I am a bit confused can you draw a schematic or block diagram of what you propose.
Well I supposed I asked for it, it is not much clearer. For future reference make all wires horizontal or vertical and don't have wires going through components.Now chips IC1 to 5 why are you only using one buffer in each chip. You have four identical buffers in each chip so that should simplify things. BUT you can not common the outputs of the buffers. I think you are getting mixed up by me saying common the MISO lines. You can only do this with the signal on the readers, this is because the chip enable line on the readers makes the signal on the readers tri-state when that chip is not being addressed. Once the signal goes through a buffer you loose that tri-state and they become normal signals that you can not join together because they are outputs. You will need separate receive buffers and you need to connect them to either different input pins or you need to multiplex them into one.When drawing a schematic their is no need to show a chip with the pins in the physical order you can order them as you like as long as you number them. Also with things like the buffers you can show each buffer individually, not all four joined together to make the flow simpler. The whole point of a schematic is to show the interconnections and signal flow. This does not mean a lot of rectangles with wires flying all over the place.
That is crap. All the lines can be common apart from the SDA, that is the one you must put through the multiplexer.This is a circuit I used on a Raspberry Pi, it will also work for any 3V3 Arduino. If you have a 5V Arduino you must put a potential divider on each output pin from the Arduino to the reader. That is all the pins except Dout. And power the multiplexer with 5V.
have u try it on arduino?
do you have sourcecode to multiplexing rfid with arduino