RFID chessboard

Question

I want to make a electronic chessboard that detects the position of every piece on the chessboard. So I did some research, and one way would be to put RFID tags under every chess piece. Each tag should identify which type of piece it is (black bishop, white king, etc). One transceiver circuit and a 1-to-64 multiplexer for the whole board. Also, 64 little antennas, each one underneath each board position.

I have several questions:

1. How does the multiplexer thing work?
2. Where should I buy the materials to do this if I decide this method is the one I'm going for?
3. Are there any more efficient methods for doing this?

Answer 1

How does the multiplexer thing work?

Instead of duplicating the circuitry for all the 64 detectors, which then produce 64 output signals, somewhere in the chain of things from antenna to signal you stop duplicating the circuit. There then needs to be a way to select which output of the 64 replicated parts to feed into the remaining non-replicated circuitry. That part is called a multiplexer. You can think of it as a N-to-1 selector in this case.

Some signals are easier to multiplex than others, so you have to trade that off with the benefits of not replicating the remaining circuitry. For example, the least replication would be if you multiplex right after the coils. However, that is a low level analog signal on receiving and has significant power on transmitting. It won't be easy to do that.

Further downstream there are likely easier signals to multiplex, but the more downstream you do this, the less benefit you get of not having to replicate circuitry. Everything is a tradeof.

Where should I buy the materials to do this if I decide this method is the one I'm going for?

Off topic.

Are there any more efficient methods for doing this?

Possibly, but this question is too broad.

Answer 2

I have used a tutorial about the 16-Channel Analog Multiplexer/Demultiplexer CD74HC4067 by pmdwayhk, that helped me for the same project in question.

I put up a picture of my very provisional test setup. With that I could multiplex through 4 antennas. One side of the four coils were connected together and fed into the reader and the other 4 sides fed into the mux-board and from the SIG port also to the reader. I could read the RFID-Information on the tags.