Learning by
building.

Each NFC sticker tag (MIFARE Classic 1K) is associated with an album or playlist stored on a MicroSD card. Tapping the tag triggers the MFRC522 reader, which communicates the tag's UID via SPI to an Elegoo Uno R3. The Uno maps that UID to an audio file and sends playback commands over UART to a DFPlayer Mini, which drives a connected speaker.

The result: a completely offline, screen-free music player where the physical sticker is the interface. Stick them to album art prints, custom cards, or wherever feels right.

Following a component-by-component testing strategy — each piece verified in isolation before integration. Currently: MFRC522 wired via SPI (MOSI, MISO, SCK, SS, RST), confirmed 3.3V logic compatibility with the Uno's 5V system.

Key technical considerations addressed: SPI pin mapping on the Uno R3, logic-level voltage safety (MFRC522 is 3.3V; direct connection to Uno's 3.3V pin is viable for most setups), and UART wiring on the DFPlayer Mini with a 1kΩ current-limiting resistor on TX.

Immediate: Complete MFRC522 SPI verification, then integrate DFPlayer Mini and test end-to-end NFC → audio playback. Build a clean enclosure — thinking wood and brushed aluminum to lean into the physical-object aesthetic.

Future features: A companion app (or web UI) to re-assign stickers without re-flashing firmware. Support for multiple sticker "modes" (album, playlist, podcast). Eventually: an LED visual layer that responds to the music — tying this into a larger audiovisual installation concept I'm developing.