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70 lines
2.5 KiB
70 lines
2.5 KiB
4 years ago
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# Decode GPS data - Wio Terminal
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In this part of the lesson, you will decode the NMEA messages read from the GPS sensor by the Wio Terminal, and extract the latitude and longitude.
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## Decode GPS data
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Once the raw NMEA data has been read from the serial port, it can be decoded using an open source NMEA library.
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### Task - decode GPS data
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Program the device to decode the GPS data.
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1. Open the `gps-sensor` app project if it's not already open
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1. Add a library dependency for the [TinyGPSPlus](https://github.com/mikalhart/TinyGPSPlus) library to the projects `platformio.ini` file. This library has code for decoding NMEA data.
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```ini
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lib_deps =
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mikalhart/TinyGPSPlus @ 1.0.2
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```
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1. In `main.cpp`, add an include directive for the TinyGPSPlus library:
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```cpp
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#include <TinyGPS++.h>
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```
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1. Below the declaration of `Serial3`, declare a TinyGPSPlus object to process the NMEA sentences:
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```cpp
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TinyGPSPlus gps;
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```
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1. Change the contents of the `print_gps_data` function to be the following:
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```cpp
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if (gps.encode(Serial3.read()))
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{
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if (gps.location.isValid())
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{
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Serial.print(gps.location.lat(), 6);
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Serial.print(F(","));
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Serial.print(gps.location.lng(), 6);
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Serial.print(" - from ");
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Serial.print(gps.satellites.value());
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Serial.println(" satellites");
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}
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}
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```
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This code reads the next character from the UART serial port into the `gps` NMEA decoder. After each character, it will check to see if the decoder has read a valid sentence, then check to see if it has read a valid location. If the location is valid, it send it to the serial monitor, along with the number of satellites that contributed to this fix.
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1. Build and upload the code to the Wio Terminal.
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1. Once uploaded, you can monitor the GPS location data using the serial monitor.
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```output
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> Executing task: platformio device monitor <
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--- Available filters and text transformations: colorize, debug, default, direct, hexlify, log2file, nocontrol, printable, send_on_enter, time
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--- More details at http://bit.ly/pio-monitor-filters
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--- Miniterm on /dev/cu.usbmodem1201 9600,8,N,1 ---
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--- Quit: Ctrl+C | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
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47.6423109,-122.1390293 - from 3 satellites
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```
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> 💁 You can find this code in the [code-gps-decode/wio-terminal](code-gps-decode/wio-terminal) folder.
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😀 Your GPS sensor program with data decoding was a success!
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