What is the best way to multiplex 64 coils?

Question

I'm trying to make a digital chessboard. The design consists of 64 coils, one under each square. A microcontroller's PWM sweeps the frequency over a given range, such as 50 kHz to 350 kHz. The signal is amplified and sent to the coil. Each chess piece has an LC pair with a unique resonant frequency. When the coil's frequency matches the resonant frequency of the LC circuit, the microcontroller should be able to detect a voltage peak in the coil.

My question is: what is the best way to multiplex the coils? Should I use an electronic switch and activate them one at a time? Or should I activate all of them and use a multiplexer to get one output? If my design is "flawed," I'm also open to your suggestions.

Answer 1

The essence of the DGT suggestion from BitLauncher in comments is that it uses 8 file-wise transmit coils, and 8 rank-wise receive coils, so half of the multiplexing is already done by the geometry of the situation. Now you have only 1:8 mux and demux to do electronically.

The mux/demux operations are also uni-directional, transmitter to the transmit coils, receive coils to the receiver, rather than bidirectional multiplexing to the 64 per-square coils.

Of course with 8 parallel receivers, you need not have a receive demux, and could get a significant reduction in the time it takes to read the board.