tdsgrab.py

#!/usr/bin/env python2
#
# Copyright (C) 2013 Christopher Hewitt
#
# Permission is hereby granted, free of charge, to any person obtaining a 
# copy of this software and associated documentation files (the "Software"), 
# to deal in the Software without restriction, including without limitation 
# the rights to use, copy, modify, merge, publish, distribute, sublicense, 
# and/or sell copies of the Software, and to permit persons to whom the 
# Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in 
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 
# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
# DEALINGS IN THE SOFTWARE.

import sys
import argparse

try:
    import serial
    import serial.tools.list_ports
except ImportError as e:
    print("error: missing dependency (pyserial)")
    sys.exit(-1)

class TDSGrab(object):

    def __init__(self, port, baudrate, timeout, hardware_flagging, software_flagging):
        self.port = port
        self.baudrate = baudrate
        self.timeout = timeout
        self.hardware_flagging = hardware_flagging
        self.software_flagging = software_flagging
        self.serial = serial.Serial()

    def connect(self):
        """Connect to serial device"""
        try:
            if not self.serial.isOpen():
                self.serial = serial.Serial(
                    self.port, 
                    self.baudrate, 
                    timeout=self.timeout, 
                    rtscts=self.hardware_flagging, 
                    xonxoff=self.software_flagging
                )
                print("connected to %s") % (self.port)
        except serial.SerialException as e:
            msg = "unable to connect to %s" % (self.port)
            raise Exception(msg, e)

    def disconnect(self):
        """Disconnect from serial device"""
        try:
            if self.serial.isOpen():
                self.serial.close()
                print("disconnected from %s") % (self.port)
        except serial.SerialException as e:
            msg = "unable to disconnect from %s" % (self.port)
            raise Exception(msg, e)

    def grab_image(self, filename):
        """Wait for an image and save to filename"""
        try:
            if self.serial.isOpen():
                self.serial.flushInput()

                # open file for writing
                data_file = None
                try:
                    data_file = open(filename, "w")
                except IOError as e:
                    msg = "error opening '%s' for writing" % (self.port)
                    raise Exception(msg, e)

                print("waiting for data")
                while True:
                    # look for start of data and write to file
                    data = self.serial.read(8)
                    if data:
                        print("receiving data")
                        data_file.write(data)
                        while True:
                            # continually read and then write to file until nothing left
                            data = self.serial.read(8)
                            if data:
                                data_file.write(data)
                            else:
                                break
                        break

                # done with file
                print("data written to '%s'") % (filename)
                data_file.close()
        except serial.SerialException as e:
            msg = "error: problem reading image data from port"
            raise Exception(msg, e)

class ListPorts(argparse.Action):
    """List available serial ports"""
    def __call__(self, parser, namespace, action, option_string):
        print("available ports:")
        for port in serial.tools.list_ports.comports():
            print(port[0])
        parser.exit()

def main():
    # runtime argument parsing
    epilog = """\
additional information:
  BAUD is expected to be one of the following:
     300, 600, 1200, 2400, 4800, 9600, 19200
  A nonstandard baud rate will produce a warning

  FLOW is expected to be one of the following:
     hw                 hardware flow control
     sw                 software flow control
     both               both flow controls
     none               no flow control
"""
    parser = argparse.ArgumentParser(
        description="Download images from Tektronix TDS oscilloscopes over RS-232 link.", 
        epilog=epilog, 
        formatter_class=argparse.RawDescriptionHelpFormatter
    )
    parser.add_argument("-v", "--version", action="version", version="%(prog)s 0.1")
    parser.add_argument("-l", "--list", action=ListPorts, nargs=0, help="list available serial ports")
    parser.add_argument("-p", "--port", help="serial device to connect to (default: %(default)s)", default="/dev/ttyS0")
    parser.add_argument("-b", "--baud", help="baudrate for connection (default: %(default)s)", default=9600)
    parser.add_argument("-f", "--flow", help="select flow control method (default: %(default)s)", default="hw")
    parser.add_argument("filename", help="filename to write to")
    args = parser.parse_args()

    # verify port
    ports = ()
    for port in serial.tools.list_ports.comports():
        ports = ports + (port[0],)
    if args.port not in ports:
        print("warning: port does not appear to be available... proceeding anyway")
    port = args.port

    # verify baudrate
    if args.baud not in (300, 600, 1200, 2400, 4800, 9600, 19200):
        print("warning: strange baudrate... proceeding anyway")
    baudrate = args.baud

    # timeout for serial read blocking in seconds
    timeout = 0.250

    # verify flow control method
    hardware_flagging = args.flow in ("hw", "both")
    software_flagging = args.flow in ("sw", "both")

    # assume filename is correct
    filename = args.filename

    # start grabbing
    tdsgrab = TDSGrab(port, baudrate, timeout, hardware_flagging, software_flagging)
    try:
        try:
            tdsgrab.connect()
            tdsgrab.grab_image(filename)
        finally:
            tdsgrab.disconnect()
    except Exception as e:
        print("%s (%s)") % (e.args[0], e.args[1])
    except KeyboardInterrupt:
        pass

if __name__ == "__main__":
    main()

# vim: autoindent tabstop=4 shiftwidth=4 expandtab softtabstop=4 filetype=python