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- # The MIT License (MIT)
- #
- # Copyright (c) 2016 Scott Shawcroft for Adafruit Industries
- #
- # Permission is hereby granted, free of charge, to any person obtaining a copy
- # of this software and associated documentation files (the "Software"), to deal
- # in the Software without restriction, including without limitation the rights
- # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- # copies of the Software, and to permit persons to whom the Software is
- # furnished to do so, subject to the following conditions:
- #
- # The above copyright notice and this permission notice shall be included in
- # all copies or substantial portions of the Software.
- #
- # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- # THE SOFTWARE.
-
- """
- `adafruit_bus_device.i2c_device` - I2C Bus Device
- ====================================================
- """
-
- __version__ = "2.2.2"
- __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_BusDevice.git"
-
- class I2CDevice:
- """
- Represents a single I2C device and manages locking the bus and the device
- address.
-
- :param ~busio.I2C i2c: The I2C bus the device is on
- :param int device_address: The 7 bit device address
-
- .. note:: This class is **NOT** built into CircuitPython. See
- :ref:`here for install instructions <bus_device_installation>`.
-
- Example:
-
- .. code-block:: python
-
- import busio
- from board import *
- from adafruit_bus_device.i2c_device import I2CDevice
-
- with busio.I2C(SCL, SDA) as i2c:
- device = I2CDevice(i2c, 0x70)
- bytes_read = bytearray(4)
- with device:
- device.readinto(bytes_read)
- # A second transaction
- with device:
- device.write(bytes_read)
- """
- def __init__(self, i2c, device_address):
- # Verify that a deivce with that address exists.
- while not i2c.try_lock():
- pass
- try:
- i2c.writeto(device_address, b'')
- except OSError:
- raise ValueError("No I2C device at address: %x" % device_address)
- finally:
- i2c.unlock()
-
- self.i2c = i2c
- self.device_address = device_address
-
- def readinto(self, buf, **kwargs):
- """
- Read into ``buf`` from the device. The number of bytes read will be the
- length of ``buf``.
-
- If ``start`` or ``end`` is provided, then the buffer will be sliced
- as if ``buf[start:end]``. This will not cause an allocation like
- ``buf[start:end]`` will so it saves memory.
-
- :param bytearray buffer: buffer to write into
- :param int start: Index to start writing at
- :param int end: Index to write up to but not include
- """
- self.i2c.readfrom_into(self.device_address, buf, **kwargs)
-
- def write(self, buf, **kwargs):
- """
- Write the bytes from ``buffer`` to the device. Transmits a stop bit if
- ``stop`` is set.
-
- If ``start`` or ``end`` is provided, then the buffer will be sliced
- as if ``buffer[start:end]``. This will not cause an allocation like
- ``buffer[start:end]`` will so it saves memory.
-
- :param bytearray buffer: buffer containing the bytes to write
- :param int start: Index to start writing from
- :param int end: Index to read up to but not include
- :param bool stop: If true, output an I2C stop condition after the buffer is written
- """
- self.i2c.writeto(self.device_address, buf, **kwargs)
-
- def __enter__(self):
- while not self.i2c.try_lock():
- pass
- return self
-
- def __exit__(self, *exc):
- self.i2c.unlock()
- return False
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