This post will describe the circuit and code to make a simple GPS receiver. This will be the core of the GPS Tracker.


Teensy 3.1 GPS Receiver v.0.4

Breadboard Setup:

  1. Plug the Teensy into the lower numbered end of the breadboard as shown.
  2. Using short jumpers connect the Teensy GND pin to the “-” rail on the breadboard and the Vin to the “+” rail of the breadboard. You can add jumpers to connect the + rails on each side and the – rails. be sure not to cross them.
  3. The GPS module does not fit into the breadboard. Solder 4 wires onto the GPS units VCC, GND, TXD and RXD pins. These will be used to connect the GPS to the breadboard.
  4. Plug the TFT display into the breadboard as shown.


Refer to the “Welcome to Teensy 3.1” card that came with your Teensy or follow this link to a similar diagram online.


  • GND to breadboard “-” rail.
  • VCC to breadboard “+” rail.
  • RXD to Teensy TX1.
  • TXD to Teensy RX1.

TFT Display:

Looking at display side of the TFT with the pins on the bottom the pins are labeled from left to right:

Teensy Vin1 GND1 D102 3.3V D9 D11 D14 VIN3 D12


  1. connect to breadboard + and – rails.
  2. The Teensy digital pins (Dx) are labeled in grey on the “Welcome” card with D0 starting next to the GND pin.
  3. TFT Pin LED connects to the Breadboard “+” rail via a 100 ohm resistor.
  4. SCK moved to D14 to free D13 for PTT on the APRS Tracker

Loading the sketch:

  1. Open a new sketch in Teensyduino: File New.
  2. Delete the new file’s content so it is empty.
  3. ********************************************************************************************
  4. ************* the Github is a WIP, link will be fixed ASAP ************************************
  5. Open the W2DEN_GPS_vx.x on my GitHub site ( ).
  6. Copy the entire contents of the file and paste it into the new Teensyduino file you just created.
  7. Compile and load into your Teensy.

If you have everything set up correctly the file should compile, load into the Teensy. The display should light up and in a minute or two display the GPS data similar to the picture above. (Note: recent updates have changed the display format slightly, your s will be similar.)

Pour yourself a tall cold one, if you made it this far you deserve it. It took me about 3 weeks to get this far…. I hope, with these instructions, you can get this running in a few hours.

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