Reflex Game – ECE 315 | Grace O. Zongo

Overview

Multi-sheet PCB designed in Altium for a microcontroller-based reflex game built around the Seeed Studio XIAO RP2350. The board drives a chain of 12 addressable LEDs as the visual stimulus, uses a piezo buzzer for audio feedback, and integrates regulated 3.3 V power and voltage supervision. ECE 315 Intro Microprocessor Lab, UW–Madison, Spring 2026.

XIAO RP2350 12-LED chain Altium multi-sheet 5 V → 3.3 V LDO Watchdog supervisor

Subsystems

Serial LED Array

12 addressable LEDs daisy-chained on a single MCU data line, each with its own decoupling cap.

Power

TLV1117LV33 LDO regulates the 5 V input down to a clean 3.3 V rail, with test points for bring-up.

Buzzer Driver

Piezo buzzer driven by a low-side NMOS, with a gate pulldown and a Schottky flyback diode.

Reset & Voltage Supervisor

MCP131X-2X monitors the 3.3 V rail (2.93 V threshold) with watchdog input, manual reset, and an indicator LED.

Schematics & PCB

Serial LED array schematic — Serial LED array: 12 daisy-chained addressable LEDs

Altium PCB layout: LEDs arranged in a ring around the UW–Madison crest

Assembled reflex-game PCB — Assembled board: XIAO RP2350, 12 RGB LEDs, button, buzzer

Demo

Quick demo of the assembled board running the reflex game.

What I Learned

Multi-sheet hierarchical schematic capture in Altium.
Embedded support circuitry around a digital MCU: decoupling, low-side switching, flyback protection.
Brown-out and watchdog supervision for reliability beyond the MCU's internal POR.
End-to-end PCB workflow: schematic → DRC → layout → bring-up → firmware demo.

Reflex Game – ECE 315 PCB Design Lab