Wearable LED horns. ESP32-S3 firmware driving a WS2812B strip, controlled over BLE from a phone.
| Board | LilyGO T-Energy S3 (ESP32-S3-WROOM, 18650 holder, USB-C) |
| LED data | IO4 → WS2812B strip, 60 LEDs |
| Battery sense | IO3, 1:2 divider (wired on-board, nothing to solder) |
| Mic | none yet — see Audio below |
Charging is handled entirely by the board’s charge IC. Plug in USB-C and it charges; there is no firmware involved.
Use a protected 18650 if you can. The firmware cuts out at 3200mV and deep sleeps, which covers the ESP32 — but the LED strip draws ~0.5–1mA per pixel even while showing black, straight off the cell, and no amount of firmware stops that. On an unprotected cell, pull the battery when you’re done rather than trusting the cutoff to hold overnight.
pio run -t upload # build + flash (auto-detects the port)
pio device monitor # serial, 115200
./test/run.sh # native tests, no hardware needed
If upload can’t find the board: hold BOOT, tap RST, release BOOT, retry.
web/index.html is the controller — a single self-contained page using Web
Bluetooth. That needs a browser which supports the API and a secure context:
Chrome/Edge on desktop, or Bluefy on iOS. Safari and Firefox don’t support
Web Bluetooth at all, and file:// won’t work anywhere.
On the phone, load this in Bluefy:
Served by GitHub Pages off main, so deploying is just a push. HTTPS is
enforced, and plain HTTP 301s up — which matters, because Web Bluetooth fails
silently on an insecure origin rather than telling you why.
On desktop, serve it locally (localhost counts as a secure context, so no
certificate needed):
cd web && python3 -m http.server 8000 # then http://localhost:8000
There is no LAN equivalent for the phone. Bluefy requires HTTPS, so
http://<laptop-ip>:8000 is rejected — the hosted URL is the only phone route.
Hit Connect and pick Kwynumbra. Exposed over BLE: effect, brightness, three colors, BPM, and battery percent (standard Battery Service, so a plain BLE scanner shows it too).
A service worker caches the page, so it works with no signal — but only after one successful online load. Open it on WiFi and add it to the home screen before heading anywhere without service. Verify by killing WiFi and cellular and reopening it.
Hosting is irrelevant offline; the service worker is the whole story. It’s network-first, so an online load always gets the latest push and a cold offline launch that was never cached gets nothing.
Note that colors, effects, BPM and brightness all travel over BLE — none of that needs the page to be updated. Only UI changes require a fresh load.
GitHub Pages, main at root, custom domain horns.kwyn.io (a CNAME to
kwyn.github.io in DigitalOcean DNS, TTL 300).
The custom domain on the project repo is doing real work. Without it, project
pages inherit the kwyn.github.io user-site domain and 301 to www.kwyn.io,
which points at an unrelated DigitalOcean host — so the plain
kwyn.github.io/kwynumbra-horns/ path does not serve this. Don’t remove the
custom domain expecting to fall back to it.
Pages also gets the content types right, which a raw-file CDN may not: a service
worker served as text/plain refuses to register.
rainbow, chase, bass pulse, spectrum. The last two are sound-reactive
and currently sit dark — see below.
There is no microphone on the T-Energy S3. sampleAudio() feeds silence, so the
FFT runs on zeros and the two sound-reactive effects produce nothing. The band
analysis in audio.cpp is intact and still calibrated; attaching a mic means
rewriting sampleAudio() and nothing else.
Likely part: INMP441 I2S MEMS mic on a long shielded lead, mic at the horns and the board at the battery pack.