smartmeter-lora

Sends data from a smart power meter to homeassistant via LoRa

implements listen-before-send to prevent interference with LoRaWAN or other devices.
the current config uses SF7BW250 and sends every 60s which is reasonably above the 1% duty-cycle from Germanys regulations
encrypts data using ChaCha20-Poly1305

Requirements

rustup: so you can install the nightly version required by this project
cbindgen: The CLI, for generating C bindings to the SML library
rust-src for the currently used toolchain. E.g. rustup component add rust-src --toolchain nightly-2022-07-01-x86_64-unknown-linux-gnu
poppler: Provides pdftotext which is used to convert the SML specification to code
Zephyr RTOS dependencies
Currently, the build system builds the rust part for thumbv6m-none-eabi but it should be easy to extend if more platforms are needed

Very useful for development but maybe a little expensive and physically large.

Seemed like a good idea at first but is a VERY BAD choice and only kept for reference of how to use this board in zephyr.

doesn't have a cryptographically secure RNG(Random Number Generator). My implementation uses an insecure way to turn the temperature sensor into entropy.
it's support in zephyr is pretty bad(no USB, no power management, consumes 6mA in idle)
power circuitry is excluded from the schematics
official documentation

openssl rand -out key.bin 32
objcopy --change-addresses 0xf8000 -I binary -O ihex key.bin key.hex

west flash -r openocd -d build-send --skip-rebuild --hex-file key.hex

lora2mqtt --port /dev/ttyACM0 --baud-rate 115200 --key /path/to/key.bin --mqtt-uri "tcp://127.0.0.1:1883"