# SPDX-FileCopyrightText: 2017 Carter Nelson for Adafruit Industries
#
# SPDX-License-Identifier: MIT
"""
`adafruit_onewire.device`
====================================================
Provides access to a single device on the 1-Wire bus.
* Author(s): Carter Nelson
"""
__version__ = "0.0.0+auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_OneWire.git"
try:
from typing import Optional, Type
from circuitpython_typing import ReadableBuffer, WriteableBuffer
from types import TracebackType
from adafruit_onewire.bus import OneWireBus, OneWireAddress
except ImportError:
pass
_MATCH_ROM = b"\x55"
[docs]
class OneWireDevice:
"""A class to represent a single device on the 1-Wire bus."""
def __init__(self, bus: OneWireBus, address: OneWireAddress):
self._bus = bus
self._address = address
def __enter__(self) -> "OneWireDevice":
self._select_rom()
return self
def __exit__(
self,
exception_type: Optional[Type[type]],
exception_value: Optional[BaseException],
traceback: Optional[TracebackType],
) -> bool:
return False
[docs]
def readinto(
self, buf: WriteableBuffer, *, start: int = 0, end: Optional[int] = None
) -> None:
"""
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 WriteableBuffer buf: Buffer to write into
:param int start: Index to start writing at
:param int end: Index to write up to but not include
"""
self._bus.readinto(buf, start=start, end=end)
if start == 0 and end is None and len(buf) >= 8:
if self._bus.crc8(buf):
raise RuntimeError("CRC error.")
[docs]
def write(
self, buf: ReadableBuffer, *, start: int = 0, end: Optional[int] = None
) -> None:
"""
Write the bytes from ``buf`` to the device.
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 ReadableBuffer buf: 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
"""
return self._bus.write(buf, start=start, end=end)
def _select_rom(self) -> None:
self._bus.reset()
self.write(_MATCH_ROM)
self.write(self._address.rom)