pylibftdi / README.rst

pylibftdi

pylibftdi is a minimal Pythonic interface to FTDI devices using libftdi.

Features:
  • Supports Python 2 and Python 3
  • Supports parallel and serial devices
  • Support for multiple devices
  • File-like interface wherever appropriate
  • Cross-platform
Limitations:
  • Currently only one port per device is used; I've not tested with dual port devices yet.
  • The API might change prior to reaching a 1.0 release.

Usage

The primary interface is the Device class in the pylibftdi package; this gives serial access on relevant FTDI devices (e.g. the UM232R), providing a file-like interface (read, write). Baudrate is controlled with the baudrate property.

If a Device instance is created with mode='t' (text mode) then read() and write() can use the given encoding (defaulting to latin-1). This doesn't make a lot of difference on Python 2 (and can be omitted), but allows easier integration with passing unicode strings between devices in Python 3.

Multiple devices are supported by passing the desired device serial number (as a string) in the device_id parameter - this is the first parameter in both Device() and BitBangDevice() constructors. Alternatively the device 'description' can be given, and an attempt will be made to match this if matching by serial number fails.

Examples

>>> from pylibftdi import Device
>>>
>>> with Device(mode='t') as dev:
...     dev.baudrate = 115200
...     dev.write('Hello World')

The pylibftdi.BitBangDevice wrapper provides access to the parallel IO mode of operation through the port and direction properties. These provide an 8 bit IO port including all the relevant bit operations to make things simple.

>>> from pylibftdi import BitBangDevice
>>>
>>> with BitBangDevice('FTE00P4L') as bb:
...     bb.direction = 0x0F  # four LSB are output(1), four MSB are input(0)
...     bb.port |= 2         # set bit 1
...     bb.port &= 0xFE      # clear bit 0

There is support for a number of external devices and protocols, including interfacing with HD44780 LCDs using the 4-bit interface.

History & Motivation

This package is the result of various bits of work using FTDI's devices, primarily for controlling external devices. Some of this is documented on the codedstructure blog, codedstructure.blogspot.com

At least two other open-source Python FTDI wrappers exist, and each of these may be best for some projects.

  • ftd2xx - ctypes binding to FTDI's own D2XX driver
  • pyftdi - a C extension libftdi binding

pylibftdi exists in the gap between these two projects; ftd2xx uses the (closed-source) D2XX driver, but provides a high-level Python interface, while pyftdi works with libftdi but is very low-level. The aim for pylibftdi is to work with the libftdi, but to provide a high-level Pythonic interface. Various wrappers and utility functions are also part of the distribution; following Python's batteries included approach, there are various interesting devices supported out-of-the-box - or at least there will be soon!

Plans

  • Add more examples: SPI devices, knight-rider effects, input devices, MIDI...
  • Perhaps add support for D2XX driver, though the name then becomes a slight liability ;)
  • General code quality improvements: solid unit tests, decent documentation.

License

Copyright (c) 2010-2012 Ben Bass <benbass@codedstructure.net>

pylibftdi is released under the MIT licence; see the file "LICENSE.txt" for information.

All trademarks referenced herein are property of their respective holders. libFTDI itself is developed by Intra2net AG. No association with Intra2net is claimed or implied, but I have found their library helpful and had fun with it...

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