Colead SL-5868P
The Colead SL5868P is an inexpensive sound level meter with RS232 capability. It has Lp and Leq measurement modes, and can trigger alarm conditions based on a configured level.
It is rebranded under many names, but appears to generally have the SL-5868P model designation. It's available for under $100.
Hardware
- Nuvoton W78E052D 8-bit microcontroller
- Holtek HT1621B LCD driver
Photos
Protocol
TODO: serialcomm
The meter sends two measurements per second. When a new measurement is ready, the device sends 0x10. The PC responds with 0x20, which causes the device to transmit a 10-byte structure containing configuration and measurement.
Commands
| Command | Direction | Description |
|---|---|---|
| 0x10 | Device -> PC | Measurement ready |
| 0x20 | PC -> Device | Send measurement |
Data structure
| Byte | Description |
|---|---|
| 0 | ? |
| 1 | ? |
| 2 | ? |
| 3 | ? |
| 4 | ? |
| 5 | BCD-encoded dB value, most significant digit (0x0a = ignore this digit) |
| 6 | BCD-encoded dB value, second digit |
| 7 | BCD-encoded dB value, least significant digit |
| 8 | Measurement status: 0x00=invalid, 0x01=valid |
| 9 | Checksum: sum of bytes 0-8 |