GPS Finder/Telemetry for RC-Plane


Introduction: 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.

Step 1: What You Need

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

Step 2: Schematics/Building

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.

Step 3: Flashing the Quickstart Board

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.

Step 4: Get It Work

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).

Step 5: Update

first update of the software:

0.2 fix some problems with calculating bearing and heading

upload the source files



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    thank you.

    But what about the 5 volt LCD (ks0108) pins going to the propeller pins?

    4 replies

    I figured out the brightness dilemma from the data sheet.

    ok, so I have the propeller connected to the lcd and gps. I see the image fine. The contrast works but, the brightness seems low. Is there anyway to increase the brightness?
    Also when I connect the accelerometer, i get no image. When i disconnect the accelerometer i get an image. I notice that the pins on the propeller has SDA, SCL as 28 and 30. On your diagram it has 28 and 29. I hooked it up according to your diagram I get the same image. I connected it to 28 and 30...I still get no image.
    Also, i check the data sheet for the GPS module, but I don't see where I can connect an antenna.

    Mr. Gelstronic,
    By the way, Very very cool project. I'm having an issue when I tried connecting your project together. I really can't figure it out. Now, I connected the GPS, LCD, 2-axis and Parralax board. I did not connect the rx/tx yet. I just connected those device to test in phases. But the issue i'm having is I'm getting no graphics at all. The code loaded fine to RAM and NVRAM without any issue. I checked all my pins to the board to LCD move than 3x. But I get the same result. Is there any words of wisdom you can provide please?

    Thanks(in advance).

    i have the image now. There were two issues. the LCD wiring and the .spin file loads. The image is there now. I will continue to connect the other parts.

    Thank you.

    ok, I have the contrast working now. i have the LCD hook to the propeller quick board with nothing else (GPS, Accell., and strain.) But I stilll don't see any image.

    did you check the proper LCD contrast with the poti ?

    1 reply

    yes, i check but, nothing lit. When I connect pin 20 to ground it lights. But the adjustment does nothing. I have 2 LCDs and its the same. So, I rewired the LCD more than twice. Maybe I'm missing something from your diagram.

    by the propeller board being 3.3V logic...would the devices (gps, axis and app) on the receiver damage the propeller board? I say that because those devices are tied to 5 volts.

    1 reply

    to be sure you can use a 1K resistor in the line between GPS/TX and Prop/RX

    Can I use the Propeller Mini? Found here:

    5 replies

    use protoboard:

    or cluso's cpu blade:

    One more thing. What is the range? What if the drone falls in some wooded areas? Will the signal be lost or degraded?

    be sure to use a data transmitter with enough power :-)

    And a good antenna

    No, there are not all I/O pins accessible at the prop-mini

    perfect. I mis-interpreted the setup anyway. For some reason I though the quickstart board was on the aircraft, so I wanted it smaller. I see now that it is located on the ground station, mounted behind the monitor. Thanks for this instructable!


    I have a question for you. Its possible to run your code into another board? like arduino..

    Thank you

    2 replies

    No, code works only for propeller microcontroller from parallax

    thank you for quick response. I try to buy parallax board to Romania place :) . Anyway your project is very nice and i want to use to bait boat action. Can you help me with some idea to memorize the few places where my boat is running? Is some stuff on the market but is very expensive for me)aprox (6-800eur)

    I appreciate your help
    Tank you