GoKawiilEngineer builds battery-free NFC business card with animated LEDs and onboard MCU
A hobbyist designed a PCB business card that uses an NFC chip's energy-harvesting capability to power 21 LEDs and an ATtiny412 microcontroller, all without a battery. Tapping the card against a phone triggers an LED animation, drawing power solely from the phone's NFC field via chips like the NXP NTAG I2C Plus or STMicro ST25DV-KC that can route excess harvested voltage to external components. The creator built the project in about three months as a way to learn KiCad, and has published the full design files publicly.