A Simple Light Follower

1/*
2A simple light follower
3 
4author: Arturo Guadalupi <a.guadalupi@arduino.cc>
5  */
6#include <Servo.h>
7Servo myservo;
8int up_average;
9int down_average;
10int  A0_val;
11int A1_val;
12int A2_val;
13int A3_val;
14int val = 90;
15int diff;
16const  int threshold = 50;
17void setup() {
18  pinMode(A0, INPUT); 
19  pinMode(A1,  INPUT);
20  pinMode(A2, INPUT);
21  pinMode(A3, INPUT);
22  myservo.attach(11);
23  myservo.write(val);
24}
25void loop() {
26  A0_val = analogRead(A0); //reading  data from sensors
27  A1_val = analogRead(A1); 
28  A2_val = analogRead(A2);
29  A3_val = analogRead(A3);
30  
31  down_average = (A0_val + A1_val)/2; //the  sum of the two lower sensors /2
32  up_average = (A2_val + A3_val)/2;	  //the  sum of the two upper sensors /2
33  diff = abs(up_average-down_average); //checking  the difference between the two averages
34  if ((up_average > down_average) &&  (diff > threshold))
35    {
36     if (val < 180) //if different from max val
37       {
38       val++;
39       myservo.write(val);
40       }
41    }
42  if((down_average > up_average) && (diff > threshold))
43    {
44    if (val  > 0) //if different from min val
45      {
46      val--;
47      myservo.write(val);
48      }
49    }
50  delay(25);
51}

1/*
2A simple light follower
3 
4author: Arturo Guadalupi <a.guadalupi@arduino.cc>
5   */
6#include <Servo.h>
7Servo myservo;
8int up_average;
9int down_average;
10int   A0_val;
11int A1_val;
12int A2_val;
13int A3_val;
14int val = 90;
15int diff;
16const   int threshold = 50;
17void setup() {
18  pinMode(A0, INPUT); 
19  pinMode(A1,   INPUT);
20  pinMode(A2, INPUT);
21  pinMode(A3, INPUT);
22  myservo.attach(11);
23   myservo.write(val);
24}
25void loop() {
26  A0_val = analogRead(A0); //reading   data from sensors
27  A1_val = analogRead(A1); 
28  A2_val = analogRead(A2);
29   A3_val = analogRead(A3);
30  
31  down_average = (A0_val + A1_val)/2; //the   sum of the two lower sensors /2
32  up_average = (A2_val + A3_val)/2;	  //the   sum of the two upper sensors /2
33  diff = abs(up_average-down_average); //checking   the difference between the two averages
34  if ((up_average > down_average) &&   (diff > threshold))
35    {
36     if (val < 180) //if different from max val
37        {
38       val++;
39       myservo.write(val);
40       }
41    }
42   if((down_average > up_average) && (diff > threshold))
43    {
44    if (val   > 0) //if different from min val
45      {
46      val--;
47      myservo.write(val);
48       }
49    }
50  delay(25);
51}