Can You Baby? — Baby Replay
An IMU toy: a child moves freely for 5 seconds, a parent replays it, and a similarity score appears — built in one day at the TOYTHON physical-AI hackathon.
Overview
Two NUCODE NU-40 DK boards (nRF52840) each carry an LSM6DS3TR-C IMU and an SSD1306 OLED, run identical firmware, and settle their roles by runtime pairing; if pairing fails the toy drops to solo play, so a lost link never kills the game. The first scorer used DTW and was thrown out after the PC harness scored unrelated random signals at 85% and a reversed replay at 88%; it was rewritten around two channels — intensity (gravity-removed acceleration) and posture (gravity direction) — with ±0.8 s timing and ±25% speed tolerance and chance-level subtraction. It makes no claim about developmental assessment or educational effect.
My Work
- ▸nRF52 I2C traps (zero-length transfers dropped, hangs on silent devices) — bit-bang probe
- ▸1200-baud touch remote DFU · two-node E2E tester · remote-machine flash scripts
- ▸9-slide deck in the official 15-seconds-per-slide format + demo video guide
Features
- Solo: hand the toy over / Duo: the recording crosses over BLE and is replayed
- OLED guidance screens · rest-baseline calibration · battery-safe serial guard
- Web host simulator — on-screen buttons, number keys, phone shake (DeviceMotion)
Highlights
- 17-scenario scoring test — faithful replays (81–99) and different moves (0–49) never meet
- Firmware with zero external libraries · Web Bluetooth host with no build step
- Toy runs without the host, host runs without the toy (simulator) — by design
Timeline
Tech Stack
</>nRF52840 · IMU · BLE · Web Bluetooth · one-day build