Dual-Axis Arduino Solar Tracker

1#include <Servo.h>
2
3
4// Define servos
5Servo horizontalServo;  // Rotates base left/right
6Servo verticalServo;    // Tilts panel up/down
7
8
9// LDR pin assignments
10const int ldr1 = A1; // top-left
11const int ldr2 = A2; // top-right
12const int ldr3 = A3; // bottom-left
13const int ldr4 = A4; // bottom-right
14
15
16// Servo positions
17int horizontalPos = 90;
18int verticalPos = 90;
19
20
21// Function to read averaged LDR value
22int readLDR(int pin) {
23  int total = 0;
24  for (int i = 0; i < 5; i++) {
25    total += analogRead(pin);
26    delay(2);
27  }
28  return total / 5;
29}
30
31
32void setup() {
33  // Attach servos
34  horizontalServo.attach(9);
35  verticalServo.attach(10);
36
37
38  // Start at center
39  horizontalServo.write(horizontalPos);
40  verticalServo.write(verticalPos);
41
42
43  // Start serial monitor
44  Serial.begin(9600);
45  delay(500);
46}
47
48
49void loop() {
50  // Read LDR values (averaged)
51  int val1 = readLDR(ldr1);  // top-left
52  int val2 = readLDR(ldr2);  // top-right
53  int val3 = readLDR(ldr3);  // bottom-left
54  int val4 = readLDR(ldr4);  // bottom-right
55
56
57  // Show readings
58  Serial.print("LDR1: "); Serial.print(val1);
59  Serial.print(" | LDR2: "); Serial.print(val2);
60  Serial.print(" | LDR3: "); Serial.print(val3);
61  Serial.print(" | LDR4: "); Serial.println(val4);
62
63
64  // Calculate averages
65  int topAvg    = (val1 + val2) / 2;
66  int bottomAvg = (val3 + val4) / 2;
67  int leftAvg   = (val1 + val3) / 2;
68  int rightAvg  = (val2 + val4) / 2;
69
70
71  // Differences
72  int verticalDiff   = topAvg - bottomAvg;
73  int horizontalDiff = leftAvg - rightAvg;
74
75
76  // Sensitivity threshold
77  int threshold = 30;
78
79
80  // Vertical tracking
81  if (abs(verticalDiff) > threshold) {
82    if (verticalDiff < 0 && verticalPos < 180) { // MORE light at bottom → TILT DOWN
83      verticalPos--;
84    } else if (verticalDiff > 0 && verticalPos > 0) { // MORE light at top → TILT UP
85      verticalPos++;
86    }
87    verticalServo.write(verticalPos);
88  }
89
90
91  // Horizontal tracking
92  if (abs(horizontalDiff) > threshold) {
93    if (horizontalDiff < 0 && horizontalPos < 180) { // MORE light at right → ROTATE RIGHT
94      horizontalPos++;
95    } else if (horizontalDiff > 0 && horizontalPos > 0) { // MORE light at left → ROTATE LEFT
96      horizontalPos--;
97    }
98    horizontalServo.write(horizontalPos);
99  }
100
101
102  delay(30); // Smoother tracking
103}