Universal controller firmware foundation for adapters, controllers, and input systems.

Joypad OS is a modular, high-performance firmware platform for building controller adapters, custom controllers, and input/output bridges across USB, Bluetooth, and native game console protocols.

Formerly known as USBRetro, this project now serves as the foundational firmware layer of the Joypad ecosystem — a universal platform for extending how controllers work, connect, and evolve.

Joypad OS focuses on real-time controller I/O, protocol translation, and flexible routing, making it easy to build everything from classic console adapters to next-generation, assistive, and AI-augmented input devices.

• Universal input/output translation — Convert USB HID devices into native console protocols and vice versa.
• Modular firmware apps — Build specific bridges like usb2usb, usb2gc, snes2usb, passthrough adapters, merged inputs, and hybrid devices — all on a shared core.
• Flexible routing & passthrough — Support multi-output controllers, input merging, chaining devices, and advanced mods.
• Hardware-agnostic foundation — Designed to run across RP2040 today, with future portability to ESP32 and nRF platforms.
• Foundation for accessibility & assistive play — Enables custom controllers and input extensions for gamers with diverse needs.

Joypad OS is the real-time nervous system of the Joypad platform.

USB Controllers:

• Xbox (OG/360/One/Series X|S, 360 Wireless Adapter)
• PlayStation (Classic/DS3/DS4/DualSense)
• Nintendo (Switch Pro, Switch 2 Pro, NSO GameCube, GameCube adapter)
• 8BitDo (PCE 2.4g, M30, BT Adapters)
• Hori (Horipad, Pokken Tournament)
• Logitech Wingman
• Sega Astro City Mini
• Google Stadia
• Raphnet adapters (PCEngine, etc.)
• Generic HID gamepads

Bluetooth Controllers (via USB dongle or Pico W):

• PlayStation (DS3/DS4/DualSense)
• Nintendo (Switch Pro, Switch 2 Pro, Wii U Pro, Wiimote)
• Xbox (One/Series Bluetooth models)
• Google Stadia

Peripherals:

• USB Bluetooth dongles (connect BT controllers via USB host)
• USB Keyboards (full HID support)
• USB Mice (PCEngine mouse, Nuon spinner, 3DO mouse)
• USB Hubs (up to 8 devices for 3DO)

Complete hardware compatibility list

1. Download latest .uf2 from Releases
2. Enter bootloader:
   • USB-2-PCE / NUON / 3DO: Hold BOOT + connect USB-C
   • GC USB: Just connect USB-C (no button)
3. Drag .uf2 file to RPI-RP2 drive
4. Done! Drive auto-ejects when complete

Full installation guide

# Install ARM toolchain (macOS)
brew install --cask gcc-arm-embedded cmake git

# Clone and initialize
git clone https://github.com/joypad-ai/joypad-os.git
cd joypad-os && make init

# Build specific product
make usb2pce_kb2040   # PCEngine adapter
make usb2gc_kb2040    # GameCube adapter
make usb2dc_kb2040    # Dreamcast adapter
make usb2nuon_kb2040  # Nuon adapter

make init          # Initialize submodules (one-time setup)
make all           # Build all products
make clean         # Clean build artifacts

# Console adapters (USB/BT input)
make usb2pce_kb2040       # PCEngine (KB2040)
make usb2gc_kb2040        # GameCube (KB2040)
make usb2gc_rp2040zero    # GameCube (RP2040-Zero)
make usb2dc_kb2040        # Dreamcast (KB2040)
make usb2nuon_kb2040      # Nuon (KB2040)
make usb2loopy_kb2040     # Casio Loopy (KB2040)
make usb23do_rp2040zero   # 3DO (RP2040-Zero)

# Native controller adapters
make n642dc_kb2040        # N64 → Dreamcast (KB2040)
make n642usb_kb2040       # N64 → USB (KB2040)
make snes2usb_kb2040      # SNES → USB (KB2040)
make snes23do_rp2040zero  # SNES → 3DO (RP2040-Zero)

# USB/BT passthrough
make usb2usb_feather      # USB → USB (Feather USB Host)
make usb2usb_rp2040zero   # USB → USB (RP2040-Zero)
make usb2usb_rp2350usba   # USB → USB (Waveshare RP2350-USB-A)
make bt2usb_pico_w        # Bluetooth → USB (Pico W)

Output firmware files appear in releases/ directory.

Complete build guide

• Installation Guide - Flashing firmware, troubleshooting
• Hardware Compatibility - Supported controllers, boards, DIY builds
• Build Guide - Developer setup, architecture

• GameCube/Wii - Profiles, keyboard mode, rumble
• PCEngine/TurboGrafx-16 - Multitap, mouse, button modes
• Sega Dreamcast - VMU emulation, rumble, profiles
• Nuon - Controller, Tempest 3000 spinner, IGR
• 3DO - 8-player support, mouse, profiles
• Casio Loopy - Experimental support

Joypad OS uses a modular architecture:

• RP2040 - Dual-core ARM Cortex-M0+ microcontroller
• TinyUSB - USB host stack for polling USB devices
• PIO - Programmable I/O for timing-critical console protocols
• Dual-Core: Core 0 handles USB input, Core 1 runs console output
• Router - Flexible input→output routing (SIMPLE/MERGE/BROADCAST)
• Apps - Per-product configuration (router, profiles, features)

See CLAUDE.md for detailed architecture

• Discord: community.joypad.ai - Community chat
• Issues: GitHub Issues - Bug reports
• Email: support@controlleradapter.com - Product support

• Ha Thach - TinyUSB
• David Shadoff - PCEMouse foundation
• FCare - USBTo3DO 3DO protocol implementation
• mackieks - MaplePad Dreamcast Maple Bus implementation
• Ryzee119 - tusb_xinput
• SelvinPL - lufa-hid-parser
• JonnyHaystack - joybus-pio

Joypad OS is licensed under the Apache-2.0 License.

The Joypad name and branding are trademarks of Joypad Inc.