pyFirmata / README.rst

pyFirmata

pyFirmata is a Python interface for the Firmata protocol. It is compliant with Firmata 2.1.

Prerequirement

Arduino

The Firmata firmware is included in Arduino 0012 or later. Use File -> Examples > Firmata > StandardFirmata to get the sketch with the standard firmware and upload it to your Arduino.

Other devices

Make the Firmata firmaware available on your device. Please refer to the documentation of this device to archive this.

Installation

pyFirmata depends on pySerial_ . Please install pySerial first.

Dowload the Source_ and upack it.

$ wget https://bitbucket.org/tino/pyfirmata/get/0.9.4.tar.gz
-O pyfirmata-0.9.4.tar.gz
$ tar -xzf pyfirmata-0.9.4.tar.gz && mv tino-pyfirmata-599e57b5f400
pyfirmata-0.9.4

$ cd pyfirmata-0.9.4 $ su python setup.py install

Or if you like to use the latest source.

$ hg clone ssh://hg@bitbucket.org/tino/pyfirmata $ cd pyfirmata $ su python setup.py install

Usage

Basic usage:

>>> from pyfirmata import Arduino, util
>>> board = Arduino('/dev/tty.usbserial-A6008rIF')
>>> board.digital[13].write(1)

To use analog ports, it is probably handy to start an iterator thread. Otherwise the board will keep sending data to your serial, until it overflows:

>>> it = util.Iterator(board)
>>> it.start()
>>> board.analog[0].enable_reporting()
>>> board.analog[0].read()
0.661440304938

If you use a pin more often, it can be worth it to use the get_pin method of the board. It let's you specify what pin you need by a string, composed of 'a' or 'd' (depending on wether you need an analog or digital pin), the pin number, and the mode ('i' for input, 'o' for output, 'p' for pwm). All seperated by :. Eg. a:0:i for analog 0 as input, or d:3:p for digital pin 3 as pwm.:

>>> analog_0 = board.get_pin('a:0:i')
>>> analog_0.read()
0.661440304938
>>> pin3 = board.get_pin('d:3:p')
>>> pin3.write(0.6)

Examples

The examples/ folder contains a few example scripts for the usage of pyfirmata. Please follow the comments in the files for the setup.

Board layout

If you want to use a board with a different layout than the standard Arduino, or the Arduino Mega (for which there exist the shortcut classes pyfirmata.Arduino and pyfirmata.ArduinoMega), instantiate the Board class with a dictionary as the layout argument. This is the layout dict for the Mega for example:

>>> mega = {
...         'digital' : tuple(x for x in range(54)),
...         'analog' : tuple(x for x in range(16)),
...         'pwm' : tuple(x for x in range(2,14)),
...         'use_ports' : True,
...         'disabled' : (0, 1, 14, 15) # Rx, Tx, Crystal
...         }

Todo

The next things on my list are to implement the new protocol changes in firmata:

  • Capability Query, which would eliminate the need to instantiate a board

with the layout dict, as it will be able to determine the layout itself (http://firmata.org/wiki/Proposals#Capability_Query_.28added_in_version_2.2.29) - Pin State Query, which allows it to populate on-screen controls with an accurate representation of the hardware's configuration (http://firmata.org/wiki/Proposals#Pin_State_Query_.28added_in_version_2.2.29)

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