Stepper Motor Control Box

My second internship at Teradyne's Nextest division, and this time I designed the stepper motor control box entirely on my own. The goal was a lightweight, precise motor controller — I chose Arduino for the brains and built the control logic from scratch in code I wrote myself.

The operator controls motor speed and direction via a potentiometer, which maps to a percentage of one full revolution — giving highly precise, repeatable positioning. The LCD screen displays live step count and revolution percentage so there's always clear feedback. Directional control is bidirectional: CW and CCW buttons give the operator full command.

The pandemic sent me home partway through prototyping — the late-night desk shot below shows exactly that: stepper motor, Arduino, breadboard, LCD, and potentiometer wired up at home to keep development moving.

Features:

• Potentiometer speed control — maps to % of one full revolution
• Bidirectional CW / CCW control
• LCD displays step count and revolution percentage
• Custom wire harnesses and extension cables
• Arduino firmware written from scratch

The HTR Motor Controller I originally designed with a fellow intern in 2019 needed to cross the finish line as a fully orderable, production-ready part. That meant turning rough draft assembly notes into official release documentation — complete with a BOM, parts list, wiring schematic, and application/operation guide. I owned that process end to end and got it done.

By the end of the summer, the HTR Motor Controller had everything needed to be ordered, assembled, and operated by someone who had never seen it before.

• Larger wire, cable, and tubing management
• Wire harnesses and connector assembly
• Wiring schematics and diagrams
• Fuse replacement and electrical maintenance
• Oscilloscope practice