drewp

Cheap usb rfid reader

Posted in hardware, rfid, rpi by Drew Perttula at 2019-04-07T11:29:47.873309-07:00

This PN532 board has better read range than my first try, which was this RC-522 board. But, the PN532 possibly uses I2C clock stretching, which makes it fail sometimes on my Raspberry Pi 3B+. The flakiness sometimes takes hours to show up, and I couldn't find a software way to reset it short of a reboot.

What seems to work better is to make it a USB board with a CP2102 usb serial chip. Now I have [raspberry pi 3B+] -> [usb serial] -> [PN532 in UART mode]. The libnfc path for it is LIBNFC_DEFAULT_DEVICE=pn532_uart:/dev/ttyUSB0.

Here's how to connect the boards right against each other:

drewp - April 11, 2019
https://planb.nicecupoftea.org/2019/03/27/an-i2c-heat-sensor-with-a-raspberry-pi-camera/ talks about doing software i2c on some gpio pins, which might have helped.
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Cheap usb rfid reader