Installation

Unsurprisingly, pylibftdi depends on libftdi, and installing this varies according to your operating system. Chances are that following one of the following instructions will install the required prerequisites. If not, be aware that libftdi in turn relies on libusb.

Installing pylibftdi itself is straightforward - it is a pure Python package (using ctypes for bindings), and has no dependencies outside the Python standard library for installation. Don’t expect it to work happily without libftdi installed though :-)

$ pip install pylibftdi

Depending on your environment, you may want to set up a virtual environment.

Windows

I perform only limited testing of pylibftdi on Windows, but it should work correctly provided the requirements of libftdi and libusb are correctly installed.

Recent libftdi binaries for Windows seem to be available from the picusb project on Sourceforge. Download libftdi1-1.5_devkit_x86_x64_19July2020.zip or later from that site, which includes the required drivers, or search for ‘libftdi windows’ for other options.

Mac OS X

I suggest using homebrew to install libftdi:

$ brew install libftdi

On macOS, Apple does not include a built-in FTDI driver (it was removed in macOS Monterey), but FTDI’s own VCP driver may be installed by other software and will conflict with libftdi. See the Troubleshooting section for details.

Linux

There are two steps in getting a sensible installation in Linux systems:

  1. Getting libftdi and its dependencies installed

  2. Ensuring permissions allow access to the device without requiring root privileges. Symptoms of this not being done are programs only working properly when run with sudo, giving ‘-4’ or ‘-8’ error codes in other cases.

Each of these steps will be slightly different depending on the distribution in use.

Debian (Raspberry Pi) / Ubuntu etc

On Debian-based systems (including Ubuntu, Raspberry Pi OS, etc), the runtime library package provides what pylibftdi needs:

$ sudo apt-get install libftdi1-2

The following works to give normal users access to FTDI devices without needing root permissions:

  1. Create a file /etc/udev/rules.d/99-libftdi.rules. You will need sudo access to create this file.

  2. Put the following in the file:

    SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", GROUP="dialout", MODE="0660"
SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6010", GROUP="dialout", MODE="0660"
SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6011", GROUP="dialout", MODE="0660"
SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6014", GROUP="dialout", MODE="0660"
SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6015", GROUP="dialout", MODE="0660"

The list of USB product IDs above matches the default used by pylibftdi, but some FTDI devices may use other USB PIDs. You could try removing the match on idProduct altogether, just matching on the FTDI vendor ID as follows:

SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", GROUP="dialout", MODE="0660"

Or use lsusb or similar to determine the exact values to use (or try checking dmesg output on device insertion / removal). udevadm monitor --environment is also helpful, but note that the environment ‘keys’ it gives are different to the attributes (filenames within /sys/devices/…) which the ATTRS will match. Perhaps ENV{} matches work just as well, though I’ve only tried matching on ATTRS.

Note that changed udev rules files will be picked up automatically by the udev daemon, but will only be acted upon on device actions, so unplug/plug in the device to check whether you’re latest rules iteration actually works :-)

Also note that the udev rules above assume that your user is in the ‘dialout’ group - if not, add it to your user with the following, though note that this will not apply immediately, not a full reboot may be needed on some systems:

sudo usermod -aG dialout $USER

See https://wiki.debian.org/udev for more on writing udev rules.

Arch Linux

The libftdi package (sensibly enough) provides the libftdi library:

$ sudo pacman -S libftdi

Similar udev rules to those above for Debian should be included (again in /etc/udev/rules.d/99-libftdi.rules or similar), though the GROUP directive should be changed to set the group to ‘users’:

SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", GROUP="users", MODE="0660"
SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6010", GROUP="users", MODE="0660"
(etc...)

Testing installation

Connect your device, and run the following (as a regular user):

$ python3 -m pylibftdi.examples.list_devices

If all goes well, the program should report information about each connected device. If no information is printed, but it is when run with sudo, a possibility is permissions problems - see the section under Linux above regarding udev rules.

If the above works correctly, then try the following:

$ python3 -m pylibftdi.examples.led_flash

Even without any LED connected, this should ‘work’ without any error - quit with Ctrl-C. Likely errors at this point are either permissions problems (e.g. udev rules not working), or not finding the device at all - although the earlier stage is likely to have failed if this were the case.