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

   1 #!/usr/bin/env python
   2
   3 import re
   4
   5 class GPSData:
   6         def __init__(self):
   7                 self.reset()
   8
   9         def reset(self):
  10                 self.time = None
  11                 self.lat = None
  12                 self.lon = None
  13                 self.quality = None
  14                 self.nsat = None
  15                 self.hdop = None
  16                 self.ele = None
  17
  18         def parse_nmea_string(self, string):
  19                 try:
  20                         string = string.lstrip('$')
  21                         (data, dummy, csum) = string.rpartition('*')
  22
  23                         mycsum = 0
  24                         for byte in data:
  25                                 mycsum ^= ord(byte)
  26
  27                         if mycsum != int(csum, 16): # can throw with invalid csum
  28                                 return
  29
  30                         data = data.split(',')
  31
  32                         if data[0] == 'GPGGA':
  33                                 self.reset()
  34
  35                                 # time
  36                                 (temp, n) = re.subn('^(\d{2})(\d{2})(\d{2}\.\d+)$', '\\1:\\2:\\3', data[1])
  37                                 if n == 1:
  38                                         self.time = temp
  39
  40                                 # latitude
  41                                 (temp, n) = re.subn('^(\d{2})(\d{2})\.(.*)$', '\\1.\\2\\3', data[2])
  42                                 if n == 1:
  43                                         self.lat = temp + data[3]
  44
  45                                 # longitude
  46                                 (temp, n) = re.subn('^0?(\d{2,3}?)(\d{2})\.(.*)$', '\\1.\\2\\3', data[4])
  47                                 if n == 1:
  48                                         self.lon = temp + data[5]
  49
  50                                 # quality
  51                                 if int(data[6]) == 0:
  52                                         self.quality = "none"
  53                                 elif int(data[6]) == 1:
  54                                         self.quality = "normal"
  55                                 elif int(data[6]) == 2:
  56                                         self.quality = "diff"
  57                                 elif int(data[6]) == 3:
  58                                         self.quality = "precision"
  59                                 else:
  60                                         self.quality = None
  61
  62                                 # other params
  63                                 self.nsat = int(data[7])
  64                                 self.hdop = data[8]
  65                                 self.ele = data[9]
  66                 except:
  67                         return
  68
  69         def dump(self):
  70                 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)