Developing pylibftdi

How do I checkout and use the latest development version?

pylibftdi is currently developed on GitHub, though started out as a Mercurial repository on There may still be references to old bitbucket issues in the docs.

pylibftdi is developed using poetry, and a Dockerfile plus Makefile make use development tasks straightforward. In any case, start with a local clone of the repository:

$ git clone
$ cd pylibftdi

There are then two main approaches, though pick and mix the different elements to suit:

poetry and docker If make and docker are available in your environment, the easiest way to do development may be to simply run make shell. This creates an Ubuntu-based docker environment with libftdi, poetry, and other requirements pre-installed, and drops into a shell where the current pylibftdi code is installed.

make on its own will run through all the unittests and linting available for pylibftdi, and is a useful check to make sure things haven’t been broken.

The downside of running in a docker container is that USB support to actual FTDI devices may be lacking…

editable install with pip This assumes that the venv and pip packages are installed; on some (e.g. Ubuntu) Linux environments, these may need installing as OS packages. Once installed, perform an ‘editable’ install as follows:

.../pylibftdi$ python3 -m venv env
.../pylibftdi$ source env/bin/activate
(env) .../pylibftdi$ python3 -m pip install -e .

Note this also creates a virtual environment within the project directory; see here

How do I run the tests?

From the root directory of a cloned pylibftdi repository, run the following:

(env) .../pylibftdi$ python3 -m unittest discover
Ran 37 tests in 0.038s


Note that other test runners (such as pytest) will also run the tests and may be easier to extend.

How can I determine and select the underlying libftdi library?

Since pylibftdi 0.12, the Driver exposes libftdi_version() and libusb_version() methods, which return a tuple whose first three entries correspond to major, minor, and micro versions of the libftdi driver being used.

Note there are two major versions of libftdi - libftdi1 can coexist with the earlier 0.x versions - it is now possible to select which library to load when instantiating the Driver. Note on at least Ubuntu Linux, the libftdi1 OS package actually refers to libftdi 0.20 (or similar), whereas libftdi1-2 refers to the more recent 1.x release (currently 1.5):

Python 3.10.6 (main, May 29 2023, 11:10:38) [GCC 11.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from pylibftdi import Driver
>>> Driver().libftdi_version()
libftdi_version(major=1, minor=5, micro=0, version_str='1.5', snapshot_str='unknown')
>>> Driver("ftdi1").libftdi_version()
libftdi_version(major=1, minor=5, micro=0, version_str='1.5', snapshot_str='unknown')
>>> Driver("ftdi").libftdi_version()
libftdi_version(major=0, minor=0, micro=0, version_str='< 1.0 - no ftdi_get_library_version()', snapshot_str='unknown')

If both are installed, pylibftdi prefers libftdi1 (e.g. libftdi 1.5) over libftdi (e.g. 0.20). Since different OSs require different parameters to be given to find a library, the default search list given to ctypes.util.find_library is defined by the Driver._lib_search attribute, and this may be updated as appropriate. By default it is as follows:

_lib_search = {
    "libftdi": ["ftdi1", "libftdi1", "ftdi", "libftdi"],
    "libusb": ["usb-1.0", "libusb-1.0"],

This covers Windows (which requires the ‘lib’ prefix), Linux (which requires its absence), and Mac OS X, which is happy with either.