NMEA Date & Time Sentence

[wirefree101]

I seek local time details from an external GPS device. NMEA's ZDA sentence furnishes this information. See here for details.

I wish to gain an understanding of how the different sentence types are generated and can be queried. As a starter, I have attempted the following...

In the following code, replacing "$GPGGA" with "$GPZDA" yields no result.

import socket  
  
address, services = socket.bt_discover()  
print "Discovered: %s, %s" % (address, services)  
target = (address, services.values()[0])  
  
conn = socket.socket(socket.AF_BT, socket.SOCK_STREAM)  
conn.connect(target)  
to_gps = conn.makefile("r", 0)  
  
while True:  
        msg = to_gps.readline()  
        if msg.startswith("$GPGGA"):  
                gps_data = msg.split(",")  
                lat = gps_data[2]  
                lon = gps_data[4]  
                break  
  
to_gps.close()  
conn.close()  
print "You are now at latitude %s and longitude %s" % (lat, lon)

Would greatly appreciate assistance with addressing the concern.

Best,
wirefree

[ltomuta]

Why don't you try

import socket  
  
address, services = socket.bt_discover()  
print "Discovered: %s, %s" % (address, services)  
target = (address, services.values()[0])  
  
conn = socket.socket(socket.AF_BT, socket.SOCK_STREAM)  
conn.connect(target)  
to_gps = conn.makefile("r", 0)  
  
while True:  
        msg = to_gps.readline()  
        print msg
        if msg.startswith("$GPZDA"):  
                break 
  
to_gps.close()  
conn.close()

This way you could at least see if a $GPZDA sentence is received and then figure out how to decode it.