moca-hcho: Bluetooth 5 BLE formaldehyde/temperature/humidity sensor beacon

moca-hcho is a simple Bluetooth Low Energy sensor beacon that uses a Sensirion SFA30 Formaldehyde Sensor Module to sense formaldehyde/temperature/humidity. This information is measured and sent periodically using Bluetooth BLE advertisements, which can be received by any Bluetooth 4.0+ device within range.

Overview:

• Enclosure: Hammond 1551V4WH vented sensor enclosure (wall-mountable)
• Sensor: Sensirion SFA30 Formaldehyde sensor module
• Microcontroller: Fanstel BT832 Bluetooth module with Nordic nRF52832
• Power supply: external +5V power supply
• Firmware (less than 1 kLOC) is written in Rust using the Embassy embedded async/await framework
• Data is sent periodically using Bluetooth BLE advertisements that are very simple to send and receive
• Not FCC/Bluetooth/etc certified/qualified but a "best effort" -style approach is used by using qualified BT832 module with integrated antenna + qualified Nordic S112 SoftDevice Bluetooth stack.

Potential future improvements

• Tidy up the code...currently the code is very crude and could use a lot of polish and some tests should be written
• Improve environmental coupling of the sensor. The vented enclosure works fine, but SFA30 Design-In Guide suggests even better environmental coupling options
• Add encryption. Unencrypted advertisements can be read or spoofed by anyone
• Re-evaluate the feasibility of using a battery

License

Hardware is licensed under Creative Commons Attribution 4.0 International.

Firmware is licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.