I recently got a NFC implant (Yey, I'm a cyborg) and became very curious about the possibilities of this technology and noticed how many other services rely on it (transportation, credit cards, door access and so on) and since the phone NFC reader are absolute crap in terms of range when it comes to a NFC the size of a rice grain under skin I decided to build a tool to explore and develop other prototypes based on these tags. Kind of like a multi-meter but for NFC.
Looking at several boards capable to read and access the memory of NFC/RFID the PN532 seemed the most mature to start with. Trying to match it with the Feather Bluefruit that has 3v3 voltage I opted for the breakout board rather than the shield version that has 5v logic.
The features that I want to develop with the prototype are:
- Read NFC tags and display their type and UUID values on the display (Done)
- Access the memory side of NFCs (WIP)
- Provide simple notifications via RGB led of the state of the device & Buzzer (WIP)
- Implement storing the read data to the SD card that is present behind the display (WIP)
Lessons learned the hard way during this iteration :)
- the breakout board of the PN532 works at 3v3 logic while the shield versions works at 5v
- the PN532 antenna present on the breakout board has to be 0.7-10 mm further away from other electronic components or battery since it messed with the magnetic field and the range of reading decreases dramatically. Initially I wanted a slimmer case but because of this I had to compromise with another 5mm just so the implant in my hand was read easily. Also to get better reception I did a grove on the back of the device exposing the antenna.