# Pico Environment Sensor

This firmware, written in Rust using [embassy-rs](https://github.com/embassy-rs/embassy), is designed for the [Raspberry Pi Pico 2 W](https://www.raspberrypi.com/documentation/microcontrollers/pico-series.html#pico2w-technical-specification) platform using the RP2350 microcontroller. Its application is an environment-sensing device which can measure CO2 concentration in the atmosphere, ambient temperature and humidity. 

The effects of increased CO2 concentration on cognitive function become increasingly pronounced at CO2 concentrations exceeding 1000 ppm. There's a fantastic [YouTube video](https://www.youtube.com/watch?v=1Nh_vxpycEA) by Kurtis Baute and Tom Scott which you can watch for a short summary. Open your window right now!

## Building

### Prerequisites

- Rust compiler & cargo package manager: https://www.rust-lang.org/
- RPi Pico SDK: https://github.com/raspberrypi/pico-sdk
- RPi picotool: https://github.com/raspberrypi/picotool
- ARM bare metal compiler toolchain
    - `arm-none-eabi-gcc` (& `arm-none-eabi-newlib`) on Arch Linux, your system may have different package names
- The ARMv8 or RISC-V Rust toolchain:
  - ARMv8: `rustup target add thumbv8m.main-none-eabihf`
  - RISC-V: `rustup target add riscv32imac-unknown-none-elf`

### Environment configuration

This build system assumes the environment variables: `PICO_BOARD`, `PICO_PLATFORM` & `PICO_SDK_PATH` are set. `picotool` should also be available in the `PATH`.

The [env-vars.sh](./scripts/env-vars.sh) script sets these values to `pico2_w`, `rp2350-arm-s` and my personal Pico SDK path, respectively. The environment variable definitions in this file can be set with `source ./scripts/env-vars.sh`.

### Compiling & running

- `cargo build` (or `cargo build --release`)

If you wish to run the binary on your Pico (connected in BOOTSEL mode):

- `cargo run` (or `cargo run --release`)