Build a GPS Tracker Using Heltec V4 and REYAX RYS352A GNSS Module

Have you ever wondered how GPS trackers display their location on a map in real time?

In this project, I've built a GPS tracker using the Heltec WiFi LoRa 32 V4 and the REYAX RYS352A Multi-GNSS module. The tracker receives live coordinates from GNSS satellites, displays them on the onboard OLED display, and hosts a web page that shows the current location and travelled path on OpenStreetMap.

Unlike many GPS tracking projects, this one doesn't require any cloud platform or external server.

You'll need:

1. Heltec WiFi LoRa 32 V4
2. REYAX RYS352A GNSS Module
3. Breadboard
4. Breadboard Power Supply
5. 12V Battery
6. USB Type-C Cable
7. Jumper Wires

1. 🛰️ Multi-GNSS Positioning – Supports GPS, GLONASS, Galileo, BeiDou, and QZSS for improved satellite availability and reliable positioning.
2. 🌍 Browser-Based Live Tracking – View the current location and travelled path on an interactive OpenStreetMap interface using any web browser.
3. ☁️ No Cloud Platform Required – The Heltec board hosts the tracking webpage locally, eliminating the need for third-party cloud services or subscriptions.
4. 📍 Live GPS Information – Displays the current latitude, longitude, and connected satellite count on the onboard OLED display.
5. 📡 Embedded Web Server – The ESP32 hosts a lightweight web server, allowing multiple devices on the same Wi-Fi network to access the tracking page.
6. 🔌 Minimal Hardware Connections – Only a few wiring connections are required, making the project beginner-friendly and easy to assemble.
7. 🚗 Real-Time Travel Path – Continuously updates the marker position and records the travelled route as the tracker moves.
8. ⚡ Easy to Extend – The project can be expanded with geofencing, LoRa communication, Home Assistant integration, SD card logging, or cloud connectivity.

The circuit requires only a few connections between the REYAX RYS352A GNSS module and the Heltec WiFi LoRa 32 V4.

The GNSS module communicates with the Heltec board through UART. Connect the TX pin of the RYS352A to GPIO38 (UART RX) of the Heltec board. Power the module using the 3.3 V supply and connect the grounds together.

If you're using the dedicated GNSS Molex connector on the Heltec board, the module can be connected directly without jumper wires, making the hardware assembly even simpler.

Once powered on, the Heltec WiFi LoRa 32 V4 first connects to the configured Wi-Fi hotspot and starts an embedded web server. At the same time, the REYAX RYS352A GNSS module begins searching for navigation satellites.

After acquiring a valid satellite fix, the module continuously sends NMEA location data to the Heltec board through UART communication. The firmware extracts the latitude, longitude, and satellite count using the TinyGPS++ library and displays this information on the onboard OLED.

The board also hosts a browser-based tracking webpage. Entering the displayed IP address into any web browser connected to the same Wi-Fi network opens an interactive OpenStreetMap interface. As the tracker moves, the current location marker updates automatically and the travelled path is drawn in real time.

One of the main advantages of this project is that all processing is performed locally on the Heltec board, eliminating the need for any third-party cloud platform or external server.

We took the tracker outdoors for the best GNSS reception.

During testing, we observed:

1. Satellite count increasing
2. Marker following the movement
3. Red trail recording the travelled path

The tracker successfully:

1. Receives multi-GNSS data
2. Displays live coordinates
3. Hosts its own tracking webpage
4. Updates the travelled path automatically

For the complete tutorial, source code and detailed explanation visit play with Circuit: GPS Tracker using Reyax GNSS Module and Heltec V4 Board