pyFirmata is a Python interface for the Firmata protocol. It is fully compatible with Firmata 2.1, and has some functionality of version 2.2. It runs on Python 2.7, 3.3 and 3.4.
Test status:
The preferred way to install is with pip:
pip install pyfirmata
You can also install from source with python setup.py install. You will
need to have setuptools installed:
git clone https://github.com/tino/pyFirmata cd pyFirmata python setup.py install
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
A better option is to use a with block. This way the Iterator is managed
automagically, and you don't have to take care of calling board.exit()
to stop the Iterator thread when you're done:
>>> with board: >>> 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)
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
... }
If you want to use ultrasonic ranging sensors that use a pulse to
measure distances (like the very cheap and common HC-SR04
- see http://www.micropik.com/PDF/HCSR04.pdf),
you'll need to use a``pulseIn`` compatible Firmata in your board.
You can download it from the pulseIn branch
of the Firmata repository:
https://github.com/jgautier/arduino-1/tree/pulseIn
Just plug the sensor Trig and Echo pins
to a digital pin on your board.
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 ping result (echo time) into distance:
>>> from pyfirmata.util import ping_time_to_distance >>> echo_pin = board.get_pin('d:7:o') >>> ping_time_to_distance(echo_pin.ping()) 20.485458055607776
The next things on my list are to implement the new protocol changes in firmata:
- 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)