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#!/usr/bin/python
# Copyright (C) 2007 by Jaroslaw Zachwieja
# Modified (C) 2012 by Tim Redfern
# Published under the terms of GNU General Public License v2 or later.
# License text available at http://www.gnu.org/licenses/licenses.html#GPL
import serial,string,threading,time,sys,random
class GpsPoller(threading.Thread):
latitude = 0
longitude = 0
changed = False
fix=0
satellites=0
gps =""
def __init__(self,port,test=False):
self.test=test
self.port=port
self.gps = serial.Serial(port, 9600, timeout=1)
threading.Thread.__init__(self)
self.fixname=("no fix","no fix","2D fix","3D fix")
def check(self):
if self.changed:
self.changed=False
return (self.latitude,self.longitude)
else:
return False
def run(self):
if self.test:
print "GpsPoller: serving random data"
else:
print "GpsPoller: serving data from",self.port
try:
while True:
if self.test:
self.latitude=random.random()*90
self.longitude=random.random()*90
self.changed=True
time.sleep(0.5)
else:
line=""
try:
line = self.gps.read(1)
line = line+self.gps.readline()
datablock = line.split(',')
#print line
except:
print "caught serial error"
try:
if line[0:6] =='$GPGSV':
self.satellites=string.atoi(datablock[3])
if line[0:6] =='$GPGSA':
self.fix=string.atoi(datablock[2])
if line[0:6] == '$GPGGA':
latitude_in = string.atof(datablock[2])
longitude_in = string.atof(datablock[4])
#altitude = string.atof(datablock[8])
#speed_in = string.atof(datablock[7])
#heading = string.atof(datablock[8])
if datablock[3] == 'S':
latitude_in = -latitude_in
if datablock[5] == 'W':
longitude_in = -longitude_in
latitude_degrees = int(latitude_in/100)
latitude_minutes = latitude_in - latitude_degrees*100
longitude_degrees = int(longitude_in/100)
longitude_minutes = longitude_in - longitude_degrees*100
latitude = latitude_degrees + (latitude_minutes/60)
longitude = longitude_degrees + (longitude_minutes/60)
if latitude!=self.latitude or longitude!=self.longitude:
self.latitude=latitude
self.longitude=longitude
self.changed=True
except:
print "caught corrupt NMEA sentence"
except StopIteration:
pass
def __del__(self):
if self.gps!="":
self.gps.close()
if __name__ == '__main__':
gpsp = GpsPoller(sys.argv[1])
gpsp.start()
while 1:
# In the main thread, every 5 seconds print the current value
time.sleep(1.0)
check=gpsp.check()
print time.ctime(),gpsp.fixname[gpsp.fix],":satellites in view", gpsp.satellites
if check!=False:
print "changed:",check[0],check[1]
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