I think more than half of those bracelets actually work. libnfc sucks badly btw (no non-blocking reads that don't have terrible failure modes) so I had to make a new node.js nfc library that uses constant polling:

  https://github.com/Juul/node-nfc

It works fine but... meh I'm not impressed with the solution.

There's another cheaper and potentially better solution. These things + an arduino:

  http://www.ebay.com/itm/RFID-RC522-RF-IC-Card-Sensor-Arduino-module-with-2-tags-MFRC522-DC-3-3V-/321777701478?_trksid=p2141725.m3641.l6368

  http://www.aliexpress.com/item/10pcs-lot-MFRC-522-RC522-RFID-RF-IC-card-inductive-module-MFRC522/32246552121.html

There's already an arduino library for it:

  http://playground.arduino.cc/Learning/MFRC522 

The Beagle Bone Black has 6 serial ports so we can use the single USB port for the magnet stripe card reader and eliminate the need for a USB hub, saving a few more dollars per door.

I'll get an order of 10 pack of 3.3v arduinos and a 10 pack of MFRC522s approved and ordered so we can try it out.

--

marc/juul