Designing a PCB businesscard seems to be the go-to for a hobbyist electronic engineers. Most people design either a passive PCB, USB HID/MSD device or battery powered LED frenzy. Uptill now I haven’t seen any cart that has a RFID, not even regular paper ones. As usual it started with a brainfart and I designed a burner PCB. Usually I try to design a perfect one which in the end needs at least two revisions to make it perfect. Now I tried a different route and designed a small pcb with solderjumpers and lot of bodge options:
The main ingredient is a nice little NFC EEPROM from NXP: NT3H1101. This is the 1K version which can be read or writen over both NFC and I2C and also has an energy harvesting mode which allows a small and powerefficient microcontroller to do some extra fancy and interacting stuff. To interact 4 buttons and a LED are added. The LED tells you in which state the microcontroller is and the buttons change the URL that is sent to the phone (or RFID reader).
After playing with the burner PCB I came with a simple but robust firmware and designed the final design. Pressing one button will alter the URL the next time the PCB is presented to the reader. Unfortunately I forgot to connect the LED to the microcontroller as I was too busy with getting the silkscreen and soldermask right. I still need to tackle the sharp and protruding components on the front, which will ruin your wallet. The back PCB art is done by printing my regular businesscard to waterslide decal and apply it to the back. The process is described here.
Note: the name and telephonenumber is blurred on purpose