Examples

Basic usage

>>> import pifacedigitalio

>>> pfd = pifacedigitalio.PiFaceDigital() # creates a PiFace Digtal object

>>> pfd.leds[1].turn_on()    # turn on/set high the second LED
>>> pfd.leds[1].set_high()   # turn on/set high the second LED
>>> pfd.leds[2].toggle()     # toggle third LED
>>> pfd.switches[3].value    # check the logical status of switch3
0
>>> pfd.relays[0].value = 1  # turn on/set high the first relay

>>> pfd.output_pins[6].value = 1
>>> pfd.output_pins[6].turn_off()

>>> pfd.input_pins[6].value
0

>>> pfd.output_port.all_off()
>>> pfd.output_port.value = 0xAA
>>> pfd.output_port.toggle()

>>> bin(pfd.input_port.value)  # fourth switch pressed (logical input port)
'0b1000'

>>> bin(pfd.gpiob.value)  # fourth switch pressed (physical input port)
'0b11110111'

>>> pfd.deinit_board()  # disables interrupts and closes the file

Here are some functions you might want to use if objects aren’t your thing:

>>> import pifacedigitalio as p
>>> p.init()
>>> p.digital_write(0, 1)    # writes pin0 high
>>> p.digital_write(5, 1, 2) # writes pin5 on board2 high
>>> p.digital_read(4)        # reads pin4 (on board0)
0
>>> p.digital_read(2, 3)     # reads pin2 (on board3)
1
>>> p.deinit()

Interrupts

Instead of polling for input we can use the InputEventListener to register actions that we wish to be called on certain input events.

>>> import pifacedigitalio
>>> def toggle_led0(event):
...     event.chip.leds[0].toggle()
...
>>> pifacedigital = pifacedigitalio.PiFaceDigital()
>>> listener = pifacedigitalio.InputEventListener(chip=pifacedigital)
>>> listener.register(0, pifacedigitalio.IODIR_FALLING_EDGE, toggle_led0)
>>> listener.activate()

When input 0 is pressed, led0 will be toggled. To stop the listener, call it’s deactivate method:

>>> listener.deactivate()

The Event object has some interesting attributes. You can access them like so:

>>> import pifacedigitalio
>>> pifacedigital = pifacedigitalio.PiFaceDigital()
>>> listener = pifacedigitalio.InputEventListener(chip=pifacedigital)
>>> listener.register(0, pifacedigitalio.IODIR_RISING_EDGE, print)
>>> listener.activate()

This would print out the event informaion whenever you unpress switch 0:

interrupt_flag:    0b1
interrupt_capture: 0b11111111
pin_num:           0
direction:         1
chip:              <pifacedigitalio.core.PiFaceDigital object at 0xb682dab0>
timestamp:         1380893579.447889