Bluetooth LE temperature sensor using embassy-rs. This is the result of a direct port of a very similar project using Zephyr RTOS.
This time around the language of choice is Rust and the embassy ecosystem.
The main purpose of this firmware is to interface with the MCP9808 sensor and emit Bluetooth LE advertising packets that can be collected by tempsys-scan. The MCP9808 has a sleep mode, which is used to limit power consumption.
This is the packet format for the events emitted by Tempsys.
| Manufacturer Id | Version | Counter | Voltage | Temperature |
|---|---|---|---|---|
| u16 | u8 | u8 | u16 | i16 |
- Manufacturer Id is fixed to 0xFFFF for testing purposes.
- Version of this packet format, currently 1.
- This counter is incremented every time the firmware performs a reading. It will wrap around once it spills over.
- Voltage: 16 bit LE unsigned value of the battery voltage in millivolts.
- Temperature: 16 bit LE signed value of the temperature in Celsius. You should divide by 100 to get the actual value.
Warning
If the temperature reading is equal to i16::MAX an error has occurred and
this value should be discarded.
- Download the latest release of this package.
- Download the nRF softdevice S113 from
here.
Tested with version
7.3.0.
Execute these commands using probe-rs
# Optionally erase the chip
probe-rs erase --chip nrf52840_xxAA
probe-rs download --verify --binary-format hex --chip nRF52840_xxAA s113_nrf52_7.X.X_softdevice.hex
probe-rs run --chip nrf52840_xxAA tempsys-firmware- Migrate to postcard for serialization and return a proper Result instead of
i16::MAXto denote errors.