It's easy to use the LPS33HW or LPS35HW sensors with Python and CircuitPython, and the Adafruit CircuitPython LPS35HW module.  This module allows you to easily write Python code that reads the pressure and temperature and will work with either 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 LPS35HW or LPS33HW to your board for an I2C connection, exactly  as shown below.  Here's an example of wiring a Feather M4 to the sensor with I2C:

  • Board 3V to sensor VIN (red wire)
  • Board GND to sensor GND (black wire)
  • Board SCL to sensor SCL (yellow wire)
  • Board SDA to sensor SDA (blue wire)

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 SDI

CircuitPython Installation of LPS35HW Library

Next you'll need to install the Adafruit CircuitPython LPS35HW 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_lps35hw.mpy
  • adafruit_bus_device
  • adafruit_register

You can also download the adafruit_lps35hw.mpy from its releases page on Github.

Before continuing make sure your board's lib folder or root filesystem has the adafruit_lps35hw.mpy, adafruit_bus_device, and adafruit_register files and folders copied over.

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

Python Installation of LPS35HW 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-lps35hw

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 & Python Usage

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

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

import time
import board
import busio
import adafruit_lps35hw

i2c = busio.I2C(board.SCL, board.SDA)
lps35hw = adafruit_lps35hw.LPS35HW(i2c)

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

  • pressure - The barometric pressure in hPa.
  • temperature - The temperature in degrees C.

For example to print the pressure and temperature values:

print("Pressure: %.2f hPa" % lps35hw.pressure)
print("Temperature: %.2f C"% lps35hw.temperature)

For more details, check out the library documentation.

That's all there is to using the LPS33HW/LPS35HW sensor with CircuitPython!

Full Example Code

# SPDX-FileCopyrightText: 2019 Bryan Siepert, written for Adafruit Industries
# SPDX-License-Identifier: Unlicense
import time
import board
import adafruit_lps35hw

i2c = board.I2C()  # uses board.SCL and board.SDA
# i2c = board.STEMMA_I2C()  # For using the built-in STEMMA QT connector on a microcontroller
lps = adafruit_lps35hw.LPS35HW(i2c)

while True:
    print("Pressure: %.2f hPa" % lps.pressure)
    print("Temperature: %.2f C" % lps.temperature)

This guide was first published on Jun 11, 2019. It was last updated on Apr 20, 2024.

This page (Python and CircuitPython) was last updated on Apr 20, 2024.

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