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Making a LilyPad Night-Light
Ed

Created by

Ed

13. July 2026FI
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Making a LilyPad Night-Light

Give your fabric a sense of sight. A LilyPad light sensor tells the microcontroller how bright the room is, and a short program switches an LED on when it gets dark. Sew it into a bag, a hat or a bedside patch for a soft glow that only appears at night — your first sensor-driven wearable.

Intermediate
1-2 hours

Instructions

1

Sew the board, sensor and LED

Sew a LilyPad Arduino, a LilyPad light sensor and a LilyPad LED onto felt. Wire it: the LED's + tab to pin 5 and its - tab to -; the sensor's + tab to the board's +, its - tab to -, and its signal (S) tab to analog pin A2. Keep the power (+), ground (-) and signal lines from crossing anywhere.

Materials for this step:

LilyPad Arduino Simple BoardLilyPad Arduino Simple Board1 piece
LilyPad Light SensorLilyPad Light Sensor1 piece
LilyPad LED - 5 pcsLilyPad LED - 5 pcs1 pack
Conductive Thread - 60g (Stainless Steel)Conductive Thread - 60g (Stainless Steel)1 spool
Wool Felt SheetWool Felt Sheet1 sheet

Tools needed:

Hand Sewing Needles (Assorted, 30-Pack)Hand Sewing Needles (Assorted, 30-Pack)
2

Connect the programmer

Plug the LilyPad FTDI onto the programming header and connect the USB cable to your computer. Open the Arduino IDE and select the LilyPad Arduino board and its serial port.

Tools needed:

Computer with Arduino IDEComputer with Arduino IDE
LilyPad FTDI Basic Breakout - 5VLilyPad FTDI Basic Breakout - 5V
USB-B CableUSB-B Cable
3

Upload the night-light sketch

Paste this sketch and click Upload. It reads the light sensor and turns the LED on whenever the room is darker than the threshold.

lilypad_night_light.inoarduino
// LilyPad night-light: LED comes on when it gets dark.
// LED on pin 5, light sensor signal on analog pin A2.

const int LED_PIN = 5;       // LED
const int LIGHT_PIN = A2;    // light sensor signal
int threshold = 400;        // lower = waits for darker; raise to trigger sooner

void setup() {
  pinMode(LED_PIN, OUTPUT);
}

void loop() {
  int light = analogRead(LIGHT_PIN);  // 0 (dark) .. 1023 (bright)

  if (light < threshold) {
    digitalWrite(LED_PIN, HIGH);       // dark -> LED on
  } else {
    digitalWrite(LED_PIN, LOW);        // bright -> LED off
  }

  delay(100);
}
4

Calibrate the threshold

Cover the sensor with your hand — the LED should come on; in a bright room it should stay off. If it triggers too early or too late, change the threshold number in the sketch and re-upload: higher turns it on in more light, lower waits for darker.

5

Go wireless and wear it

Unplug the FTDI, sew a LilyPad coin-cell holder to the board (+ to +, - to -), drop in a CR2032 and switch on. Sew the felt onto a bag, hat or cushion — it now glows on its own whenever the light drops.

Materials for this step:

LilyPad Coin Cell Battery Holder - w/Switch - 20mmLilyPad Coin Cell Battery Holder - w/Switch - 20mm1 piece
CR2032 Coin Cell BatteryCR2032 Coin Cell Battery1 piece

Materials

7

Tools Required

4
Estimated Total
What the maker bought. Materials shown without a price are sourced wherever you buy them.
$76.60

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