It's easy to use the HUSB238 with Python or CircuitPython, and the Adafruit_CircuitPython_HUSB238 module. This module allows you to easily write Python code to control the power delivery chip.
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 breakout to your board exactly as follows. For testing, you can connect the + and - outputs from the breakout to a multimeter with alligator clips. You'll set the multimeter to read DC voltage (labeled with a "V" and one dashed and one solid line). The following is the breakout wired to a Feather RP2040 using a solderless breadboard:
- USB C PD power supply to breakout USB C port
- Board GND to breakout GND (black wire)
- Board SCL to breakout SCL (yellow wire)
- Board SDA to breakout SDA (blue wire)
- Breakout + to multimeter positive (red wire)
- Breakout - to multimeter negative (black wire)
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.
For testing, you can connect the + and - outputs from the breakout to a multimeter with alligator clips. You'll set the multimeter to read DC voltage (labeled with a "V" and one dashed and one solid line).
Here's the Raspberry Pi wired with I2C using a solderless breadboard:
- USB C PD power supply to breakout USB C port
- Pi GND to breakout GND (black wire)
- Pi SCL to breakout SCL (yellow wire)
- Pi SDA to breakout SDA (blue wire)
- Breakout + to multimeter positive (red wire)
- Breakout - to multimeter negative (black wire)
Python Installation of HUSB238 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-husb238
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_HUSB238 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_husb238.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.
# SPDX-FileCopyrightText: Copyright (c) 2023 Liz Clark for Adafruit Industries # # SPDX-License-Identifier: MIT """ Simple test for the HUSB238. Reads available voltages and then sets each available voltage. Reads the set voltage and current from the attached PD power supply. """ import time import board import adafruit_husb238 i2c = board.I2C() # Initialize HUSB238 pd = adafruit_husb238.Adafruit_HUSB238(i2c) voltages = pd.available_voltages print("The following voltages are available:") for i, volts in enumerate(voltages): print(f"{volts}V") v = 0 while True: while pd.attached: print(f"Setting to {voltages[v]}V!") pd.voltage = voltages[v] print(f"It is set to {pd.voltage}V/{pd.current}A") print() v = (v + 1) % len(voltages) time.sleep(2)
For this example, it's best to test with the output from the breakout connected to a multimeter in DC voltage mode. DC voltage mode is labeled with a V and two lines, one dashed and one solid. For information on using a multimeter, check out this guide.
In the example, the HUSB238 is instantiated over I2C. Then, the available voltages are read from the attached USB-C PD power supply. In the loop, the available voltages are set, one by one, by the HUSB238. You'll see these output on your multimeter. The voltage and current are read from the PD supply and are printed to the serial console.
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