========
PyFtdi
========
Overview
~~~~~~~~
PyFtdi_ aims at providing a user-space driver for modern FTDI_ devices,
implemented in pure Python language.
Modern FTDI_ devices include:
* FT232R (single port, clock up to 6 MHz, 3Mbps)
* FT2232D (dual port, clock up to 6 MHz)
* FT232H (single port, clock up to 30 MHz)
* FT2232H (dual port, clock up to 30 MHz)
* FT4232H (quad port, clock up to 30 MHz)
* FT230X (single port, clock up to 48 Mhz, 3Mbps)
Other FTDI_ devices could also be supported (including FT232* devices),
although these devices are not a primary goal for PyFtdi_, and therefore have
not been tested with PyFtdi_.
Primary goals
~~~~~~~~~~~~~
PyFtdi_ currently supports the following features:
* UART/Serial USB converter, up to 12Mbps (depending on the FTDI device
capability)
* Bitbang/GPIO support
* SPI master
* I2C master
* JTAG master
PyFtdi_ provides a pyserial_ compliant API, so it can be used as a drop-in
module to access USB-serial converters based on FTDI_ devices.
Requirements
~~~~~~~~~~~~
Python_ 3.5 or above is required.
PyFtdi_ relies on PyUSB_, which itself depends on one of the following native
libraries:
* libusb_, tested with 1.0.20
may still work, but are fully untested there are nowaways obsolete.
PyFtdi_ does not depend on any other native library, and only uses standard
Python modules along with PyUSB_
PyFTDI_ has been tested with PyUSB_ 1.0.0. PyUSB_ 1.0.0b1 or below is no longer
supported.
Note about previous releases
----------------------------
``open()``, ``open_mpsse()`` and ``open_bitbang`` arguments have changed in
v0.22.0, be sure to update your code or even better use the URL variants
(``open_from_url``, ``open_mpsse_from_url`` or ``open_bitbang_from_url``).
If you have no choice but using previous releases of software, such as
* Python_ (2.6+, 3.3+),
* other PyUSB_ backends such as the deprecated libusb-0.1, or openusb,
* PyUSB_ 1.0.0b1 or below,
* pyserial_ 2.6+ (previous versions of pyserial_ will NOT work)
please checkout the latest PyFTDI_ 0.1x series (0.13.3) which provides support
for these deprecated environmement, but is no longer actively maintained.
Status
~~~~~~
This project is still in beta development stage.
However, PyFtdi_ is being forked from a closed-source software implementation
that has been successfully used for over several years - including serial
@ 3Mbps, spi and jtag protocols. PyFtdi_ is developed as an open-source
solution.
Supported features
------------------
* All FTDI device ports (UART, MPSSE) can be used simultaneously.
* Several FTDI adapters can be accessed simultaneously from the same Python
runtime instance.
* Serial port, up to 12 Mbps. PyFtdi_ includes a pyserial_ emulation layer that
offers transparent access to the FTDI serial ports through a pyserial_-
compliant API. The ``serialext`` directory contains a minimal serial terminal
demonstrating the use of this extension, and a dispatcher automatically
selecting the serial backend (pyserial_, PyFtdi_), based on the serial port
name.
* SPI master. For now, SPI Mode 0 (CPOL=0, CPHA=0) is the only supported
mode. It should be easy to extend the SPI master to deal with less common
modes. PyFtdi_ can be used with pyspiflash_ module that demonstrates how to
use the FTDI SPI master with a pure-Python serial flash device driver for
several common devices.
* I2C master. For now, only 7-bit address are supported.
* JTAG is under development and is not fully supported yet.
Installation
~~~~~~~~~~~~
* Install native dependency. The actual command to install depends on your OS
and/or your distribution. Examples:
* Debian Linux
apt-get install libusb-1.0
* Homebrew macOS
brew install libusb
* Install Python dependencies
pip3 install pyusb
pip3 install pyserial
pip3 install pyftdi_
Troubleshooting
---------------
*"Error: No backend available"*
libusb native library cannot be loaded. Try helping the dynamic loader:
* On Linux: ``export LD_LIBRARY_PATH=<path>``
where ``<path>`` is the directory containing the ``libusb-1.*.so``
library file
* On macOS: ``export DYLD_LIBRARY_PATH=.../lib``
where ``<path>`` is the directory containing the ``libusb-1.*.dylib``
library file
*"Error: Access denied (insufficient permissions)"*
The system may already be using the device.
* On OS X 10.9+: starting with Mavericks, OS X ships with a native FTDI
driver that preempts access to the FTDI device.
The driver can be unloaded this way:
``sudo kextunload [-v] -bundle com.apple.driver.AppleUSBFTDI``
You may want to use an alias or a tiny script such as
``pyftdi/tools/uphy.sh``
Please note that the system automatically reloads the driver, so it may be
useful to move the kernel extension so that the system never loads it.
* This error message may also be triggered whenever the communication port is
already in use.
*"serial.serialutil.SerialException: Unable to open USB port"*
May be caused by a conflict with the FTDI virtual COM port (VCOM). Try
uninstalling the driver. On macOS, refer to this FTDI macOs
`guide <http://www.ftdichip.com/Support/Documents/AppNotes/AN_134_FTDI_Drivers_Installation_Guide_for_MAC_OSX.pdf>`_.
*Slow initialisation on OS X El Capitan*
It may take several seconds to open or enumerate FTDI devices.
If you run libusb <= v1.0.20, be sure to read the
`issue <https://github.com/libusb/libusb/commit/5e45e0741daee4fa295c6cc977edfb986c872152>`_
with OS X 10.11+.
URL Scheme
~~~~~~~~~~
There are generally two ways to open a connection to an Ftdi() object. The
first method is to use the ``open()`` methods which accept VID, PID, and serial
parameters (among others). These methods are:
* ``open()``
* ``open_mpsse()``
* ``open_bitbang()``
The second way to open a connection is to specify connection details using a
URL. The URL scheme is defined as:
``protocol://[vendor[:product[:index|:serial]]]/interface``
Where:
* protocol: always ``ftdi``
* vendor: the USB vendor ID of the manufacturer
* ex: ``ftdi`` or ``0x403``
* product: the USB product ID of the device
* ex: ``232h`` or ``0x6014``
* Supported product IDs: ``0x6001``, ``0x6010``, ``0x6011``, ``0x6014``, ``0x6015``
* Supported product aliases:
* ``232``, ``232r``, ``232h``, ``2232d``, ``2232h``, ``4232h``, ``230x``
* ``ft`` prefix for all aliases is also accepted, as for example ``ft232h``
* serial: the serial number as a string
* index: an integer (not particularly useful, as it depends on the enumeration
order on the USB buses)
* interface: the interface of FTDI device, starting from 1
* ex: ``1`` for 232\*, ``1`` or ``2`` for 2232\*, ``1``-``4`` for 4232\* devices
All parameters but the interface are optional, PyFtdi tries to find the best
match. Therefore, if you have a single FTDI device connected to your system,
``ftdi:///1`` should be enough.
You can also ask PyFtdi to enumerate all the compatible devices with the
special ``ftdi:///?`` syntax.
URLs can be used with the same methods as above by appending ``_from_url`` to
the method name such as:
* ``open_from_url()``
* ``open_mpsse_from_url()``
* ``open_bitbang_from_url()``
Development
~~~~~~~~~~~
PyFtdi_ is developed on macOS platforms (64-bit kernel), and is validated on a
regular basis on Linux hosts.
As it contains no native code, it should work on any PyUSB_ and libusb_
supported platforms. However, Ms Windows is a seamless source of issues and is
not supported. Your mileage may vary.
Examples
~~~~~~~~
See pyftdi_/tests directory for GPIO examples.
See pyspiflash_ module for SPI examples.
.. include:: serialext/README.rst
.. _PyFtdi: https://www.github.com/eblot/
.. _FTDI: http://www.ftdichip.com/
.. _PyUSB: https://walac.github.io/pyusb/
.. _Python: https://www.python.org/
.. _pyserial: https://pythonhosted.org/pyserial/
.. _libftdi: https://www.intra2net.com/en/developer/libftdi/
.. _pyspiflash: https://github.com/eblot/pyspiflash/
.. _libusb: http://www.libusb.info/
.. _macos_guide: http://www.ftdichip.com/Support/Documents/AppNotes/AN_134_FTDI_Drivers_Installation_Guide_for_MAC_OSX.pdf
