# 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__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_BusDevice.git"
[docs]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 device 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
[docs] 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)
[docs] 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)
#pylint: disable-msg=too-many-arguments
[docs] def write_then_readinto(self, out_buffer, in_buffer, *,
out_start=0, out_end=None, in_start=0, in_end=None, stop=True):
"""
Write the bytes from ``out_buffer`` to the device, then immediately
reads into ``in_buffer`` from the device. The number of bytes read
will be the length of ``in_buffer``.
Transmits a stop bit after the write, if ``stop`` is set.
If ``out_start`` or ``out_end`` is provided, then the output buffer
will be sliced as if ``out_buffer[out_start:out_end]``. This will
not cause an allocation like ``buffer[out_start:out_end]`` will so
it saves memory.
If ``in_start`` or ``in_end`` is provided, then the input buffer
will be sliced as if ``in_buffer[in_start:in_end]``. This will not
cause an allocation like ``in_buffer[in_start:in_end]`` will so
it saves memory.
:param bytearray out_buffer: buffer containing the bytes to write
:param bytearray in_buffer: buffer containing the bytes to read into
:param int out_start: Index to start writing from
:param int out_end: Index to read up to but not include
:param int in_start: Index to start writing at
:param int in_end: Index to write up to but not include
:param bool stop: If true, output an I2C stop condition after the buffer is written
"""
if out_end is None:
out_end = len(out_buffer)
if in_end is None:
in_end = len(in_buffer)
if hasattr(self.i2c, 'writeto_then_readfrom'):
# In linux, at least, this is a special kernel function call
self.i2c.writeto_then_readfrom(self.device_address, out_buffer, in_buffer,
out_start=out_start, out_end=out_end,
in_start=in_start, in_end=in_end, stop=stop)
else:
# If we don't have a special implementation, we can fake it with two calls
self.write(out_buffer, start=out_start, end=out_end, stop=stop)
self.readinto(in_buffer, start=in_start, end=in_end)
#pylint: enable-msg=too-many-arguments
def __enter__(self):
while not self.i2c.try_lock():
pass
return self
def __exit__(self, *exc):
self.i2c.unlock()
return False