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Sensirion I²C STC3X Arduino Library

This is the Sensirion STC3X library for Arduino allowing you to communicate with a sensor of the STC3X family over I²C.

<img src="images/stc3x.png" width="300px">

Click here to learn more about the Sensirion STC3X sensor family.

The measured gas mixture depends on the STC3x product and configured binary gas. Please refer to the datasheet and API documentation to get a list of supported binary gases.

Supported sensor types

Sensor nameI²C Addresses
STC31-C0x29
STC310x29

The following instructions and examples use a STC31-C.

Installation of the library

This library can be installed using the Arduino Library manager: Start the Arduino IDE and open the Library Manager via

SketchInclude LibraryManage Libraries...

Search for the Sensirion I2C STC3X library in the Filter your search... field and install it by clicking the install button.

If you cannot find it in the library manager, download the latest release as .zip file and add it to your Arduino IDE via

SketchInclude LibraryAdd .ZIP Library...

Don't forget to install the dependencies listed below the same way via library manager or Add .ZIP Library

Dependencies

Sensor wiring

Use the following pin description to connect your STC3X to the standard I²C bus of your Arduino board:

<img src="images/stc3x-pinout.png" width="300px">
PinCable ColorNameDescriptionComments
1redVDDSupply Voltage2.7V to 5.5V
2yellowSCLI2C: Serial clock input
3blackGNDGround
4greenSDAI2C: Serial data input / output

The recommended voltage is 3.3V.

Board specific wiring

You will find pinout schematics for recommended board models below:

<details><summary>Arduino Uno</summary> <p>
STC3XSTC3X PinCable ColorBoard Pin
VDD1red3.3V
SCL2yellowD19/SCL
GND3blackGND
SDA4greenD18/SDA
<img src="images/Arduino-Uno-Rev3-i2c-pinout-3.3V.png" width="600px"> </p> </details> <details><summary>Arduino Nano</summary> <p>
STC3XSTC3X PinCable ColorBoard Pin
VDD1red3.3V
SCL2yellowA5
GND3blackGND
SDA4greenA4
<img src="images/Arduino-Nano-i2c-pinout-3.3V.png" width="600px"> </p> </details> <details><summary>Arduino Micro</summary> <p>
STC3XSTC3X PinCable ColorBoard Pin
VDD1red3.3V
SCL2yellow~D3/SCL
GND3blackGND
SDA4greenD2/SDA
<img src="images/Arduino-Micro-i2c-pinout-3.3V.png" width="600px"> </p> </details> <details><summary>Arduino Mega 2560</summary> <p>
STC3XSTC3X PinCable ColorBoard Pin
VDD1red3.3V
SCL2yellowD21/SCL
GND3blackGND
SDA4greenD20/SDA
<img src="images/Arduino-Mega-2560-Rev3-i2c-pinout-3.3V.png" width="600px"> </p> </details> <details><summary>ESP32 DevKitC</summary> <p>
STC3XSTC3X PinCable ColorBoard Pin
VDD1red3V3
SCL2yellowGPIO 22
GND3blackGND
SDA4greenGPIO 21
<img src="images/esp32-devkitc-i2c-pinout-3.3V.png" width="600px"> </p> </details>

Quick Start

  1. Install the libraries and dependencies according to Installation of the library

  2. Connect the STC3X sensor to your Arduino as explained in Sensor wiring

  3. Open the exampleUsage sample project within the Arduino IDE:

    FileExamplesSensirion I2C STC3XexampleUsage

    The provided example is working with a STC31-C, I²C address 0x29. In order to use the code with another product or I²C address you need to change it in the code of examples/exampleUsage. You find the list with pre-defined addresses in src/SensirionI2CSTC3X.h.

  4. Click the Upload button in the Arduino IDE or SketchUpload

  5. When the upload process has finished, open the Serial Monitor or Serial Plotter via the Tools menu to observe the measurement values. Note that the Baud Rate in the used tool has to be set to 115200 baud.

Additional Examples

Forced Recalibration

There is a detailed explenation, see Documentation.

To run the example, open the exampleUsageFrc sample project within the Arduino IDE.

Example for mesaurement with RHT Compenstation

To run the example, open the measurementWithCompenstation sample project within the Arduino IDE.

Contributing

Contributions are welcome!

We develop and test this driver using our company internal tools (version control, continuous integration, code review etc.) and automatically synchronize the master branch with GitHub. But this doesn't mean that we don't respond to issues or don't accept pull requests on GitHub. In fact, you're very welcome to open issues or create pull requests :)

This Sensirion library uses clang-format to standardize the formatting of all our .cpp and .h files. Make sure your contributions are formatted accordingly:

The -i flag will apply the format changes to the files listed.

clang-format -i src/*.cpp src/*.h

Note that differences from this formatting will result in a failed build until they are fixed. :

License

See LICENSE.