Adafruit INA228 I2C Power Monitor

by Liz Clark

published February 07, 2025, last edited February 10, 2025

posted in Adafruit Products Arduino Compatibles CircuitPython Breakout Boards/ Batteries/Power STEMMA

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Beginner

Product guide

CircuitPython and Python

It's easy to use the INA228 with Python or CircuitPython, and the Adafruit_CircuitPython_INA228 module. This module allows you to easily write Python code to monitor high or low side power measurements.

You can use this driver 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 the monitor to your board exactly as follows. The following is the monitor wired to a Feather RP2040 using the STEMMA connector for low side monitoring:

Board STEMMA 3V to breakout VIN (red wire)
Board STEMMA GND to breakout GND (black wire)
Board STEMMA SCL to breakout SCL (yellow wire)
Board STEMMA SDA to breakout SDA (blue wire)
Breakout Vin- to GND (black wire)
Breakout VBus to highest potential voltage (red wire)
Breakout Vin+ to load's lowest potential (yellow wire)

Here is the monitor wired to a Feather RP2040 using the STEMMA connector for high side monitoring:

Board STEMMA 3V to breakout VIN (red wire)
Board STEMMA GND to breakout GND (black wire)
Board STEMMA SCL to breakout SCL (yellow wire)
Board STEMMA SDA to breakout SDA (blue wire)
Breakout Vin- to load's highest potential (yellow wire)
Breakout VBus to breakout Vin+ (red wire)
Breakout Vin+ to highest project voltage (red wire)

The following is the monitor wired to a Feather RP2040 using a solderless breadboard for low side monitoring:

Board 3.3V to breakout VIN (red wire)
Board GND to breakout GND (black wire)
Board SCL to breakout SCL (yellow wire)
Board SDA to breakout SDA (blue wire)
Breakout VIN- to GND (black wire)
Breakout VBUS to highest potential voltage (red wire)
Breakout VIN+ to load's lowest potential (yellow wire)

Here is the monitor wired to a Feather RP2040 using a solderless breadboard for high side monitoring:

Board 3.3V to breakout VIN (red wire)
Board GND to breakout GND (black wire)
Board SCL to breakout SCL (yellow wire)
Board SDA to breakout SDA (blue wire)
Breakout VIN- to load's highest potential (yellow wire)
Breakout VBUS to breakout VIN+ (red wire)
Breakout VIN+ to highest project voltage (red wire)

For high side monitoring, you can solder the VBus jumper closed on the back of the breakout to simplify your wiring.

Python Computer Wiring

Since there are 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 using the STEMMA connector for low side monitoring:

Pi 3.3V to breakout VIN (red wire)
Pi GND to breakout GND (black wire)
Pi SCL to breakout SCL (yellow wire)
Pi SDA to breakout SDA (blue wire)
Breakout VIN- to GND (black wire)
Breakout VBUS to highest potential voltage (red wire)
Breakout VIN+ to load's lowest potential (yellow wire)

Here's the wiring using the STEMMA connector for high side monitoring:

Pi 3.3V to breakout VIN (red wire)
Pi GND to breakout GND (black wire)
Pi SCL to breakout SCL (yellow wire)
Pi SDA to breakout SDA (blue wire)
Breakout Vin- to load's highest potential (yellow wire)
Breakout VBus to breakout Vin+ (red wire)
Breakout Vin+ to highest project voltage (red wire)

Here's the Raspberry Pi wired with I2C using a solderless breadboard for low side monitoring:

Pi 3.3V to breakout VIN (red wire)
Pi GND to breakout GND (black wire)
Pi SCL to breakout SCL (yellow wire)
Pi SDA to breakout SDA (blue wire)
Breakout VIN- to GND (black wire)
Breakout VBUS to highest potential voltage (red wire)
Breakout VIN+ to load's lowest potential (yellow wire)

Here's the wiring using a solderless breadboard for high side monitoring:

Pi 3.3V to breakout VIN (red wire)
Pi GND to breakout GND (black wire)
Pi SCL to breakout SCL (yellow wire)
Pi SDA to breakout SDA (blue wire)
Breakout Vin- to load's highest potential (yellow wire)
Breakout VBus to breakout Vin+ (red wire)
Breakout Vin+ to highest project voltage (red wire)

For high side monitoring, you can solder the VBus jumper closed on the back of the breakout to simplify your wiring.

Python Installation of INA228 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:

pip3 install adafruit-circuitpython-ina228

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 Usage

To use with CircuitPython, you need to first install the Adafruit_CircuitPython_INA228 library, and its dependencies, into the lib folder on your CIRCUITPY drive. Then you need to update code.py with the example script.

Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, and copy the entire lib folder and the code.py file to your CIRCUITPY drive.

Your CIRCUITPY/lib folder should contain the following folders and file:

adafruit_bus_device/
adafruit_register/
adafruit_ina228.mpy

Python Usage

Once you have the library pip3 installed on your computer, copy or download the following example to your computer, and run the following, replacing code.py with whatever you named the file:

python3 code.py

Example Code

If running CircuitPython: Once everything is saved to the CIRCUITPY drive, connect to the serial console to see the data printed out!

If running Python: The console output will appear wherever you are running Python.

Download Project Bundle

Copy Code

# SPDX-FileCopyrightText: Copyright (c) 2025 Liz Clark for Adafruit Industries
#
# SPDX-License-Identifier: MIT

import time

import board

import adafruit_ina228

i2c = board.I2C()
ina228 = adafruit_ina228.INA228(i2c)
print("Adafruit INA228 Test")

print(f"Bus conversion time: {ina228.conversion_time_bus} microseconds")
print(f"Shunt conversion time: {ina228.conversion_time_shunt} microseconds")
print(f"Samples averaged: {ina228.averaging_count}")

while True:
    print("\nCurrent Measurements:")
    print(f"Current: {ina228.current:.2f} mA")
    print(f"Bus Voltage: {ina228.voltage:.2f} V")
    print(f"Shunt Voltage: {ina228.shunt_voltage*1000:.2f} mV")
    print(f"Power: {ina228.power:.2f} mW")
    print(f"Energy: {ina228.energy:.2f} J")
    print(f"Temperature: {ina228.temperature:.2f} °C")
    time.sleep(1)

# SPDX-FileCopyrightText: Copyright (c) 2025 Liz Clark for Adafruit Industries
#
# SPDX-License-Identifier: MIT

import time

import board

import adafruit_ina228

i2c = board.I2C()
ina228 = adafruit_ina228.INA228(i2c)
print("Adafruit INA228 Test")

print(f"Bus conversion time: {ina228.conversion_time_bus} microseconds")
print(f"Shunt conversion time: {ina228.conversion_time_shunt} microseconds")
print(f"Samples averaged: {ina228.averaging_count}")

while True:
    print("\nCurrent Measurements:")
    print(f"Current: {ina228.current:.2f} mA")
    print(f"Bus Voltage: {ina228.voltage:.2f} V")
    print(f"Shunt Voltage: {ina228.shunt_voltage*1000:.2f} mV")
    print(f"Power: {ina228.power:.2f} mW")
    print(f"Energy: {ina228.energy:.2f} J")
    print(f"Temperature: {ina228.temperature:.2f} °C")
    time.sleep(1)

First, the sensor is instantiated over I2C. Then, in the loop, the measurements for current, bus voltage, shunt voltage, power, energy and temperature are printed to the serial console.