This project creates a smart night light that turns on when motion is detected and gradually dims over time. The light uses an RGB LED or LED strip and features smooth fade-out effects, making it perfect for bedrooms, hallways, and children’s rooms.<\/p>\n
Difficulty:<\/strong> Beginner A PIR sensor detects motion. When motion is detected, the LED turns on at full brightness. After a set period without motion, the light gradually dims over several seconds rather than turning off abruptly. An optional ambient light sensor (LDR) can be added so the light only activates when it is dark enough.<\/p>\n VCC<\/th>\n 5V<\/th>\n GND<\/th>\n GND<\/th>\n OUT<\/th>\n Digital Pin 2<\/th>\n Anode<\/th>\n Digital Pin 9 (via 220\u03a9)<\/th>\n Anode<\/th>\n Digital Pin 10 (via 220\u03a9)<\/th>\n Anode<\/th>\n Digital Pin 11 (via 220\u03a9)<\/th>\n Cathode<\/th>\n GND<\/th>\n One leg<\/th>\n 5V<\/th>\n Other leg<\/th>\n Analog Pin A0 and 10k\u03a9 to GND<\/th>\n<\/tbody>\n \u8868<\/p>\n This smart night light provides gentle illumination when you need it and automatically fades out, making it perfect for bedrooms and hallways. The gradual dimming effect is much more pleasant than abrupt switching off.<\/p>\n","protected":false},"excerpt":{"rendered":" Project Overview This project creates a smart night light that turns on when motion is detected and gradually dims over time. The light uses an RGB LED or LED strip and features smooth fade-out effects, making it perfect for bedrooms, hallways, and children’s rooms. Difficulty: Beginner Estimated time: 1-2 hours Estimated cost: $15-25 How It […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-3906","post","type-post","status-publish","format-standard","hentry","category-projects"],"blocksy_meta":[],"yoast_head":"\r\n
\nEstimated time:<\/strong> 1-2 hours
\nEstimated cost:<\/strong> $15-25<\/p>\nHow It Works<\/h2>\n
Materials Needed<\/h2>\n
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Circuit Diagram<\/h2>\n
Connection Table (RGB LED Version)<\/h3>\n
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Component<\/th>\n Pin<\/th>\n Arduino Pin<\/th>\n<\/thead>\n \nPIR Sensor<\/th>\n PIR Sensor<\/th>\n PIR Sensor<\/th>\n RGB LED (Red)<\/th>\n RGB LED (Green)<\/th>\n RGB LED (Blue)<\/th>\n RGB LED<\/th>\n LDR<\/th>\n LDR<\/th>\n Arduino Code<\/h2>\n
\/\/ PIR Night Light with Auto Dimming\n\nconst int pirPin = 2;\nconst int redPin = 9;\nconst int greenPin = 10;\nconst int bluePin = 11;\nconst int ldrPin = A0;\n\nint redValue = 255;\nint greenValue = 180;\nint blueValue = 100;\n\nunsigned long lastMotionTime = 0;\nconst unsigned long holdTime = 30000;\nconst unsigned long fadeDuration = 5000;\n\nbool lightsOn = false;\nint currentBrightness = 0;\nunsigned long fadeStartTime = 0;\n\nvoid setup() {\n Serial.begin(9600);\n \n pinMode(pirPin, INPUT);\n pinMode(redPin, OUTPUT);\n pinMode(greenPin, OUTPUT);\n pinMode(bluePin, OUTPUT);\n \n setBrightness(0);\n \n Serial.println(\"Night Light Ready\");\n delay(60000);\n}\n\nvoid setColor(int r, int g, int b) {\n analogWrite(redPin, r);\n analogWrite(greenPin, g);\n analogWrite(bluePin, b);\n}\n\nvoid setBrightness(int percent) {\n int r = map(percent, 0, 100, 0, redValue);\n int g = map(percent, 0, 100, 0, greenValue);\n int b = map(percent, 0, 100, 0, blueValue);\n setColor(r, g, b);\n currentBrightness = percent;\n}\n\nbool isDark() {\n int ldrValue = analogRead(ldrPin);\n return ldrValue < 500;\n}\n\nvoid fadeOut() {\n unsigned long elapsed = millis() - fadeStartTime;\n if (elapsed >= fadeDuration) {\n setBrightness(0);\n lightsOn = false;\n } else {\n int brightness = 100 - (elapsed * 100 \/ fadeDuration);\n setBrightness(brightness);\n }\n}\n\nvoid loop() {\n if (!isDark() && lightsOn) {\n setBrightness(0);\n lightsOn = false;\n }\n \n bool motionDetected = digitalRead(pirPin) == HIGH;\n \n if (motionDetected && isDark()) {\n lastMotionTime = millis();\n \n if (!lightsOn) {\n setBrightness(100);\n lightsOn = true;\n } else if (currentBrightness < 100) {\n setBrightness(100);\n }\n fadeStartTime = 0;\n }\n \n if (lightsOn) {\n if (millis() - lastMotionTime > holdTime) {\n if (fadeStartTime == 0) {\n fadeStartTime = millis();\n }\n fadeOut();\n } else {\n fadeStartTime = 0;\n }\n }\n \n delay(50);\n}\n<\/code><\/pre>\nWS2812B LED Strip Version<\/h2>\n
#include <FastLED.h>\n\n#define LED_PIN 6\n#define NUM_LEDS 5\n#define BRIGHTNESS 128\n\nCRGB leds[NUM_LEDS];\n\nconst int pirPin = 2;\nconst int ldrPin = A0;\n\nunsigned long lastMotionTime = 0;\nconst unsigned long holdTime = 30000;\nconst unsigned long fadeDuration = 5000;\n\nbool lightsOn = false;\nint currentBrightness = 0;\nunsigned long fadeStartTime = 0;\n\nvoid setup() {\n FastLED.addLeds<WS2812B, LED_PIN, GRB>(leds, NUM_LEDS);\n FastLED.setBrightness(0);\n \n pinMode(pirPin, INPUT);\n \n delay(60000);\n}\n\nvoid setBrightness(int percent) {\n int brightness = map(percent, 0, 100, 0, BRIGHTNESS);\n FastLED.setBrightness(brightness);\n FastLED.show();\n currentBrightness = percent;\n}\n\nvoid setColor(CRGB color) {\n for (int i = 0; i < NUM_LEDS; i++) {\n leds[i] = color;\n }\n FastLED.show();\n}\n\nvoid loop() {\n int ldrValue = analogRead(ldrPin);\n bool isDark = ldrValue < 500;\n bool motionDetected = digitalRead(pirPin) == HIGH;\n \n if (motionDetected && isDark) {\n lastMotionTime = millis();\n \n if (!lightsOn) {\n setColor(CRGB::White);\n setBrightness(100);\n lightsOn = true;\n } else if (currentBrightness < 100) {\n setBrightness(100);\n }\n fadeStartTime = 0;\n }\n \n if (lightsOn) {\n if (millis() - lastMotionTime > holdTime) {\n if (fadeStartTime == 0) {\n fadeStartTime = millis();\n }\n unsigned long elapsed = millis() - fadeStartTime;\n if (elapsed >= fadeDuration) {\n setBrightness(0);\n lightsOn = false;\n } else {\n int brightness = 100 - (elapsed * 100 \/ fadeDuration);\n setBrightness(brightness);\n }\n }\n }\n \n delay(50);\n}\n<\/code><\/pre>\nInstallation Steps<\/h2>\n
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Project Extensions<\/h2>\n
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Conclusion<\/h2>\n