Functions for working with the HTS221

The functionality is useful for use cases where you need complete control over the sensor or to debug the registers. If you just want to get started quickly see HTS221.Server module.

To read registers you will need to provide a HTS221.Transport.t().

{:ok, transport} = HTS221.Transport.init(HTS221.Transport.I2C, bus_name: "i2c-1")

Reading Registers

After opening the transport you can read or write registers.

{:ok, %HTS221.Temperature{} = temp} = HTS221.read_temperature(transport)

While this library provides some common helper functions to read particular registers it does not provide all the registers currently. However, the library does provide the HTS221.Register protocol and HTS221.read_register/2 that will allow you to provide support for any register.

Writing Registers

To write a register you will need to use HTS221.write_register/2.

# this will provide the default register values
ctrl_reg1 = %HTS221.CTRLReg1{}

HTS221.write_register(transport, ctrl_reg1)

Calibration

Each HTS221 is calibrated that the factory and the calibration that is stored in non-volatile memory is specific to each sensor. The calibration contains data about how to calculate the temperature and humidity and thus you will need to the calibration values to make those calculations.

This library provides functionality for reading the calibration and using it to calculate the temperature and humidity.

{:ok, %HTS221.Calibration{} = calibration} = HTS221.read_calibration(transport)

{:ok, %HTS221.Temperature{} = temp} = HTS221.read_temperature(transport)

temp_in_celsius = HTS221.calculate_temperature(temp, calibration)

the same steps are required for calculating humidity