Build a Smart GPS Tracker with Seeed XIAO ESP32-S3

GPS trackers are incredibly useful for monitoring assets, vehicles, pets, or even loved ones. But many DIY implementations rely on expensive cellular modules and data plans — until now. In this project, we’ll walk through building a fully functional GPS tracker that uses Wi-Fi instead of GSM, includes geofencing, and even sends SMS alerts when your device leaves a defined area — all without a SIM card.

This version uses the small but powerful Seeed Studio XIAO ESP32-S3 microcontroller together with a Neo-6M GPS module. By integrating with the free GeoLinker cloud platform, the tracker sends its GPS coordinates over Wi-Fi so you can visualize locations on a map and handle advanced features like geofence crossings.

What You’ll Build

Your GPS tracker will:

• Read GPS coordinates using an external GPS module.
• Connect to Wi-Fi and send location data to the cloud.
• Display movement history on an interactive map.
• Detect geofence breaches and trigger an alert.
• Send SMS notifications when boundaries are crossed.

How It Works

Here’s a simplified overview of the system:

GPS Collection: The Neo-6M module captures satellite signals and outputs latitude/longitude.

Processing: The ESP32-S3 reads GPS data via UART at 9600 baud.

Cloud Upload: Coordinates are sent to GeoLinker over Wi-Fi at set intervals (e.g., every 15 seconds).

Mapping & History: GeoLinker stores each point with a timestamp and plots them on a map.

Geofencing: The tracker uses the Haversine formula to measure distance from a set “home” coordinate.

SMS Alerts: If the device leaves the defined radius, an SMS is automatically triggered.

Offline Buffering: Lost Wi-Fi? Data is temporarily stored and synced once reconnected.

This setup provides a reliable tracker with features typically found in commercial IoT solutions — but at a fraction of the cost and complexity.

Step-by-Step Assembly

Wiring

• GPS VCC → XIAO 5V
• GPS GND → XIAO GND
• GPS TX → XIAO GPIO44 (RX)
• GPS RX → XIAO GPIO43 (TX)

Add an external GPS antenna to the Neo-6M for better signal.

Simple serial wiring enables the GPS module to stream NMEA data to the ESP32 continuously.

GeoLinker Cloud Setup

GeoLinker provides the backend that:

• Stores incoming GPS data
• Renders it visually on a map
• Handles SMS alerts via a cloud API

To set this up:

• Create an account on the GeoLinker platform.
• Generate your unique API key.
• Link a mobile number for SMS alerts.

The free tier offers enough data points and SMS capacity for most hobbyist projects.

Code Highlights

Your Arduino sketch will:

Initialize GPS serial and Wi-Fi.

• Set up GeoLinker with your API key and device ID.
• Upload data in timed intervals.
• Compute geofence distance using the Haversine formula.
• Send SMS when the device moves outside the preset radius.

You can further customize:

• Update intervals (more frequent updates for finer tracking)
• Geofence radius (from meters to kilometers)
• Multiple geofences
• Speed or battery alerts

Real-World Testing

In practical tests, the tracker:

• Connected to a phone hotspot via Wi-Fi
• Continued local GPS buffering when Wi-Fi dropped
• Synced stored points once reconnected
• Sent SMS notifications as expected when the geofence was breached

The result is a consistent and fault-tolerant tracker suitable for many real use cases.

Where You Can Use It

• Fleet & vehicle tracking
• Asset security
• Child or elderly location alerts
• Pet monitoring

Any mobile object that needs safe-zone notifications

Conclusion

This GPS Tracker with Seeed Studio XIAO ESP32-S3 project shows how Wi-Fi-based GPS tracking can replace more expensive cellular alternatives, adding powerful features like geofencing and SMS alerts. Using a compact board like the XIAO ESP32-S3 and free tools like GeoLinker makes it accessible to makers, students, and hobbyists alike.
Ready to prototype? Jump into the code and circuit, and make your own smart tracker today!