git.maemo.org Git - uberlogger/blob - nmea.py

   1 #!/usr/bin/env python
   2 #
   3 # Copyright (C) 2010 Dmitry Marakasov
   4 #
   5 # This file is part of UberLogger.
   6 #
   7 # UberLogger is free software: you can redistribute it and/or modify
   8 # it under the terms of the GNU General Public License as published by
   9 # the Free Software Foundation, either version 3 of the License, or
  10 # (at your option) any later version.
  11 #
  12 # UberLogger is distributed in the hope that it will be useful,
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 # GNU General Public License for more details.
  16 #
  17 # You should have received a copy of the GNU General Public License
  18 # along with UberLogger.  If not, see <http://www.gnu.org/licenses/>.
  19 #
  20
  21 import re
  22
  23 class GPSData:
  24         def __init__(self):
  25                 self.reset()
  26
  27         def reset(self):
  28                 self.time = None
  29                 self.lat = None
  30                 self.lon = None
  31                 self.quality = None
  32                 self.nsat = None
  33                 self.hdop = None
  34                 self.ele = None
  35
  36         def parse_nmea_string(self, string):
  37                 try:
  38                         string = string.lstrip('$')
  39                         (data, dummy, csum) = string.rpartition('*')
  40
  41                         mycsum = 0
  42                         for byte in data:
  43                                 mycsum ^= ord(byte)
  44
  45                         if mycsum != int(csum, 16): # can throw with invalid csum
  46                                 return
  47
  48                         data = data.split(',')
  49
  50                         if data[0] == 'GPGGA':
  51                                 self.reset()
  52
  53                                 # time
  54                                 (temp, n) = re.subn('^(\d{2})(\d{2})(\d{2}\.\d+)$', '\\1:\\2:\\3', data[1])
  55                                 if n == 1:
  56                                         self.time = temp
  57
  58                                 # latitude
  59                                 (temp, n) = re.subn('^(\d{2})(\d{2})\.(.*)$', '\\1.\\2\\3', data[2])
  60                                 if n == 1:
  61                                         self.lat = temp + data[3]
  62
  63                                 # longitude
  64                                 (temp, n) = re.subn('^0?(\d{2,3}?)(\d{2})\.(.*)$', '\\1.\\2\\3', data[4])
  65                                 if n == 1:
  66                                         self.lon = temp + data[5]
  67
  68                                 # quality
  69                                 if int(data[6]) == 0:
  70                                         self.quality = "none"
  71                                 elif int(data[6]) == 1:
  72                                         self.quality = "normal"
  73                                 elif int(data[6]) == 2:
  74                                         self.quality = "diff"
  75                                 elif int(data[6]) == 3:
  76                                         self.quality = "precision"
  77                                 else:
  78                                         self.quality = None
  79
  80                                 # other params
  81                                 self.nsat = int(data[7])
  82                                 self.hdop = data[8]
  83                                 self.ele = data[9]
  84                 except:
  85                         return
  86
  87         def dump(self):
  88                 return "Time: %s\tQuality: %s\nLat: %s\tSat: %s\nLon: %s\tHDOP: %s\nEle: %s" % (self.time, self.quality, self.lat, self.nsat, self.lon, self.hdop, self.ele)