Build Your Own
Smart Chess Board

Full Circuit

Interactive circuit diagram. Zoom and pan using the scroll wheel and left/right click. Hover on a pin to show the label. View the project on Cirkit

ESP32 + PCB Wiring

Overview of the ESP32 connected to the main PCB - showing shift register signals, sensor rows/cols, LED data, pull-up resistors and power lines.

Plastic PCB Wiring

DIY plastic PCB wiring, 3D model on MakerWorld.

Transistor Circuits - Column Drivers

PNP transistors should be used to switch 5V power to each sensor column via the shift register outputs. This prevents voltage drop and protects the shift register from overcurrent. If you don't use them, don't be surprised when the magnets aren't detected. I didn't use them for my own prototype because I just copied the original Concept-Bytes PCB 1:1, it luckily worked for me but as soon as other people started building it and having issues, that's when we realized the original PCB design is REALLY BAD !

PNP Configuration NPN Configuration

Original PCB Layout

The original Concept-Bytes PCB design, useful if you want to connect the ESP32 to it

PCB Bottom Side

Build and test the PCB, following the schematics above. This is mine, notice it doesn't use transistors nor a level shifter, but they're highly recommended for reliability.

PCB Top Side

Top view of the PCB with and without the ESP32 mounted. GND and Shift Register QA are routed on this side.

PCB top view without ESP32 PCB top view with ESP32 mounted

PCB Thickness Reference

The default board can fit PCBs up to 12mm thick or 8mm when using the LED strip/wire spacers. Mine was 9mm and I used spacers so it wouldn't fit by 1mm. If your PCB doesn't fit, scale and move the "BorderScale" object part in BambuStudio to achieve the thickness you prefer.

Cut the LED Strip

Cut the WS2812B LED strip at every 8th LED along the marked cut lines. You'll have 8 segments of 8 LEDs each (64 LEDs total)

Glue Strip End

Remove the bi-adhesive backing and glue the first LED into position: there is a notch in the plastic PCB indicating where the LED center should be placed. Start from one corner and make sure the data arrow direction is correct.

Serpentine Routing

Route the strips in a serpentine (zig-zag) pattern - each row reverses direction (critical for correct LED data signal flow). If you want to add spacers, now's the time to insert them between the strip and the board surface before pushing down on the glue.

Strip Installation Complete

Front and back views of the completed LED strip installation.

Front view Back view

With Spacers Installed

The strip will have some slack which might cause accidental ungluing, to prevent it you can add spacers. Make sure your ESP32 PCB is thin enough to fit under the board with them in place.

Front with spacers Back with spacers

Apply Glue on Sensor Holder

Put a small dab of glue where the sensor will sit.

Place the Sensor

Bend the A3144 sensor pins 90 degrees and place it on the holder as shown in the picture, pins should stick out the back.

Push Sensor into Glue

Press the sensor into the holder and glue.

Reinforce with More Glue

Add more glue around the sensor to secure it firmly, you don't want it moving around when you start soldering wires to it.

Pass GND Wires Through Guides

Thread the ground wires through the built-in wire guides on the board. These keep the wiring tidy and prevent shorts.

Move Sensor GND Over Pin

Bend the GND wires over the sensor's GND pins. This creates distance from the plastic and forces the wire to stay tight and close to the pin, making it easier to solder. Cut the sensor GND pins flush to keep things tidy.

LED Strip GND Connection

Connect the LED strip GND pads to the same ground bus.

Solder LED Strip GND

Solder GND wires to the LED strip GND pads.

Solder Sensor GND

Solder the ground wires to each sensor's GND pin.

Solder GND Wires

Continue soldering all GND connections row by row until every sensor and LED strip segment shares a common ground.

In progress Completed

Cover GND Wires

Apply tape over the ground wires to insulate them and prevent shorts with other wires.

Solder All LED Strip Wires

Solder the LED data and 5V wires between each LED strip segment following the serpentine layout.

Cover All LED Strip Wires

Insulate all LED strip connections with tape to prevent shorts.

Pass Row Wires

Thread row wires through the board as you did for the GND wires, connecting each sensor's output pin in the same row. I melted some PLA with my soldering iron over the wires to secure them in place.

Solder Row Wires

Solder each row wire to the output pin of every sensor in that row. Each row goes to a different ESP32 GPIO pin.

In progress Completed

Pass 5V Wires - Method 1

First method: route the 5V wires through the wire guides along each column. Tape is required to insulate the 5V wires from the GND/row wires.

Routing Completed

Pass 5V Wires - Method 2 (Alternative)

Alternative routing method for the 5V column wires - choose whichever you prefer. This spacer requires a thin ESP32 PCB to fit under the board, but allows easier wire routing on top of other GND/row wires, avoiding the need of tape to prevent shorts.

Cut Extra Pin Length

Trim the excess sensor pin length with flush cutters to keep things tidy and prevent shorts.

Before cutting After cutting

Solder 5V Connections

Solder the 5V wires to each sensor's VCC pin along the column. Each column wire will connect back to a transistor on the PCB (or to the shift register outputs if not using transistors)

All Wires Soldered

Two perspectives showing the full sensor wiring - GND, row & column.

Completed Plastic PCB

Back and front views of the fully assembled plastic PCB - ready to be connected to the main ESP32 PCB.

Back Front

Iron Disc Size

12×1mm iron discs - these sit under each square to spread the magnetic field from the piece's magnet, making detection possible across the whole square surface. They also keep the pieces in place.

Disc diameter (12mm) Disc holder diameter

Glue Iron Discs

Glue one iron disc centered on each of the 64 squares. Make sure they're flush against the board surface and securely attached.

Gluing Done (1) Done (64)

Glue magnets

Glue one or two neodymium magnets into the bottom of each chess piece. The magnets should be flush with the piece's base for optimal detection. Make sure to orient the magnets with the south pole facing the board! To determine which side is the south pole, simply power the board and try both sides, only 1 side will work. TIP: you can use a hairdryer to soften the PLA plastic to make inserting magnets easier

Glue Parchment Paper

Apply a sheet of parchment paper (baking paper) under each square. This acts as a light diffuser, spreading each LED's light evenly across the square ring, for a uniform glow without weird shadows.

Light Test & Final Look

Test how light shines through the rings. With no light backing the rings should not be visible.

Light backing No light backing

Apply Tape

Use double-sided tape or insulating tape on the PCB mounting area to secure it and prevent shorts against the bare metal wires.

PCB Placement

Mount the main PCB in position. Ensure it's secure and the row/column wires are oriented correctly towards their soldering pads.

Solder Rows & Columns to PCB

Solder each row wire and column wire to the correct PCB pads. Double-check against the schematic - each row wire goes to a specific GPIO pin and each column goes to a transistor output (or shift register output if not using transistors).

Overview Close-up

Demo Video