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’s dark enough.<\/p>\n Adjust the RGB values for different color temperatures:<\/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-3907","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
Option 1: RGB LED (Common Cathode)<\/h3>\n
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Component<\/th>\n Pin<\/th>\n Arduino Pin<\/th>\n<\/thead>\n \nPIR Sensor<\/td>\n VCC<\/td>\n 5V<\/td>\n<\/tr>\n PIR Sensor<\/td>\n GND<\/td>\n GND<\/td>\n<\/tr>\n PIR Sensor<\/td>\n OUT<\/td>\n Digital Pin 2<\/td>\n<\/tr>\n RGB LED (Red)<\/td>\n Anode<\/td>\n Digital Pin 9 (through 220\u03a9)<\/td>\n<\/tr>\n RGB LED (Green)<\/td>\n Anode<\/td>\n Digital Pin 10 (through 220\u03a9)<\/td>\n<\/tr>\n RGB LED (Blue)<\/td>\n Anode<\/td>\n Digital Pin 11 (through 220\u03a9)<\/td>\n<\/tr>\n RGB LED<\/td>\n Cathode<\/td>\n GND<\/td>\n<\/tr>\n LDR<\/td>\n One leg<\/td>\n 5V<\/td>\n<\/tr>\n LDR<\/td>\n Other leg<\/td>\n Analog Pin A0 and 10k\u03a9 resistor to GND<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Arduino Code<\/h2>\n
\/\/ PIR Night Light with Auto Dimming\n\/\/ Uses RGB LED with smooth fade-out effect\n\nconst int pirPin = 2;\nconst int redPin = 9;\nconst int greenPin = 10;\nconst int bluePin = 11;\nconst int ldrPin = A0; \/\/ Optional\n\n\/\/ Color settings (warm white)\nint redValue = 255;\nint greenValue = 180;\nint blueValue = 100;\n\n\/\/ Timing\nunsigned long lastMotionTime = 0;\nconst unsigned long holdTime = 30000; \/\/ 30 seconds before dimming\nconst unsigned long fadeDuration = 5000; \/\/ 5 second fade-out\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 \/\/ Turn off lights initially\n setBrightness(0);\n \n Serial.println(\"Night Light Ready\");\n Serial.println(\"Waiting 60 seconds for PIR warm-up...\");\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 \/\/ percent: 0-100\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 \/\/ Adjust threshold based on your environment\n return ldrValue < 500; \/\/ Dark when reading < 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 \/\/ Check if it's dark enough (optional)\n if (!isDark() && lightsOn) {\n \/\/ It's daytime, turn off lights immediately\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 \/\/ Turn on lights immediately\n setBrightness(100);\n lightsOn = true;\n Serial.println(\"Motion detected - Lights ON\");\n } else if (currentBrightness < 100) {\n \/\/ Fade back up if dimming was in progress\n setBrightness(100);\n Serial.println(\"Motion detected - Fade cancelled\");\n }\n }\n \n if (lightsOn) {\n \/\/ Check if it's time to dim\n if (millis() - lastMotionTime > holdTime) {\n if (fadeStartTime == 0) {\n fadeStartTime = millis();\n Serial.println(\"No motion - Starting fade-out\");\n }\n fadeOut();\n } else {\n \/\/ Reset fade timer if motion occurs during fade\n fadeStartTime = 0;\n }\n }\n \n delay(50);\n}\n<\/code><\/pre>\nCode for WS2812B LED Strip<\/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 Serial.begin(9600);\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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Customizing Colors<\/h2>\n
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Project Extensions<\/h2>\n
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Conclusion<\/h2>\n