BoulderTimer is a fullscreen countdown timer for bouldering sessions and local competitions. A Raspberry Pi 3B+ draws the clock on any HDMI TV. You start, pause and reset it from a browser on any device in the same network.
It is the plain, cheap cousin of Timeotron 3000, which counts speed-climbing runs on an LED matrix.
What I did#
I wrote all of it in Python, about 1,500 lines for the timer, display, audio and web server.
The Pi runs Raspberry Pi OS Lite with no desktop. pygame draws straight to the screen, so there is no X11 to install or break. A small Flask server passes commands from the browser to the clock. The page is at bz-clock.local, so nobody types an IP address.
Before the start there is a three-second warmup with short beeps, then a long beep. The last three seconds beep again, and a long beep ends the round. A voice warns when one minute is left.
The clock sizes itself to the real screen resolution, so the same code fits an HD or a 4K TV. After the install everything works offline.
An install script sets up the Pi. Another script copies new code to it and restarts the clock.