Python & CircuitPython

It's easy to use the SHT31-D sensor with Python and CircuitPython, and the Adafruit CircuitPython SHT31D module.  This module allows you to easily write Python code that reads the humidity and temperature from the sensor.

You can use this sensor with any CircuitPython microcontroller board or with a computer that has GPIO and Python thanks to Adafruit_Blinka, our CircuitPython-for-Python compatibility library.

CircuitPython Microcontroller Wiring

First wire up a SHT31-D to your board exactly as shown on the previous pages for Arduino using an I2C connection.  Here's an example of wiring a Feather M0 to the sensor with I2C:

  • Board 3V to sensor VIN
  • Board GND to sensor GND
  • Board SCL to sensor SCL
  • Board SDA to sensor SDA

Python Computer Wiring

Since there's dozens of Linux computers/boards you can use we will show wiring for Raspberry Pi. For other platforms, please visit the guide for CircuitPython on Linux to see whether your platform is supported

Here's the Raspberry Pi wired with I2C:

  • Pi 3V3 to sensor VIN
  • Pi GND to sensor GND
  • Pi SCL to sensor SCK
  • Pi SDA to sensor SDA

CircuitPython Installation of SHT31D Library

Next you'll need to install the Adafruit CircuitPython SHT31D library on your CircuitPython board.  

First make sure you are running the latest version of Adafruit CircuitPython for your board.

Next you'll need to install the necessary libraries to use the hardware--carefully follow the steps to find and install these libraries from Adafruit's CircuitPython library bundle.  Our introduction guide has a great page on how to install the library bundle for both express and non-express boards.

Remember for non-express boards like the, you'll need to manually install the necessary libraries from the bundle:

  • adafruit_sht31d.mpy
  • adafruit_bus_device

Before continuing make sure your board's lib folder or root filesystem has the adafruit_sht31d.mpy, and adafruit_bus_device files and folders copied over.

Next connect to the board's serial REPL so you are at the CircuitPython >>> prompt.

Python Installation of SHT31D Library

You'll need to install the Adafruit_Blinka library that provides the CircuitPython support in Python. This may also require enabling I2C on your platform and verifying you are running Python 3. Since each platform is a little different, and Linux changes often, please visit the CircuitPython on Linux guide to get your computer ready!

Once that's done, from your command line run the following command:

  • sudo pip3 install adafruit-circuitpython-sht31d

If your default Python is version 3 you may need to run 'pip' instead. Just make sure you aren't trying to use CircuitPython on Python 2.x, it isn't supported!

CircuitPython and Python Usage

To demonstrate the usage of the sensor we'll initialize it and read the humidity and temperature from the board's Python REPL.

Run the following code to import the necessary modules and initialize the I2C connection with the sensor:

Download: file
import board
import busio
import adafruit_sht31d
i2c = busio.I2C(board.SCL, board.SDA)
sensor = adafruit_sht31d.SHT31D(i2c)

Now you're ready to read values from the sensor using any of these properties:

  • relative_humidity - The relative humidity measured by the sensor, this is a value from 0-100%.
  • temperature - The temperature measured by the sensor, a value in degrees Celsius.
Download: file
print('Humidity: {0}%'.format(sensor.relative_humidity))
print('Temperature: {0}C'.format(sensor.temperature))

That's all there is to using the SHT31D with Python and CircuitPython!

Below is a complete example that measures the sensor readings and prints them every two seconds.  Save this as code.py on your board and open the REPL to see the output.

import time
import board
import busio
import adafruit_sht31d

# Create library object using our Bus I2C port
i2c = busio.I2C(board.SCL, board.SDA)
sensor = adafruit_sht31d.SHT31D(i2c)

loopcount = 0
while True:
    print("\nTemperature: %0.1f C" % sensor.temperature)
    print("Humidity: %0.1f %%" % sensor.relative_humidity)
    loopcount += 1
    time.sleep(2)
    # every 10 passes turn on the heater for 1 second
    if loopcount == 10:
        loopcount = 0
        sensor.heater = True
        print("Sensor Heater status =", sensor.heater)
        time.sleep(1)
        sensor.heater = False
        print("Sensor Heater status =", sensor.heater)
This guide was first published on Dec 08, 2015. It was last updated on Dec 08, 2015. This page (Python & CircuitPython) was last updated on Apr 20, 2019.