PIR Sensor for Drawer/Light Switch: Gesture-Controlled Lighting

Project Overview

This project creates a gesture-controlled light switch that turns lights on and off with a simple hand wave. Using a PIR sensor, the system detects motion and toggles a relay that controls the light. A short wave turns the light on, and another wave turns it off. It’s perfect for situations where your hands are dirty or full.

Difficulty: Beginner
Estimated time: 1-2 hours
Estimated cost: $15-25

How It Works

A PIR sensor detects hand movement within a short range (10-30cm). Each time motion is detected, the Arduino toggles a relay that controls the light. The system includes a status LED to indicate the current state and a timeout to prevent rapid toggling (debounce).

Unlike traditional motion-sensing lights that turn on and then off automatically, this system maintains the state until another gesture is detected, giving you full control.

Materials Needed

• Arduino Nano or Arduino Uno (1)
• HC-SR501 PIR sensor (1) – with sensitivity set to minimum range
• Relay module (5V, single channel)
• LED (for status indication)
• Resistor (220Ω for LED)
• Jumper wires
• Power supply (5V 1A)
• Project enclosure
• Optional: AC power cord and outlet (for controlling a lamp)

Circuit Diagram

Connection Table

PIR Sensor Adjustment

For gesture control, you want very short range (10-30cm):

• Turn sensitivity potentiometer fully counter-clockwise (minimum range).
• Set time delay to minimum (fully counter-clockwise).
• Set jumper to non-repeatable mode (L) for single triggers.

Arduino Code

// Gesture-Controlled Light Switch
// Wave hand to toggle light on/off

const int pirPin = 2;
const int relayPin = 3;
const int ledPin = 13;

bool lightState = false;
unsigned long lastTriggerTime = 0;
const unsigned long debounceDelay = 1000; // 1 second debounce

void setup() {
  Serial.begin(9600);
  
  pinMode(pirPin, INPUT);
  pinMode(relayPin, OUTPUT);
  pinMode(ledPin, OUTPUT);
  
  digitalWrite(relayPin, LOW);
  digitalWrite(ledPin, LOW);
  
  Serial.println("Gesture Light Switch Ready");
  Serial.println("Wave hand to toggle light");
  delay(30000); // Short warm-up (30 seconds is enough for gesture use)
}

void toggleLight() {
  lightState = !lightState;
  digitalWrite(relayPin, lightState ? HIGH : LOW);
  digitalWrite(ledPin, lightState ? HIGH : LOW);
  
  Serial.print("Light ");
  Serial.println(lightState ? "ON" : "OFF");
}

void loop() {
  bool motion = digitalRead(pirPin) == HIGH;
  
  if (motion && (millis() - lastTriggerTime > debounceDelay)) {
    lastTriggerTime = millis();
    toggleLight();
  }
  
  delay(50);
}

Enhanced Version with LED Feedback

// Enhanced version with LED fade effect
const int pirPin = 2;
const int relayPin = 3;
const int ledPin = 13;

bool lightState = false;
unsigned long lastTriggerTime = 0;
const unsigned long debounceDelay = 1000;
unsigned long fadeStartTime = 0;
bool fading = false;

void fadeLED(int start, int end) {
  int duration = 500; // 500ms fade
  unsigned long startTime = millis();
  while (millis() - startTime < duration) {
    int brightness = map(millis() - startTime, 0, duration, start, end);
    analogWrite(ledPin, brightness);
    delay(5);
  }
  analogWrite(ledPin, end);
}

void toggleLight() {
  lightState = !lightState;
  digitalWrite(relayPin, lightState ? HIGH : LOW);
  
  if (lightState) {
    fadeLED(0, 255);
  } else {
    fadeLED(255, 0);
  }
  
  Serial.print("Light ");
  Serial.println(lightState ? "ON" : "OFF");
}

void setup() {
  Serial.begin(9600);
  pinMode(pirPin, INPUT);
  pinMode(relayPin, OUTPUT);
  pinMode(ledPin, OUTPUT);
  digitalWrite(relayPin, LOW);
  digitalWrite(ledPin, LOW);
  delay(30000);
}

void loop() {
  bool motion = digitalRead(pirPin) == HIGH;
  if (motion && (millis() - lastTriggerTime > debounceDelay)) {
    lastTriggerTime = millis();
    toggleLight();
  }
  delay(50);
}

Mounting Options

Drawer/Cabinet Lighting

1. Mount PIR sensor inside the drawer or cabinet facing upward/outward.
2. Install LED strip inside the drawer/cabinet.
3. Connect LED strip to relay (use appropriate power supply for LED strip).
4. Wave hand near the drawer to toggle lights on/off.

Desk/Workbench Lamp

1. Mount PIR sensor near the lamp base.
2. Connect lamp plug to relay-controlled outlet.
3. Wave hand near the lamp to toggle.

Installation Steps

1. Adjust PIR sensor: Set sensitivity to minimum range.
2. Assemble circuit: Build on breadboard and test.
3. Upload code: Test gesture detection (wave hand within 10-20cm).
4. Mount sensor: Position sensor in desired location.
5. Connect light: Wire the lamp or LED strip to the relay.
6. Enclose electronics: Place Arduino and relay in a safe enclosure.
7. Final test: Wave hand to turn light on/off.

Project Extensions

• Dimmer function: Add a second PIR sensor for dimming control (wave left to dim, right to brighten).
• Color control: Use RGB LED strip and cycle colors with multiple gestures.
• Multiple zones: Add multiple PIR sensors to control different lights.
• Smart home integration: Add ESP32 to send state to Home Assistant.
• Battery backup: Add rechargeable battery for portable use.

Troubleshooting

• Light toggles randomly: Reduce sensitivity further. Add physical shield to limit detection area.
• No detection: Adjust sensitivity upward slightly. Ensure hand is within detection zone.
• Multiple toggles per gesture: Increase debounceDelay.
• Relay not switching: Check relay wiring. Test with LED first.

Safety Notes

• If controlling AC-powered lights, ensure relay is rated for the load.
• Keep all wiring away from water.
• Use a proper enclosure to prevent electrical shock.

Conclusion

This gesture-controlled light switch adds a touch of magic to any room. It’s perfect for kitchens (hands full of dishes), workshops (hands covered in paint), or simply for the novelty of waving to control lights.