Sensirion I2C SCD4x Driver

A platform-agnostic no_std Rust driver for the Sensirion SCD4x CO2 sensor family (SCD40/SCD41), built on embedded-hal traits. Based on embedded-i2c-scd4x and sgpc3-rs.

Sensirion SCD4x

The SCD4x is a miniature CO2, temperature, and relative humidity sensor using photoacoustic NDIR sensing.

Further information: Datasheet SCD4x

Features

• Full SCD4x command set (periodic & single-shot measurements, calibration, configuration)
• SCD41-specific commands behind the scd41 feature flag (single-shot, power down/wake up)
• Async support via the embedded-hal-async feature
• Optional thiserror integration for std environments
• Optional defmt support for embedded logging
• Blocking and non-blocking measurement modes

Usage

Add to your Cargo.toml:

[dependencies]
scd4x = "0.5"

# For SCD41-specific features (single-shot, power management):
# scd4x = { version = "0.5", features = ["scd41"] }

# For async support:
# scd4x = { version = "0.5", features = ["embedded-hal-async"] }

Full Examples

• Linux / Raspberry Pi — blocking driver with linux-embedded-hal
• ESP32-C3 Embassy — async driver with esp-hal and Embassy

CLI Utility

Run the built-in CLI to read serial number and measurements (Linux only):

cargo run --features="util"

License

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.

Contributing

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.