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GPS On Screen Display Example Programs
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GPS Example 1
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| The GPS examples are simple programs in MPASM assembler showing how to use the OSD project board to display GPS
data. Order to develop on PROJ-RS232, PROJ-TTL or OSDSER. These are not the programs
running on the current versions of our GPS overlay products. The source code is sold under our single user development licence, please read before
ordering. Fitness of this software for any specific purpose is specifically disclaimed. The altitude shown above
may not be displayed by example 1 depending on the receiver used. It will not be shown when the Garmin GPS25-HVS
is used. |
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GPS Example 3
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The program is compatible with any GPS receiver that sends data using the NMEA 0183 standard, 4800 baud, 8N1, once per second update rate. The common GPS data sentences
are shown below. The GPS display program ignores the data sentences shown in grey. Each $GPRMC and $GPGGA
data sentence, shown in red is parsed and the data in the sentence displayed. The data contained in each sentence
is shown below. Three versions of the program are contained in the example. GPS example 1 shows how the GPS data
can be buffered and the variables used for calculation before display. The calculation produces the heading indicator
shown in the video above. GPS example 2 displays the data as each part of the sentence is received. It does not
have a heading indicator. GPS example 3 displays the speed in kilometers from the $GPVTG data sentence together with the time and date from the $GPRMC. The altitude from the
$GPGGA sentence may not be displayed by example 1 dependent on the order that the sentences are transmitted. |
$GPGLL,5227.3690,N,00004.2495,W,100826,A,A*5B
$GPBOD,,T,,M,,*47
$PGRME,25.0,M,50.0,M,55.9,M*15
$PGRMZ,-45,f,2*06
$GPRTE,1,1,c,*37
$GPVTG,11.18,T,,M,0.10,N,0.0,K*58
$GPRMC,101328,A,5227.3688,N,00004.2494,W,0.0,0.0,301100,3.1,W,A*12
$GPRMB,A,,,,,,,,,,,,A,A*0B
$GPGGA,101328,5227.3688,N,00004.2494,W,1,03,2.6,-13.8,M,47.1,M,,*4A
$GPGSA,A,2,02,08,,,,,,26,,,,,2.8,2.6,1.0*32
$GPGSV,3,1,10,02,56,114,00,08,34,064,44,09,18,245,00,10,35,186,00*79
$GPGSV,3,2,10,15,08,340,00,17,19,287,00,23,19,319,00,26,67,295,46*7A
$GPGSV,3,3,10,27,04,066,00,31,08,027,00*76 |
| Data type |
Data sentence |
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Latitude |
$GPRMC |
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Longitude |
$GPRMC |
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Time ( UTC ) |
$GPRMC |
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Date |
$GPRMC |
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Heading ( Track made good, degrees true ) |
$GPRMC |
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Speed ( over ground in knots ) |
$GPRMC |
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Altitude ( in metres above/below mean-sea-level (geoid) ) |
$GPGGA ( not example 1 ) |
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Speed over ground in kilometres per hour |
$GPVTG ( example 3 only ) |
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© The BlackBoxCameraTM Company Limited 2009
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