Cal STAR

Space Technologies and Rocketry is UC Berkeley's high-power rocketry team: eighteen complete vehicles, three liquid engines, and a 27,326 ft apogee record over ten years of launches. I'm on the avionics subteam. This page is the club, the software monorepo we build it on, and what I do inside it.

Repo

github.com/calstar/STAR — public, docs at calstar.github.io/STAR

Club

stars.berkeley.edu · public wiki

Subteams

Sponsors include Boeing, Blue Origin, GM, Dassault Systèmes, Onshape, Ansys, JLCPCB, and the Space Sciences Laboratory. Applications open each fall at apply.starberkeley.org.

Everything from the firmware on a sensor board, to the ground station that records a hotfire, to the optimizer that designed the engine lives in one repository. It is a collection of mostly-independent subprojects, each with its own README, setup script, and ./dev.sh; a top-level setup.sh dispatches so editing the P&ID never forces you to build Rust and elodin-db. CI runs per-directory: the C++ DAQ integration test, PlatformIO firmware builds plus host unit tests, pytest gates and frontend builds for each design tool, a 5 MB large-file guard, and Doxygen to GitHub Pages on every push to main.

How they fit together

        design tools                          test / flight pipeline
  +------------------------+     +------------------------------------------+
  | EngineDesign/          |     | firmware/  (ESP32 boards: PT/TC/RTD/...) |
  |   optimizes geometry   |     |      |  sensor data / heartbeat          |
  |   & pressure curves    |     |      v  (lib/DAQv2-Comms wire protocol)  |
  |                        |     | daq-server/                              |
  | pid-designer/          |     |   DAQ bridge -> Elodin DB -> backend     |
  |   lays out the P&ID    |     |   -> web GUI + state machine + control   |
  | feed-twin/             |     |                                          |
  | star-openrocket/       |     |                                          |
  +------------------------+     +------------------------------------------+
         all four build on lib/stardesign (server) + lib/stardesign-ui (client)
         and mount one shared userdata volume: browse a teammate's design,
         take a copy, or share one and edit it together.

The design tools deploy together at *.starberkeley.org behind a single Google login restricted to @berkeley.edu. Caddy asks the auth service about every request before forwarding it, so the apps carry no auth code of their own, and local development, which never runs Caddy, never sees a login screen. The DAQ server is the deliberate exception: it runs natively under systemd on the test stand, because the C++ bridge, elodin-db, and the board links need the hardware.

Each avionics board is an ESP32-S3 running a small state machine: boot, self-test the ADC and sensors, wait for the server to send its configuration, then stream sensor data and exchange heartbeats. If it loses the server's heartbeat it aborts on its own. Packets are packed binary over UDP, defined once in lib/DAQv2-Comms, so firmware and server can never disagree about the wire format. On the ground the DAQ server is eleven coordinated processes:

./dev.sh --sim runs the whole pipeline against simulated boards, so the full-stack integration test needs no test stand. The predecessor of this stack, the Diablo static-fire ground control firmware, is still public at calstar/Diablo-FSW and calstar/DiabloAvionics.

• Avionics for high-power rockets (~30,000 ft apogee): custom PCBs in Altium Designer, soldered and tested under strict mass and volume limits.
• ESP32-S3 board firmware for the PT, TC, RTD, LC, and ATCOMM boards.
• The packed-binary UDP wire protocol (lib/DAQv2-Comms) both ends of the pipeline speak.
• The C++/TypeScript ground DAQ pipeline that runs liquid-engine hotfires across 13 networked boards.
• Tuned the actuator/valve board’s hotfire state machine: heartbeat timeout, abort, and connection-loss transitions.
• The mobile experience for STARProject, the team’s internal task tracker.

Board-level design credit is shared across the avionics leads; PCB sources live in the club's Altium 365 workspace rather than the public repo. My software contributions are in calstar/STAR. Tools I actually use: Altium Designer · KiCad 8 · Fusion 360 · ESP-IDF · PlatformIO · Saleae Logic 2. The rest of what I build is at /projects.