#! /usr/bin/python

#---------------------------------
#  Test of serial port
#
# O.M., 05 July 2008
#---------------------------------

import serial
from time import gmtime, strftime

COM_PORT = 'COM4'

print '''
=================================================
Test of GPS with USB output.

Use TeraTerm to veryfy what COM port is used,
and change the constant "COM_PORT" if necessary.

CTRL-C to break.
UiB, Dept. of Earth Science
05 July 2008
=================================================

'''
counter = 0

try:
	Interval = int(raw_input('Logging interval [seconds]: '))
except:
	print 'Input not valid'
	exit(0)

FileName = "c:/GPS/" + strftime("GPS-data-%Y-%j-%H%M%S.txt")
print "Logging data to", FileName
f = open(FileName, "w") 
print

#-- Open serial port 
try:
	ser = serial.Serial(port=COM_PORT,
					    baudrate=4800,
					    bytesize=serial.EIGHTBITS,
                        parity=serial.PARITY_NONE,
                        stopbits=serial.STOPBITS_ONE,
                        timeout=None
                        )
except:
	print "Cannot open", COM_PORT, '- use TeraTerm to veryfy what COM port is used by the GPS.'
	exit(0)


counter = Interval


#----------   M A I N   L O O P   -------------

while True:					# Runs forever
	line = ser.readline()
	
	if '$GPRMC' in line:
		s = line.split(',')         #---- Split this line into array (use ',' as field delimiter)
		if counter == Interval:
			print line,
			try:
				print '   ', s[9], s[1].split('.')[0], s[3], s[4], s[5], s[6]
			except:
				pass
			f.write(line)	#--- Write to file
			f.flush()
			counter = 0
		counter += 1
		
ser.close()
exit(0)