SHT4x package

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1 Introduction

The SHT4x software package provides basic functionality for using the temperature and humidity sensor sht4x, as well as an optional software averaging filter. This article introduces the basic features of the software package, as well as testing commands using Finsh/MSH.

The basic functionality is mainly determined by the sht4x sensor, which measures temperature and humidity within the input voltage range of 1.8v-3.3v. The measurement range and accuracy are shown in the table below:

Feature	Range	Accuracy
Temperature	-40℃ - 125℃	±0.3℃
Humidity	0% - 100%	±3%

1.1 Directory Structure

Name	Description
sht4x.h	Header file for using the sensor
sht4x.c	Source code for using the sensor
SConscript	Default build script for RT-Thread
README.md	Package usage instructions
sht4x_datasheet.pdf	Official data sheet

1.2 License

The SHT4x software package is licensed under Apache-2.0. See the LICENSE file for details.

1.3 Dependencies

Depends on the RT-Thread I2C device driver framework.

2 Getting the Software Package

To use the sht4x software package, select it in the RT-Thread package manager. The specific path is:

RT-Thread online packages
    peripheral libraries and drivers  --->
        [*] sht4x: digital humidity and temperature sensor sht4x driver library  --->                                            
            Version (latest)  --->

The configuration instructions for each feature are as follows:

• sht4x: digital humidity and temperature sensor sht4x driver library: Select to use the sht4x software package.
• Version: Configure the software package version. The default is the latest version.

Then allow the RT-Thread package manager to update automatically, or use the pkgs --update command to update the package to the BSP.

3 Using the sht4x Software Package

After obtaining the sht4x software package as described above, you can use the sensor sht4x and test it using the API and Finsh/MSH commands provided in the following sections.

3.1 API

3.1.1 Initialization

sht4x_device_t sht4x_init(const char *i2c_bus_name)

Automatically initialize the corresponding sht4x device based on the bus name. The specific parameters and return information are described in the following table:

Parameter	Description
i2c_bus_name	Name of the I2C device
Returns	Description
!= NULL	Returns the sht4x device object
= NULL	The search fails

3.1.2 Deinitialization

void sht4x_deinit(sht4x_device_t dev)

If the device is no longer in use, deinitialization will reclaim the relevant resources of the sht4x device. The specific parameter is described in the table below:

Parameter	Description
dev	sht4x device object

3.1.3 Read Serial Number

rt_uint32_t sht4x_read_serial(sht4x_device_t dev);

Reads the serial number of the sht4x sensor and returns the serial number as an rt_uint32_t. The specific parameters and return information are described in the following table:

Parameter	Description
dev	sht4x device object
Returns	Description
!= 0	SHT4 serial number
= 0	Failed to read

3.1.4 Read Temperature

float sht4x_read_temperature(sht4x_device_t dev)

Reads the temperature measurement value from the sht4x sensor and returns the temperature value as a float. The specific parameters and return information are described in the following table:

Parameter	Description
dev	sht4x device object
Returns	Description
!= 0.0	Measured temperature value
= 0.0	Measurement failed

3.1.5 Read Humidity

float sht4x_read_humidity(sht4x_device_t dev)

Reads the humidity measurement value from the sht4x sensor and returns the humidity value as a float. The specific parameters and return information are described in the following table:

Parameter	Description
dev	sht4x device object
Returns	Description
!= 0.0	Measured humidity value
= 0.0	Measurement failed

3.2 Finsh/MSH Testing Commands

The sht4x software package provides a variety of testing commands, which can be used by enabling the Finsh/MSH feature in RT-Thread. These commands are very useful for applications development and debugging based on sht4x as they accurately read the temperature and humidity measured by the sensor. The complete list of commands can be viewed by entering sht4x.

msh />sht4x
Usage:
sht4x probe <dev_name>   - probe sensor by given name
sht4x read               - read sensor sht4x data
msh />

3.2.1 Detecting the Sensor on a Specified I2C Bus

When using the sht4x command for the first time, simply enter sht4x probe <dev_name>, where <dev_name> is the specified I2C bus, such as i2c0. If the sensor is present, no error message will be displayed. If the sensor is not found on the bus, a prompt will be displayed indicating that the corresponding I2C device could not be found. The following is an example log:

msh />sht4x probe i2c1   # Successful detection, no error message.
msh />
msh />sht4x probe i2c88  # Detection failed, prompt for not finding the corresponding I2C device.
[E/sht4x] can't find sht4x device on 'i2c88'
msh />

3.2.2 Reading Data

After successful detection, entering sht4x read can obtain the temperature and humidity, including the prompt information. The following is an example log:

msh />sht4x read
read sht4x sensor humidity   : 54.7 %
read sht4x sensor temperature: 27.3 ℃
msh />

4 Notes

None.

5 Contact Information

• Maintainer: flyingcys
• Homepage: https://github.com/RT-Thread-packages/peripherals/sensors/sht4x