GPS Finder/Telemetry for RC-Plane

Where is my plane or my dog or whatever ?

With this Instructable we build a GPS-Finder without using a cellphone/mobile network.

It is for short distance 1-2 miles/km depending on the radio data link you'll use.

The project needs the parallax propeller microcontroller, i use the Parallax Quickstart board.

The transmitter simply consists of a gps-module and a radio data link.

Here is the part list:

• 2 pcs. GPS-Modules (around 10 bucks on ebay) output NMEA sentences, GGA, RMC at 9600 baud
• Microcontroller board : P8X32A Propeller QuickStart
• 2 Axis compass modul : MMC2120MG
• Display:KS0108 128x64 Graphic LCD
• 2 pcs. Radio Data Modul : APC220
• case 100x75x40mm
• 3 pushbutton
• 3 resistor 10K
• trimmer resistor 20K
• Resistor for LED backlight of display, see datasheet (depends on color)
• wires
• soldering iron
• tools to work on the case

optional for power supply

• 2x 7805
• 4x 100nF
• 2x 100µF

Here are the schematics of the Receiver and Transmitter, optional you can build a 5V power supply if you've

no 5V at you model etc.

Be shure to fix the compass modul/case horizontally because it is not tilt compensated

The data link need the same baudrate than gps modul, in this case 9600 baud, if you use the apc220 here

is a good link to configure.

Now it's time to flash the Quickstart board with the attached binary.

Install the Propeller Tool and connect the board via usb with you pc.

Open the attached file and load it to eeprom.

After power on you have to wait for finding satellites (min.5)

Then the main screen with the matrix appears.

With the first button you can switch between matrix and a direction arrow.

With the 2nd and 3rd button you can increase/decrease the scale of the matrix.

The screen also shows the current position of the transmitter the distance between RX/TX

and the number of satellites (RX/TX).

first update of the software:

0.2 fix some problems with calculating bearing and heading

upload the source files