libscd's Introduction

Lib SCD

LibSCD is s Rust driver implementation for SCD30, SCD40 and SCD41 sensors using the embedded-hal and embedded-hal-async interfaces.

Usage

Add the crate as a dependency in Cargo.toml and select the required features:

[dependencies.libscd]
version = "0.3"
features = ["defmt", "sync", "scd40"]

Then we can start consuming data from SCD40 using blocking I2C communication:

#[embassy_executor::main]
async fn main(_spawner: Spawner) {
    let p = embassy_stm32::init(Default::default());

    let i2c = I2c::new(
        p.I2C2,
        p.PB10,
        p.PB3,
        Irqs,
        NoDma,
        NoDma,
        Hertz(100_000),
        Default::default(),
    );

    let mut scd = Scd40::new(i2c, Delay);

    // When re-programming, the controller will be restarted,
    // but not the sensor. We try to stop it in order to
    // prevent the rest of the commands failing.
    _ = scd.stop_periodic_measurement();

    info!("Sensor serial number: {:?}", scd.serial_number());
    if let Err(e) = scd.start_periodic_measurement() {
        defmt::panic!("Failed to start periodic measurement: {:?}", e);
    }

    loop {
        if scd.data_ready().unwrap() {
            let m = scd.read_measurement().unwrap();
            info!("CO2: {}\nHumidity: {}\nTemperature: {}", m.co2, m.humidity, m.temperature)
        }

        Delay.delay_ms(1000)
    }
}

Crate Feature Flags

The support for each sensor and sync/async mode is controlled by a feature:

Feature	Description
sync	Enables the blocking driver implementation for the selected sensors
async	Enables the async driver implementation for the selected sensors
scd30	Enables the driver for the SCD30 sensor
scd40	Enables the driver for the SCD40 sensor
scd41	Enables the driver for the SCD41 sensor
defmt	Derive `defmt::Format` for the error type