Willard the Smart Car splits its brain across three boards: a Raspberry Pi handles high‑level Cognition, an Arduino‑compatible Elegoo board drives movement as the Reflex layer, and an ESP32 serves as the Interaction layer that injects personality. The author chose the SparkFun ESP32 Thing Plus for its USB‑C port and built‑in Qwiic connector, allowing tidy daisy‑chaining of Arduino Modulino sensors.

Three Modulino modules now give the droid eyes, expression and voice: a distance sensor acts as “social eyes,” pixel LEDs render facial cues, and a buzzer provides a “voice box.” Using granular synthesis and a sinusoidal vibrato loop, the code slides pitch from 300 Hz to 900 Hz, creating a croaky, inquisitive tone.

The droid greets a child when a hand enters a 20 cm range, then locks interaction until it passes 45 cm, preventing stutter. Future work adds vision: the Raspberry Pi will run Google Mediapipe and OpenCV to recognize faces and let the ESP32 select a personality profile for each user.