#!/usr/bin/env python
############################################################################
#
#   Copyright (C) 2012, 2013 PX4 Development Team. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in
#    the documentation and/or other materials provided with the
#    distribution.
# 3. Neither the name PX4 nor the names of its contributors may be
#    used to endorse or promote products derived from this software
#    without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
############################################################################

#
# Serial firmware uploader for the PX4FMU bootloader
#
# The PX4 firmware file is a JSON-encoded Python object, containing
# metadata fields and a zlib-compressed base64-encoded firmware image.
#
# The uploader uses the following fields from the firmware file:
#
# image
#       The firmware that will be uploaded.
# image_size
#       The size of the firmware in bytes.
# board_id
#       The board for which the firmware is intended.
# board_revision
#       Currently only used for informational purposes.
#

# for python2.7 compatibility
from __future__ import print_function

import sys
import argparse
import binascii
import serial
import struct
import json
import zlib
import base64
import time
import array
import os

from sys import platform as _platform


class firmware(object):
        '''Loads a firmware file'''

        desc = {}
        image = bytes()
        crctab = array.array('I', [
            0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
            0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
            0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
            0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
            0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
            0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
            0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
            0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
            0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
            0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
            0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
            0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
            0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
            0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
            0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
            0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
            0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
            0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
            0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
            0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
            0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
            0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
            0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
            0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
            0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
            0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
            0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
            0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
            0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
            0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
            0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
            0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d])
        crcpad = bytearray(b'\xff\xff\xff\xff')

        def __init__(self, path):

                # read the file
                f = open(path, "r")
                self.desc = json.load(f)
                f.close()

                self.image = bytearray(zlib.decompress(base64.b64decode(self.desc['image'])))

                # pad image to 4-byte length
                while ((len(self.image) % 4) != 0):
                        self.image.append('\xff')

        def property(self, propname):
                return self.desc[propname]

        def __crc32(self, bytes, state):
                for byte in bytes:
                        index = (state ^ byte) & 0xff
                        state = self.crctab[index] ^ (state >> 8)
                return state

        def crc(self, padlen):
                state = self.__crc32(self.image, int(0))
                for i in range(len(self.image), (padlen - 1), 4):
                        state = self.__crc32(self.crcpad, state)
                return state


class uploader(object):
        '''Uploads a firmware file to the PX FMU bootloader'''

        # protocol bytes
        INSYNC          = b'\x12'
        EOC             = b'\x20'

        # reply bytes
        OK              = b'\x10'
        FAILED          = b'\x11'
        INVALID         = b'\x13'     # rev3+

        # command bytes
        NOP             = b'\x00'     # guaranteed to be discarded by the bootloader
        GET_SYNC        = b'\x21'
        GET_DEVICE      = b'\x22'
        CHIP_ERASE      = b'\x23'
        CHIP_VERIFY     = b'\x24'     # rev2 only
        PROG_MULTI      = b'\x27'
        READ_MULTI      = b'\x28'     # rev2 only
        GET_CRC         = b'\x29'     # rev3+
        GET_OTP         = b'\x2a'     # rev4+  , get a word from OTP area
        GET_SN          = b'\x2b'     # rev4+  , get a word from SN area
        REBOOT          = b'\x30'
        
        INFO_BL_REV     = b'\x01'        # bootloader protocol revision
        BL_REV_MIN      = 2             # minimum supported bootloader protocol 
        BL_REV_MAX      = 4             # maximum supported bootloader protocol 
        INFO_BOARD_ID   = b'\x02'        # board type
        INFO_BOARD_REV  = b'\x03'        # board revision
        INFO_FLASH_SIZE = b'\x04'        # max firmware size in bytes

        PROG_MULTI_MAX  = 60            # protocol max is 255, must be multiple of 4
        READ_MULTI_MAX  = 60            # protocol max is 255, something overflows with >= 64
        
        NSH_INIT        = bytearray(b'\x0d\x0d\x0d')
        NSH_REBOOT_BL   = b"reboot -b\n"
        NSH_REBOOT      = b"reboot\n"
        MAVLINK_REBOOT_ID1 = bytearray(b'\xfe\x21\x72\xff\x00\x4c\x00\x00\x80\x3f\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xf6\x00\x01\x00\x00\x48\xf0')
        MAVLINK_REBOOT_ID0 = bytearray(b'\xfe\x21\x45\xff\x00\x4c\x00\x00\x80\x3f\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xf6\x00\x00\x00\x00\xd7\xac')

        def __init__(self, portname, baudrate):
                # open the port, keep the default timeout short so we can poll quickly
                self.port = serial.Serial(portname, baudrate, timeout=0.5)
                self.otp = b''
                self.sn = b''

        def close(self):
                if self.port is not None:
                        self.port.close()

        def __send(self, c):
#               print("send " + binascii.hexlify(c))
                self.port.write(c)

        def __recv(self, count=1):
                c = self.port.read(count)
                if len(c) < 1:
                        raise RuntimeError("timeout waiting for data (%u bytes)" % count)
#               print("recv " + binascii.hexlify(c))
                return c

        def __recv_int(self):
                raw = self.__recv(4)
                val = struct.unpack("<I", raw)
                return val[0]

        def __getSync(self):
                self.port.flush()
                c = bytes(self.__recv())
                if c != self.INSYNC:
                        raise RuntimeError("unexpected %s instead of INSYNC" % c)
                c = self.__recv()
                if c == self.INVALID:
                        raise RuntimeError("bootloader reports INVALID OPERATION")
                if c == self.FAILED:
                        raise RuntimeError("bootloader reports OPERATION FAILED")
                if c != self.OK:
                        raise RuntimeError("unexpected response 0x%x instead of OK" % ord(c))

        # attempt to get back into sync with the bootloader
        def __sync(self):
                # send a stream of ignored bytes longer than the longest possible conversation
                # that we might still have in progress
#               self.__send(uploader.NOP * (uploader.PROG_MULTI_MAX + 2))
                self.port.flushInput()
                self.__send(uploader.GET_SYNC
                            + uploader.EOC)
                self.__getSync()

#       def __trySync(self):
#               c = self.__recv()
#               if (c != self.INSYNC):
#                       #print("unexpected 0x%x instead of INSYNC" % ord(c))
#                       return False;
#               c = self.__recv()
#               if (c != self.OK):
#                       #print("unexpected 0x%x instead of OK" % ord(c))
#                       return False
#               return True

        # send the GET_DEVICE command and wait for an info parameter
        def __getInfo(self, param):
                self.__send(uploader.GET_DEVICE + param + uploader.EOC)
                value = self.__recv_int()
                self.__getSync()
                return value

        # send the GET_OTP command and wait for an info parameter
        def __getOTP(self, param):
                t = struct.pack("I", param) # int param as 32bit ( 4 byte ) char array.
                self.__send(uploader.GET_OTP + t + uploader.EOC)
                value = self.__recv(4)
                self.__getSync()
                return value

        # send the GET_OTP command and wait for an info parameter
        def __getSN(self, param):
                t = struct.pack("I", param) # int param as 32bit ( 4 byte ) char array.
                self.__send(uploader.GET_SN + t + uploader.EOC)
                value = self.__recv(4)
                self.__getSync()
                return value

        def __drawProgressBar(self, progress, maxVal):
                if maxVal < progress:
                    progress = maxVal

                percent = (float(progress) / float(maxVal)) * 100.0

                sys.stdout.write("\rprogress:[%-20s] %.2f%%" % ('='*int(percent/5.0), percent))
                sys.stdout.flush()


        # send the CHIP_ERASE command and wait for the bootloader to become ready
        def __erase(self):
                self.__send(uploader.CHIP_ERASE
                            + uploader.EOC)
                # erase is very slow, give it 20s
                deadline = time.time() + 20
                while time.time() < deadline:

                        #Draw progress bar (erase usually takes about 9 seconds to complete)
                        estimatedTimeRemaining = deadline-time.time()-11.0
                        if estimatedTimeRemaining > 0:
                            self.__drawProgressBar(10.0-estimatedTimeRemaining, 10.0)
                        else:
                            self.__drawProgressBar(10.0, 10.0)
                            sys.stdout.write(" (timeout: %d seconds) " % int(time.time()-deadline) )

                        try:
                                self.__getSync()
                                self.__drawProgressBar(10.0, 10.0)
                                sys.stdout.write("\nerase complete!\n")
                                return
                        except RuntimeError:
                                # we timed out, that's OK
                                continue

                raise RuntimeError("timed out waiting for erase")

        # send a PROG_MULTI command to write a collection of bytes
        def __program_multi(self, data):
                
                if runningPython3 == True:
                    length = len(data).to_bytes(1, byteorder='big')
                else:
                    length = chr(len(data))
            
                self.__send(uploader.PROG_MULTI)
                self.__send(length)
                self.__send(data)
                self.__send(uploader.EOC)
                self.__getSync()

        # verify multiple bytes in flash
        def __verify_multi(self, data):
            
                if runningPython3 == True:
                    length = len(data).to_bytes(1, byteorder='big')
                else:
                    length = chr(len(data))
                
                self.__send(uploader.READ_MULTI)
                self.__send(length)
                self.__send(uploader.EOC)
                self.port.flush()
                programmed = self.__recv(len(data))
                if programmed != data:
                        print("got    " + binascii.hexlify(programmed))
                        print("expect " + binascii.hexlify(data))
                        return False
                self.__getSync()
                return True

        # send the reboot command
        def __reboot(self):
                self.__send(uploader.REBOOT
                            + uploader.EOC)
                self.port.flush()

                # v3+ can report failure if the first word flash fails
                if self.bl_rev >= 3:
                        self.__getSync()

        # split a sequence into a list of size-constrained pieces
        def __split_len(self, seq, length):
                return [seq[i:i+length] for i in range(0, len(seq), length)]

        # upload code
        def __program(self, fw):
                code = fw.image
                groups = self.__split_len(code, uploader.PROG_MULTI_MAX)

                uploadProgress = 0
                for bytes in groups:
                        self.__program_multi(bytes)

                        #Print upload progress (throttled, so it does not delay upload progress)
                        uploadProgress += 1
                        if uploadProgress % 256 == 0:
                            self.__drawProgressBar(uploadProgress, len(groups))
                self.__drawProgressBar(100, 100)
                print("\nprogram complete!")

        # verify code
        def __verify_v2(self, fw):
                self.__send(uploader.CHIP_VERIFY
                            + uploader.EOC)
                self.__getSync()
                code = fw.image
                groups = self.__split_len(code, uploader.READ_MULTI_MAX)
                for bytes in groups:
                        if (not self.__verify_multi(bytes)):
                                raise RuntimeError("Verification failed")

        def __verify_v3(self, fw):
                expect_crc = fw.crc(self.fw_maxsize)
                self.__send(uploader.GET_CRC
                            + uploader.EOC)
                report_crc = self.__recv_int()
                self.__getSync()
                if report_crc != expect_crc:
                        print("Expected 0x%x" % expect_crc)
                        print("Got      0x%x" % report_crc)
                        raise RuntimeError("Program CRC failed")

        # get basic data about the board
        def identify(self):
                # make sure we are in sync before starting
                self.__sync()

                # get the bootloader protocol ID first
                self.bl_rev = self.__getInfo(uploader.INFO_BL_REV)
                if (self.bl_rev < uploader.BL_REV_MIN) or (self.bl_rev > uploader.BL_REV_MAX):
                        print("Unsupported bootloader protocol %d" % uploader.INFO_BL_REV)
                        raise RuntimeError("Bootloader protocol mismatch")

                self.board_type = self.__getInfo(uploader.INFO_BOARD_ID)
                self.board_rev = self.__getInfo(uploader.INFO_BOARD_REV)
                self.fw_maxsize = self.__getInfo(uploader.INFO_FLASH_SIZE)

        # upload the firmware
        def upload(self, fw):
                # Make sure we are doing the right thing
                if self.board_type != fw.property('board_id'):
                        raise RuntimeError("Firmware not suitable for this board")
                if self.fw_maxsize < fw.property('image_size'):
                        raise RuntimeError("Firmware image is too large for this board")

                # OTP added in v4:
                if self.bl_rev > 3:
                    for byte in range(0,32*6,4):
                        x = self.__getOTP(byte)
                        self.otp  = self.otp + x
                        print(binascii.hexlify(x).decode('Latin-1') + ' ', end='')
                    # see src/modules/systemlib/otp.h in px4 code:
                    self.otp_id = self.otp[0:4]
                    self.otp_idtype = self.otp[4:5]
                    self.otp_vid = self.otp[8:4:-1]
                    self.otp_pid = self.otp[12:8:-1]
                    self.otp_coa = self.otp[32:160]
                    # show user:
                    try:
                            print("type: " + self.otp_id.decode('Latin-1'))
                            print("idtype: " + binascii.b2a_qp(self.otp_idtype).decode('Latin-1'))
                            print("vid: " + binascii.hexlify(self.otp_vid).decode('Latin-1'))
                            print("pid: "+ binascii.hexlify(self.otp_pid).decode('Latin-1'))
                            print("coa: "+ binascii.b2a_base64(self.otp_coa).decode('Latin-1'))
                            print("sn: ", end='')
                            for byte in range(0,12,4):
                                    x = self.__getSN(byte)
                                    x = x[::-1]  # reverse the bytes
                                    self.sn  = self.sn + x
                                    print(binascii.hexlify(x).decode('Latin-1'), end='') # show user
                            print('')
                    except Exception:
                            # ignore bad character encodings
                            pass
                print("erase...")
                self.__erase()

                print("program...")
                self.__program(fw)

                print("verify...")
                if self.bl_rev == 2:
                        self.__verify_v2(fw)
                else:
                        self.__verify_v3(fw)

                print("done, rebooting.")
                self.__reboot()
                self.port.close()
                
        def send_reboot(self):
                try:
                    # try reboot via NSH first
                    self.__send(uploader.NSH_INIT)
                    self.__send(uploader.NSH_REBOOT_BL)
                    self.__send(uploader.NSH_INIT)
                    self.__send(uploader.NSH_REBOOT)
                    # then try MAVLINK command
                    self.__send(uploader.MAVLINK_REBOOT_ID1)
                    self.__send(uploader.MAVLINK_REBOOT_ID0)
                except:
                    return
                
                

# Detect python version
if sys.version_info[0] < 3:
    runningPython3 = False
else:
    runningPython3 = True

# Parse commandline arguments
parser = argparse.ArgumentParser(description="Firmware uploader for the PX autopilot system.")
parser.add_argument('--port', action="store", required=True, help="Serial port(s) to which the FMU may be attached")
parser.add_argument('--baud', action="store", type=int, default=115200, help="Baud rate of the serial port (default is 115200), only required for true serial ports.")
parser.add_argument('firmware', action="store", help="Firmware file to be uploaded")
args = parser.parse_args()

# warn people about ModemManager which interferes badly with Pixhawk
if os.path.exists("/usr/sbin/ModemManager"):
        print("==========================================================================================================")
        print("WARNING: You should uninstall ModemManager as it conflicts with any non-modem serial device (like Pixhawk)")
        print("==========================================================================================================")

# Load the firmware file
fw = firmware(args.firmware)
print("Loaded firmware for %x,%x, size: %d bytes, waiting for the bootloader..." % (fw.property('board_id'), fw.property('board_revision'), fw.property('image_size')))
print("If the board does not respond within 1-2 seconds, unplug and re-plug the USB connector.")

# Spin waiting for a device to show up
while True:
        portlist = []
        patterns = args.port.split(",")
        # on unix-like platforms use glob to support wildcard ports. This allows
        # the use of /dev/serial/by-id/usb-3D_Robotics on Linux, which prevents the upload from
        # causing modem hangups etc
        if "linux" in _platform or "darwin" in _platform:
                import glob
                for pattern in patterns:
                        portlist += glob.glob(pattern)
        else:
                portlist = patterns

        for port in portlist:

                #print("Trying %s" % port)
                
                # create an uploader attached to the port
                try:
                        if "linux" in _platform:
                        # Linux, don't open Mac OS and Win ports
                                if not "COM" in port and not "tty.usb" in port:
                                        up = uploader(port, args.baud)
                        elif "darwin" in _platform:
                                # OS X, don't open Windows and Linux ports
                                if not "COM" in port and not "ACM" in port:
                                        up = uploader(port, args.baud)
                        elif "win" in _platform:
                                # Windows, don't open POSIX ports
                                if not "/" in port:
                                        up = uploader(port, args.baud)
                except Exception:
                        # open failed, rate-limit our attempts
                        time.sleep(0.05)

                        # and loop to the next port
                        continue

                # port is open, try talking to it
                try:
                        # identify the bootloader
                        up.identify()
                        print("Found board %x,%x bootloader rev %x on %s" % (up.board_type, up.board_rev, up.bl_rev, port))

                except Exception:
                        # most probably a timeout talking to the port, no bootloader, try to reboot the board
                        print("attempting reboot on %s..." % port)
                        print("if the board does not respond, unplug and re-plug the USB connector.")
                        up.send_reboot()

                        # wait for the reboot, without we might run into Serial I/O Error 5 
                        time.sleep(0.5)

                        # always close the port
                        up.close()
                        continue

                try:
                        # ok, we have a bootloader, try flashing it
                        up.upload(fw)

                except RuntimeError as ex:

                        # print the error
                        print("\nERROR: %s" % ex.args)

                finally:
                        # always close the port
                        up.close()

                # we could loop here if we wanted to wait for more boards...
                sys.exit(0)