If you want to use released versions of pyjoulescope, Install from PyPI. It’s quick and easy! If you want unrelease pyjoulescope software or you want to develop pyjoulescope, see Install from Source.

Install Python

You will need to install Python 3.8+ x64 for your platform, if it is not already on your system.


Download the latest Python release for Windows. If in doubt, select the “Windows x86-64 executable installer”. Install Python and allow it to update your path. Open a Command Prompt and type:

> python -VV
Python 3.9.4 (tags/v3.9.4:1f2e308, Apr  6 2021, 13:40:21) [MSC v.1928 64 bit (AMD64)]

Note that Windows usually installs python 3 as python.exe. This documentation often uses the executable “python3”.


The easiest way to install Python on macOS is through Homebrew. Follow the instructions to install brew, then type:

$ brew install python3 libusb
$ python3 -VV


Use your package manager to install python. On Debian-based systems, including Ubuntu, use apt:

$ sudo apt install python3-dev python3-pip libusb-1.0
$ python3 -VV

The user must have sufficient permissions to access Joulescopes. Many linux systems, including Debian, Ubuntu, and Raspberry Pi OS, use udev. We include a udev script in the repository to give permissions to all users. To install it:

$ wget
$ sudo cp 99-joulescope.rules /etc/udev/rules.d/
$ sudo udevadm control --reload-rules

Install from PyPI

PyPI is the “Python Package Index” which distributes most python packages. To install this python package from PyPI using pip (or pipenv):

pip3 install -U joulescope

That’s it! The extra “-U” will upgrade to the latest version, just in case.

The joulescope package requires Python 3.6+ and 64-bit Python. If your system does not meet these requirements, then the installation will fail with an error message.


If you get an error showing “CERTIFICATE_VERIFY_FAILED”, your corporate IT policy is likely blocking the pypi SSL certificate. You have several options:

  1. Contact your IT department to correct the problem.

  2. Ignore the SSL validation (slight security risk):

    pip3 install --trusted-host --trusted-host -U joulescope

For more discussion, see StackOverflow <>.

Install from Source

The pyjoulescope package repository is open-source on GitHub. You can clone the repository:

git clone

You can also download the tarbal (Linux, macOS):

curl -Ol

or the ZIP file (Windows):

Change directory into the extracted file. Install the developer dependencies:

pip3 install -U -e .[dev]

If you plan on using pyjoulescope, you should install it:

pip3 install -U .

Using virtualenv

Although not required, the developers recommend using [virtualenv]( to minimize any dependency conflicts with different python applications.

First install virtualenv:

pip3 install -U virtualenv

And then create a new virtual environment:

virtualenv ~/venv/joulescope

You need to activate the virtual environment whenever you start a new terminal.

On POSIX (Linux, Mac OS X with homebrew):

source ~/venv/joulescope/bin/activate

On Windows:

virtualenv c:\venv\joulescope
source c:\venv\joulescope\Scripts\activate

Developing Joulescope

If you plan on developing pyjoulescope, you probably want to run directly from the source code directory. First, install the dependencies:

pip3 install -U -r requirements.txt

You can then build the native modules and adjust your PYTHONPATH so that python finds the joulescope package.

For Linux and macOS:

python build_ext --inplace
export PYTHONPATH=`cwd`

For Windows:

python build_ext --inplace