Note: The time between seeing satellites and actually getting a lock is dependent on the satellite. Be in view of the open sky for best results (and even then it may take a while to get a lock). Once the module has a lock, the lock should stay for a while.

Make a directory inside your “tessel-code” folder called “gps”, change directory into that folder, and initialize a tessel project:

mkdir gps; cd gps; t2 init


Plug the GPS module into Tessel port A with the hexagon/icon side down and the electrical components on the top, then plug Tessel into your computer via USB.


Install by typing npm install gps-a2235h into the command line.


Rename “index.js” to “gps.js” and replace the file’s contents with the following:

// Any copyright is dedicated to the Public Domain.

This gps example logs a stream of data:
coordinates, detected satellites, timestamps, and altitude.
For best results, try it while outdoors.

var tessel = require('tessel');
var gpsLib = require('gps-a2235h');

var gps = gpsLib.use(tessel.port['A']);

// Wait until the module is connected
gps.on('ready', function () {
  console.log('GPS module powered and ready. Waiting for satellites...');
  // Emit coordinates when we get a coordinate fix
  gps.on('coordinates', function (coords) {
    console.log('Lat:',, '\tLon:', coords.lon, '\tTimestamp:', coords.timestamp);

  // Emit altitude when we get an altitude fix
  gps.on('altitude', function (alt) {
    console.log('Got an altitude of', alt.alt, 'meters (timestamp: ' + alt.timestamp + ')');

  // Emitted when we have information about a fix on satellites
  gps.on('fix', function (data) {
    console.log(data.numSat, 'fixed.');

  gps.on('dropped', function(){
    // we dropped the gps signal
    console.log("gps signal dropped");

gps.on('error', function(err){
  console.log("got this error", err);

Save the file.


In your command line, t2 run gps.js Check out your location! If you’re having trouble getting a location fix, try going outside; you probably don’t have satellites indoors.

Bonus: Set up a geofence so that you are inside it. (Hint: you may need to check the documentation.)


What else can you do with a GPS module? Try a community-created project.