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#!/usr/bin/env python
#
# backend for serial IO for POSIX compatible systems, like Linux, OSX
#
# This file is part of pySerial. https://github.com/pyserial/pyserial
# (C) 2001-2016 Chris Liechti <cliechti@gmx.net>
#
# SPDX-License-Identifier: BSD-3-Clause
#
# parts based on code from Grant B. Edwards <grante@visi.com>:
# ftp://ftp.visi.com/users/grante/python/PosixSerial.py
#
# references: http://www.easysw.com/~mike/serial/serial.html
# Collection of port names (was previously used by number_to_device which was
# removed.
# - Linux /dev/ttyS%d (confirmed)
# - cygwin/win32 /dev/com%d (confirmed)
# - openbsd (OpenBSD) /dev/cua%02d
# - bsd*, freebsd* /dev/cuad%d
# - darwin (OS X) /dev/cuad%d
# - netbsd /dev/dty%02d (NetBSD 1.6 testing by Erk)
# - irix (IRIX) /dev/ttyf%d (partially tested) names depending on flow control
# - hp (HP-UX) /dev/tty%dp0 (not tested)
# - sunos (Solaris/SunOS) /dev/tty%c (letters, 'a'..'z') (confirmed)
# - aix (AIX) /dev/tty%d
# pylint: disable=abstract-method
import errno
import fcntl
import os
import select
import struct
import sys
import termios
import serial
from serial.serialutil import SerialBase, SerialException, to_bytes, \
portNotOpenError, writeTimeoutError, Timeout
class PlatformSpecificBase(object):
BAUDRATE_CONSTANTS = {}
def _set_special_baudrate(self, baudrate):
raise NotImplementedError('non-standard baudrates are not supported on this platform')
def _set_rs485_mode(self, rs485_settings):
raise NotImplementedError('RS485 not supported on this platform')
# some systems support an extra flag to enable the two in POSIX unsupported
# paritiy settings for MARK and SPACE
CMSPAR = 0 # default, for unsupported platforms, override below
# try to detect the OS so that a device can be selected...
# this code block should supply a device() and set_special_baudrate() function
# for the platform
plat = sys.platform.lower()
if plat[:5] == 'linux': # Linux (confirmed) # noqa
import array
# extra termios flags
CMSPAR = 0o10000000000 # Use "stick" (mark/space) parity
# baudrate ioctls
TCGETS2 = 0x802C542A
TCSETS2 = 0x402C542B
BOTHER = 0o010000
# RS485 ioctls
TIOCGRS485 = 0x542E
TIOCSRS485 = 0x542F
SER_RS485_ENABLED = 0b00000001
SER_RS485_RTS_ON_SEND = 0b00000010
SER_RS485_RTS_AFTER_SEND = 0b00000100
SER_RS485_RX_DURING_TX = 0b00010000
class PlatformSpecific(PlatformSpecificBase):
BAUDRATE_CONSTANTS = {
0: 0o000000, # hang up
50: 0o000001,
75: 0o000002,
110: 0o000003,
134: 0o000004,
150: 0o000005,
200: 0o000006,
300: 0o000007,
600: 0o000010,
1200: 0o000011,
1800: 0o000012,
2400: 0o000013,
4800: 0o000014,
9600: 0o000015,
19200: 0o000016,
38400: 0o000017,
57600: 0o010001,
115200: 0o010002,
230400: 0o010003,
460800: 0o010004,
500000: 0o010005,
576000: 0o010006,
921600: 0o010007,
1000000: 0o010010,
1152000: 0o010011,
1500000: 0o010012,
2000000: 0o010013,
2500000: 0o010014,
3000000: 0o010015,
3500000: 0o010016,
4000000: 0o010017
}
def _set_special_baudrate(self, baudrate):
# right size is 44 on x86_64, allow for some growth
buf = array.array('i', [0] * 64)
try:
# get serial_struct
fcntl.ioctl(self.fd, TCGETS2, buf)
# set custom speed
buf[2] &= ~termios.CBAUD
buf[2] |= BOTHER
buf[9] = buf[10] = baudrate
# set serial_struct
fcntl.ioctl(self.fd, TCSETS2, buf)
except IOError as e:
raise ValueError('Failed to set custom baud rate ({}): {}'.format(baudrate, e))
def _set_rs485_mode(self, rs485_settings):
buf = array.array('i', [0] * 8) # flags, delaytx, delayrx, padding
try:
fcntl.ioctl(self.fd, TIOCGRS485, buf)
buf[0] |= SER_RS485_ENABLED
if rs485_settings is not None:
if rs485_settings.loopback:
buf[0] |= SER_RS485_RX_DURING_TX
else:
buf[0] &= ~SER_RS485_RX_DURING_TX
if rs485_settings.rts_level_for_tx:
buf[0] |= SER_RS485_RTS_ON_SEND
else:
buf[0] &= ~SER_RS485_RTS_ON_SEND
if rs485_settings.rts_level_for_rx:
buf[0] |= SER_RS485_RTS_AFTER_SEND
else:
buf[0] &= ~SER_RS485_RTS_AFTER_SEND
if rs485_settings.delay_before_tx is not None:
buf[1] = int(rs485_settings.delay_before_tx * 1000)
if rs485_settings.delay_before_rx is not None:
buf[2] = int(rs485_settings.delay_before_rx * 1000)
else:
buf[0] = 0 # clear SER_RS485_ENABLED
fcntl.ioctl(self.fd, TIOCSRS485, buf)
except IOError as e:
raise ValueError('Failed to set RS485 mode: {}'.format(e))
elif plat == 'cygwin': # cygwin/win32 (confirmed)
class PlatformSpecific(PlatformSpecificBase):
BAUDRATE_CONSTANTS = {
128000: 0x01003,
256000: 0x01005,
500000: 0x01007,
576000: 0x01008,
921600: 0x01009,
1000000: 0x0100a,
1152000: 0x0100b,
1500000: 0x0100c,
2000000: 0x0100d,
2500000: 0x0100e,
3000000: 0x0100f
}
elif plat[:6] == 'darwin': # OS X
import array
IOSSIOSPEED = 0x80045402 # _IOW('T', 2, speed_t)
class PlatformSpecific(PlatformSpecificBase):
osx_version = os.uname()[2].split('.')
# Tiger or above can support arbitrary serial speeds
if int(osx_version[0]) >= 8:
def _set_special_baudrate(self, baudrate):
# use IOKit-specific call to set up high speeds
buf = array.array('i', [baudrate])
fcntl.ioctl(self.fd, IOSSIOSPEED, buf, 1)
elif plat[:3] == 'bsd' or \
plat[:7] == 'freebsd' or \
plat[:6] == 'netbsd' or \
plat[:7] == 'openbsd':
class ReturnBaudrate(object):
def __getitem__(self, key):
return key
class PlatformSpecific(PlatformSpecificBase):
# Only tested on FreeBSD:
# The baud rate may be passed in as
# a literal value.
BAUDRATE_CONSTANTS = ReturnBaudrate()
else:
class PlatformSpecific(PlatformSpecificBase):
pass
# load some constants for later use.
# try to use values from termios, use defaults from linux otherwise
TIOCMGET = getattr(termios, 'TIOCMGET', 0x5415)
TIOCMBIS = getattr(termios, 'TIOCMBIS', 0x5416)
TIOCMBIC = getattr(termios, 'TIOCMBIC', 0x5417)
TIOCMSET = getattr(termios, 'TIOCMSET', 0x5418)
# TIOCM_LE = getattr(termios, 'TIOCM_LE', 0x001)
TIOCM_DTR = getattr(termios, 'TIOCM_DTR', 0x002)
TIOCM_RTS = getattr(termios, 'TIOCM_RTS', 0x004)
# TIOCM_ST = getattr(termios, 'TIOCM_ST', 0x008)
# TIOCM_SR = getattr(termios, 'TIOCM_SR', 0x010)
TIOCM_CTS = getattr(termios, 'TIOCM_CTS', 0x020)
TIOCM_CAR = getattr(termios, 'TIOCM_CAR', 0x040)
TIOCM_RNG = getattr(termios, 'TIOCM_RNG', 0x080)
TIOCM_DSR = getattr(termios, 'TIOCM_DSR', 0x100)
TIOCM_CD = getattr(termios, 'TIOCM_CD', TIOCM_CAR)
TIOCM_RI = getattr(termios, 'TIOCM_RI', TIOCM_RNG)
# TIOCM_OUT1 = getattr(termios, 'TIOCM_OUT1', 0x2000)
# TIOCM_OUT2 = getattr(termios, 'TIOCM_OUT2', 0x4000)
if hasattr(termios, 'TIOCINQ'):
TIOCINQ = termios.TIOCINQ
else:
TIOCINQ = getattr(termios, 'FIONREAD', 0x541B)
TIOCOUTQ = getattr(termios, 'TIOCOUTQ', 0x5411)
TIOCM_zero_str = struct.pack('I', 0)
TIOCM_RTS_str = struct.pack('I', TIOCM_RTS)
TIOCM_DTR_str = struct.pack('I', TIOCM_DTR)
TIOCSBRK = getattr(termios, 'TIOCSBRK', 0x5427)
TIOCCBRK = getattr(termios, 'TIOCCBRK', 0x5428)
class Serial(SerialBase, PlatformSpecific):
"""\
Serial port class POSIX implementation. Serial port configuration is
done with termios and fcntl. Runs on Linux and many other Un*x like
systems.
"""
def open(self):
"""\
Open port with current settings. This may throw a SerialException
if the port cannot be opened."""
if self._port is None:
raise SerialException("Port must be configured before it can be used.")
if self.is_open:
raise SerialException("Port is already open.")
self.fd = None
# open
try:
self.fd = os.open(self.portstr, os.O_RDWR | os.O_NOCTTY | os.O_NONBLOCK)
except OSError as msg:
self.fd = None
raise SerialException(msg.errno, "could not open port {}: {}".format(self._port, msg))
#~ fcntl.fcntl(self.fd, fcntl.F_SETFL, 0) # set blocking
try:
self._reconfigure_port(force_update=True)
except:
try:
os.close(self.fd)
except:
# ignore any exception when closing the port
# also to keep original exception that happened when setting up
pass
self.fd = None
raise
else:
self.is_open = True
try:
if not self._dsrdtr:
self._update_dtr_state()
if not self._rtscts:
self._update_rts_state()
except IOError as e:
if e.errno in (errno.EINVAL, errno.ENOTTY):
# ignore Invalid argument and Inappropriate ioctl
pass
else:
raise
self.reset_input_buffer()
self.pipe_abort_read_r, self.pipe_abort_read_w = os.pipe()
self.pipe_abort_write_r, self.pipe_abort_write_w = os.pipe()
fcntl.fcntl(self.pipe_abort_read_r, fcntl.F_SETFL, os.O_NONBLOCK)
fcntl.fcntl(self.pipe_abort_write_r, fcntl.F_SETFL, os.O_NONBLOCK)
def _reconfigure_port(self, force_update=False):
"""Set communication parameters on opened port."""
if self.fd is None:
raise SerialException("Can only operate on a valid file descriptor")
# if exclusive lock is requested, create it before we modify anything else
if self._exclusive is not None:
if self._exclusive:
try:
fcntl.flock(self.fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
except IOError as msg:
raise SerialException(msg.errno, "Could not exclusively lock port {}: {}".format(self._port, msg))
else:
fcntl.flock(self.fd, fcntl.LOCK_UN)
custom_baud = None
vmin = vtime = 0 # timeout is done via select
if self._inter_byte_timeout is not None:
vmin = 1
vtime = int(self._inter_byte_timeout * 10)
try:
orig_attr = termios.tcgetattr(self.fd)
iflag, oflag, cflag, lflag, ispeed, ospeed, cc = orig_attr
except termios.error as msg: # if a port is nonexistent but has a /dev file, it'll fail here
raise SerialException("Could not configure port: {}".format(msg))
# set up raw mode / no echo / binary
cflag |= (termios.CLOCAL | termios.CREAD)
lflag &= ~(termios.ICANON | termios.ECHO | termios.ECHOE |
termios.ECHOK | termios.ECHONL |
termios.ISIG | termios.IEXTEN) # |termios.ECHOPRT
for flag in ('ECHOCTL', 'ECHOKE'): # netbsd workaround for Erk
if hasattr(termios, flag):
lflag &= ~getattr(termios, flag)
oflag &= ~(termios.OPOST | termios.ONLCR | termios.OCRNL)
iflag &= ~(termios.INLCR | termios.IGNCR | termios.ICRNL | termios.IGNBRK)
if hasattr(termios, 'IUCLC'):
iflag &= ~termios.IUCLC
if hasattr(termios, 'PARMRK'):
iflag &= ~termios.PARMRK
# setup baud rate
try:
ispeed = ospeed = getattr(termios, 'B{}'.format(self._baudrate))
except AttributeError:
try:
ispeed = ospeed = self.BAUDRATE_CONSTANTS[self._baudrate]
except KeyError:
#~ raise ValueError('Invalid baud rate: %r' % self._baudrate)
# may need custom baud rate, it isn't in our list.
ispeed = ospeed = getattr(termios, 'B38400')
try:
custom_baud = int(self._baudrate) # store for later
except ValueError:
raise ValueError('Invalid baud rate: {!r}'.format(self._baudrate))
else:
if custom_baud < 0:
raise ValueError('Invalid baud rate: {!r}'.format(self._baudrate))
# setup char len
cflag &= ~termios.CSIZE
if self._bytesize == 8:
cflag |= termios.CS8
elif self._bytesize == 7:
cflag |= termios.CS7
elif self._bytesize == 6:
cflag |= termios.CS6
elif self._bytesize == 5:
cflag |= termios.CS5
else:
raise ValueError('Invalid char len: {!r}'.format(self._bytesize))
# setup stop bits
if self._stopbits == serial.STOPBITS_ONE:
cflag &= ~(termios.CSTOPB)
elif self._stopbits == serial.STOPBITS_ONE_POINT_FIVE:
cflag |= (termios.CSTOPB) # XXX same as TWO.. there is no POSIX support for 1.5
elif self._stopbits == serial.STOPBITS_TWO:
cflag |= (termios.CSTOPB)
else:
raise ValueError('Invalid stop bit specification: {!r}'.format(self._stopbits))
# setup parity
iflag &= ~(termios.INPCK | termios.ISTRIP)
if self._parity == serial.PARITY_NONE:
cflag &= ~(termios.PARENB | termios.PARODD | CMSPAR)
elif self._parity == serial.PARITY_EVEN:
cflag &= ~(termios.PARODD | CMSPAR)
cflag |= (termios.PARENB)
elif self._parity == serial.PARITY_ODD:
cflag &= ~CMSPAR
cflag |= (termios.PARENB | termios.PARODD)
elif self._parity == serial.PARITY_MARK and CMSPAR:
cflag |= (termios.PARENB | CMSPAR | termios.PARODD)
elif self._parity == serial.PARITY_SPACE and CMSPAR:
cflag |= (termios.PARENB | CMSPAR)
cflag &= ~(termios.PARODD)
else:
raise ValueError('Invalid parity: {!r}'.format(self._parity))
# setup flow control
# xonxoff
if hasattr(termios, 'IXANY'):
if self._xonxoff:
iflag |= (termios.IXON | termios.IXOFF) # |termios.IXANY)
else:
iflag &= ~(termios.IXON | termios.IXOFF | termios.IXANY)
else:
if self._xonxoff:
iflag |= (termios.IXON | termios.IXOFF)
else:
iflag &= ~(termios.IXON | termios.IXOFF)
# rtscts
if hasattr(termios, 'CRTSCTS'):
if self._rtscts:
cflag |= (termios.CRTSCTS)
else:
cflag &= ~(termios.CRTSCTS)
elif hasattr(termios, 'CNEW_RTSCTS'): # try it with alternate constant name
if self._rtscts:
cflag |= (termios.CNEW_RTSCTS)
else:
cflag &= ~(termios.CNEW_RTSCTS)
# XXX should there be a warning if setting up rtscts (and xonxoff etc) fails??
# buffer
# vmin "minimal number of characters to be read. 0 for non blocking"
if vmin < 0 or vmin > 255:
raise ValueError('Invalid vmin: {!r}'.format(vmin))
cc[termios.VMIN] = vmin
# vtime
if vtime < 0 or vtime > 255:
raise ValueError('Invalid vtime: {!r}'.format(vtime))
cc[termios.VTIME] = vtime
# activate settings
if force_update or [iflag, oflag, cflag, lflag, ispeed, ospeed, cc] != orig_attr:
termios.tcsetattr(
self.fd,
termios.TCSANOW,
[iflag, oflag, cflag, lflag, ispeed, ospeed, cc])
# apply custom baud rate, if any
if custom_baud is not None:
self._set_special_baudrate(custom_baud)
if self._rs485_mode is not None:
self._set_rs485_mode(self._rs485_mode)
def close(self):
"""Close port"""
if self.is_open:
if self.fd is not None:
os.close(self.fd)
self.fd = None
os.close(self.pipe_abort_read_w)
os.close(self.pipe_abort_read_r)
os.close(self.pipe_abort_write_w)
os.close(self.pipe_abort_write_r)
self.pipe_abort_read_r, self.pipe_abort_read_w = None, None
self.pipe_abort_write_r, self.pipe_abort_write_w = None, None
self.is_open = False
# - - - - - - - - - - - - - - - - - - - - - - - -
@property
def in_waiting(self):
"""Return the number of bytes currently in the input buffer."""
#~ s = fcntl.ioctl(self.fd, termios.FIONREAD, TIOCM_zero_str)
s = fcntl.ioctl(self.fd, TIOCINQ, TIOCM_zero_str)
return struct.unpack('I', s)[0]
# select based implementation, proved to work on many systems
def read(self, size=1):
"""\
Read size bytes from the serial port. If a timeout is set it may
return less characters as requested. With no timeout it will block
until the requested number of bytes is read.
"""
if not self.is_open:
raise portNotOpenError
read = bytearray()
timeout = Timeout(self._timeout)
while len(read) < size:
try:
ready, _, _ = select.select([self.fd, self.pipe_abort_read_r], [], [], timeout.time_left())
if self.pipe_abort_read_r in ready:
os.read(self.pipe_abort_read_r, 1000)
break
# If select was used with a timeout, and the timeout occurs, it
# returns with empty lists -> thus abort read operation.
# For timeout == 0 (non-blocking operation) also abort when
# there is nothing to read.
if not ready:
break # timeout
buf = os.read(self.fd, size - len(read))
# read should always return some data as select reported it was
# ready to read when we get to this point.
if not buf:
# Disconnected devices, at least on Linux, show the
# behavior that they are always ready to read immediately
# but reading returns nothing.
raise SerialException(
'device reports readiness to read but returned no data '
'(device disconnected or multiple access on port?)')
read.extend(buf)
except OSError as e:
# this is for Python 3.x where select.error is a subclass of
# OSError ignore BlockingIOErrors and EINTR. other errors are shown
# https://www.python.org/dev/peps/pep-0475.
if e.errno not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
raise SerialException('read failed: {}'.format(e))
except select.error as e:
# this is for Python 2.x
# ignore BlockingIOErrors and EINTR. all errors are shown
# see also http://www.python.org/dev/peps/pep-3151/#select
if e[0] not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
raise SerialException('read failed: {}'.format(e))
if timeout.expired():
break
return bytes(read)
def cancel_read(self):
if self.is_open:
os.write(self.pipe_abort_read_w, b"x")
def cancel_write(self):
if self.is_open:
os.write(self.pipe_abort_write_w, b"x")
def write(self, data):
"""Output the given byte string over the serial port."""
if not self.is_open:
raise portNotOpenError
d = to_bytes(data)
tx_len = length = len(d)
timeout = Timeout(self._write_timeout)
while tx_len > 0:
try:
n = os.write(self.fd, d)
if timeout.is_non_blocking:
# Zero timeout indicates non-blocking - simply return the
# number of bytes of data actually written
return n
elif not timeout.is_infinite:
# when timeout is set, use select to wait for being ready
# with the time left as timeout
if timeout.expired():
raise writeTimeoutError
abort, ready, _ = select.select([self.pipe_abort_write_r], [self.fd], [], timeout.time_left())
if abort:
os.read(self.pipe_abort_write_r, 1000)
break
if not ready:
raise writeTimeoutError
else:
assert timeout.time_left() is None
# wait for write operation
abort, ready, _ = select.select([self.pipe_abort_write_r], [self.fd], [], None)
if abort:
os.read(self.pipe_abort_write_r, 1)
break
if not ready:
raise SerialException('write failed (select)')
d = d[n:]
tx_len -= n
except SerialException:
raise
except OSError as e:
# this is for Python 3.x where select.error is a subclass of
# OSError ignore BlockingIOErrors and EINTR. other errors are shown
# https://www.python.org/dev/peps/pep-0475.
if e.errno not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
raise SerialException('write failed: {}'.format(e))
except select.error as e:
# this is for Python 2.x
# ignore BlockingIOErrors and EINTR. all errors are shown
# see also http://www.python.org/dev/peps/pep-3151/#select
if e[0] not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
raise SerialException('write failed: {}'.format(e))
if not timeout.is_non_blocking and timeout.expired():
raise writeTimeoutError
return length - len(d)
def flush(self):
"""\
Flush of file like objects. In this case, wait until all data
is written.
"""
if not self.is_open:
raise portNotOpenError
termios.tcdrain(self.fd)
def reset_input_buffer(self):
"""Clear input buffer, discarding all that is in the buffer."""
if not self.is_open:
raise portNotOpenError
termios.tcflush(self.fd, termios.TCIFLUSH)
def reset_output_buffer(self):
"""\
Clear output buffer, aborting the current output and discarding all
that is in the buffer.
"""
if not self.is_open:
raise portNotOpenError
termios.tcflush(self.fd, termios.TCOFLUSH)
def send_break(self, duration=0.25):
"""\
Send break condition. Timed, returns to idle state after given
duration.
"""
if not self.is_open:
raise portNotOpenError
termios.tcsendbreak(self.fd, int(duration / 0.25))
def _update_break_state(self):
"""\
Set break: Controls TXD. When active, no transmitting is possible.
"""
if self._break_state:
fcntl.ioctl(self.fd, TIOCSBRK)
else:
fcntl.ioctl(self.fd, TIOCCBRK)
def _update_rts_state(self):
"""Set terminal status line: Request To Send"""
if self._rts_state:
fcntl.ioctl(self.fd, TIOCMBIS, TIOCM_RTS_str)
else:
fcntl.ioctl(self.fd, TIOCMBIC, TIOCM_RTS_str)
def _update_dtr_state(self):
"""Set terminal status line: Data Terminal Ready"""
if self._dtr_state:
fcntl.ioctl(self.fd, TIOCMBIS, TIOCM_DTR_str)
else:
fcntl.ioctl(self.fd, TIOCMBIC, TIOCM_DTR_str)
@property
def cts(self):
"""Read terminal status line: Clear To Send"""
if not self.is_open:
raise portNotOpenError
s = fcntl.ioctl(self.fd, TIOCMGET, TIOCM_zero_str)
return struct.unpack('I', s)[0] & TIOCM_CTS != 0
@property
def dsr(self):
"""Read terminal status line: Data Set Ready"""
if not self.is_open:
raise portNotOpenError
s = fcntl.ioctl(self.fd, TIOCMGET, TIOCM_zero_str)
return struct.unpack('I', s)[0] & TIOCM_DSR != 0
@property
def ri(self):
"""Read terminal status line: Ring Indicator"""
if not self.is_open:
raise portNotOpenError
s = fcntl.ioctl(self.fd, TIOCMGET, TIOCM_zero_str)
return struct.unpack('I', s)[0] & TIOCM_RI != 0
@property
def cd(self):
"""Read terminal status line: Carrier Detect"""
if not self.is_open:
raise portNotOpenError
s = fcntl.ioctl(self.fd, TIOCMGET, TIOCM_zero_str)
return struct.unpack('I', s)[0] & TIOCM_CD != 0
# - - platform specific - - - -
@property
def out_waiting(self):
"""Return the number of bytes currently in the output buffer."""
#~ s = fcntl.ioctl(self.fd, termios.FIONREAD, TIOCM_zero_str)
s = fcntl.ioctl(self.fd, TIOCOUTQ, TIOCM_zero_str)
return struct.unpack('I', s)[0]
def fileno(self):
"""\
For easier use of the serial port instance with select.
WARNING: this function is not portable to different platforms!
"""
if not self.is_open:
raise portNotOpenError
return self.fd
def set_input_flow_control(self, enable=True):
"""\
Manually control flow - when software flow control is enabled.
This will send XON (true) or XOFF (false) to the other device.
WARNING: this function is not portable to different platforms!
"""
if not self.is_open:
raise portNotOpenError
if enable:
termios.tcflow(self.fd, termios.TCION)
else:
termios.tcflow(self.fd, termios.TCIOFF)
def set_output_flow_control(self, enable=True):
"""\
Manually control flow of outgoing data - when hardware or software flow
control is enabled.
WARNING: this function is not portable to different platforms!
"""
if not self.is_open:
raise portNotOpenError
if enable:
termios.tcflow(self.fd, termios.TCOON)
else:
termios.tcflow(self.fd, termios.TCOOFF)
def nonblocking(self):
"""DEPRECATED - has no use"""
import warnings
warnings.warn("nonblocking() has no effect, already nonblocking", DeprecationWarning)
class PosixPollSerial(Serial):
"""\
Poll based read implementation. Not all systems support poll properly.
However this one has better handling of errors, such as a device
disconnecting while it's in use (e.g. USB-serial unplugged).
"""
def read(self, size=1):
"""\
Read size bytes from the serial port. If a timeout is set it may
return less characters as requested. With no timeout it will block
until the requested number of bytes is read.
"""
if not self.is_open:
raise portNotOpenError
read = bytearray()
poll = select.poll()
poll.register(self.fd, select.POLLIN | select.POLLERR | select.POLLHUP | select.POLLNVAL)
if size > 0:
while len(read) < size:
# print "\tread(): size",size, "have", len(read) #debug
# wait until device becomes ready to read (or something fails)
for fd, event in poll.poll(self._timeout * 1000):
if event & (select.POLLERR | select.POLLHUP | select.POLLNVAL):
raise SerialException('device reports error (poll)')
# we don't care if it is select.POLLIN or timeout, that's
# handled below
buf = os.read(self.fd, size - len(read))
read.extend(buf)
if ((self._timeout is not None and self._timeout >= 0) or
(self._inter_byte_timeout is not None and self._inter_byte_timeout > 0)) and not buf:
break # early abort on timeout
return bytes(read)
class VTIMESerial(Serial):
"""\
Implement timeout using vtime of tty device instead of using select.
This means that no inter character timeout can be specified and that
the error handling is degraded.
Overall timeout is disabled when inter-character timeout is used.
"""
def _reconfigure_port(self, force_update=True):
"""Set communication parameters on opened port."""
super(VTIMESerial, self)._reconfigure_port()
fcntl.fcntl(self.fd, fcntl.F_SETFL, 0) # clear O_NONBLOCK
if self._inter_byte_timeout is not None:
vmin = 1
vtime = int(self._inter_byte_timeout * 10)
elif self._timeout is None:
vmin = 1
vtime = 0
else:
vmin = 0
vtime = int(self._timeout * 10)
try:
orig_attr = termios.tcgetattr(self.fd)
iflag, oflag, cflag, lflag, ispeed, ospeed, cc = orig_attr
except termios.error as msg: # if a port is nonexistent but has a /dev file, it'll fail here
raise serial.SerialException("Could not configure port: {}".format(msg))
if vtime < 0 or vtime > 255:
raise ValueError('Invalid vtime: {!r}'.format(vtime))
cc[termios.VTIME] = vtime
cc[termios.VMIN] = vmin
termios.tcsetattr(
self.fd,
termios.TCSANOW,
[iflag, oflag, cflag, lflag, ispeed, ospeed, cc])
def read(self, size=1):
"""\
Read size bytes from the serial port. If a timeout is set it may
return less characters as requested. With no timeout it will block
until the requested number of bytes is read.
"""
if not self.is_open:
raise portNotOpenError
read = bytearray()
while len(read) < size:
buf = os.read(self.fd, size - len(read))
if not buf:
break
read.extend(buf)
return bytes(read)
# hack to make hasattr return false
cancel_read = property()
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