Arduino Servo and light sensor

behavior_exp.ino

#include <Servo.h>      // include the servo library

Servo servoMotor;       // creates an instance of the servo object to control a servo
int servoPin = 2;       // Control pin for servo motor
int pos = 0;    // variable to store the servo position 

int now, previousTime, interval = 0;


//for smoothing of values
const int numReadings = 10;

int readings[numReadings];      // the readings from the analog input
int index = 0;                  // the index of the current reading
int total = 0;                  // the running total
int average = 0;                // the average



void setup() { 
  Serial.begin(9600);       // initialize serial communications
  servoMotor.attach(servoPin);  // attaches the servo on pin 2 to the servo object
  
  for (int thisReading = 0; thisReading < numReadings; thisReading++)
    readings[thisReading] = 0; 

} 

void loop() 
{ 
  int lightValue = getSmoothValue();
  Serial.println(lightValue);      // print it
  
  
  
  if (lightValue < 100){  
    now = millis();
    if(now - previousTime > 5000){
      startKnocking();
      //timer.setInterval(10000, startKnocking);
    }
  }
  else if (lightValue > 100){
    previousTime = millis();
    stopKnocking();
  }
}

void startKnocking(){
    for(pos = 0; pos < 90; pos += 5)  // goes from 0 degrees to 180 degrees 
    {                                  // in steps of 1 degree 
      servoMotor.write(pos);              // tell servo to go to position in variable 'pos' 
      delay(5);                       // waits 15ms for the servo to reach the position 
    } 
    for(pos = 90; pos>=1; pos-=5)     // goes from 180 degrees to 0 degrees 
    {                                
      servoMotor.write(pos);              // tell servo to go to position in variable 'pos' 
      delay(5);                       // waits 15ms for the servo to reach the position 
    } 
  
}
void stopKnocking(){
  Serial.println("____________________STOP_____________");
  servoMotor.write(0);
}

int getSmoothValue(){
  // subtract the last reading:
  total= total - readings[index];         
  // read from the sensor:  
  readings[index] = analogRead(A0); 
  // add the reading to the total:
  total= total + readings[index];       
  // advance to the next position in the array:  
  index = index + 1;                    

  // if we're at the end of the array...
  if (index >= numReadings)              
    // ...wrap around to the beginning: 
    index = 0;                           

  // calculate the average:
  average = total / numReadings;         
  // send it to the computer as ASCII digits
  return average;            
}