The schematics are drawn in three separate pages. You can download .pdf versions of the schematics. The schematics are drawn using the SPLAN tool of Abacom sPlan 8.0, ELECTRONIC-SOFTWARE-SHOP. The original schematics files can be received on request.
ICode RFID reader schematics (.pdf)
I have chosen the CLRC632 RFID reader. It is an older IC, bulky and more expensive, but well documented. Modern redesigns could also use other IC’s that support the ISO/IEC 15693 protocol.
In this schematic, you see a standard configuration, however with non-symmetrical driving of the antennas. The tuning is done by experiments. The schematic also shows a 5V to 24V DC converter, needed for the antenna switches.
The Scrabble board is controlled by software on an Arduino Pro Micro module. This module is compact, and features an integrated USB connection. the schematic shows an optional Flash memory IC (not implemented currently) and a connection for a DGT3000 electronic chess clock (not implemented currently).
Each row and each column of the board has a RFID antenna structure underneath it. These 30 antennas are multiplexed by use of PIN diode switches.
Each rack (in the current tournament version only 2) contains an antenna, which can identify which tiles are on the rack. The antennas are switched by the same mechanism as the board antennas.