Last night I successfully modified my RFID Arduino demonstration code to use the MFRC522 chip, by way of the RFID-RC522 module which was included with my CrowPi. Thanks, CrowPi!
The whole point of all of this exploration is for possible use in #badgelife, and the MFRC522 is a sea change from the commercial RFID reader in my last post. I’m not saying interfacing the Arduino with commercial readers isn’t useful, there are probably a number of people out there interested in DIY physical access control at a DIY-friendly price point. In fact, I found an electromagnetic cabinet lock for $6 from China!
But now that that point has been made, we’re on to exploring other creative uses.
- Most importantly, the MFRC522 reads HF (13.56MHz) MIFARE tags rather than LF (125KHz) tags. This changes the game a little bit. It allows us to scan hotel room keys, which from my explorations are ALL HF tags nowadays, and the vast majority are MIFARE.
- LF reader chips are more expensive and less available — generally…
- Due to the size of the wavelength (125KHz LF wavelength is ~2400m, while 13.56MHz HF wavelength is more along the lines of 22m), it seems like it’s WAY easier to design a PCB-printed antenna for HF than LF.