**Part 1** In this video, we'll be learning how to use a GPS module with an Arduino and C++. We'll explore how a GPS works, how to wire up and code the Arduino to get coordinates, and as a final step, we'll add a few other components to build a device that takes in a target location and uses GPS to tell you the direction and distance to your destination. Let's get into it. GPS is one of the most incredible things that we, as a species, have made. Figuring out where you are used to be a skill that our ancestors spent years mastering, but now you can do it far more precisely with a module that costs a little more than a cup of coffee. But how does it work? How does such an inexpensive and small module have the ability to locate you anywhere on Earth? Above you, there is a system of strategically placed GPS satellites orbiting around the Earth, about 30 of them. These satellites beam out radio messages containing the exact time the signal was sent and where the satellite is. This device listens for those messages and does some calculations to figure out how far away each satellite is, using the speed of light. If it can get a signal from four or more satellites at once, it can determine its latitude, longitude, altitude, and even get a very accurate time reading from the satellite's atomic clock. This module will let your project read the time from an atomic clock in space. A simplified example of how this locating with distances works: imagine I was lost somewhere in Australia, but I knew I was exactly 2,000 kilometers away from Sydney and 1,450 kilometers away from Cairns. With a bit of math, I could precisely find my location and know that I'm in Alice Springs. It gets more complicated in 3D space and on the Earth's surface, but it's the same idea. Knowing how far away the satellites are and where they are, you can find where you are. Let's plug it in and start receiving those satellite signals. To follow along, you'll need a GPS module, a USB cable to plug in your Arduino, and an Arduino. We're using the Arduino R4 here, but this will also work on the R3, and with some effort, you can get it working on an ESP32. You'll need some jumper wires to connect everything. Links to all of these are below and in the written guide, which is also linked down there. We'll start by connecting the GPS antenna to the GPS module. I'll use blue tack to secure it to the GPS module to prevent it from dangling and possibly getting damaged. Next, power the GPS by connecting the ground pin of the GPS to a ground pin of the Arduino, and then connect the VCC pin of the GPS to the 5V power output of the Arduino. You can find these pin labels on the other side of the board. This GPS module can also be powered with 3.3V if your project needs it. The GPS uses UART to send data to our Arduino. The Arduino usually uses pins 0 and 1 for UART, but it also shares those pins with the USB UART connection. If we wanted to print data to the serial module on our computer and read the GPS module, those two things would conflict because they're sharing the same pins. So instead, we're using pins 2 and 3 for UART and using software serial to mimic the UART connection. We'll look at this more later when we get into the code section. This pin conflict is no longer an issue on the Arduino R4, but we're using 2 and 3 to ensure this will work on every Arduino Uno. Another important thing is that this GPS module uses 3.3V logic, which is different from our Arduino's 5V logic. If we send a 5V signal or data from our Arduino to our GPS, which is designed for 3.3V, we might damage it. In this guide, we're only sending data from the GPS to the Arduino, which shouldn't cause issues. So, connect the TX pin of our GPS, the transmitter pin, to pin 2 of our Arduino, which will be the receiver pin. This connection won't damage anything because the 5V Arduino can read a 3.3V signal. If you want to send data from the Arduino to the GPS, you'll need a logic level converter to do so safely. Now, we're in the Arduino IDE where we'll program everything. Plug in your Arduino and ensure you have the correct board and COM port selected. Paste in the first demo code from the written guide linked below, where you'll also find all the other demo code covered in this video. We start by importing the software serial library, setting up pins 2 and 3 with that library, and calling it GPS serial. Usually, pins 0 and 1 are used for UART connections on the Arduino Uno, but with this library, we can emulate that UART hardware in software. This adds some processing overhead to our Arduino, but for what we're doing here, we probably won't notice the difference. **Part 2** The extra processing power it consumes is minimal. Then, we start the software serial communication at a baud rate of 9600, which is important because the GPS module communicates at 9600 and needs to match it. We also start our regular serial connection to communicate with the serial monitor, ensuring it matches the baud rate of 9600. When the GPS module sends a message, it's held in the UART buffer, which holds the message until we're ready to deal with it. The line `if gpsserial.available` checks that buffer and returns true if there is a message. If true, we read that serial message, store it in `gpsReading`, and print it out. This is basic UART communication. Compile and upload that to our board, and if we go to our serial monitor, we're getting an output from our GPS module. I'll make that a bit bigger and unplug the Arduino to stop it from scrolling. I'll highlight one of these messages. Let's turn off the time because we don't need to see that. It starts from GPRMC and goes down to GPGL. Yours might look like mine with a lot of commas and not much information. This is what it looks like when the GPS hasn't locked onto enough satellites. I'm inside a big metal warehouse, so it's difficult to receive those signals, and I'm not able to get our position yet. You can confirm this by seeing a 'V' here. When your GPS module can get enough satellites and start finding your location, that letter will change to 'A', and the red light on the module will start flashing. It may take your module a few minutes to find the satellites if it hasn't been powered on for a while. If you're inside a giant metal building, you might need to move closer to a window or head outside to get a lock onto those satellites. We found that if we took it outside and powered the GPS for a few minutes to get a lock and that light starts flashing, we could then bring it inside and work on it, and it kept that lock indoors. This also brings up a conversation about accuracy and operating conditions. Essentially, the more stuff between the GPS receiver and the satellites in space, the less accurate it will be. When we were outside with a clear view of the sky, the GPS module was accurate to about a meter. However, when it was cloudy and we were between buildings and under trees, it was accurate to about two or three meters. Inside the giant metal warehouse, that accuracy blows out to 10, maybe even 50 meters. The more things that might block the signals between this and the satellites above, the less accurate your GPS will be. Now we have a lock. I'll unplug the Pico and pause it. We can see the letter 'A' there, the LED is flashing, and we have more information from the GPS. Nestled in here is helpful information like our current latitude and longitude, the current time and date, an estimation of our altitude, and more. For a more in-depth breakdown of everything, check the written guide linked below. All our information is there, but it's hard to use in our projects. This weird format is called NMEA, a standard format, and it's the hardest part of using GPS in your projects: handling that output string and extracting the information you want. One option is to paste this output message into an LLM like ChatGPT, Claude, or DeepSeek to help extract the data you want. They're familiar with this NMEA format, but we've also written a library to do that for you. On the course page, you'll find a link to download that library, which comes as a zip file. To use the library, hit Sketch, then Include Library, Add .ZIP Library, navigate to the zip folder you downloaded, and open it. This installs the library for us to use. On the written page, you'll find the second lot of demo code, which we'll paste in. This code demonstrates how to use the library. Starting off, we import the GPS library we downloaded and create our GPS reader with the software serial we set up. Whenever we want to read the GPS, we use `.getData`, which gets all the GPS information, bundles it together, and stores it in `GPSData`. Commented below is all the information stored in this GPS data structure: does it have a fix, the latitude, the longitude, the speed in knots, the current time and date (not in your time zone but central time), how many satellites it's connected to, an estimate of your current altitude, and three things called HDOP, PDOP, and VDOP. These are ratings of how accurate the reading of your horizontal, vertical, and overall position are. The lower the number, the better. Anything under five is probably good enough for your project. Under that, we print some of these out to see how we use them. If you want latitude, call `GPSData.latitude`. For longitude, `.longitude.satellites`, whatever you want, just put `.whatever` on the end to get that information. Upload this to the board, and we're getting usable data from our GPS module. Note that the GPS only gets new data every second. If we try to get data more than once a second, it will keep outputting the old reading until it gets a new one every second. **Part 3** With that, you can now get GPS coordinates and other helpful information to add to your project. Before we finish, let's do something cool. We'll add a magnetometer, essentially a compass module, to figure out which direction we're pointing, an OLED screen to display that information, and a AA battery pack to power it all. We'll create a system that takes our current coordinates, compares them to a target coordinate, and shows us how far it is and which direction to head. We'll go through this quickly. For more detail, check the written guide linked below. These modules are I2C and plugged into the handy quick connector on the Arduino R4. If you're not using the R4, you'll need a quick connector to DuPont breakouts and manually wire it to your board. To use the OLED and magnetometer, install additional libraries from the library manager: Adafruit MMC56X3 and Adafruit SSD1306. The magnetometer needs calibration by finding its maximum and minimum axis values. If you haven't got those, we'll show you how in the written guide. Once done, paste in our third and final demo code. For a breakdown of how this code works, check the written guide. Before uploading to the board, change a few things. Ensure you place your magnetometer calibration data here and input your target latitude and longitude. You can get that data from Google Maps by clicking a point and finding the latitude and longitude, which can be plugged into the code. Upload that to the board, which might take a while due to the compilation. Another important thing is that the quick connector on the Arduino R4 uses wire one. If you're not using the quick connector, delete that and use wire. Scroll down to where we initialize the magnetometer and replace that with wire as well. Only do this if you're not using the quick connector on the R4. Let's give that a go. Power it on, and it should take a bit to look for satellites. I'll take it outside for a walk to get a lock. We have a lock, and now we have a device with an arrow pointing to our target coordinate, the distance, altitude, current position, and target position. With a few inexpensive off-the-shelf components and a few hundred lines of code, we've created a fun GPS project. To someone 50 years ago, this would be incredible technology, and 100 years ago, it would seem like magic. All thanks to the satellites in space and our GPS receiver. That wraps it up. You now know how to add a GPS to your project and get helpful information through that UART connection. If you made anything cool with this or need help, head over to our community forums. We're all makers there and happy to help. Till next time, happy making!