I am building a Raspberry Pi B+ powered survey device. It would use NFC scanners for multiple choice questions. It should display a question on LCD screen and the user should have his NFC tag scanned by NFC scanner corresponding to his choice.
I am planning on using SunFounder's NFC scanner for Raspberry Pi, however, if I use separate GPIO pins for separate scanners, I can only read from 3 scanners which is not enough.
According to the user manual, NFC scanner uses 5 GPIO pins + 5V + GND out 26 available like this:
- one is connected to GPIO 10 (SPIO_MOSI)
- GPIO 9 (SPIO_MISO)
- GPIO 8 (SPI_CE0)
- GPIO 17
- 5V, GND
I found no comments whatsoever which pin is used for what.
The device needs to identify NFC tag and the answer chosen (ie, scanner which read NFC tag).
Now the questions are can I reuse some (all) of the pins used to transfer NFC tag information and do I need to use some logic, for example, Charlieplexing to identify scanner?