication for debugging
 Serial.begin(9600);
// turn the green LED on
 digitalWrite(greenLed, HIGH);
// move the servo to the unlocked position
 myServo.write(0);
// print status to the serial monitor
 Serial.println("the box is unlocked!");
 }
void loop(){
// if the box is unlocked
 if(locked == false){
// read the value of the switch pin
 switchVal = digitalRead(switchPin);
// if the button is pressed, lock the box
 if(switchVal == HIGH){
 // set the locked variable to "true"
 locked = true;
// change the status LEDs
 digitalWrite(greenLed,LOW);
 digitalWrite(redLed,HIGH);
// move the servo to the locked position
 myServo.write(90);
// print out status
 Serial.println("the box is locked!");
// wait for the servo to move into position
 delay (1000);
 }
 }
// if the box is locked
 if(locked == true){
// check the value of the piezo
 knockVal = analogRead(piezo);
// if there are not enough valid knocks
 if(numberOfKnocks < 3 && knockVal > 0){
// check to see if the knock is in range
 if(checkForKnock(knockVal) == true){
// increment the number of valid knocks
 numberOfKnocks++;
 }
// print status of knocks
 Serial.print(3 - numberOfKnocks);
 Serial.println(" more knocks to go");
 }
// if there are three knocks
 if(numberOfKnocks >= 3){
 // unlock the box
 locked = false;
// move the servo to the unlocked position
 myServo.write(0);
// wait for it to move
 delay(20);
// change status LEDs
 digitalWrite(greenLed,HIGH);
 digitalWrite(redLed,LOW);
 Serial.println("the box is unlocked!");
 }
 }
 }
// this function checks to see if a 
 // detected knock is within max and min range
 boolean checkForKnock(int value){
 // if the value of the knock is greater than
  // the minimum, and larger than the maximum
 if(value > quietKnock && value < loudKnock){
 // turn the status LED on
 digitalWrite(yellowLed, HIGH);
 delay(50);
 digitalWrite(yellowLed, LOW);
 // print out the status
 Serial.print("Valid knock of value ");
 Serial.println(value);
return true;
 }
 // if the knock is not within range
 else {
 // print status
 Serial.print("Bad knock value ");
 Serial.println(value);
return false;
 }
 }