python-gpiozero/gpiozero/pins/pigpiod.py

from __future__ import (
    unicode_literals,
    absolute_import,
    print_function,
    division,
    )
str = type('')

import warnings
import pigpio
import os

from . import Pin
from .data import pi_info
from ..exc import (
    PinInvalidFunction,
    PinSetInput,
    PinFixedPull,
    PinInvalidPull,
    PinInvalidBounce,
    PinInvalidState,
    PinNonPhysical,
    PinNoPins,
    )


class PiGPIOPin(Pin):
    """
    Uses the `pigpio`_ library to interface to the Pi's GPIO pins. The pigpio
    library relies on a daemon (``pigpiod``) to be running as root to provide
    access to the GPIO pins, and communicates with this daemon over a network
    socket.

    While this does mean only the daemon itself should control the pins, the
    architecture does have several advantages:

    * Pins can be remote controlled from another machine (the other
      machine doesn't even have to be a Raspberry Pi; it simply needs the
      `pigpio`_ client library installed on it)
    * The daemon supports hardware PWM via the DMA controller
    * Your script itself doesn't require root privileges; it just needs to
      be able to communicate with the daemon

    You can construct pigpiod pins manually like so::

        from gpiozero.pins.pigpiod import PiGPIOPin
        from gpiozero import LED

        led = LED(PiGPIOPin(12))

    This is particularly useful for controlling pins on a remote machine. To
    accomplish this simply specify the host (and optionally port) when
    constructing the pin::

        from gpiozero.pins.pigpiod import PiGPIOPin
        from gpiozero import LED
        from signal import pause

        led = LED(PiGPIOPin(12, host='192.168.0.2'))

    .. note::

        In some circumstances, especially when playing with PWM, it does appear
        to be possible to get the daemon into "unusual" states. We would be
        most interested to hear any bug reports relating to this (it may be a
        bug in our pin implementation). A workaround for now is simply to
        restart the ``pigpiod`` daemon.

    .. _pigpio: http://abyz.co.uk/rpi/pigpio/
    """

    _CONNECTIONS = {} # maps (host, port) to (connection, pi_info)
    _PINS = {}

    GPIO_FUNCTIONS = {
        'input':   pigpio.INPUT,
        'output':  pigpio.OUTPUT,
        'alt0':    pigpio.ALT0,
        'alt1':    pigpio.ALT1,
        'alt2':    pigpio.ALT2,
        'alt3':    pigpio.ALT3,
        'alt4':    pigpio.ALT4,
        'alt5':    pigpio.ALT5,
        }

    GPIO_PULL_UPS = {
        'up':       pigpio.PUD_UP,
        'down':     pigpio.PUD_DOWN,
        'floating': pigpio.PUD_OFF,
        }

    GPIO_EDGES = {
        'both':    pigpio.EITHER_EDGE,
        'rising':  pigpio.RISING_EDGE,
        'falling': pigpio.FALLING_EDGE,
        }

    GPIO_FUNCTION_NAMES = {v: k for (k, v) in GPIO_FUNCTIONS.items()}
    GPIO_PULL_UP_NAMES = {v: k for (k, v) in GPIO_PULL_UPS.items()}
    GPIO_EDGES_NAMES = {v: k for (k, v) in GPIO_EDGES.items()}

    def __new__(
            cls, number, host=os.getenv('PIGPIO_ADDR', 'localhost'),
            port=int(os.getenv('PIGPIO_PORT', 8888))):
        try:
            return cls._PINS[(host, port, number)]
        except KeyError:
            self = super(PiGPIOPin, cls).__new__(cls)
            cls.pi_revision(host, port) # implicitly creates connection
            self._connection, self._pi_info = cls._CONNECTIONS[(host, port)]
            try:
                self._pi_info.physical_pin('GPIO%d' % number)
            except PinNoPins:
                warnings.warn(
                    PinNonPhysical(
                        'no physical pins exist for GPIO%d' % number))
            self._host = host
            self._port = port
            self._number = number
            self._pull = 'up' if self._pi_info.pulled_up('GPIO%d' % number) else 'floating'
            self._pwm = False
            self._bounce = None
            self._when_changed = None
            self._callback = None
            self._edges = pigpio.EITHER_EDGE
            try:
                self._connection.set_mode(self._number, pigpio.INPUT)
            except pigpio.error as e:
                raise ValueError(e)
            self._connection.set_pull_up_down(self._number, self.GPIO_PULL_UPS[self._pull])
            self._connection.set_glitch_filter(self._number, 0)
            self._connection.set_PWM_range(self._number, 255)
            cls._PINS[(host, port, number)] = self
            return self

    def __repr__(self):
        if self._host == 'localhost':
            return "GPIO%d" % self._number
        else:
            return "GPIO%d on %s:%d" % (self._number, self._host, self._port)

    @property
    def host(self):
        return self._host

    @property
    def port(self):
        return self._port

    @property
    def number(self):
        return self._number

    def close(self):
        # If we're shutting down, the connection may have disconnected itself
        # already. Unfortunately, the connection's "connected" property is
        # rather buggy - disconnecting doesn't set it to False! So we're
        # naughty and check an internal variable instead...
        if self._connection.sl.s is not None:
            self.frequency = None
            self.when_changed = None
            self.function = 'input'
            self.pull = 'up' if self._pi_info.pulled_up('GPIO%d' % self.number) else 'floating'

    def _get_function(self):
        return self.GPIO_FUNCTION_NAMES[self._connection.get_mode(self._number)]

    def _set_function(self, value):
        if value != 'input':
            self._pull = 'floating'
        try:
            self._connection.set_mode(self._number, self.GPIO_FUNCTIONS[value])
        except KeyError:
            raise PinInvalidFunction('invalid function "%s" for pin %r' % (value, self))

    def _get_state(self):
        if self._pwm:
            return self._connection.get_PWM_dutycycle(self._number) / 255
        else:
            return bool(self._connection.read(self._number))

    def _set_state(self, value):
        if self._pwm:
            try:
                self._connection.set_PWM_dutycycle(self._number, int(value * 255))
            except pigpio.error:
                raise PinInvalidState('invalid state "%s" for pin %r' % (value, self))
        elif self.function == 'input':
            raise PinSetInput('cannot set state of pin %r' % self)
        else:
            # write forces pin to OUTPUT, hence the check above
            self._connection.write(self._number, bool(value))

    def _get_pull(self):
        return self._pull

    def _set_pull(self, value):
        if self.function != 'input':
            raise PinFixedPull('cannot set pull on non-input pin %r' % self)
        if value != 'up' and self._pi_info.pulled_up('GPIO%d' % self._number):
            raise PinFixedPull('%r has a physical pull-up resistor' % self)
        try:
            self._connection.set_pull_up_down(self._number, self.GPIO_PULL_UPS[value])
            self._pull = value
        except KeyError:
            raise PinInvalidPull('invalid pull "%s" for pin %r' % (value, self))

    def _get_frequency(self):
        if self._pwm:
            return self._connection.get_PWM_frequency(self._number)
        return None

    def _set_frequency(self, value):
        if not self._pwm and value is not None:
            self._connection.set_PWM_frequency(self._number, value)
            self._connection.set_PWM_dutycycle(self._number, 0)
            self._pwm = True
        elif self._pwm and value is not None:
            self._connection.set_PWM_frequency(self._number, value)
        elif self._pwm and value is None:
            self._connection.set_PWM_dutycycle(self._number, 0)
            self._pwm = False

    def _get_bounce(self):
        return None if not self._bounce else self._bounce / 1000000

    def _set_bounce(self, value):
        if value is None:
            value = 0
        elif value < 0:
            raise PinInvalidBounce('bounce must be 0 or greater')
        self._connection.set_glitch_filter(self._number, int(value * 1000000))

    def _get_edges(self):
        return self.GPIO_EDGES_NAMES[self._edges]

    def _set_edges(self, value):
        f = self.when_changed
        self.when_changed = None
        try:
            self._edges = self.GPIO_EDGES[value]
        finally:
            self.when_changed = f

    def _get_when_changed(self):
        if self._callback is None:
            return None
        return self._callback.callb.func

    def _set_when_changed(self, value):
        if self._callback is not None:
            self._callback.cancel()
            self._callback = None
        if value is not None:
            self._callback = self._connection.callback(
                    self._number, self._edges,
                    lambda gpio, level, tick: value())

    @classmethod
    def pi_info(
            cls, host=os.getenv('PIGPIO_ADDR', 'localhost'),
            port=int(os.getenv('PIGPIO_PORT', 8888))):
        try:
            connection, info = cls._CONNECTIONS[(host, port)]
        except KeyError:
            connection = pigpio.pi(host, port)
            revision = '%04x' % connection.get_hardware_revision()
            info = pi_info(revision)
            cls._CONNECTIONS[(host, port)] = (connection, info)
        return info