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# Copyright 2021-2022 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# -----------------------------------------------------------------------------
# Imports
# -----------------------------------------------------------------------------
import asyncio
import logging
import serial_asyncio
from bumble.transport.common import StreamPacketSink, StreamPacketSource, Transport
# -----------------------------------------------------------------------------
# Logging
# -----------------------------------------------------------------------------
logger = logging.getLogger(__name__)
# -----------------------------------------------------------------------------
# Constants
# -----------------------------------------------------------------------------
DEFAULT_POST_OPEN_DELAY = 0.5 # in seconds
# -----------------------------------------------------------------------------
# Classes and Functions
# -----------------------------------------------------------------------------
# -----------------------------------------------------------------------------
class SerialPacketSource(StreamPacketSource):
def __init__(self) -> None:
super().__init__()
self._ready = asyncio.Event()
async def wait_until_ready(self) -> None:
await self._ready.wait()
def connection_made(self, transport: asyncio.BaseTransport) -> None:
logger.debug('connection made')
self._ready.set()
def connection_lost(self, exc: Exception | None) -> None:
logger.debug('connection lost')
self.on_transport_lost()
# -----------------------------------------------------------------------------
async def open_serial_transport(spec: str) -> Transport:
'''
Open a serial port transport.
The parameter string has this syntax:
<device-path>[,<speed>][,rtscts][,dsrdtr][,delay]
When <speed> is omitted, the default value of 1000000 is used
When "rtscts" is specified, RTS/CTS hardware flow control is enabled
When "dsrdtr" is specified, DSR/DTR hardware flow control is enabled
When "delay" is specified, a short delay is added after opening the port
Examples:
/dev/tty.usbmodem0006839912172
/dev/tty.usbmodem0006839912172,1000000
/dev/tty.usbmodem0006839912172,rtscts
/dev/tty.usbmodem0006839912172,rtscts,delay
'''
speed = 1000000
rtscts = False
dsrdtr = False
delay = 0.0
if ',' in spec:
parts = spec.split(',')
device = parts[0]
for part in parts[1:]:
if part == 'rtscts':
rtscts = True
elif part == 'dsrdtr':
dsrdtr = True
elif part == 'delay':
delay = DEFAULT_POST_OPEN_DELAY
elif part.isnumeric():
speed = int(part)
else:
device = spec
serial_transport, packet_source = await serial_asyncio.create_serial_connection(
asyncio.get_running_loop(),
SerialPacketSource,
device,
baudrate=speed,
rtscts=rtscts,
dsrdtr=dsrdtr,
)
packet_sink = StreamPacketSink(serial_transport)
logger.debug('waiting for the port to be ready')
await packet_source.wait_until_ready()
logger.debug('port is ready')
# Try to assert DTR
assert serial_transport.serial is not None
try:
serial_transport.serial.dtr = True
logger.debug(
f"DSR={serial_transport.serial.dsr}, DTR={serial_transport.serial.dtr}"
)
except Exception as e:
logger.warning(f'could not assert DTR: {e}')
# Wait a bit after opening the port, if requested
if delay > 0.0:
logger.debug(f'waiting {delay} seconds after opening the port')
await asyncio.sleep(delay)
return Transport(packet_source, packet_sink)
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