mirror of
https://github.com/KevinMidboe/python-gpiozero.git
synced 2025-10-29 17:50:37 +00:00
336 lines
11 KiB
Python
336 lines
11 KiB
Python
from __future__ import (
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unicode_literals,
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absolute_import,
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print_function,
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division,
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)
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nstr = str
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str = type('')
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import io
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import os
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import mmap
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import errno
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import struct
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import warnings
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from time import sleep
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from threading import Thread, Event, Lock
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from collections import Counter
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from .local import LocalPiPin, LocalPiFactory
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from ..exc import (
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PinInvalidPull,
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PinInvalidEdges,
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PinInvalidFunction,
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PinFixedPull,
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PinSetInput,
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)
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class GPIOMemory(object):
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GPIO_BASE_OFFSET = 0x200000
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PERI_BASE_OFFSET = {
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'BCM2708': 0x20000000,
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'BCM2835': 0x20000000,
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'BCM2709': 0x3f000000,
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'BCM2836': 0x3f000000,
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}
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# From BCM2835 data-sheet, p.91
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GPFSEL_OFFSET = 0x00 >> 2
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GPSET_OFFSET = 0x1c >> 2
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GPCLR_OFFSET = 0x28 >> 2
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GPLEV_OFFSET = 0x34 >> 2
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GPEDS_OFFSET = 0x40 >> 2
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GPREN_OFFSET = 0x4c >> 2
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GPFEN_OFFSET = 0x58 >> 2
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GPHEN_OFFSET = 0x64 >> 2
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GPLEN_OFFSET = 0x70 >> 2
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GPAREN_OFFSET = 0x7c >> 2
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GPAFEN_OFFSET = 0x88 >> 2
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GPPUD_OFFSET = 0x94 >> 2
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GPPUDCLK_OFFSET = 0x98 >> 2
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def __init__(self):
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try:
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self.fd = os.open('/dev/gpiomem', os.O_RDWR | os.O_SYNC)
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except OSError:
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try:
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self.fd = os.open('/dev/mem', os.O_RDWR | os.O_SYNC)
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except OSError:
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raise IOError(
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'unable to open /dev/gpiomem or /dev/mem; '
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'upgrade your kernel or run as root')
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else:
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offset = self.peripheral_base() + self.GPIO_BASE_OFFSET
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else:
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offset = 0
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self.mem = mmap.mmap(self.fd, 4096, offset=offset)
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def close(self):
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self.mem.close()
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os.close(self.fd)
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def peripheral_base(self):
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try:
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with io.open('/proc/device-tree/soc/ranges', 'rb') as f:
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f.seek(4)
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return struct.unpack(nstr('>L'), f.read(4))[0]
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except IOError:
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with io.open('/proc/cpuinfo', 'r') as f:
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for line in f:
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if line.startswith('Hardware'):
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try:
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return self.PERI_BASE_OFFSET[line.split(':')[1].strip()]
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except KeyError:
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raise IOError('unable to determine RPi revision')
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raise IOError('unable to determine peripheral base')
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def __getitem__(self, index):
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return struct.unpack_from(nstr('<L'), self.mem, index * 4)[0]
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def __setitem__(self, index, value):
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struct.pack_into(nstr('<L'), self.mem, index * 4, value)
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class GPIOFS(object):
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GPIO_PATH = '/sys/class/gpio'
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def __init__(self):
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self._lock = Lock()
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self._pin_refs = Counter()
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def path(self, name):
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return os.path.join(self.GPIO_PATH, name)
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def export(self, pin):
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with self._lock:
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if self._pin_refs[pin] == 0:
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# Set the count to 1 to indicate the GPIO is already exported
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# (we'll correct this if we find it isn't, but this enables us
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# to "leave the system in the state we found it")
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self._pin_refs[pin] = 1
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result = None
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# Dirty hack to wait for udev to set permissions on
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# gpioN/direction; there's no other way around this as there's
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# no synchronous mechanism for setting permissions on sysfs
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for i in range(10):
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try:
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result = io.open(self.path('gpio%d/value' % pin), 'w+b', buffering=0)
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except IOError as e:
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if e.errno == errno.ENOENT:
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with io.open(self.path('export'), 'wb') as f:
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f.write(str(pin).encode('ascii'))
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# Pin wasn't exported, so correct the ref-count
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self._pin_refs[pin] = 0
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elif e.errno == errno.EACCES:
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sleep(i / 100)
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else:
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raise
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else:
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break
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if not result:
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raise RuntimeError('failed to export pin %d' % pin)
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else:
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result = io.open(self.path('gpio%d/value' % pin), 'w+b', buffering=0)
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self._pin_refs[pin] += 1
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return result
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def unexport(self, pin):
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with self._lock:
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self._pin_refs[pin] -= 1
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if self._pin_refs[pin] == 0:
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with io.open(self.path('unexport'), 'wb') as f:
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f.write(str(pin).encode('ascii'))
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class NativeFactory(LocalPiFactory):
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"""
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Uses a built-in pure Python implementation to interface to the Pi's GPIO
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pins. This is the default pin implementation if no third-party libraries
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are discovered.
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.. warning::
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This implementation does *not* currently support PWM. Attempting to
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use any class which requests PWM will raise an exception. This
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implementation is also experimental; we make no guarantees it will
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not eat your Pi for breakfast!
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You can construct native pin instances manually like so::
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from gpiozero.pins.native import NativeFactory
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from gpiozero import LED
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factory = NativeFactory()
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led = LED(12, pin_factory=factory)
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"""
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def __init__(self):
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super(NativeFactory, self).__init__()
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self.mem = GPIOMemory()
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self.pin_class = NativePin
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def close(self):
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super(NativeFactory, self).close()
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self.mem.close()
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class NativePin(LocalPiPin):
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"""
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Native pin implementation. See :class:`NativeFactory` for more information.
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"""
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GPIO_FUNCTIONS = {
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'input': 0b000,
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'output': 0b001,
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'alt0': 0b100,
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'alt1': 0b101,
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'alt2': 0b110,
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'alt3': 0b111,
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'alt4': 0b011,
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'alt5': 0b010,
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}
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GPIO_PULL_UPS = {
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'up': 0b10,
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'down': 0b01,
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'floating': 0b00,
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'reserved': 0b11,
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}
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GPIO_EDGES = {
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'both': (True, True),
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'rising': (True, False),
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'falling': (False, True),
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'none': (False, False),
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}
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GPIO_FUNCTION_NAMES = {v: k for (k, v) in GPIO_FUNCTIONS.items()}
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GPIO_PULL_UP_NAMES = {v: k for (k, v) in GPIO_PULL_UPS.items()}
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GPIO_EDGES_NAMES = {v: k for (k, v) in GPIO_EDGES.items()}
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def __init__(self, factory, number):
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super(NativePin, self).__init__(factory, number)
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self._func_offset = self.factory.mem.GPFSEL_OFFSET + (number // 10)
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self._func_shift = (number % 10) * 3
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self._set_offset = self.factory.mem.GPSET_OFFSET + (number // 32)
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self._set_shift = number % 32
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self._clear_offset = self.factory.mem.GPCLR_OFFSET + (number // 32)
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self._clear_shift = number % 32
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self._level_offset = self.factory.mem.GPLEV_OFFSET + (number // 32)
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self._level_shift = number % 32
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self._pull_offset = self.factory.mem.GPPUDCLK_OFFSET + (number // 32)
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self._pull_shift = number % 32
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self._edge_offset = self.factory.mem.GPEDS_OFFSET + (number // 32)
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self._edge_shift = number % 32
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self._rising_offset = self.factory.mem.GPREN_OFFSET + (number // 32)
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self._rising_shift = number % 32
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self._falling_offset = self.factory.mem.GPFEN_OFFSET + (number // 32)
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self._falling_shift = number % 32
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self._when_changed = None
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self._change_thread = None
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self._change_event = Event()
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self.function = 'input'
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self.pull = 'up' if self.factory.pi_info.pulled_up(repr(self)) else 'floating'
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self.bounce = None
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self.edges = 'both'
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def close(self):
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self.frequency = None
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self.when_changed = None
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self.function = 'input'
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self.pull = 'up' if self.factory.pi_info.pulled_up(repr(self)) else 'floating'
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def _get_function(self):
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return self.GPIO_FUNCTION_NAMES[(self.factory.mem[self._func_offset] >> self._func_shift) & 7]
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def _set_function(self, value):
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try:
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value = self.GPIO_FUNCTIONS[value]
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except KeyError:
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raise PinInvalidFunction('invalid function "%s" for pin %r' % (value, self))
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self.factory.mem[self._func_offset] = (
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self.factory.mem[self._func_offset]
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& ~(7 << self._func_shift)
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| (value << self._func_shift)
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)
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def _get_state(self):
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return bool(self.factory.mem[self._level_offset] & (1 << self._level_shift))
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def _set_state(self, value):
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if self.function == 'input':
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raise PinSetInput('cannot set state of pin %r' % self)
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if value:
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self.factory.mem[self._set_offset] = 1 << self._set_shift
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else:
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self.factory.mem[self._clear_offset] = 1 << self._clear_shift
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def _get_pull(self):
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return self.GPIO_PULL_UP_NAMES[self._pull]
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def _set_pull(self, value):
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if self.function != 'input':
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raise PinFixedPull('cannot set pull on non-input pin %r' % self)
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if value != 'up' and self.factory.pi_info.pulled_up(repr(self)):
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raise PinFixedPull('%r has a physical pull-up resistor' % self)
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try:
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value = self.GPIO_PULL_UPS[value]
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except KeyError:
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raise PinInvalidPull('invalid pull direction "%s" for pin %r' % (value, self))
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self.factory.mem[self.factory.mem.GPPUD_OFFSET] = value
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sleep(0.000000214)
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self.factory.mem[self._pull_offset] = 1 << self._pull_shift
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sleep(0.000000214)
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self.factory.mem[self.factory.mem.GPPUD_OFFSET] = 0
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self.factory.mem[self._pull_offset] = 0
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self._pull = value
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def _get_edges(self):
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rising = bool(self.factory.mem[self._rising_offset] & (1 << self._rising_shift))
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falling = bool(self.factory.mem[self._falling_offset] & (1 << self._falling_shift))
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return self.GPIO_EDGES_NAMES[(rising, falling)]
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def _set_edges(self, value):
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try:
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rising, falling = self.GPIO_EDGES[value]
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except KeyError:
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raise PinInvalidEdges('invalid edge specification "%s" for pin %r' % self)
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f = self.when_changed
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self.when_changed = None
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try:
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self.factory.mem[self._rising_offset] = (
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self.factory.mem[self._rising_offset]
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& ~(1 << self._rising_shift)
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| (rising << self._rising_shift)
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)
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self.factory.mem[self._falling_offset] = (
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self.factory.mem[self._falling_offset]
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& ~(1 << self._falling_shift)
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| (falling << self._falling_shift)
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)
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finally:
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self.when_changed = f
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def _enable_event_detect(self):
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self._change_thread = Thread(target=self._change_watch)
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self._change_thread.daemon = True
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self._change_event.clear()
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self._change_thread.start()
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def _disable_event_detect(self):
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self._change_event.set()
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self._change_thread.join()
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self._change_thread = None
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def _change_watch(self):
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offset = self._edge_offset
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mask = 1 << self._edge_shift
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self.factory.mem[offset] = mask # clear any existing detection bit
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while not self._change_event.wait(0.001):
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if self.factory.mem[offset] & mask:
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self.factory.mem[offset] = mask
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self._call_when_changed()
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