Welcome to pyFirmata’s documentation!

Module reference:

Installation

The preferred way to install is with pip:

pip install pyfirmata

If you install from source with python setup.py install, don’t forget to install pyserial as well.

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)

Board layout

If you want to use a board with a different layout than the standard Arduino, or the Arduino Mega (for wich 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
...         }

Ping support (pulseIn)

If you want to use ultrasonic range sensors that use a pulse to measure distance (like the very cheap and common HC-SR04 - See datasheet, you will need to use a pulseIn compatible Firmata on your card.

You can download it from the pulseIn branch of the Firmata repository:

Simply connect the sensor’s Trig and Echo pins to a digital pin on your board.

../../../blob/master/Examples/Figures/ping.png

And then use the ping method on the pin:

>>> echo_pin = board.get_pin('d:7:o')
>>> echo_pin.ping()
1204

You can use the ping_time_to_distance function to convert the result of the ping (echo time) in distance:

>>> from pyfirmata.util import ping_time_to_distance
>>> echo_pin = board.get_pin('d:7:o')
>>> ping_time_to_distance(echo_pin.ping())
20.4854580555607776

NOTE

The codes will only work if you download and load the pulseIn:: code on the Arduino board! It has to be exactly the code quoted!

credits

Indices and tables