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116 lines
3.6 KiB
116 lines
3.6 KiB
5 years ago
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#!/usr/bin/env python3
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#
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# Python Serial Port Extension for Win32, Linux, BSD, Jython
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# module for serial IO for POSIX compatible systems, like Linux
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# see __init__.py
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#
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# (C) 2015 Chris Liechti <cliechti@gmx.net>
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#
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# SPDX-License-Identifier: BSD-3-Clause
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"""\
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Support asyncio with serial ports. EXPERIMENTAL
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Posix platforms only, Python 3.4+ only.
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Windows event loops can not wait for serial ports with the current
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implementation. It should be possible to get that working though.
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"""
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import asyncio
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import serial
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import logger
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class SerialTransport(asyncio.Transport):
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def __init__(self, loop, protocol, serial_instance):
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self._loop = loop
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self._protocol = protocol
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self.serial = serial_instance
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self._closing = False
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self._paused = False
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# XXX how to support url handlers too
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self.serial.timeout = 0
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self.serial.nonblocking()
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loop.call_soon(protocol.connection_made, self)
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# only start reading when connection_made() has been called
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loop.call_soon(loop.add_reader, self.serial.fd, self._read_ready)
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def __repr__(self):
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return '{self.__class__.__name__}({self._loop}, {self._protocol}, {self.serial})'.format(self=self)
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def close(self):
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if self._closing:
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return
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self._closing = True
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self._loop.remove_reader(self.serial.fd)
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self.serial.close()
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self._loop.call_soon(self._protocol.connection_lost, None)
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def _read_ready(self):
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data = self.serial.read(1024)
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if data:
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self._protocol.data_received(data)
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def write(self, data):
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self.serial.write(data)
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def can_write_eof(self):
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return False
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def pause_reading(self):
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if self._closing:
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raise RuntimeError('Cannot pause_reading() when closing')
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if self._paused:
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raise RuntimeError('Already paused')
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self._paused = True
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self._loop.remove_reader(self._sock_fd)
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if self._loop.get_debug():
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logger.debug("%r pauses reading", self)
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def resume_reading(self):
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if not self._paused:
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raise RuntimeError('Not paused')
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self._paused = False
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if self._closing:
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return
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self._loop.add_reader(self._sock_fd, self._read_ready)
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if self._loop.get_debug():
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logger.debug("%r resumes reading", self)
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#~ def set_write_buffer_limits(self, high=None, low=None):
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#~ def get_write_buffer_size(self):
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#~ def writelines(self, list_of_data):
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#~ def write_eof(self):
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#~ def abort(self):
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@asyncio.coroutine
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def create_serial_connection(loop, protocol_factory, *args, **kwargs):
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ser = serial.Serial(*args, **kwargs)
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protocol = protocol_factory()
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transport = SerialTransport(loop, protocol, ser)
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return (transport, protocol)
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# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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# test
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if __name__ == '__main__':
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class Output(asyncio.Protocol):
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def connection_made(self, transport):
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self.transport = transport
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print('port opened', transport)
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transport.serial.rts = False
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transport.write(b'hello world\n')
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def data_received(self, data):
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print('data received', repr(data))
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self.transport.close()
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def connection_lost(self, exc):
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print('port closed')
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asyncio.get_event_loop().stop()
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loop = asyncio.get_event_loop()
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coro = create_serial_connection(loop, Output, '/dev/ttyUSB0', baudrate=115200)
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loop.run_until_complete(coro)
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loop.run_forever()
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loop.close()
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