arduino, week 32: the traffic light is real

The kids’ track had a plan and no built hardware. Now it has built hardware.

The traffic light works. Three LEDs, breadboarded and flashed on the real board. It’s the opening project because it is the shortest path from “wires in a bag” to “a thing that visibly does something,” and that distance is the whole game when the audience is eight.

Five programs, one circuit. Rather than a project per lesson, tutorial 02 ships five interchangeable programs that all run on the same wiring — so the build happens once and the payoff repeats. One is a seven-pattern light show. One is calm_light: a single slow drift, no events, nothing to react to. I added it as an afterthought and it’s the one I keep running.

The toolchain question is closed: arduino-cli, not PlatformIO. Written down so it stops getting relitigated every time I open the repo.

Small thing I’m pleased about: I dumped the board’s flash before reflashing it. That is a habit I acquired the expensive way and it costs thirty seconds.

Also this week: the tutorials are now generated from shared sources in both Russian and English with a kids mode, rather than maintained as parallel documents. The vendored kit docs were swapped to the starter kit actually sitting on the desk instead of the one I’d guessed at, which is the sort of error that only shows up when a child asks where a part is. Two ESP32S boards and a second components kit joined the inventory, with their pin gotchas written down before they bite. And the thermometer project moved off a manual nohup onto a proper user service, and now keeps its readings in SQLite with a history view.