SL-814 dB Meter

A web-based interface for the Tondaj SL-814 sound level meter. Connects via USB-to-serial adapter and displays real-time decibel readings with a smooth animated VU meter visualization. Runs in Chrome or Edge only (uses Web Serial API).

Features

• Real-time dB readings with 60fps animated bar
• Peak hold indicator
• A/C weighting and Fast/Slow mode display
• Light/Dark theme
• English/Slovak language support
• No installation required — runs directly in browser

How to Run

1. Connect the SL-814 meter to your PC via USB-to-serial cable (Prolific PL2303)
2. Open SL-814 dB meter.html in Chrome or Edge
3. Click "Choose device & start" and select the COM port
4. Readings will stream automatically

Note: The Web Serial API requires Chrome or Edge. Firefox and Safari are not supported.

Driver Installation (Windows 11)

The Prolific PL2303 adapter requires legacy drivers on Windows 11. See driver/README.md for detailed instructions.

Quick steps:

1. Download drivers from theAmberLion/Prolific or from this repo SL-814-dB-meter/driver
2. Install PL2303_Prolific_v3.3.2.105.exe
3. In Device Manager, update the driver and select version 3.3.2.105

Protocol Reference

Serial protocol reverse-engineered by the sigrok project:
https://sigrok.org/wiki/Tondaj_SL-814