Stair Light

Note

🌟 Welcome to the SunFounder Facebook Community! Whether you’re into Raspberry Pi, Arduino, or ESP32, you’ll find inspiration, help ideas here.

  • ✅ Be the first to get free learning resources.

  • ✅ Stay updated on new products & exclusive giveaways.

  • ✅ Share your creations and get real feedback.

  • 👉 Need faster updates or support? Click [here] join our Facebook community

  • 👉 Or join our WhatsApp group: Click [here]

Kit purchase

Looking for parts? Check out our all-in-one kits below — packed with components, beginner-friendly guides, and tons of fun.

../_images/elite_explore_kit.png

Name

Includes Arduino board

PURCHASE LINK

Elite Explorer Kit

Arduino Uno R4 WiFi

BUY

Inventor Lab Kit

Arduino Uno R3

BUY

Course Introduction

In this lesson, you’ll use a PIR motion sensor, an LED, and a button with the Arduino R4 UNO to build a smart lighting system with three operating modes.

The system can automatically turn on the LED when motion is detected, keep it always on, or keep it always off. A single button toggles between these modes, and the LED behavior updates accordingly.

Note

If this is your first time working with an Arduino project, we recommend downloading and reviewing the basic materials first.

Required Components

In this project, we need the following components:

SN

COMPONENT INTRODUCTION

QUANTITY

PURCHASE LINK

1

Arduino UNO R4 Minima

1

BUY

2

USB Type-C cable

1

3

Breadboard

1

BUY

4

Wires

Several

BUY

5

PIR Motion Sensor

1

BUY

6

Button

1

BUY

7

LED

1

BUY

8

1kΩ resistor

1

BUY

Wiring

../_images/stair_light_bb.png

Common Connections:

  • LED

    • Connect the LED cathode to the to a 220Ω resistor, then to negative power bus on the breadboard, anode to 3 on the Arduino.

  • PIR

    • ＋: Connect to 2 on the Arduino.

    • －: Connect to breadboard’s negative power bus.

  • Button

    • Connect to the breadboard’s negative power bus, and the other end to 4 on the Arduino board.

Writing the Code

Note

  • You can copy this code into Arduino IDE.

  • Don’t forget to select the board(Arduino UNO R4 Minima) and the correct port before clicking the Upload button.

const int PIR_PIN = 2;    // PIR motion sensor signal pin
const int LED_PIN = 3;    // LED pin
const int BUTTON_PIN = 4; // Button pin

int mode = 0;  // 0 = Auto, 1 = Always ON, 2 = Always OFF
bool lastButtonState = HIGH;
unsigned long lastMotionTime = 0;
const unsigned long LIGHT_DELAY = 3000; // 3s delay

void setup() {
  pinMode(PIR_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP); // Internal pull-up

  digitalWrite(LED_PIN, LOW);
  Serial.begin(9600);
  Serial.println("Mode 0: Auto, Mode 1: Always ON, Mode 2: Always OFF");
}

void loop() {
  // ---- Button detection (toggle between modes) ----
  bool buttonState = digitalRead(BUTTON_PIN);
  if (buttonState == LOW && lastButtonState == HIGH) {
    mode = (mode + 1) % 3;  // Cycle through 0->1->2->0
    Serial.print("Mode: ");
    if (mode == 0) Serial.println("Auto");
    else if (mode == 1) Serial.println("Always ON");
    else Serial.println("Always OFF");
    delay(200); // Debounce
  }
  lastButtonState = buttonState;

  // ---- Mode control ----
  if (mode == 1) {
    // Always ON
    digitalWrite(LED_PIN, HIGH);
  } else if (mode == 2) {
    // Always OFF
    digitalWrite(LED_PIN, LOW);
  } else {
    // Auto mode (PIR control)
    int motion = digitalRead(PIR_PIN);
    if (motion == HIGH) {
      digitalWrite(LED_PIN, HIGH);
      lastMotionTime = millis(); // Record time when motion detected
    } else if (millis() - lastMotionTime > LIGHT_DELAY) {
      digitalWrite(LED_PIN, LOW);
    }
  }
}