Python & CircuitPython

It's easy to use the TLD493D with CircuitPython and the Adafruit CircuitPython TLV493D module.  This module allows you to easily write Python code that reads the three-dimensional magnetic field measurements.

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

CircuitPython Microcontroller Wiring

Wiring the TLV493D is easy, since it only requires power and two wires for an I2C connection. Additionally, the STEMMA QT connectors give you additional solderless options for wiring:

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

CircuitPython Installation of the TLV493D Library

You'll need to install the Adafruit CircuitPython TLV394D 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 CircuitPython starter guide has a great page on how to install the library bundle.

For non-express boards like the Trinket M0 or Gemma M0, you'll need to manually install the necessary libraries from the bundle:

  • adafruit_tlv493d.mpy
  • adafruit_bus_device

Before continuing make sure your board's lib folder or root filesystem has the adafruit_tlv493d.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 TLV493D 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-tlv493d

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 magnetic measurements from the board's Python REPL.

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

Now you're ready to read the magnetic values from the sensor using the property provided by the library. 

Here is an example showing how to print the magnetic values:

You can find more details about what the library allows by reading the library documentation.

That's it! Using the TLD493D 3-axis magnetometer with CircuitPython makes it easy to get started.

Example Code

import time
import board
import busio
import adafruit_tlv493d

i2c = busio.I2C(board.SCL, board.SDA)
tlv = adafruit_tlv493d.TLV493D(i2c)

while True:
    print("X: %s, Y: %s, Z: %s mT"%tlv.magnetic)
    time.sleep(1)
This guide was first published on Sep 11, 2019. It was last updated on Sep 11, 2019. This page (Python & CircuitPython) was last updated on Sep 19, 2019.