[ntp:questions] Using mode byte for Accord GPS Clock

David L. Mills mills at udel.edu
Tue Dec 4 19:05:17 UTC 2007


Venu,

It is easy to add more bits to the mode word. How about 32? You and 
other driver programmers should come to some loose agreement on how to 
exploit these bits.

Dave

venu gopal wrote:
>     Hi all,
> 
>         The 'mode' field a.k.a 'ttl' for NMEA reference driver is used
> to select the NMEA
>     sentence. I cannot use the unused fudge flags 'flag1' and 'flag4'
> as they are unavailable
>     before the serial port is opened. Somehow I have to select both
> the baudrate and the
>     NMEA sentence from the 'mode' field itself.
> 
>     Currently 'mode' field with values 0,1,2,4 are used in NMEA
> reference driver with default
>     baudrate of 4800. Can I use the 'mode' field with value 8 and the
> rest of the three bits to
>     select NMEA sentence.
> 
>         1. Mode value 8  => 9600, GPXXX
>         2. Mode value 9  => 9600, GPRMC
>         3. Mode value 10 => 9600, GPGGA
>         4. Mode value 11  => 9600, GPGLL
>         5. Mode value 12 => 9600, GPZDG (Accord custom NMEA sentence)
>         6. Mode value 13 => 9600, GPZDA
> 
>     So the 4th bit of the 'mode' field is used to check if baudrate
> needs to be changed,
>     while the rest of the 3 bits denote the NMEA sentence to be selected.
> 
>    Comments plz...
> 
>     Venu.




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