May be a bit crude sounding, but what about using a reed switch or hall
effect sensor undereach square. then put a round magnet under each chess piece ?
You can wire the sensors in an x/y matrix similiar to a keypad arrangements.
just expand the  the units to include each row and each column.  This will give
you the sense reporting you need. You can then have the software trach the
movement from say square  A2 to say A4 indicating the movement of a pawn


Just a thought.

Eddie Turner, kc4awz

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