Saturn 3D Control Pad USB Extension Unit


USB Extension Unit for Sega 3D Control Pad

Where to Buy

Available at:
Kaden Ken-chan and BOOTH

Product Overview

This is an extension unit for converting Sega Saturn's 3D Control Pad (a.k.a. Multi-Controller in Japan) into a USB gamepad.
By replacing the standard unit with this product, 3D Control Pad can be used as a USB gamepad.
The USB connector uses Type-C.

Note: A USB cable is not included with the product. Please prepare it yourself.

The firmware is open-source, allowing users to edit it freely. You can write the edited firmware via USB.


Product Features

One-Touch Conversion to USB

By swapping the standard unit with this product, 3D Control Pad can be used as a USB gamepad.

Insert the USB cable while this product is attached to 3D Control Pad.
When you connect this product to a PC or similar device via a USB cable without attaching it to 3D Control Pad, it will boot in firmware writing mode.

Editable Firmware

The source code for the firmware is open-source.

You can write the firmware via USB.
When the extension unit is not inserted into 3D Control Pad and you plug the USB into a PC, the product will boot in firmware writing mode.

Mode Switching Support

Supports the mode toggle switch on the 3D Control Pad unit. Button assignments for + Mode / 〇 Mode are as follows (in the case of standard firmware):

3D Control Pad Buttons + Mode 〇 Mode
A 1 1
B 2 2
C 3 3
X 4 4
Y 5 5
Z 6 6
L 7 Z-axis
R 8 Z-rotation
Start 9 9
Analog Stick N/A X-axis/Y-axis
D-pad Hat Switch Hat Switch

Tested OS / Game Consoles

  • Retro Freak
  • Windows10
  • Windows11
  • Raspberry PI 3
    • Raspberry Pi OS
    • Recalbox for RASPBERRY PI 3
    • RetroPi 4.7.1 for RASPBERRY PI 2/3
  • Raspberry PI 4
    • Raspberry Pi OS
    • Recalbox for RASPBERRY PI 4/400
    • RetroPi 4.7.1 for RASPBERRY PI 4/400
Game Consoles with Confirmed Operation

The following game consoles have been confirmed to work based on user reports:

    • Requires firmware to be switched to the Xinput version (firmware details are at the end of this article)
    • Enabling the analog setting in the game controller settings will make the analog stick operational

Additional Specifications

USB Connector: Type-C
Microcontroller Used: PIC Microcontroller (PIC16F1459)

Product Photos

Operation Verification

The method for operation verification is the same as that for the SFC Controller USB Gamepad board.
Please check here for more details.

Controller Settings in Steam

If you are using the standard firmware in Steam, please configure from Big Picture Mode. This page can be a reference.
Steamのコントローラー設定!ゲームパッド画面からのカスタマイズ方法 - Apple Geek LABO

If the controller is not recognized in Big Picture Mode, go to Steam Settings → Controller → General Controller Settings, and select "SS3D Gamepad" to assign buttons.

No need for the above settings if you are using the xinput version of the firmware.

Firmware Writing

Installing the Firmware Writing Software

You will need the writing software provided by Microchip's MLA (Microchip Libraries for Applications) for firmware writing.
You can download the MLA installer from here.

Upon installing MLA, the writing software will be located in the following folder:
<Installation Folder>\mla\v2018_11_26\apps\usb\device\bootloaders\utilities\bin\win\HIDBootloader.exe

Firmware Writing

Follow the steps below to write the firmware:

  1. Launch the writing software.
  2. Remove the extension unit from the Marcon body and insert the USB into the PC. This will boot the product in firmware writing mode.
    Once booted in firmware writing mode, the writing software will connect.
  3. Click the folder icon (Import Firmware Image) at the top left and select the pre-built firmware (.hex file) to load.
  4. The second icon from the left (Erase/Program/Verify Device) will become active. Click it to write.

This completes the firmware writing process.

After that, unplug the USB cable once, attach the extension unit to Marcon, and reinsert the USB cable. You can then play with the firmware you've written.

Firmware Collection

The firmware is publicly available on GitHub.

To download from GitHub, click "Raw" at the top right to display the raw data, then right-click to save with the extension .hex.

Original Firmware

The firmware that is written at the time of purchase.
Operates as a Direct input gamepad.

Xinput version
This version supports Xinput.
Please use this version if you are using it with POLYMEGA.

Development Diary

セガサターンのマルコンをUSB化する拡張ユニットを作りました - GEEKY Fab