From autonomous coolers to navigation aids for the visually impaired, you can pair GPS modules with your Arduino to realize countless projects ranging from silly and fun to practical and utilitarian. Before you delve into those projects, let’s explore at how GPS works, what it’s capable of, and how you can connect it to your Arduino.
How Does GPS Work?
All GPS (which stands for Global Positioning System) units work in the same basic way. The GPS network is made up of 24 satellites that orbit the earth in precise, predefined trajectories while broadcasting radio signals that contain data about the satellite’s precise location. Each satellite’s orbit and accompanying radio signal is unique.
GPS receivers are configured to:
1. Accept the incoming signals from the various satellites.
2. Compare the location data and its transmission time.
3. Use this information to triangulate the receiver’s precise location.
The GPS device needs at least three signals to determine its position in two-dimensional space and at least four signals to determine its location in three-dimensional space. Depending on location, time of day, and the presence or absence of structures that may block the signal, we can expect a receiver to track as many as eight satellites at any given moment.
Arduino GPS Capabilities
Based on your location data, GPS receivers can determine time and distance to another location, your bearing, even your speed/rate of travel (by comparing real-time changes in location and the time to move from one to the next). This is all just with a single GPS unit operating alone.
When you begin to add custom software and other GPS-enabled devices to the equation, the possibilities multiply exponentially. For instance, by using two GPS-enabled devices in tandem (like an Arduino and a smartphone), you can compare or transmit the location data of both to perform tasks such as:
- Find a lost pet
- Monitor a child coming home from school
- Make your cooler follow you around at the picnic (convenient and a great party trick)
You can use speed and location information to enrich wearables by tracking not only your route but also your speed over time (an especially useful addition for runners).
If your projects involve precise data about the location, direction, or speed of one or more objects, learning to work with GPS modules will be a big help in realizing them.
How to Connect GPS Module to Arduino
Connecting GPS units to Arduino won’t take long , since the GPS units are equipped to output serial data and the Arduino has several different ways to receive serial information. Follow these steps to connect these devices.
1. Start by selecting the right GPS module. Because not all the Arduino pins are voltage-regulated, make sure you’ve chosen a GPS unit with an appropriate power supply, or one that has its own regulator to ensure that the Arduino won’t damage it (for instance, the output of a 5V board can damage an unregulated 3.3V GPS).
2. Once you have a compatible GPS receiver, connect it to a 5V power from the Arduino and a ground pin. Connect the RX and TX pins on the GPS to serial pins on the Arduino.
3. Use the Arduino’s serial monitor to make sure the GPS is outputting data. Be aware that many GPS modules have long “cold start” times, so be patient and give it a minute or two before you decide whether it’s connected correctly.
The initial serial output will look like nonsense, but it’s the native language of the GPS network. Typically, you’ll see lines that begin $GPXXX where “XXX” are three other letters. These letter codes establish that it’s GPS data and they provide information about what kind of data is being coded (estimated position, velocity, etc.).
The letter code is followed by a string of numbers that represent, in order:
- Timestamp
- Latitude
- Longitude
- Quality of the signal (corrected/uncorrected, etc.)
- Number of satellites used in the coordinate
- Information about altitude
- Any corrections
On its own, this raw data (called NMEA data, from a standard which preceded the invention of GPS and is currently the standard for all GPS units) isn’t easily readable or helpful to the average user. However, installing an Arduino GPS library like the TinyGPS Library will transform the raw data into readable information in a format like this:
Location: LATITUDE, LONGITUDE Date/Time: XX/XX/XXXX XX:XX:XX.XX
As you can see, the data will now display as straightforward coordinates, time-stamped with the day, month, year, and time down to hundredths of a second.
GPS and Arduino
GPS modules offer useful information about geographical location, altitude, speed, and more, all of which we can implement into a wide variety of applications. GPS is based on a sophisticated array of satellites orbiting the earth and emitting radio frequencies, but fortunately, the tools and software we need to access and use this data are readily available and easy to explore. To learn more about how Arduino’s and GPS modules work together, check out our hands-on Arduino GPS tutorial.