Compatible with ChessConnect (optional, premium feature with a free trial):

Build guide: [https://joojoooo.github.io/OpenChess/](https://joojoooo.github.io/OpenChess/)

The original PCB is difficult to source and has several design flaws:

• Connects the 74HC595 pin 13 OE' to 5V, disabling it
• Even if you fix OE', it often still WON'T WORK with 3.3V input signals! You need a level-shifter or the HCT version
• The HE sensors draw more current from the shift-register than it is rated for
• Damages your 3.3V MCU by wiring GPIO input pins to 5V sensor outputs

So I decided to build my own without a PCB: I bought all the required components individually from AliExpress for around 20€ and designed a “plastic PCB” to keep everything in place.

The board was also re-designed from the ground up, improving on the original in several key ways:

• 💡 Consistent brightness and color Each white square now has a dark backing and each dark square has a white backing, ensuring even, same color illumination. The ring is -0.4mm less thick, which makes it more bright and visible in a well lit room. A black mask blocks all light bleed. The LED is more distant from the board and the sensor is raised above the LED, this additional distance eliminates internal shadows
• 🎨 Reduced filament changes from 18 down to just 6 so it's more easily printable without AMS by doing manual filament changes (the black grid in the original model caused many changes and it's useless, the PCB alone blocks light between adjacent squares)
• ⬛⬜ Larger squares Fully utilizes the 256×256 plate area (+2mm width and height for each square)
• 🔌 USB-C port: Dedicated USB-C female connector cutout moved to the side so the USB-C wire is not in the way of a player

Software got new features and HUGE improvements (had to rewrite almost everything)

If you need help building or have any question or suggestion: click here to join the Discord server

This is NOT an easy project, proceed only if you know what you're doing, building it takes skill, patience and time: took me multiple days, several hours a day (~20h total), just to assemble and solder things together + countless hours troubleshooting and designing 3D models and source code.