This is a simple guide to start using the stock GPS receiver that came with your MediaTek LinkIt.
For this project you will need:
- A solderless bread board
- Jumper Wires
- Two LED's
- Stock GPS Antenna
- MediaTek LinkIt
- A push button switch
Optional - micro SD Card to log Coordinates
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Step 1: Wiring It Up
Place a jumper wire from the digital ground to the bread board (Black) as well as from one of the LED driver pins (Red). Make sure to place the long leg of the LED to the hot row on the bread board.
For the second LED place a jumper from the ground row of the first LED to the ground row of the second (Yellow). Then run a jumper from another LED driver pin to the hot row of the second LED.
Run two jumpers from two different digital pins (one will be programmed as hot) and connect your switch between them.
Step 2: Coding
The basic flow for controlling the LinkIt GPS is:
powerOn(): Power on GPS
setMode(): Set up work mode (optional)
getData(): Query and process GPS data
powerOff(): Power off GPS
If getData() comes back as all zeros, then the GPS has not yet acquired it's satellites. I set up my logger to have a cycle time of 4 Hz and compare each data point to the one previous. If the data points are more than 50m apart (in my area that is equivalent to 2.05 seconds) the GPS is not considered to have fully acquired satellites.
PS If you pan to use your tracker at insanely high speeds (over 700km/hr) you will need to increase number of minutes used to determine if the signal is accurate enough to log. My formula allows for a maximum speed of 720km/hr (aprox 450 Mph).
If you are using a memory card make sure to save to it regularly, as the LinkIt one sometimes freezes (likely because my code is not fully optimized).
Step 3: Testing
Once the LinkIt has established an accurate connection with it's satellites the first LED (Blue) will come on. If the switch is pressed the GPS coordinates will be logged to the SD card and the second LED (Red) will begin to flash.
To stop tracking, simply click the switch again. And the second LED will stop flashing signalling that the LinkIt has stopped saving the Coordinates.
NOTE: If the second LED (Red) stays on or off solid and the switch is unresponsive, it means that the logger has frozen and needs to be rebooted.
Have a great day and make sure to share any improvements or ideas in the comments!