LBD

Lott-Bespitting Diode (LBD)

A high-intensity IR blaster built on the RP2040. Browser-native control over WebSerial, MOSFET-driven IR output, 38kHz NEC modulation. Fully open source.

Home Page · Controller

Named for Mrs. Lott, the worst teacher I ever had, and her classroom projector.

Features

• Web Controller: Full single-page app to manage IR remotes, browse the Flipper-IRDB, compose NEC signals, and transmit over WebSerial
• In-Browser Schematic Viewer: Browse all hardware schematics directly on the landing page via KiCanvas
• Auto-Generated BOM: Bill of materials extracted from KiCad schematics and embedded in the landing page, updated on every push
• IRDB Integration: Browse and import from Lucaslhm/Flipper-IRDB directly from the controller
• NEC Protocol Engine: CircuitPython firmware with hardware-timed 38kHz carrier modulation
• Library Management: Organize remotes and signals in folders with drag-and-drop, favorites, and inline editing

Project Structure

app/                  # Web front-end
  index.html          # Landing page (hero, BOM, schematic viewer, docs)
  controller.html     # WebSerial controller app
  landing/
    index.css         # Landing page styles (dark theme, purple/amber)
    index.js          # Landing page interactivity (tabs, viewer)
    insults.json      # Footer quotes
    three-scene.js    # Three.js particle background
  controller/
    style.css         # Controller styles
    scripts/
      app.js          # Init, event listeners, tab switching
      state.js        # State management, library CRUD, localStorage
      serial.js       # WebSerial connection, log bar
      transmit.js     # Hex input, NEC encoding, transmit history, save form
      library-ui.js   # Library pane, remote view, favorites, inline edits
      sidebar.js      # Sidebar toggle, resize, tree rendering
      modals.js       # Modal dialogs (folder, rename, delete, clear)
      drag-drop.js    # Drag-and-drop reordering in sidebar tree
      import.js       # .ir file parsing and import
      irdb.js         # Flipper-IRDB browsing and import
      utils.js        # escHtml, escAttr helpers

firmware/             # CircuitPython firmware

Hardware

The embedded PCB design isn't finalized yet. Build the prototype on a breadboard or perfboard using the prototype schematic.

The full design targets a custom PCB with an RP2040, MOSFET-switched IR LED array, USB-C, and external flash. Five KiCad schematics cover the main board, power regulation, flash memory, USB connector, and a simplified prototype variant.

Firmware

The CircuitPython firmware implements a standard NEC protocol engine:

• 38kHz carrier modulation via pulseio.PulseOut
• Listens for 4-byte NEC arrays over USB serial
• Drives a status LED and the IR output on GPIO
• Header: 9000µs mark / 4500µs space
• Bit coding: 560µs mark + 1690µs (1) or 560µs (0)
• Compatible with any NEC IR receiver

import time
import board
import pwmio

# 38kHz carrier wave initialization
ir_pwm = pwmio.PWMOut(board.GP16, frequency=38000, duty_cycle=0)

def pulse_nec(mark_us, space_us):
    # Enable carrier wave modulation for duration of mark
    ir_pwm.duty_cycle = 32768  # 50% duty cycle
    time.sleep_us(mark_us)

    # Disable carrier wave modulation for duration of space
    ir_pwm.duty_cycle = 0
    time.sleep_us(space_us)

Web Interface

Two pages are served via GitHub Pages:

Setup & Flash

Build the prototype on a breadboard or perfboard using the prototype schematic.

Step 3: Deploy Firmware

Copy the contents of firmware/ onto the CIRCUITPY volume root:

• code.py
• lib/

Step 4: Plug It In & Open the Controller

Keep the device connected via USB, then open the web controller in a Chromium-based browser. Click Connect to establish the WebSerial session.

To run locally (required for development):

git clone https://github.com/chaowoses/LottBespittingDiode.git
cd LottBespittingDiode
python -m http.server 8080
# open http://localhost:8080

License & Terms of Use

[!CAUTION] STRICTLY PROHIBITED FOR ILLEGAL USE

This project is designed solely for personal engineering research, hardware prototyping, and authorized testing. You may only operate this device on equipment you personally own or have explicit permission to control. The creator assumes no liability for misuse, property disruption, or equipment damage.

This project (software, firmware, schematics, PCB layouts, and documentation) is licensed under the GNU General Public License v3.0 (GPL-3.0).

Copyright © 2026 Josh Felder (Chaos). All Rights Reserved.