Python & CircuitPython

It's easy to use the INA219 sensor with Python and CircuitPython, and the Adafruit CircuitPython INA219 module.  This module allows you to easily write Python code that reads the current and more 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 INA219 to your board exactly as shown on the previous pages for Arduino using an I2C interface. In addition connect some load to measure the current from in series to the sensor's Vin- and Vin+ pins as mentioned on the wiring page.

Here's an example of wiring a Feather M0 to the sensor with I2C:

  • Board 3V to sensor Vcc
  • 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

In addition connect some load to measure the current from in series to the sensor's Vin- and Vin+ pins as mentioned on the wiring page.

Here's the Raspberry Pi wired with I2C:

  • Pi 3V3 to sensor Vcc
  • Pi GND to sensor Gnd
  • Pi SCL to sensor Scl
  • Pi SDA to sensor Sda

CircuitPython Installation of INA219 Library

Next you'll need to install the Adafruit CircuitPython INA219 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.  For example the Circuit Playground Express 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 Trinket M0, Gemma M0, and Feather/Metro M0 basic you'll need to manually install the necessary libraries from the bundle:

  • adafruit_ina219.mpy
  • adafruit_bus_device

Before continuing make sure your board's lib folder or root filesystem has the adafruit_ina219.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 INA219 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-ina219

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 current and more from the board's Python REPL.  Run the following code to import the necessary modules and initialize the I2C connection with the sensor:

import board
import busio
import adafruit_ina219
i2c = busio.I2C(board.SCL, board.SDA)
sensor = adafruit_ina219.INA219(i2c)

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

  • shunt_voltage - The shunt voltage in volts.
  • bus_voltage - The bus voltage in volts.
  • current - The current in milliamps.
print("Bus Voltage:   {} V".format(ina219.bus_voltage))
print("Shunt Voltage: {} mV".format(ina219.shunt_voltage / 1000))
print("Current:       {} mA".format(ina219.current))

That's all there is to using the INA219 with CircuitPython!

Here's a full example to print the voltage and current every second.  Save this as on your board's filesystem and check the output from the serial REPL.

Full Example Code

import time

from board import SCL, SDA
import busio

import adafruit_ina219

i2c_bus = busio.I2C(SCL, SDA)

ina219 = adafruit_ina219.INA219(i2c_bus)

print("ina219 test")

while True:
    print("Bus Voltage:   {} V".format(ina219.bus_voltage))
    print("Shunt Voltage: {} mV".format(ina219.shunt_voltage / 1000))
    print("Load Voltage:  {} V".format(ina219.bus_voltage + ina219.shunt_voltage))
    print("Current:       {} mA".format(ina219.current))

This guide was first published on Oct 26, 2012. It was last updated on Sep 19, 2018. This page (Python & CircuitPython) was last updated on Aug 12, 2018.