IoT-For-Beginners/translations/pcm/3-transport/lessons/1-location-tracking/single-board-computer-gps-decode.md

Decode GPS data - Virtual IoT Hardware and Raspberry Pi

For dis part of di lesson, you go decode di NMEA messages wey di GPS sensor read from di Raspberry Pi or Virtual IoT Device, and you go comot di latitude and longitude.

Decode GPS data

Once you don read di raw NMEA data from di serial port, you fit decode am using one open source NMEA library.

Task - decode GPS data

Program di device make e decode di GPS data.

1. Open di gps-sensor app project if e never open before.

2. Install di pynmea2 Pip package. Dis package get code wey fit decode NMEA messages.

   pip3 install pynmea2
   

3. Add dis code to di imports for di app.py file to import di pynmea2 module:

   import pynmea2
   

4. Change wetin dey inside di print_gps_data function to dis one:

   msg = pynmea2.parse(line)
   if msg.sentence_type == 'GGA':
       lat = pynmea2.dm_to_sd(msg.lat)
       lon = pynmea2.dm_to_sd(msg.lon)
   
       if msg.lat_dir == 'S':
           lat = lat * -1
   
       if msg.lon_dir == 'W':
           lon = lon * -1
   
       print(f'{lat},{lon} - from {msg.num_sats} satellites')
   

   Dis code go use di pynmea2 library to parse di line wey e read from di UART serial port.

   If di sentence type for di message na GGA, e mean say na position fix message, and e go process am. Di latitude and longitude values go dey read from di message and e go convert am to decimal degrees from di NMEA (d)ddmm.mmmm format. Di dm_to_sd function na im dey do dis conversion.

   Di direction for di latitude go dey check, and if di latitude dey south, di value go change to negative number. Same thing for longitude, if e dey west, e go change to negative number.

   At di end, di coordinates go show for di console, plus di number of satellites wey dem use to get di location.

5. Run di code. If you dey use virtual IoT device, make sure say di CounterFit app dey run and di GPS data dey send.

   pi@raspberrypi:~/gps-sensor $ python3 app.py 
   47.6423109,-122.1390293 - from 3 satellites
   

💁 You fit find dis code for di code-gps-decode/virtual-device folder, or di code-gps-decode/pi folder.

😀 Your GPS sensor program wey decode data don work well!

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Disclaimer:
Dis dokyument don use AI translation service Co-op Translator do di translation. Even as we dey try make am accurate, abeg sabi say machine translation fit get mistake or no dey correct well. Di original dokyument wey dey for im native language na di one wey you go take as di correct source. For important mata, e good make professional human translator check am. We no go fit take blame for any misunderstanding or wrong interpretation wey fit happen because you use dis translation.