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Federica Lionetto
#!/usr/bin/env python
#
# Python Serial Port Extension for Win32, Linux, BSD, Jython
# module for serial IO for POSIX compatible systems, like Linux
# see __init__.py
#
# (C) 2001-2010 Chris Liechti <cliechti@gmx.net>
# this is distributed under a free software license, see license.txt
#
# 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
import sys, os, fcntl, termios, struct, select, errno, time
from serial.serialutil import *
# Do check the Python version as some constants have moved.
if (sys.hexversion < 0x020100f0):
import TERMIOS
else:
TERMIOS = termios
if (sys.hexversion < 0x020200f0):
import FCNTL
else:
FCNTL = fcntl
# 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)
def device(port):
return '/dev/ttyS%d' % port
TCGETS2 = 0x802C542A
TCSETS2 = 0x402C542B
BOTHER = 0o010000
def set_special_baudrate(port, baudrate):
# right size is 44 on x86_64, allow for some growth
import array
buf = array.array('i', [0] * 64)
try:
# get serial_struct
FCNTL.ioctl(port.fd, TCGETS2, buf)
# set custom speed
buf[2] &= ~TERMIOS.CBAUD
buf[2] |= BOTHER
buf[9] = buf[10] = baudrate
# set serial_struct
res = FCNTL.ioctl(port.fd, TCSETS2, buf)
except IOError, e:
raise ValueError('Failed to set custom baud rate (%s): %s' % (baudrate, e))
baudrate_constants = {
0: 0000000, # hang up
50: 0000001,
75: 0000002,
110: 0000003,
134: 0000004,
150: 0000005,
200: 0000006,
300: 0000007,
600: 0000010,
1200: 0000011,
1800: 0000012,
2400: 0000013,
4800: 0000014,
9600: 0000015,
19200: 0000016,
38400: 0000017,
57600: 0010001,
115200: 0010002,
230400: 0010003,
460800: 0010004,
500000: 0010005,
576000: 0010006,
921600: 0010007,
1000000: 0010010,
1152000: 0010011,
1500000: 0010012,
2000000: 0010013,
2500000: 0010014,
3000000: 0010015,
3500000: 0010016,
4000000: 0010017
}
elif plat == 'cygwin': # cygwin/win32 (confirmed)
def device(port):
return '/dev/com%d' % (port + 1)
def set_special_baudrate(port, baudrate):
raise ValueError("sorry don't know how to handle non standard baud rate on this platform")
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[:7] == 'openbsd': # OpenBSD
def device(port):
return '/dev/cua%02d' % port
def set_special_baudrate(port, baudrate):
raise ValueError("sorry don't know how to handle non standard baud rate on this platform")
baudrate_constants = {}
elif plat[:3] == 'bsd' or \
plat[:7] == 'freebsd':
def device(port):
return '/dev/cuad%d' % port
def set_special_baudrate(port, baudrate):
raise ValueError("sorry don't know how to handle non standard baud rate on this platform")
baudrate_constants = {}
elif plat[:6] == 'darwin': # OS X
version = os.uname()[2].split('.')
# Tiger or above can support arbitrary serial speeds
if int(version[0]) >= 8:
def set_special_baudrate(port, baudrate):
# use IOKit-specific call to set up high speeds
import array, fcntl
buf = array.array('i', [baudrate])
IOSSIOSPEED = 0x80045402 #_IOW('T', 2, speed_t)
fcntl.ioctl(port.fd, IOSSIOSPEED, buf, 1)
else: # version < 8
def set_special_baudrate(port, baudrate):
raise ValueError("baud rate not supported")
def device(port):
return '/dev/cuad%d' % port
baudrate_constants = {}
elif plat[:6] == 'netbsd': # NetBSD 1.6 testing by Erk
def device(port):
return '/dev/dty%02d' % port
def set_special_baudrate(port, baudrate):
raise ValueError("sorry don't know how to handle non standard baud rate on this platform")
baudrate_constants = {}
elif plat[:4] == 'irix': # IRIX (partially tested)
def device(port):
return '/dev/ttyf%d' % (port+1) #XXX different device names depending on flow control
def set_special_baudrate(port, baudrate):
raise ValueError("sorry don't know how to handle non standard baud rate on this platform")
baudrate_constants = {}
elif plat[:2] == 'hp': # HP-UX (not tested)
def device(port):
return '/dev/tty%dp0' % (port+1)
def set_special_baudrate(port, baudrate):
raise ValueError("sorry don't know how to handle non standard baud rate on this platform")
baudrate_constants = {}
elif plat[:5] == 'sunos': # Solaris/SunOS (confirmed)
def device(port):
return '/dev/tty%c' % (ord('a')+port)
def set_special_baudrate(port, baudrate):
raise ValueError("sorry don't know how to handle non standard baud rate on this platform")
baudrate_constants = {}
elif plat[:3] == 'aix': # AIX
def device(port):
return '/dev/tty%d' % (port)
def set_special_baudrate(port, baudrate):
raise ValueError("sorry don't know how to handle non standard baud rate on this platform")
baudrate_constants = {}
else:
# platform detection has failed...
sys.stderr.write("""\
don't know how to number ttys on this system.
! Use an explicit path (eg /dev/ttyS1) or send this information to
! the author of this module:
sys.platform = %r
os.name = %r
serialposix.py version = %s
also add the device name of the serial port and where the
counting starts for the first serial port.
e.g. 'first serial port: /dev/ttyS0'
and with a bit luck you can get this module running...
""" % (sys.platform, os.name, VERSION))
# no exception, just continue with a brave attempt to build a device name
# even if the device name is not correct for the platform it has chances
# to work using a string with the real device name as port parameter.
def device(portum):
return '/dev/ttyS%d' % portnum
def set_special_baudrate(port, baudrate):
raise SerialException("sorry don't know how to handle non standard baud rate on this platform")
baudrate_constants = {}
#~ raise Exception, "this module does not run on this platform, sorry."
# whats up with "aix", "beos", ....
# they should work, just need to know the device names.
# load some constants for later use.
# try to use values from TERMIOS, use defaults from linux otherwise
TIOCMGET = hasattr(TERMIOS, 'TIOCMGET') and TERMIOS.TIOCMGET or 0x5415
TIOCMBIS = hasattr(TERMIOS, 'TIOCMBIS') and TERMIOS.TIOCMBIS or 0x5416
TIOCMBIC = hasattr(TERMIOS, 'TIOCMBIC') and TERMIOS.TIOCMBIC or 0x5417
TIOCMSET = hasattr(TERMIOS, 'TIOCMSET') and TERMIOS.TIOCMSET or 0x5418
#TIOCM_LE = hasattr(TERMIOS, 'TIOCM_LE') and TERMIOS.TIOCM_LE or 0x001
TIOCM_DTR = hasattr(TERMIOS, 'TIOCM_DTR') and TERMIOS.TIOCM_DTR or 0x002
TIOCM_RTS = hasattr(TERMIOS, 'TIOCM_RTS') and TERMIOS.TIOCM_RTS or 0x004
#TIOCM_ST = hasattr(TERMIOS, 'TIOCM_ST') and TERMIOS.TIOCM_ST or 0x008
#TIOCM_SR = hasattr(TERMIOS, 'TIOCM_SR') and TERMIOS.TIOCM_SR or 0x010
TIOCM_CTS = hasattr(TERMIOS, 'TIOCM_CTS') and TERMIOS.TIOCM_CTS or 0x020
TIOCM_CAR = hasattr(TERMIOS, 'TIOCM_CAR') and TERMIOS.TIOCM_CAR or 0x040
TIOCM_RNG = hasattr(TERMIOS, 'TIOCM_RNG') and TERMIOS.TIOCM_RNG or 0x080
TIOCM_DSR = hasattr(TERMIOS, 'TIOCM_DSR') and TERMIOS.TIOCM_DSR or 0x100
TIOCM_CD = hasattr(TERMIOS, 'TIOCM_CD') and TERMIOS.TIOCM_CD or TIOCM_CAR
TIOCM_RI = hasattr(TERMIOS, 'TIOCM_RI') and TERMIOS.TIOCM_RI or TIOCM_RNG
#TIOCM_OUT1 = hasattr(TERMIOS, 'TIOCM_OUT1') and TERMIOS.TIOCM_OUT1 or 0x2000
#TIOCM_OUT2 = hasattr(TERMIOS, 'TIOCM_OUT2') and TERMIOS.TIOCM_OUT2 or 0x4000
if hasattr(TERMIOS, 'TIOCINQ'):
TIOCINQ = TERMIOS.TIOCINQ
else:
TIOCINQ = hasattr(TERMIOS, 'FIONREAD') and TERMIOS.FIONREAD or 0x541B
TIOCOUTQ = hasattr(TERMIOS, 'TIOCOUTQ') and TERMIOS.TIOCOUTQ or 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 = hasattr(TERMIOS, 'TIOCSBRK') and TERMIOS.TIOCSBRK or 0x5427
TIOCCBRK = hasattr(TERMIOS, 'TIOCCBRK') and TERMIOS.TIOCCBRK or 0x5428
class PosixSerial(SerialBase):
"""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._isOpen:
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 IOError, msg:
self.fd = None
raise SerialException(msg.errno, "could not open port %s: %s" % (self._port, msg))
#~ fcntl.fcntl(self.fd, FCNTL.F_SETFL, 0) # set blocking
try:
self._reconfigurePort()
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._isOpen = True
self.flushInput()
def _reconfigurePort(self):
"""Set communication parameters on opened port."""
if self.fd is None:
raise SerialException("Can only operate on a valid file descriptor")
custom_baud = None
vmin = vtime = 0 # timeout is done via select
if self._interCharTimeout is not None:
vmin = 1
vtime = int(self._interCharTimeout * 10)
try:
orig_attr = termios.tcgetattr(self.fd)
iflag, oflag, cflag, lflag, ispeed, ospeed, cc = orig_attr
except termios.error, msg: # if a port is nonexistent but has a /dev file, it'll fail here
raise SerialException("Could not configure port: %s" % 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)
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%s' % (self._baudrate))
except AttributeError:
try:
ispeed = ospeed = 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' % self._baudrate)
else:
if custom_baud < 0:
raise ValueError('Invalid baud rate: %r' % 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' % self._bytesize)
# setup stopbits
if self._stopbits == STOPBITS_ONE:
cflag &= ~(TERMIOS.CSTOPB)
elif self._stopbits == STOPBITS_ONE_POINT_FIVE:
cflag |= (TERMIOS.CSTOPB) # XXX same as TWO.. there is no POSIX support for 1.5
elif self._stopbits == STOPBITS_TWO:
cflag |= (TERMIOS.CSTOPB)
else:
raise ValueError('Invalid stop bit specification: %r' % self._stopbits)
# setup parity
iflag &= ~(TERMIOS.INPCK|TERMIOS.ISTRIP)
if self._parity == PARITY_NONE:
cflag &= ~(TERMIOS.PARENB|TERMIOS.PARODD)
elif self._parity == PARITY_EVEN:
cflag &= ~(TERMIOS.PARODD)
cflag |= (TERMIOS.PARENB)
elif self._parity == PARITY_ODD:
cflag |= (TERMIOS.PARENB|TERMIOS.PARODD)
else:
raise ValueError('Invalid parity: %r' % 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. = for non blocking"
if vmin < 0 or vmin > 255:
raise ValueError('Invalid vmin: %r ' % vmin)
cc[TERMIOS.VMIN] = vmin
# vtime
if vtime < 0 or vtime > 255:
raise ValueError('Invalid vtime: %r' % vtime)
cc[TERMIOS.VTIME] = vtime
# activate settings
if [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:
set_special_baudrate(self, custom_baud)
def close(self):
"""Close port"""
if self._isOpen:
if self.fd is not None:
os.close(self.fd)
self.fd = None
self._isOpen = False
def makeDeviceName(self, port):
return device(port)
# - - - - - - - - - - - - - - - - - - - - - - - -
def inWaiting(self):
"""Return the number of characters 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._isOpen: raise portNotOpenError
read = bytearray()
while len(read) < size:
try:
ready,_,_ = select.select([self.fd],[],[], self._timeout)
# 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 select.error, e:
# ignore EAGAIN errors. all other errors are shown
# see also http://www.python.org/dev/peps/pep-3151/#select
if e[0] != errno.EAGAIN:
raise SerialException('read failed: %s' % (e,))
except OSError, e:
# ignore EAGAIN errors. all other errors are shown
if e.errno != errno.EAGAIN:
raise SerialException('read failed: %s' % (e,))
return bytes(read)
def write(self, data):
"""Output the given string over the serial port."""
if not self._isOpen: raise portNotOpenError
d = to_bytes(data)
tx_len = len(d)
if self._writeTimeout is not None and self._writeTimeout > 0:
timeout = time.time() + self._writeTimeout
else:
timeout = None
while tx_len > 0:
try:
n = os.write(self.fd, d)
if timeout:
# when timeout is set, use select to wait for being ready
# with the time left as timeout
timeleft = timeout - time.time()
if timeleft < 0:
raise writeTimeoutError
_, ready, _ = select.select([], [self.fd], [], timeleft)
if not ready:
raise writeTimeoutError
else:
# wait for write operation
_, ready, _ = select.select([], [self.fd], [], None)
if not ready:
raise SerialException('write failed (select)')
d = d[n:]
tx_len -= n
except OSError, v:
if v.errno != errno.EAGAIN:
raise SerialException('write failed: %s' % (v,))
return len(data)
def flush(self):
"""Flush of file like objects. In this case, wait until all data
is written."""
self.drainOutput()
def flushInput(self):
"""Clear input buffer, discarding all that is in the buffer."""
if not self._isOpen: raise portNotOpenError
termios.tcflush(self.fd, TERMIOS.TCIFLUSH)
def flushOutput(self):
"""Clear output buffer, aborting the current output and
discarding all that is in the buffer."""
if not self._isOpen: raise portNotOpenError
termios.tcflush(self.fd, TERMIOS.TCOFLUSH)
def sendBreak(self, duration=0.25):
"""Send break condition. Timed, returns to idle state after given duration."""
if not self._isOpen: raise portNotOpenError
termios.tcsendbreak(self.fd, int(duration/0.25))
def setBreak(self, level=1):
"""Set break: Controls TXD. When active, no transmitting is possible."""
if self.fd is None: raise portNotOpenError
if level:
fcntl.ioctl(self.fd, TIOCSBRK)
else:
fcntl.ioctl(self.fd, TIOCCBRK)
def setRTS(self, level=1):
"""Set terminal status line: Request To Send"""
if not self._isOpen: raise portNotOpenError
if level:
fcntl.ioctl(self.fd, TIOCMBIS, TIOCM_RTS_str)
else:
fcntl.ioctl(self.fd, TIOCMBIC, TIOCM_RTS_str)
def setDTR(self, level=1):
"""Set terminal status line: Data Terminal Ready"""
if not self._isOpen: raise portNotOpenError
if level:
fcntl.ioctl(self.fd, TIOCMBIS, TIOCM_DTR_str)
else:
fcntl.ioctl(self.fd, TIOCMBIC, TIOCM_DTR_str)
def getCTS(self):
"""Read terminal status line: Clear To Send"""
if not self._isOpen: raise portNotOpenError
s = fcntl.ioctl(self.fd, TIOCMGET, TIOCM_zero_str)
return struct.unpack('I',s)[0] & TIOCM_CTS != 0
def getDSR(self):
"""Read terminal status line: Data Set Ready"""
if not self._isOpen: raise portNotOpenError
s = fcntl.ioctl(self.fd, TIOCMGET, TIOCM_zero_str)
return struct.unpack('I',s)[0] & TIOCM_DSR != 0
def getRI(self):
"""Read terminal status line: Ring Indicator"""
if not self._isOpen: raise portNotOpenError
s = fcntl.ioctl(self.fd, TIOCMGET, TIOCM_zero_str)
return struct.unpack('I',s)[0] & TIOCM_RI != 0
def getCD(self):
"""Read terminal status line: Carrier Detect"""
if not self._isOpen: raise portNotOpenError
s = fcntl.ioctl(self.fd, TIOCMGET, TIOCM_zero_str)
return struct.unpack('I',s)[0] & TIOCM_CD != 0
# - - platform specific - - - -
def outWaiting(self):
"""Return the number of characters 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 drainOutput(self):
"""internal - not portable!"""
if not self._isOpen: raise portNotOpenError
termios.tcdrain(self.fd)
def nonblocking(self):
"""internal - not portable!"""
if not self._isOpen: raise portNotOpenError
fcntl.fcntl(self.fd, FCNTL.F_SETFL, os.O_NONBLOCK)
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._isOpen: raise portNotOpenError
return self.fd
def setXON(self, level=True):
"""\
Manually control flow - when software flow control is enabled.
This will send XON (true) and XOFF (false) to the other device.
WARNING: this function is not portable to different platforms!
"""
if not self.hComPort: raise portNotOpenError
if enable:
termios.tcflow(self.fd, TERMIOS.TCION)
else:
termios.tcflow(self.fd, TERMIOS.TCIOFF)
def flowControlOut(self, enable):
"""\
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._isOpen: raise portNotOpenError
if enable:
termios.tcflow(self.fd, TERMIOS.TCOON)
else:
termios.tcflow(self.fd, TERMIOS.TCOOFF)
# assemble Serial class with the platform specifc implementation and the base
# for file-like behavior. for Python 2.6 and newer, that provide the new I/O
# library, derrive from io.RawIOBase
try:
import io
except ImportError:
# classic version with our own file-like emulation
class Serial(PosixSerial, FileLike):
pass
else:
# io library present
class Serial(PosixSerial, io.RawIOBase):
pass
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 self.fd is None: 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._interCharTimeout is not None and self._interCharTimeout > 0)) and not buf:
break # early abort on timeout
return bytes(read)
if __name__ == '__main__':
s = Serial(0,
baudrate=19200, # baud rate
bytesize=EIGHTBITS, # number of data bits
parity=PARITY_EVEN, # enable parity checking
stopbits=STOPBITS_ONE, # number of stop bits
timeout=3, # set a timeout value, None for waiting forever
xonxoff=0, # enable software flow control
rtscts=0, # enable RTS/CTS flow control
)
s.setRTS(1)
s.setDTR(1)
s.flushInput()
s.flushOutput()
s.write('hello')
sys.stdout.write('%r\n' % s.read(5))
sys.stdout.write('%s\n' % s.inWaiting())
del s