Sensirion SHT4x Driver for Embedded HAL

A platform agnostic device driver for the Sensirion SHT4x temperature and humidity sensor family. It is based on embedded-hal traits and works in no_std environments.

In theory, it supports all of the sensor family's devices but has only been tested with the SHT40-AD1B so far.

Features

• Blocking operation

• Supports all commands specified in the datasheet

• Explicitly borrows DelayMs for command execution so that it could be shared (among multiple sensors)

• Could be instantiated with the alternative I2C address for the SHT40-BD1B

• Uses fixed-point arithmetics for converting raw sensor data into measurements in SI units

  • Based on I16F16 from the fixed crate
  • Allows conversion to floating-point values, if needed
  • Convenience methods for fixed-point conversions to milli degree Celsius or milli percent relative humidity which are commonly used by drivers for other humidity and temperature sensors from Sensirion

• Optional support for defmt

Example

use sht4x::Sht4x;
// Device-specific use declarations.

let mut delay = // Device-specific initialization of delay.
let i2c = // Device-specific initialization of I2C peripheral.
let mut sht40 = Sht4x::new(i2c);

let serial = sht40.serial_number(&mut delay);
defmt::info!("serial number: {}", serial);

let measurement = sht40.measure(Precision::Low, &mut delay);
defmt::info!("measurement: {}", &measurement);

if let Ok(measurement) = measurement {
    // Convert temperature measurand into different formats for further
    // processing.
    let int: i32 = measurement.temperature_milli_celsius();
    let fixed: I16F16 = measurement.temperature_celsius();
    let float: f32 = measurement.temperature_celsius().to_num();
}

embedded-hal-async support

This crate has optional support for the embedded-hal-async crate, which provides async versions of the I2c and DelayNs traits. Async support is an off-by-default optional feature, so that projects which aren't using embedded-hal-async can avoid the additional dependency.

To use this crate with embedded-hal-async, enable the embedded-hal-async feature flag in your Cargo.toml:

sht4x = { version = "0.2", features = ["embedded-hal-async"] }

Once the embedded-hal-async feature is enabled, construct an instance of the Sht4xAsync struct, providing types implementing the embedded_hal_async::i2c::I2c and embedded_hal_async::delay::DelayNs traits. The Sht4xAsync struct is identical to the Sht4x struct, except that its methods are async fns.

Related Work

sensor-temp-humidity-sht40 is another driver for this sensor family.

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 discretion.

Contribution

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.