WilliamWong

I designed the tractive-system low-voltage harness (120 sealed contacts, twisted-pair CAN), validated the shutdown circuit across 50 simulated fault conditions with the AIR opening in under 10ms, sized the precharge resistor to limit inrush to 8A into the 400µF DC-link, and logged pack voltage, phase current, and brake pressure over CAN at 100Hz.

Built around TI's TPS63070 single-inductor buck-boost, regulating anywhere from 3V to 16V input down (or up) to a steady 5V, with a TI LM66200 ideal-diode controller in front for reverse-polarity protection instead of the usual Schottky-diode voltage drop, and a status LED wired straight off the regulator's power-good pin.

An ESP32-S3 brain, four TB6612FNG motor drivers, and just enough plumbing to keep the whole thing from flooding my desk.

Breaks out a u-blox ZED-F9P onto a carrier board with UART, SPI, and I2C headers, a coin-cell-backed RTC for faster fixes on power-up, and a DSEL jumper to flip the module between SPI and UART. Onboard LEDs track power, PPS timing pulses, RTK fix status, and the geofence output, with SAFE and INT lines broken out for whatever needs to react to them. Still working out exactly how precise "precise" turns out to be.

A TB6612FNG breakout for driving a 12V DC motor forward, reverse, and everywhere in between, across two independent channels.

Negotiates up through the PD voltage ladder to 20V, then holds it steady out to a barrel jack for whatever needs feeding.

Seven degrees of freedom driven by eight TD-8120MG servos off a custom PWM driver board built on Adafruit's design, with an Arduino Uno R4 as the brain and Google MediaPipe doing the actual hand-tracking that tells it where to reach.

My USC capstone project: CPRPal sits on the chest during compressions and paces you with its LED ring at the AHA-recommended 100 to 120 compressions per minute.

A desktop air quality monitor shaped like a flower, built around a ScioSense ENS161 (eTVOC, eCO2, and its own onboard 1-5 AQI-UBA rating) and an ENS210 for temperature and humidity. A 28BYJ-48 stepper sweeps a needle across five positions matching the sensor's AQI-UBA output, an RGB LED fades green to red with it, and the board hosts its own Wi-Fi dashboard with live charts, 7-day on-device history, and CSV export, no app or cloud involved. Two PCB generations exist: a shield that plugs onto an ESP32-S3 dev board, and a from-scratch board built around a bare ESP32-H2 module for a much smaller footprint.

A two-board stack sized to sit directly behind the motor it drives, joined face-to-face through a Molex board-to-board connector. The MCU board runs an STM32F4 through a timer-driven commutation loop, reading absolute rotor position off an AS5048A magnetic encoder (14-bit, no back-EMF guesswork at standstill) and motion data off an onboard ISM330DHCX IMU, with an SK6805 RGB ring reporting status at a glance. The power board does the muscle work: a TMC6300 integrated gate driver/bridge switches the three phases directly, three INA240 amplifiers close the current loop, four sense networks watch bus and phase voltage, and a TCAN1462 CAN FD transceiver lets several controllers daisy-chain off one bus. USB-C and a J-Link SWD header handle bring-up.

A USB-C powered hotplate sized for a single cup of tea, closed-loop controlled to within about 2°C. An STM32F103C8T6 reads a thermistor bonded under a 3.75Ω spiral coil etched directly into the board copper (no separate heating element), and PWMs two low-side AO3400A MOSFETs to hold it there, with a second thermistor watching the driver FETs for thermal headroom. A ten-segment WS2812B bar doubles as a 0-90°C dial in 10-degree steps, nudged up or down by two buttons, and the board exposes both SWD and UART headers with BOOT0/Reset buttons for field reflashing without opening a case.