Home on John Hu

Making myself design a PCB for the comma.ai Challenge in under 24 Hrs

Mon, 12 Oct 2026 22:00:00 -0400

KiCad Result

After taking a slight fork in the road, I decided to return once again to pcb work, something I'm not fully competent in (yet). Coincidentally, comma.ai released a challenge so I decided to test my boundaries and hopefully figure out what I need to work on.

If you don’t know them, (pull up a browser now), comma.ai is a pioneering ai and self-driving company run by George Hotz, whom is also known for various “hacks”. They’ve made Openpilot, a L2 operational self driving software that is a really nice open-source version of the things that other automotive manufacturers keep behind closed doors.

About

Mon, 12 Oct 2026 00:00:00 +0000

Hi! I’m John Hu, a third year Electrical Engineering student @ Duke with strong interests in EVs, power electronics, and analog circuit design. I currently act as the club president for Duke Hyperloop, where I lead, organize, and work with a team of students to make a concept Hyperloop system.

Projects

Scara Robot Arm

Designed and built a small-scale SCARA robot arm with a 5:1 reduction.

Shoulder: NEMA 17 stepper with a GT2 timing belt
Z-axis: lead screw and a second NEMA 17
Arm: pancake NEMA 17
Controls: Arduino Uno and a CNC shield
Modeled in Fusion 360, printed in PLA, iterated on tolerances

Miniature Cycloidal Drive

Designed and built a small-scale cycloidal drive using Fusion 360, PLA prints, and AliExpress ball bearings. The goal is a compact, high-ratio gearbox for robotics without relying on off-the-shelf planetary stages. Bench testing (torque and backlash) is still in progress.

Home bench setup

Mon, 12 Oct 2026 00:00:00 +0000

Current home bench: Digilent logic analyzer, Analog Discovery (1st edition), PPS, analog ICs, ESPs, and various microcontrollers.

Resume

Mon, 12 Oct 2026 00:00:00 +0000

SCARA robot arm

Sun, 11 Oct 2026 00:00:00 +0000

Small-scale SCARA robot arm with a 5:1 reduction. Shoulder on a NEMA 17 + GT2 belt, Z on a lead screw, arm on a pancake NEMA 17, Arduino Uno + CNC shield.

Miniature cycloidal drive

Sat, 10 Oct 2026 00:00:00 +0000

CAD for a small-scale cycloidal drive modeled in Fusion 360, meant to be printed in PLA with AliExpress ball bearings.

Building a BT macropad with the nRF52840Plus

Thu, 24 Sep 2026 22:00:00 -0400

I was interested in working with BT and NFC so what better way to experiment than to make a small keyboard. In the last iteration of my adventure with keyboards, I routed a ATMEGA328P by myself with no status LEDS, way to debug anything besides tracing with a multimeter so I resolved to create a working circuit board this time with some more proper documentation.

SCARA CAD

Sun, 20 Sep 2026 00:00:00 +0000

Fusion 360 model of the SCARA arm (v0).

SCARA section view

Fri, 18 Sep 2026 00:00:00 +0000

Section view of the SCARA CAD, showing the reduction and joint stackup.

SCARA notes

Tue, 15 Sep 2026 00:00:00 +0000

Paper sketches for the SCARA arm before CAD.