In the previous installment, I was messing with the serial library on Arduino to get it to work on the older board. The purpose was this:
Pictured is an RFID reader from SparkFun that I picked up years ago and sat in my parts box since then. This RFID reader is intended to read Mifare tags and as such predates the whole NFC thing by a year or three. The programming interface is to send commands over serial to the device such as “Authenticate sector N”, “Read sector N”, etc. I’ve connected D7 to D2 so that I could use D2 as the interrupt pin to suit my Arduino.
It appears to work, in that I can dump sectors from my yubikey and a tap-and-go credit card. The sector trailer parts look valid, and the first few bytes of sector 0 have the device ID (verified by the NFC reader on my phone). I can’t seem to read any NDEF information; whether that is due to limitations in the reader, bugs in my code, or my almost zero knowledge about how all this stuff works, I’m not sure. Sketch code is over here.
As to possible applications, for that I have no real idea either, which is probably why it sat in the parts bin all this time.