ET-S48
Sound Level Meter (dBA)
A-weighted sound level over I²C
AED 129.00
Out of stockOverview
A-weighted sound level over I²C
The ET-S48 is built around the Self-contained sound level meter — firmware does A-weighting (IIR), RMS over 125ms (fast) / 1s (slow), outputs dBA / dBZ / peak over I2C. It connects over I²C slave 0x6E (firmware) (ALERT pin, SWD for updates) and is powered from VIN 3.3–5.5V, onboard LDO.
Two Qwiic / STEMMA QT connectors let you chain it with other boards without soldering, and the 2.54 mm header fits a breadboard.
Designed in Dubai by ElectroTrical — the full schematic, BOM and design notes are published below.
Good for
- Noise monitoring in offices and classrooms
- Construction-site noise logging
- Smart-city sensors
Key features
What makes it different
Function
Self-contained sound level meter: firmware does A-weighting (IIR), RMS over 125ms (fast) / 1s (slow), outputs dBA / dBZ / peak over I2C
Mic
Analog MEMS −38dBV/Pa, 65dB SNR; preamp ×23 into the STM32 12-bit ADC (oversampled to 16-bit)
Range
≈ 35–115 dBA (verify with calibrator)
Interface
I2C slave 0x6E (firmware), ALERT pin, SWD for updates
Qwiic / STEMMA QT
Two JST-SH connectors plus a 2.54 mm header — 3.3 V and 5 V hosts.
Open documentation
Schematic, BOM and layout notes published for every board.
Specifications
Technical specifications
| Function | Self-contained sound level meter: firmware does A-weighting (IIR), RMS over 125ms (fast) / 1s (slow), outputs dBA / dBZ / peak over I2C |
|---|---|
| Mic | Analog MEMS −38dBV/Pa, 65dB SNR; preamp ×23 into the STM32 12-bit ADC (oversampled to 16-bit) |
| Range | ≈ 35–115 dBA (verify with calibrator) |
| Interface | I2C slave 0x6E (firmware), ALERT pin, SWD for updates |
| Supply | VIN 3.3–5.5V, onboard LDO |
| Size | 25.4 × 17.8 mm |
|---|---|
| Mounting | 4 × M2.5 holes, 2.54 mm from each corner |
| Connectors | 2 × Qwiic / STEMMA QT (JST SH 4-pin) · 6-pin 2.54 mm header |
| Main IC | STM32G030F6P6TR (LCSC C529330) |
| Revision | Rev B |
| Libraries | ElectroTrical open firmware (STM32CubeIDE / Arduino-STM32) — must be written before launch |
|---|
| JP1 (default Closed) | Cut to turn off the LED |
|---|---|
| JP2 (default Closed) | Cut to remove the host-side I2C pull-ups |
Performance
Sound levels for reference
Pinout
Pin map and connections
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | VIN | Power | 3.3–5.5V |
| 2 | 3V3 | Power | LDO output |
| 3 | GND | Ground | Ground |
| 4 | SCL | I²C | I²C clock |
| 5 | SDA | I²C | I²C data |
| 6 | ALERT | Output | High when level > threshold, host level |
Qwiic / STEMMA QT pins: GND, VIN, SDA, SCL (same on both connectors). I²C pull-ups (10 kΩ) are on the board; cut JP2 to remove them.
Mechanical
Dimensions and what's in the box
In the box
- 1 × ET-S48 Sound Level Meter (dBA) (assembled)
- 1 × 6-pin 2.54 mm male header, unsoldered
Getting started
- Plug in a Qwiic / STEMMA QT cable, or solder the header and wire VIN, GND, SDA and SCL
- Libraries: ElectroTrical open firmware (STM32CubeIDE / Arduino-STM32) — must be written before launch
- Run an I²C scanner to confirm the address: 0x6E
Compare
Which audio board?
| Sound Level Meter (dBA) (this board)This board | ET-S47 ICS-43434 I²S MEMS Microphone | |
|---|---|---|
| What it does | A-weighted sound level over I²C | 24-bit digital microphone for ESP32 and Pi |
| Interface | I²C slave 0x6E (firmware), ALERT pin, SWD for… | Standard I2S (Philips), slave: host provides… |
| Best for | Noise monitoring in offices and classrooms | Voice and audio capture on ESP32 |
| Price | 129 AED | 22 AED |
Downloads
Documents and design files
Need a custom version of this board?
Different connector, size or sensor? We design and build custom variants.