# vim: set fileencoding=utf-8: # # GPIO Zero: a library for controlling the Raspberry Pi's GPIO pins # # Copyright (c) 2015-2021 Dave Jones # Copyright (c) 2018 Rick Ansell # Copyright (c) 2018 Mike Kazantsev # Copyright (c) 2016 Andrew Scheller # # SPDX-License-Identifier: BSD-3-Clause from __future__ import ( unicode_literals, absolute_import, print_function, division, ) str = type('') from weakref import ref from collections import defaultdict from threading import Lock from ..devices import Device from ..exc import ( PinInvalidFunction, PinSetInput, PinFixedPull, PinUnsupported, PinSPIUnsupported, PinPWMUnsupported, PinEdgeDetectUnsupported, SPIFixedClockMode, SPIFixedBitOrder, SPIFixedSelect, SPIFixedWordSize, SPIFixedRate, GPIOPinInUse, ) class Factory(object): """ Generates pins and SPI interfaces for devices. This is an abstract base class for pin factories. Descendents *must* override the following methods: * :meth:`ticks` * :meth:`ticks_diff` Descendents *may* override the following methods, if applicable: * :meth:`close` * :meth:`reserve_pins` * :meth:`release_pins` * :meth:`release_all` * :meth:`pin` * :meth:`spi` * :meth:`_get_pi_info` """ def __init__(self): self._reservations = defaultdict(list) self._res_lock = Lock() def reserve_pins(self, requester, *pins): """ Called to indicate that the device reserves the right to use the specified *pins*. This should be done during device construction. If pins are reserved, you must ensure that the reservation is released by eventually called :meth:`release_pins`. """ with self._res_lock: for pin in pins: for reserver_ref in self._reservations[pin]: reserver = reserver_ref() if reserver is not None and requester._conflicts_with(reserver): raise GPIOPinInUse('pin %s is already in use by %r' % (pin, reserver)) self._reservations[pin].append(ref(requester)) def release_pins(self, reserver, *pins): """ Releases the reservation of *reserver* against *pins*. This is typically called during :meth:`~gpiozero.Device.close` to clean up reservations taken during construction. Releasing a reservation that is not currently held will be silently ignored (to permit clean-up after failed / partial construction). """ with self._res_lock: for pin in pins: self._reservations[pin] = [ ref for ref in self._reservations[pin] if ref() not in (reserver, None) # may as well clean up dead refs ] def release_all(self, reserver): """ Releases all pin reservations taken out by *reserver*. See :meth:`release_pins` for further information). """ # Yes, this would be more efficient if it simply regenerated the # reservations list without any references to reserver instead of # (in release_pins) looping over each pin individually. However, this # then causes a subtle bug in LocalPiFactory which does something # horribly naughty (with good reason) and makes its _reservations # dictionary equivalent to a class-level one. self.release_pins(reserver, *self._reservations) def close(self): """ Closes the pin factory. This is expected to clean up all resources manipulated by the factory. It it typically called at script termination. """ pass def pin(self, spec): """ Creates an instance of a :class:`Pin` descendent representing the specified pin. .. warning:: Descendents must ensure that pin instances representing the same hardware are identical; i.e. two separate invocations of :meth:`pin` for the same pin specification must return the same object. """ raise PinUnsupported( # pragma: no cover "Individual pins are not supported by this pin factory") def spi(self, **spi_args): """ Returns an instance of an :class:`SPI` interface, for the specified SPI *port* and *device*, or for the specified pins (*clock_pin*, *mosi_pin*, *miso_pin*, and *select_pin*). Only one of the schemes can be used; attempting to mix *port* and *device* with pin numbers will raise :exc:`SPIBadArgs`. """ raise PinSPIUnsupported( # pragma: no cover 'SPI not supported by this pin factory') def ticks(self): """ Return the current ticks, according to the factory. The reference point is undefined and thus the result of this method is only meaningful when compared to another value returned by this method. The format of the time is also arbitrary, as is whether the time wraps after a certain duration. Ticks should only be compared using the :meth:`ticks_diff` method. """ raise NotImplementedError def ticks_diff(self, later, earlier): """ Return the time in seconds between two :meth:`ticks` results. The arguments are specified in the same order as they would be in the formula *later* - *earlier* but the result is guaranteed to be in seconds, and to be positive even if the ticks "wrapped" between calls to :meth:`ticks`. """ raise NotImplementedError def _get_pi_info(self): return None # pragma: no cover pi_info = property( lambda self: self._get_pi_info(), doc="""\ Returns a :class:`PiBoardInfo` instance representing the Pi that instances generated by this factory will be attached to. If the pins represented by this class are not *directly* attached to a Pi (e.g. the pin is attached to a board attached to the Pi, or the pins are not on a Pi at all), this may return :data:`None`. """) class Pin(object): """ Abstract base class representing a pin attached to some form of controller, be it GPIO, SPI, ADC, etc. Descendents should override property getters and setters to accurately represent the capabilities of pins. Descendents *must* override the following methods: * :meth:`_get_function` * :meth:`_set_function` * :meth:`_get_state` Descendents *may* additionally override the following methods, if applicable: * :meth:`close` * :meth:`output_with_state` * :meth:`input_with_pull` * :meth:`_set_state` * :meth:`_get_frequency` * :meth:`_set_frequency` * :meth:`_get_pull` * :meth:`_set_pull` * :meth:`_get_bounce` * :meth:`_set_bounce` * :meth:`_get_edges` * :meth:`_set_edges` * :meth:`_get_when_changed` * :meth:`_set_when_changed` """ def __repr__(self): return "" # pragma: no cover def close(self): """ Cleans up the resources allocated to the pin. After this method is called, this :class:`Pin` instance may no longer be used to query or control the pin's state. """ pass def output_with_state(self, state): """ Sets the pin's function to "output" and specifies an initial state for the pin. By default this is equivalent to performing:: pin.function = 'output' pin.state = state However, descendents may override this in order to provide the smallest possible delay between configuring the pin for output and specifying an initial value (which can be important for avoiding "blips" in active-low configurations). """ self.function = 'output' self.state = state def input_with_pull(self, pull): """ Sets the pin's function to "input" and specifies an initial pull-up for the pin. By default this is equivalent to performing:: pin.function = 'input' pin.pull = pull However, descendents may override this order to provide the smallest possible delay between configuring the pin for input and pulling the pin up/down (which can be important for avoiding "blips" in some configurations). """ self.function = 'input' self.pull = pull def _get_function(self): raise NotImplementedError def _set_function(self, value): raise NotImplementedError function = property( lambda self: self._get_function(), lambda self, value: self._set_function(value), doc="""\ The function of the pin. This property is a string indicating the current function or purpose of the pin. Typically this is the string "input" or "output". However, in some circumstances it can be other strings indicating non-GPIO related functionality. With certain pin types (e.g. GPIO pins), this attribute can be changed to configure the function of a pin. If an invalid function is specified, for this attribute, :exc:`PinInvalidFunction` will be raised. """) def _get_state(self): raise NotImplementedError def _set_state(self, value): raise PinSetInput( # pragma: no cover "Cannot set the state of pin %r" % self) state = property( lambda self: self._get_state(), lambda self, value: self._set_state(value), doc="""\ The state of the pin. This is 0 for low, and 1 for high. As a low level view of the pin, no swapping is performed in the case of pull ups (see :attr:`pull` for more information): .. code-block:: text HIGH - - - - > ,---------------------- | | LOW ----------------' Descendents which implement analog, or analog-like capabilities can return values between 0 and 1. For example, pins implementing PWM (where :attr:`frequency` is not :data:`None`) return a value between 0.0 and 1.0 representing the current PWM duty cycle. If a pin is currently configured for input, and an attempt is made to set this attribute, :exc:`PinSetInput` will be raised. If an invalid value is specified for this attribute, :exc:`PinInvalidState` will be raised. """) def _get_pull(self): return 'floating' # pragma: no cover def _set_pull(self, value): raise PinFixedPull( # pragma: no cover "Cannot change pull-up on pin %r" % self) pull = property( lambda self: self._get_pull(), lambda self, value: self._set_pull(value), doc="""\ The pull-up state of the pin represented as a string. This is typically one of the strings "up", "down", or "floating" but additional values may be supported by the underlying hardware. If the pin does not support changing pull-up state (for example because of a fixed pull-up resistor), attempts to set this property will raise :exc:`PinFixedPull`. If the specified value is not supported by the underlying hardware, :exc:`PinInvalidPull` is raised. """) def _get_frequency(self): return None # pragma: no cover def _set_frequency(self, value): if value is not None: raise PinPWMUnsupported( # pragma: no cover "PWM is not supported on pin %r" % self) frequency = property( lambda self: self._get_frequency(), lambda self, value: self._set_frequency(value), doc="""\ The frequency (in Hz) for the pin's PWM implementation, or :data:`None` if PWM is not currently in use. This value always defaults to :data:`None` and may be changed with certain pin types to activate or deactivate PWM. If the pin does not support PWM, :exc:`PinPWMUnsupported` will be raised when attempting to set this to a value other than :data:`None`. """) def _get_bounce(self): return None # pragma: no cover def _set_bounce(self, value): if value is not None: # pragma: no cover raise PinEdgeDetectUnsupported( "Edge detection is not supported on pin %r" % self) bounce = property( lambda self: self._get_bounce(), lambda self, value: self._set_bounce(value), doc="""\ The amount of bounce detection (elimination) currently in use by edge detection, measured in seconds. If bounce detection is not currently in use, this is :data:`None`. For example, if :attr:`edges` is currently "rising", :attr:`bounce` is currently 5/1000 (5ms), then the waveform below will only fire :attr:`when_changed` on two occasions despite there being three rising edges: .. code-block:: text TIME 0...1...2...3...4...5...6...7...8...9...10..11..12 ms bounce elimination |===================| |============== HIGH - - - - > ,--. ,--------------. ,--. | | | | | | | | | | | | LOW ----------------' `-' `-' `----------- : : : : when_changed when_changed fires fires If the pin does not support edge detection, attempts to set this property will raise :exc:`PinEdgeDetectUnsupported`. If the pin supports edge detection, the class must implement bounce detection, even if only in software. """) def _get_edges(self): return 'none' # pragma: no cover def _set_edges(self, value): raise PinEdgeDetectUnsupported( # pragma: no cover "Edge detection is not supported on pin %r" % self) edges = property( lambda self: self._get_edges(), lambda self, value: self._set_edges(value), doc="""\ The edge that will trigger execution of the function or bound method assigned to :attr:`when_changed`. This can be one of the strings "both" (the default), "rising", "falling", or "none": .. code-block:: text HIGH - - - - > ,--------------. | | | | LOW --------------------' `-------------- : : : : Fires when_changed "both" "both" when edges is ... "rising" "falling" If the pin does not support edge detection, attempts to set this property will raise :exc:`PinEdgeDetectUnsupported`. """) def _get_when_changed(self): return None # pragma: no cover def _set_when_changed(self, value): raise PinEdgeDetectUnsupported( # pragma: no cover "Edge detection is not supported on pin %r" % self) when_changed = property( lambda self: self._get_when_changed(), lambda self, value: self._set_when_changed(value), doc="""\ A function or bound method to be called when the pin's state changes (more specifically when the edge specified by :attr:`edges` is detected on the pin). The function or bound method must accept two parameters: the first will report the ticks (from :meth:`Factory.ticks`) when the pin's state changed, and the second will report the pin's current state. .. warning:: Depending on hardware support, the state is *not guaranteed to be accurate*. For instance, many GPIO implementations will provide an interrupt indicating when a pin's state changed but not what it changed to. In this case the pin driver simply reads the pin's current state to supply this parameter, but the pin's state may have changed *since* the interrupt. Exercise appropriate caution when relying upon this parameter. If the pin does not support edge detection, attempts to set this property will raise :exc:`PinEdgeDetectUnsupported`. """) class SPI(Device): """ Abstract interface for `Serial Peripheral Interface`_ (SPI) implementations. Descendents *must* override the following methods: * :meth:`transfer` * :meth:`_get_clock_mode` Descendents *may* override the following methods, if applicable: * :meth:`read` * :meth:`write` * :meth:`_set_clock_mode` * :meth:`_get_lsb_first` * :meth:`_set_lsb_first` * :meth:`_get_select_high` * :meth:`_set_select_high` * :meth:`_get_bits_per_word` * :meth:`_set_bits_per_word` .. _Serial Peripheral Interface: https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus """ def read(self, n): """ Read *n* words of data from the SPI interface, returning them as a sequence of unsigned ints, each no larger than the configured :attr:`bits_per_word` of the interface. This method is typically used with read-only devices that feature half-duplex communication. See :meth:`transfer` for full duplex communication. """ return self.transfer([0] * n) def write(self, data): """ Write *data* to the SPI interface. *data* must be a sequence of unsigned integer words each of which will fit within the configured :attr:`bits_per_word` of the interface. The method returns the number of words written to the interface (which may be less than or equal to the length of *data*). This method is typically used with write-only devices that feature half-duplex communication. See :meth:`transfer` for full duplex communication. """ return len(self.transfer(data)) def transfer(self, data): """ Write *data* to the SPI interface. *data* must be a sequence of unsigned integer words each of which will fit within the configured :attr:`bits_per_word` of the interface. The method returns the sequence of words read from the interface while writing occurred (full duplex communication). The length of the sequence returned dictates the number of words of *data* written to the interface. Each word in the returned sequence will be an unsigned integer no larger than the configured :attr:`bits_per_word` of the interface. """ raise NotImplementedError @property def clock_polarity(self): """ The polarity of the SPI clock pin. If this is :data:`False` (the default), the clock pin will idle low, and pulse high. Setting this to :data:`True` will cause the clock pin to idle high, and pulse low. On many data sheets this is documented as the CPOL value. The following diagram illustrates the waveform when :attr:`clock_polarity` is :data:`False` (the default), equivalent to CPOL 0: .. code-block:: text on on on on on on on ,---. ,---. ,---. ,---. ,---. ,---. ,---. CLK | | | | | | | | | | | | | | | | | | | | | | | | | | | | ------' `---' `---' `---' `---' `---' `---' `------ idle off off off off off off idle The following diagram illustrates the waveform when :attr:`clock_polarity` is :data:`True`, equivalent to CPOL 1: .. code-block:: text idle off off off off off off idle ------. ,---. ,---. ,---. ,---. ,---. ,---. ,------ | | | | | | | | | | | | | | CLK | | | | | | | | | | | | | | `---' `---' `---' `---' `---' `---' `---' on on on on on on on """ return bool(self.clock_mode & 2) @clock_polarity.setter def clock_polarity(self, value): self.clock_mode = self.clock_mode & (~2) | (bool(value) << 1) @property def clock_phase(self): """ The phase of the SPI clock pin. If this is :data:`False` (the default), data will be read from the MISO pin when the clock pin activates. Setting this to :data:`True` will cause data to be read from the MISO pin when the clock pin deactivates. On many data sheets this is documented as the CPHA value. Whether the clock edge is rising or falling when the clock is considered activated is controlled by the :attr:`clock_polarity` attribute (corresponding to CPOL). The following diagram indicates when data is read when :attr:`clock_polarity` is :data:`False`, and :attr:`clock_phase` is :data:`False` (the default), equivalent to CPHA 0: .. code-block:: text ,---. ,---. ,---. ,---. ,---. ,---. ,---. CLK | | | | | | | | | | | | | | | | | | | | | | | | | | | | ----' `---' `---' `---' `---' `---' `---' `------- : : : : : : : MISO---. ,---. ,---. ,---. ,---. ,---. ,---. / \\ / \\ / \\ / \\ / \\ / \\ / \\ -{ Bit X Bit X Bit X Bit X Bit X Bit X Bit }------ \\ / \\ / \\ / \\ / \\ / \\ / \\ / `---' `---' `---' `---' `---' `---' `---' The following diagram indicates when data is read when :attr:`clock_polarity` is :data:`False`, but :attr:`clock_phase` is :data:`True`, equivalent to CPHA 1: .. code-block:: text ,---. ,---. ,---. ,---. ,---. ,---. ,---. CLK | | | | | | | | | | | | | | | | | | | | | | | | | | | | ----' `---' `---' `---' `---' `---' `---' `------- : : : : : : : MISO ,---. ,---. ,---. ,---. ,---. ,---. ,---. / \\ / \\ / \\ / \\ / \\ / \\ / \\ -----{ Bit X Bit X Bit X Bit X Bit X Bit X Bit }-- \\ / \\ / \\ / \\ / \\ / \\ / \\ / `---' `---' `---' `---' `---' `---' `---' """ return bool(self.clock_mode & 1) @clock_phase.setter def clock_phase(self, value): self.clock_mode = self.clock_mode & (~1) | bool(value) def _get_clock_mode(self): raise NotImplementedError # pragma: no cover def _set_clock_mode(self, value): raise SPIFixedClockMode( # pragma: no cover "clock_mode cannot be changed on %r" % self) clock_mode = property( lambda self: self._get_clock_mode(), lambda self, value: self._set_clock_mode(value), doc="""\ Presents a value representing the :attr:`clock_polarity` and :attr:`clock_phase` attributes combined according to the following table: +------+-----------------+--------------+ | mode | polarity (CPOL) | phase (CPHA) | +======+=================+==============+ | 0 | False | False | +------+-----------------+--------------+ | 1 | False | True | +------+-----------------+--------------+ | 2 | True | False | +------+-----------------+--------------+ | 3 | True | True | +------+-----------------+--------------+ Adjusting this value adjusts both the :attr:`clock_polarity` and :attr:`clock_phase` attributes simultaneously. """) def _get_lsb_first(self): return False # pragma: no cover def _set_lsb_first(self, value): raise SPIFixedBitOrder( # pragma: no cover "lsb_first cannot be changed on %r" % self) lsb_first = property( lambda self: self._get_lsb_first(), lambda self, value: self._set_lsb_first(value), doc="""\ Controls whether words are read and written LSB in (Least Significant Bit first) order. The default is :data:`False` indicating that words are read and written in MSB (Most Significant Bit first) order. Effectively, this controls the `Bit endianness`_ of the connection. The following diagram shows the a word containing the number 5 (binary 0101) transmitted on MISO with :attr:`bits_per_word` set to 4, and :attr:`clock_mode` set to 0, when :attr:`lsb_first` is :data:`False` (the default): .. code-block:: text ,---. ,---. ,---. ,---. CLK | | | | | | | | | | | | | | | | ----' `---' `---' `---' `----- : ,-------. : ,-------. MISO: | : | : | : | : | : | : | : | ----------' : `-------' : `---- : : : : MSB LSB And now with :attr:`lsb_first` set to :data:`True` (and all other parameters the same): .. code-block:: text ,---. ,---. ,---. ,---. CLK | | | | | | | | | | | | | | | | ----' `---' `---' `---' `----- ,-------. : ,-------. : MISO: | : | : | : | : | : | : | : --' : `-------' : `----------- : : : : LSB MSB .. _Bit endianness: https://en.wikipedia.org/wiki/Endianness#Bit_endianness """) def _get_select_high(self): return False # pragma: no cover def _set_select_high(self, value): raise SPIFixedSelect( # pragma: no cover "select_high cannot be changed on %r" % self) select_high = property( lambda self: self._get_select_high(), lambda self, value: self._set_select_high(value), doc="""\ If :data:`False` (the default), the chip select line is considered active when it is pulled low. When set to :data:`True`, the chip select line is considered active when it is driven high. The following diagram shows the waveform of the chip select line, and the clock when :attr:`clock_polarity` is :data:`False`, and :attr:`select_high` is :data:`False` (the default): .. code-block:: text ---. ,------ __ | | CS | chip is selected, and will react to clock | idle `-----------------------------------------------------' ,---. ,---. ,---. ,---. ,---. ,---. ,---. CLK | | | | | | | | | | | | | | | | | | | | | | | | | | | | ----' `---' `---' `---' `---' `---' `---' `------- And when :attr:`select_high` is :data:`True`: .. code-block:: text ,-----------------------------------------------------. CS | chip is selected, and will react to clock | idle | | ---' `------ ,---. ,---. ,---. ,---. ,---. ,---. ,---. CLK | | | | | | | | | | | | | | | | | | | | | | | | | | | | ----' `---' `---' `---' `---' `---' `---' `------- """) def _get_bits_per_word(self): return 8 # pragma: no cover def _set_bits_per_word(self, value): raise SPIFixedWordSize( # pragma: no cover "bits_per_word cannot be changed on %r" % self) bits_per_word = property( lambda self: self._get_bits_per_word(), lambda self, value: self._set_bits_per_word(value), doc="""\ Controls the number of bits that make up a word, and thus where the word boundaries appear in the data stream, and the maximum value of a word. Defaults to 8 meaning that words are effectively bytes. Several implementations do not support non-byte-sized words. """) def _get_rate(self): return 100000 # pragma: no cover def _set_rate(self, value): raise SPIFixedRate( # pragma: no cover "rate cannot be changed on %r" % self) rate = property( lambda self: self._get_rate(), lambda self, value: self._set_rate(value), doc="""\ Controls the speed of the SPI interface in Hz (or baud). Note that most software SPI implementations ignore this property, and will raise :exc:`SPIFixedRate` if an attempt is made to set it, as they have no rate control (they simply bit-bang as fast as possible because typically this isn't very fast anyway, and introducing measures to limit the rate would simply slow them down to the point of being useless). """)