GM-R700 User’s Manual
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 300, R.O.C.
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6. Software Specification
6.1 ST-K700 NMEA Protocol
The ST-K700 software is capable of supporting the following NMEA message formats
NMEA Message
Prefix
Format Direction
$GPGGA(1)
*
GPS fix data.
Out
$GPGLL
Geographic position Latitude / Longitude.
Out
$GPGSA(3)
*
GNSS DOP and actives satellites
Out
$GPGSV(3)
*
Satellites in view.
Out
$GPRMC(1)
*
Recommended minimum specific GNSS data.
Out
$GPVTG(1)
*
Velocity and track over ground.
Out
$GPZDA
Date and time.
Out
*:
(1): 1sec output 1msg , (3): 3sec output 1msg , 9600 baud rate (Standard output)
6.2 General NMEA Format
The general NMEA format consists of an ASCII string commencing with a ‘$’ character and
terminating with a <CR><LF> sequence. NMEA standard messages commence with ‘GP’ then a
3-letter message identifier. The message header is followed by a comma delimited list of fields
optionally terminated with a checksum consisting of an asterix ‘*’ and a 2 digit hex value representing
the checksum. There is no comma preceding the checksum field. When present, the checksum is
calculated as a bitwise exclusive of the characters between the ‘$’ and ‘*’. As an ASCII representation,
the number of digits in each number will vary depending on the number and precision, hence the
record length will vary. Certain fields may be omitted if they are not used, in which case the field
position is reserved using commas to ensure correct interpretation of subsequent fields.
The tables below indicate the maximum and minimum widths of the fields to allow for buffer size
allocation.
