embedded-aht20

This is a platform agnostic Rust driver the AHT20 digital humidity and temperature sensors using the embedded-hal and embedded-hal-async traits.

This driver can be used both synchronously or asynchronously. It defaults to the synchronous implementation, but you can switch to the asynchronous one by using the async feature.

The device

The AHT20 sensor is a humidity and temperature sensor, that is fully calibrated, has an excellent long-term stability, and is using an I²C interface.

Its typical application scope includes: HVAC system, dehumidifier, test and inspection equipment, consumer goods, automobiles, automatic control, data recorder, weather station, household appliances, humidity regulation, medical and other related temperature and humidity detection and control.

It has a typical accuracy of ±0.3 °C for the temperature, and of ±2 % for the relative humidity.

Here are its electrical specifications:

Documentation:

• Datasheet
• Arduino driver

Features

• Perform a measurement of temperature and relative humidity.
• Do a sofware set.
• Include a no floating-point variant for systems without fpu.

Additional features

This crate relies on the weather-utils crate. When you perform a temperature and humidity measurement, the result is a struct from the weather-utils crate, giving you the features provided by this crate for free. For example, you can immediately compute the absolute humidity value (in g/m³) from the result of Aht20::measure. If you are also using an other sensor, such as the QMP6988, to get the barometric pressure, you can also compute the altitude.

Usage

To use this driver, import what you need from this crate and an embedded-hal implementation, then instantiate the device.

use embedded_aht20::{Aht20, DEFAULT_I2C_ADDRESS};
use linux_embedded_hal as hal;

fn main() -> Result<(), embedded_aht20::Error<hal::I2CError>> {
    // Create the I2C device from the chosen embedded-hal implementation,
    // in this case linux-embedded-hal
    let mut i2c = match hal::I2cdev::new("/dev/i2c-1") {
        Err(err) => {
            eprintln!("Could not create I2C device: {}", err);
            std::process::exit(1);
        }
        Ok(i2c) => i2c,
    };
    if let Err(err) = i2c.set_slave_address(DEFAULT_I2C_ADDRESS as u16) {
        eprintln!("Could not set I2C slave address: {}", err);
        std::process::exit(1);
    }

    // Create the sensor
    let mut sensor = Aht20::new(i2c, DEFAULT_I2C_ADDRESS, hal::Delay {})?;

    // Perform a temperature and humidity measurement
    let measurement = sensor.measure()?;
    println!(
        "Temperature: {:.2} °C, Relative humidity: {:.2} %",
        measurement.temperature.celcius(),
        measurement.relative_humidity
    );
    Ok(())
}

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.

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.