#include <Servo.h>
Servo servo9;
const int piezo = A0;
const int switchPin = 2;
const int yellowLed = 3;
const int greenLed = 4;
const int redLed = 5;
int knockVal;
int switchVal;
const int quietKnock = 10;
const int loudKnock = 100;
boolean locked = false;
int numberOfKnocks = 0;
void setup() {
servo9.attach(9);
pinMode(yellowLed, OUTPUT);
pinMode(greenLed, OUTPUT);
pinMode(redLed, OUTPUT);
pinMode(switchPin, INPUT);
Serial.begin(9600);
digitalWrite(greenLed, HIGH);

servo9.write(0);
Serial.println("The box is unlocked!");
}
void loop() {
if (locked == false) {
switchVal = digitalRead(switchPin);
if (switchVal == HIGH) {
locked = true;
digitalWrite(greenLed, LOW);
digitalWrite(redLed, HIGH);
servo9.write(90);
Serial.println("The box is locked!");
delay(1000);
}
}
if (locked == true) {
knockVal = analogRead(piezo);
if (numberOfKnocks < 3 && knockVal > 0) {
if (checkForKnock(knockVal) == true) { // Check for correct
// number of knocks
numberOfKnocks++;
}
Serial.print(3 - numberOfKnocks);
Serial.println(" more knocks to go");
}
if (numberOfKnocks >= 3) { // If 3 valid knocks are detected,
// the servo moves
locked = false;
servo9.write(0);
delay(20);
digitalWrite(greenLed, HIGH);
digitalWrite(redLed, LOW);
Serial.println("The box is unlocked!");
}
}
}
boolean checkForKnock(int value) { // Checks knock value
if (value > quietKnock && value < loudKnock) { // Value needs to be
// between these
digitalWrite(yellowLed, HIGH);
delay(50);
digitalWrite(yellowLed, LOW);
Serial.print("Valid knock of value ");
Serial.println(value);
return true;
}
else {
Serial.print("Bad knock value ");
Serial.println(value);
return false;
}
}