Using mode byte for Accord GPS Clock - NTP

This is a discussion on Using mode byte for Accord GPS Clock - NTP ; 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 ...

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Thread: Using mode byte for Accord GPS Clock

  1. Using mode byte for Accord GPS Clock

    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.

  2. Re: Using mode byte for Accord GPS Clock

    Hi all,
    I am sorry, the mode field and corresponding configuration should be
    as follows to preserve the existing NMEA sentences in the driver.

    Mode value 8 => 9600, GPXXX
    Mode value 9 => 9600, GPRMC
    Mode value 10 => 9600, GPGGA
    Mode value 11 => 9600, GPZDG (Accord custom NMEA sentence)
    Mode value 12 => 9600, GPGLL
    Mode value 13 => 9600, GPZDA

    Venu.


    On 12/4/07, 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.
    >


  3. Re: Using mode byte for Accord GPS Clock

    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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