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PyFtdi

Overview

PyFtdi aims at providing a user-space driver for modern FTDI devices, implemented in pure Python language.

Modern FTDI devices include:

  • FT2232D (dual port, clock up to 6 MHz)
  • FT2232H (dual port, clock up to 30 MHz)
  • FT4232H (quad port, clock up to 30 MHz)

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.

Extras

This module also contains a basic driver for Prolific PL2303 chip written in pure Python. PL2303 is not an FTDI device, but it may serve the same purpose: a USB-to-serial adapter.

As such, a Python driver for this device has been added to this project sarting at version 0.4.0, so that a PL2303 serial adaptor can be used as an FTDI alternative to drive a serial port from a USB bus.

Primary goals

It should support the following modes:

  • UART/Serial USB converter, up to 12Mbps (depending on the FTDI device capability)
  • SPI master
  • JTAG master
  • Bitbang/GPIO support (not a primary goal)

PyFtdi should provide a pyserial compliant API, to be used as a drop-in module to access USB-serial converters based on FTDI devices.

Requirements

PyFtdi relies on PyUSB, which itself depends on one of the following native libraries:

  • libusb-1.0 (recommended)
  • libusb-0.1 (deprecated)
  • openusb (not tested with pyftdi)

PyFtdi does not depend on any other native library, and only uses standard Python modules.

To use the serial port feature of PyFtdi, pyserial 2.5+ module should be installed.

Python 2.6 or above is required. Python 3.x is not yet supported.

Status

This project is still at an early alpha development stage.

However, PyFtdi is being forked from a closed-source software implementation that has been successfully used for over a year - including serial, spi and jtag protocols, based on top of the libftdi open source library.

libftdi is now being phased out from this closed-source project and replaced with PyFtdi, to ease maintenance and customization.

Meanwhile, PyFtdi is developed as an open-source solution.

Supported features

  • All FTDI device ports (UART, MPSSE) can be used simultaneously.
  • 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. PyFtdi includes several examples demonstrating how to use the FTDI SPI master with a pure-Python serial flash device driver for several common devices. 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. These tests show an average 470 KB/s read out from flash devices running with a 6 MHz SPI clock on a Core2Duo Mac Book Pro.
  • JTAG is under development and is not fully supported yet.

Development

PyFtdi is developed on Mac OS X platforms (including 64-bit kernels), 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, including but not limited to, Windows.

Examples

Serial port

serialext/tests/pyterm.py is a simple serial terminal that can be used to test the serial port feature.:

Usage: pyterm.py [options]
Pure python simple serial terminal

Options:
  -h, --help            show this help message and exit
  -d, --debug           enable debug mode
  -f, --fullmode        use full terminal mode, exit with [Ctrl]+A
  -p DEVICE, --port=DEVICE
                        serial port device name (list available ports with
                        'ftdi:///?' or 'prolific:///?')
  -b BAUDRATE, --baudrate=BAUDRATE
                        serial port baudrate
  -r RESET, --reset=RESET
                        HW reset on DTR line
  -o LOGFILE, --logfile=LOGFILE
                        path to the log file

If the PyFtdi module is not yet installed and pyterm.py is run from the archive directory, PYTHONPATH should be defined to the current directory:

PYTHONPATH=$PWD ./serialext/tests/pyterm.py -p ftdi:///?

The above command lists all the available FTDI device ports.

To start up a serial terminal session, use the -p option switch to select the proper port, for example:

PYTHONPATH=$PWD ./serialext/tests/pyterm.py -p ftdi://ftdi:2232/1
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