Build a GPS Ride Tracker with an ESP32

Why this happens

A GPS module outputs standard NMEA sentences containing position, speed and time once or more per second. An ESP32 can parse them and save them to a card, giving you a tracker you own and control. Building it teaches serial communication, parsing and file logging, and the data helps you study your routes and riding.

What you need

Step by step

1. 1

   Connect the GPS module

   Wire the GPS module's TX to an ESP32 receive pin on a spare hardware serial port, and its RX to a transmit pin if you want to configure it. Power it from 3.3 V or 5 V as its datasheet states and connect grounds. Most modules default to 9600 baud. Place the antenna with a clear view of the sky.

2. 2

   Read the raw sentences

   Upload a sketch that copies everything from the GPS serial port to the USB serial monitor. Take the board outside or near a window. At first the sentences have empty fields; after a few minutes the module gets a fix and fills in latitude, longitude, time and speed. A first fix after a long power-off takes longer than later starts.

3. 3

   Parse with a library

   Install a maintained GPS parsing library. In the sketch, feed it every character from the GPS port and, when it reports a valid new location, read latitude, longitude, speed, altitude, satellites and time. Print them to check. Only log readings when the fix is valid, so bad data does not appear in your files.

4. 4

   Log to the microSD card

   Wire the microSD module to the ESP32's SPI pins. At start-up, create a new CSV file named with the date or a counter. Once a second, append a line with time, latitude, longitude, speed in km/h, altitude and satellite count. Flush after each write. Blink an LED on each saved line so you can see it is logging.

   Tip: Start a new file for each power-on so a corrupted file never loses more than one ride.

5. 5

   Power it independently

   Power the tracker from a small power bank, or from a holder with a protected cell and a proper single-cell charging module. Do not connect it to the vehicle's battery or wiring. Measure how long it runs on a full power bank on the bench, so you know it will last your longest ride.

6. 6

   Box and mount it

   Fit everything in a weatherproof box with the GPS antenna on top, facing the sky. Secure it under a seat or on a rack with straps where it cannot fall into the wheel or block lights or controls. Seal cable entries. Switch it on before you set off and leave it alone while riding.

7. 7

   Map and analyse rides

   Copy the CSV to a computer. Most mapping software can import a CSV with latitude and longitude columns, or convert it to a GPX track. Use a spreadsheet to calculate distance, moving time and average speed. Compare rides on the same route with different conditions. Delete old files you do not need, because they show where you live and travel.

How to tell it worked

The tracker logs a valid position every second for a whole ride, the track appears correctly on a map, and the distance matches your vehicle's trip meter closely.

Questions