● ON AIR · build your own
An ambient ticker that rotates live stocks, weather, and the time — then flips to a one-tap status sign on demand. Built on an ESP32-S3 and a 4-in-1 MAX7219 LED matrix. Configured entirely over Bluetooth.
/ what it does
An ambient rotation you set and forget, and an active sign that takes over the moment you need it.
One-tap status text — BUSY, FOCUS, ON AIR — overrides the ambient rotation, with an optional auto-clear timer.
A live MM:SS countdown from 1–99 min, capped with a random animation — fireworks, sonar, sparkle — then back to ambient.
Stock quotes from Finnhub and multi-location weather from Open-Meteo, geocoded on-device. No phone tether required.
Steady H:MM when shown alone, scrolls H:MM AM/PM when mixed in. NTP-synced, timezone-aware.
A native app: multi-device switcher, preset chip grid, and a Display tab with per-category toggles plus a master on/off.
Every write is gated on a 6-digit PIN. iOS uses the native pairing dialog; the PIN rotates on factory reset.
/ under the hood
Single-file firmware, deliberately. Here's what's holding it together.
A fetch task pinned to Core 0 pulls quotes and weather while Core 1 runs a cooperative loop() — no delay(), no jank on the display.
WiFi, API keys, tickers, locations, mode, and the active sign are all set over a documented GATT service. The CLI and the iOS app speak the same protocol.
Bonded links via passkey entry, with a fallback PIN characteristic for non-pairing clients. Five wrong tries buys a lockout.
Config survives power cycles in flash; fetched data and the active sign stay in RAM, so a reboot cleanly resumes the ambient rotation.
Type a city or ZIP and the ESP32 resolves it to coordinates itself via Open-Meteo — no companion server, the device does its own lookups and fetches.
GPIO 0 is the bootloader strap at power-on but a plain button at runtime: hold it 10 s and the matrix counts down before wiping all config and forgetting every BLE bond.
/ make your own
Two off-the-shelf modules, a custom PCB, and a 3D-printed bracket. Everything you need is in the repo.
| Part | What | |
|---|---|---|
| MCU board | Freenove ESP32-S3-WROOM (FNK0099) — onboard NeoPixel, native USB-C | Buy ↗ |
| Display | DIYables 4-in-1 MAX7219 8×8 LED matrix | Buy ↗ |
| PCB | Custom board carrying both modules — EasyEDA sources, order via JLCPCB | Files ↗ |
| Bracket | 3D-printed bracket (STL included) | STL ↗ |
| Cable | USB-C for power + flashing | any |
// then flash it
git clone https://github.com/ssayala/esp32-led-simple
cd esp32-led-simple
pio run -t upload // build & flash over USB-CFirst boot scrolls the BLE name and a 6-digit PIN on the matrix. Pair from the iOS app or the Python CLI, set your WiFi, and you're live. Full walkthrough in the Getting started guide.
No toolchain? Flash it from your browser → (Chrome/Edge, over USB).
