Unsatisfied with the present options for chess computers and preferring the feel of a real board and pieces, [Max Dobres] decided that his best option would be to build his own.
Light and dark wood veneer on 8mm MDF board created a board that was thin enough for adding LEDs to display moves and for the 10mm x 1mm neodymium magnets in the pieces to trip the reed switches under each space. The LEDs were wired in a matrix and connected to an Arduino Uno by a MAX7219 LED driver, while the reed switches were connected via a Centipede card. [Dobres] notes that you’ll want to test that the reed switches are positioned correctly — otherwise they might not detect the pieces!
A small LCD screen and four buttons also connect to the Arduino for configuring options a number of options, computer difficulty, and play styles, while a Raspberry Pi acts as the main computer.
The Raspberry Pi is using ChessBoard 2.05 as a rule set with consideration for special moves (such as en passant and castling). It’s currently unsupported but used with permission by its creator, John Eriksson. The chess program Stockfish is the actual engine; be sure to adjust the skill of the AI, as it defaults to an ELO of 2600! Unfortunately, it’s a rather finicky program, only running on Python 2.7. If that doesn’t appeal to you, [Dobres] has provided a nice list of other options to help you with your own build.
He has recently updated his design and done away with the need for the Arduino in the process which — especially if you use the Pi Zero — drops the cost of this project significantly. That should leave you with enough room in your budget to build a robot to make the moves for you!
[via Max Dobres]