DIY Wi-Fi GPS Tracker with Geofencing & SMS Alerts (Seeed Studio XIAO ESP32-S3)

Overview

This project demonstrates how to build a compact, low-power GPS tracker using the Seeed Studio XIAO ESP32-S3, combining precise location tracking with intelligent geofencing capabilities. Designed with makers and IoT enthusiasts in mind, it walks through the complete hardware and firmware setup needed to track assets, vehicles, or personal devices in real time.

The tracker integrates a GPS module with the ESP32-S3’s built-in Wi-Fi and Bluetooth connectivity to transmit location data to a cloud platform. By defining virtual boundaries (geofences), the system can automatically trigger alerts whenever the device enters or exits a designated area—an essential feature for security, logistics, and smart mobility applications. The project also highlights efficient power management techniques, making it suitable for battery-powered deployments.

With clear schematics, code explanations, and real-world use cases, this build is ideal for makers looking to explore IoT tracking systems, location-based automation, or ESP32-S3 development

Core Components You’ll Need

Hardware

• Seeed Studio XIAO ESP32-S3: Handles Wi-Fi connectivity, processing, and GPS data transmission.
• Neo-6M GPS Module: Captures GPS signals and outputs location coordinates.
• External GPS Antenna: Improves signal reception.
• Breadboard & Jumper Wires: For prototyping without soldering.

Software

• Arduino IDE: To write and upload code.
• Libraries:
• GeoLinker Library – for secure cloud communication
• TinyGPSPlus – to parse GPS sentences
• WiFiClientSecure – for HTTPS connectivity

What This GPS Tracker Does

This DIY tracker combines GPS hardware with cloud APIs to deliver a feature-rich tracking solution:

• Real-time location tracking over Wi-Fi
• Geofencing alerts that notify you when the device leaves a virtual boundary
• SMS alerts with precise coordinates
• Offline data buffering so no points are lost when Wi-Fi disconnects
• Interactive map visualisation via a free cloud service called GeoLinker

How It Works: Conceptual Overview

1. GPS Data Acquisition
2. The Neo-6M GPS module receives signals from satellites and calculates latitude/longitude coordinates.
3. Microcontroller Processing
4. The XIAO ESP32-S3 reads GPS data over UART and prepares it for cloud transmission.
5. Wi-Fi Upload to Cloud
6. Coordinates are pushed to the GeoLinker cloud service at regular intervals.
7. Geofence Logic
8. The firmware continuously checks the distance between the current location and a predefined “home” point using the Haversine formula.
9. Alert System
10. If the device crosses the set geofence radius, an SMS notification is sent with the current GPS coordinates via the cloud API.
11. Offline Support
12. When Wi-Fi is unavailable, GPS points are locally buffered and uploaded automatically once connectivity is restored.

Circuit and Wiring

Connect the Neo-6M module to the XIAO ESP32-S3 as follows:

GPS Module PinXIAO ESP32-S3 PinFunctionVCC5VPowerGNDGNDGroundTXGPIO 44 (RX)GPS → MicrocontrollerRXGPIO 43 (TX)Optional configuration port

Ensure the GPS antenna is fitted securely for reliable positioning.

Setting Up GeoLinker and API Keys

1. Sign up on the GeoLinker platform: Create a free cloud account.
2. Generate an API key: Use it in your sketch to authorize data uploads and SMS alerts.
3. Link your mobile number: Required to receive SMS notifications.

The free tier typically offers 10,000 data points and a quota on SMS messages, enough for development and testing.

Source Code Highlights

The Arduino sketch includes:

• Wi-Fi setup
• GPS parsing with TinyGPSPlus
• Cloud communication via GeoLinker
• Geofence detection and SMS trigger logic
• Offline buffering

You define variables such as:

• ssid, password (Wi-Fi credentials)
• apiKey and deviceID
• updateInterval and geofence radius
• Home latitude/longitude

The code continuously reads GPS fixes, calculates distance, and sends alerts when thresholds are exceeded.

Testing and Results

To test the system:

1. Connect the device to a Wi-Fi hotspot (e.g., a phone hotspot).
2. Upload your sketch and monitor the GeoLinker dashboard.
3. Move around to simulate motion relative to your geofence.

If the device crosses the set virtual boundary, you’ll receive an SMS with the latitude and longitude, and the movement history will appear on the map.

Applications and Next Steps

This project unlocks many maker scenarios:

• Vehicle & asset tracking
• Child, elderly, or pet safety systems
• Route history and movement analytics
• Multiple geofences and customizable alerts

You can also enhance it with battery monitoring, speed alerts, or additional sensors.

Conclusion

This DIY GPS Tracker using Seeed Studio Xiao ESP32-S3 demonstrates how powerful modern microcontrollers can eliminate traditional constraints such as cellular modules and expensive data plans. With Wi-Fi connectivity, cloud logging, geofencing, and SMS alerts, you get a flexible and maker-friendly solution ready for real-world applications.