Arduino Blinds Control Project

Connect the photocell sensor and servo to your Arduino.

1. Connect a jumper wire from the 5V pin on the Arduino to a + rail on the breadboard.
2. Connect a jumper wire from a GND pin on the Arduino to the - rail next to the + rail.
3. Place the 10 kΩ resistor on the breadboard with one leg connected to the - rail.
4. Place the photocell on the breadboard with one leg connected to the resistor.
5. Connect a jumper from the + rail to the other leg of the photocell.
6. Connect a jumper from analog pin 0 to the leg of the photocell connected to the resistor.
7. Place the servo connector pins on the breadboard.
8. Connect the servo's red wire to the + rail (5V).
9. Connect the servo's black wire to the - rail (GND).
10. Connect digital pin 3 to the servo's signal wire (yellow or white).

Program the Arduino to read light levels and adjust the servo.

1. Open Arduino IDE and create a new sketch.
2. Copy the complete sketch into your IDE.
3. Adjust the upper and lower light limits based on your room's lighting (mine were 300 and 95).
4. Connect your Arduino via USB and select the correct board and port under Tools.
5. Click Upload to send the sketch to your Arduino.

#include <Servo.h>

Servo myServo;
int photoPin = 0;
int lightValue = 0;
int upperLimit = 300;
int lowerLimit = 95;
int maxPos = 180;
int minPos = 0;
int halfPos = 90;
int currentPos = 0;

void setup() {
  myServo.attach(3);
  myServo.write(halfPos);
  currentPos = halfPos;
  Serial.begin(9600);
}

void loop() {
  lightValue = analogRead(photoPin);
  
  if (lightValue >= lowerLimit && lightValue <= upperLimit) {
    // Do nothing, light is acceptable
  } else if (lightValue > upperLimit) {
    decLight();
  } else if (lightValue < lowerLimit) {
    incLight();
  }
  
  Serial.println(lightValue);
  delay(100);
}

void decLight() {
  if (currentPos - 10 >= minPos) {
    currentPos -= 10;
    myServo.write(currentPos);
  }
}

void incLight() {
  if (currentPos + 10 <= maxPos) {
    currentPos += 10;
    myServo.write(currentPos);
  }
}

Verify the servo responds to light changes.

1. Open the Serial Monitor (Tools → Serial Monitor) and set it to 9600 baud.
2. Watch the light value readings in the Serial Monitor.
3. Cover the photocell with your hand to simulate darkness—the servo should rotate to open the blinds (increase light).
4. Shine a flashlight on the photocell—the servo should rotate the opposite direction to close the blinds (decrease light).
5. If the servo doesn't move enough, adjust the upperLimit and lowerLimit values in the sketch and re-upload.