LED Strip Guide

Overview

The LED strip provides automated lighting effects during the photo booth experience. It connects to the booth computer via USB and is controlled through Chrome's Web Serial API — no extra software needed.

• Rainbow — Animated rainbow cycle with auto-rotating patterns (idle/attract)
• White Hold — Warm white fill light for photo capture
• White Tail — Smooth fade-out after capture, then returns to rainbow
• Blackout — All LEDs off

What You Need

• Arduino Nano (or Uno/Nano Every) with USB cable
• WS2812B (NeoPixel) LED strip — any length (we use 43 LEDs)
• 5V power supply for strips longer than ~15 LEDs
• 330Ω resistor (data line protection — recommended)
• 1000µF capacitor across 5V/GND (smooths power spikes — recommended)
• Jumper wires

Wiring

Connect the WS2812B strip to the Arduino Nano:

Arduino Nano     WS2812B Strip
────────────     ─────────────
Pin D2 ──[330Ω]──  DIN  (data in)
5V     ───────────  5V   (or external 5V supply)
GND    ───────────  GND  (common ground)

For longer strips (16+ LEDs), power the strip from a separate 5V supply rated at ~60mA per LED. Connect the supply GND to both the strip GND and the Arduino GND (common ground).

Important: The data pin is D2. If you use a different pin, update LED_PIN in the firmware.

Arduino Firmware

Upload this to your Arduino using the Arduino IDE or PlatformIO. You'll need the Adafruit NeoPixel library installed (Arduino IDE: Sketch → Include Library → Manage Libraries → search "NeoPixel").

Adjust LED_COUNT to match the number of LEDs on your strip.

The firmware includes 5 rainbow sub-patterns that auto-rotate every 10 seconds: smooth rainbow, fast spin, glitter sparkles, RGB fade, and Knight Rider scanner.

// Key settings at the top of the sketch:

#define LED_PIN    2     // Arduino pin connected to DIN
#define LED_COUNT  43    // Number of LEDs on your strip
#define BRIGHTNESS 160   // Max brightness 0-255

// Serial: 115200 baud
// Commands: RAINBOW, WHITE_HOLD, WHITE_TAIL, BLACKOUT
// Replies:  ACK RAINBOW, ACK WHITE_HOLD, etc.

The full firmware source is available from your booth provider. Flash it once and the Arduino remembers it permanently.

Serial Protocol

The booth sends plain-text commands over USB serial at 115200 baud, each terminated with a newline (\n):

• RAINBOW — Rainbow cycle with auto-rotating patterns
• WHITE_HOLD — Warm white (255, 200, 160) fill light
• WHITE_TAIL — Fade from warm white to black (~900ms), then auto-switches to rainbow
• BLACKOUT — All LEDs off

The Arduino replies with ACK RAINBOW, ACK WHITE_HOLD, etc. to confirm each command. Unknown commands get ERR <command>.

On power-up the Arduino sends READY and starts in warm white hold mode.

Connecting to the Booth

1. Flash the firmware and plug the Arduino into the booth computer via USB.
2. Open the setup page in Chrome or Edge (Web Serial is not supported in Firefox/Safari).
3. Click the LED button in the header bar.
4. Tick Enable LED, then click Connect.
5. A browser dialog will list available serial ports — select the Arduino (e.g. USB Serial CH340 or Arduino Nano).
6. Use the test buttons (Rainbow, White Hold, White Tail, Blackout) to verify everything works.

The browser remembers the port grant, so the strip will auto-reconnect on future page loads — no need to click Connect again.

During a Photo Session

The booth controls the LED strip automatically — no manual intervention needed:

• Idle / Attract screen — Rainbow cycle (patterns rotate every 10s)
• Countdown & capture — White Hold (warm white fill light)
• After capture — White Tail (smooth ~1s fade), then back to Rainbow

Troubleshooting

• "led-webserial.js not loaded" — The page hasn't loaded the LED helper script. Hard-refresh the page (Ctrl+Shift+R) or clear the browser cache.
• No serial ports listed? — Make sure the Arduino is plugged in and recognised by the OS. On Windows, check Device Manager for a COM port. Install the CH340 driver if using a Nano clone.
• LEDs don't light up? — Check wiring: DIN to pin D2, common GND. Verify the strip is getting 5V power.
• Wrong colours or flickering? — Confirm LED_COUNT matches your strip. Add the 330Ω resistor on the data line and the 1000µF capacitor across power.
• Connect button doesn't appear? — Web Serial requires Chrome or Edge desktop. It is not available on mobile browsers or Firefox/Safari.
• Strip works in test but not during photos? — Make sure Enable LED is ticked in the LED modal. The booth only sends commands when LED control is enabled.