TommyB builds split DIY Steam Controller that beats Valve to market

If you are tired of waiting for the mythical Steam Controller 2 to materialize, you are not alone. While rumors tease a 2026 release, hardware maker TommyB took matters into his own hands by designing and open-sourcing the OpenSplitDeck. This unique, split-half DIY controller features dual trackpads, Hall Effect joysticks, and an ergonomic form factor that splits down the middle while maintaining single-dongle communication.

This guide outlines how to assemble your own OpenSplitDeck from scratch. It is a highly rewarding project for makers who love a soldering challenge and want premium, custom input accuracy that off-the-shelf gamepads cannot match.

Tools and Materials Needed

Before heating up your soldering iron, gather the following essential materials:

• Microcontrollers: Two Seeed Studio XIAO nRF52840 Sense boards (featuring built-in battery charging circuits).
• Skins and Cases: A modified Steam Deck mod case (cut to size) and 3D printed ergonomic shells printed in PETG for flexibility.
• PCBs and Trackpads: Custom OpenSplitDeck PCBs and custom 6x6 grid capacitive trackpads.
• Components: Hall Effect joysticks (like GuliKit), original Steam Deck bumpers/triggers, and two Linear Resonating Actuators (LRAs) for premium haptics.
• Power: Two safety-rated Lithium-ion batteries (sourced from Adafruit) and physical sliding power switches.
• Assembly Tools: Soldering iron, leaded solder, hot air gun, Kapton tape, hot glue gun, and ribbon cables (FPCs).

Step-by-Step Assembly Instructions

1. Prep and Solder the MCUs

Begin by securing the Seeed Studio XIAO nRF52840 Sense microcontrollers to your custom PCBs. This board uses castellated holes, allowing you to solder them directly to the surface without through-holes. Put down Kapton tape over pre-soldered components to prevent accidental desoldering. Solder a single pad first, check your alignment, and then flow solder through the remaining edges.

2. Flash the Firmware

Connect the microcontroller to your PC via USB-C. Double-click the tiny physical reset button on the board to force it into bootloader mode. The device will mount as an external flash drive. Drag and drop the compiled UF2 firmware file (available on the OpenSplitDeck GitHub) directly onto the drive. The board will reboot automatically, illuminated by a solid red status LED.

3. Assemble the Trackpads

Insert the FPC ribbon cables into the custom trackpads. Mount the 3D-printed PETG springs to the back. Since these trackpads mount upside down inside the chassis, apply hot glue to secure the assembly to the frame. Hot glue provides excellent shock absorption and is easily peelable if you need to disassemble the controller later.

4. Wire the Batteries, Switches, and Haptics

Solder the battery connector leads (red to positive, black to negative) to the PCB. Splice the red positive wire to install a physical slide switch. Because Hall Effect sticks constantly draw power in standby mode, this switch is mandatory to prevent battery drain. Apply a layer of "safety hot glue" over the battery terminals to insulate them and prevent accidental tears. Position the LRA vibration motors adjacent to the trackpad frames for localized haptic feedback.

5. Final Shell Enclosure

Align the custom PCBs inside your modified Steam Deck mod case. Mount the bumper clips, triggers, and thumbsticks. Use the internal magnets to pull the split halves together smoothly. Leave the designated access hole open on the outer shell so you can press the MCU reset button for future firmware updates.

Troubleshooting and Expert Tips

• Trackpad Unresponsiveness: If your trackpad fails to register on boot, inspect the ultra-fine solder pads on the interface chip. Reflow the edges with a fine-tip soldering iron to fix dry joints.
• Battery Safety: Avoid cheap, unbranded Lithium-ion cells from untrusted marketplaces. Stick to certified cells with integrated protection circuits to avoid fire hazards.
• Ergonomics: Utilize the open-source files to 3D print custom middle spacers. Adding a slight angle dramatically reduces wrist strain during prolonged couch sessions.

A New Era of Input Freedom

Once assembled, you will have a high-performance, split-hand gaming powerhouse. Testing the controller in physics-heavy games like Skate demonstrates extreme precision; its 6x6 electrode grid reads full analog ranges, translating to over a thousand points of granularity per axis. You now own a truly modular controller that splits to fit your posture, defying the rigid limits of conventional gamepads.