DIY Arduino GPS Tracker 2025: Sends location and SOS call

This innovative DIY Arduino GPS Tracker project helps you in creating a compact emergency GPS tracking device using an Arduino Nano, which is suitable for carrying along with you and also in vehicles such as cars, bicycles, or motorcycles. This GPS system includes a small button that, when pressed, initiates the tracking process by sending your current location as an SMS to a predefined phone number. The location can be easily viewed on a map using a Google Maps web link from the SMS received.

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Key Components for Your DIY GPS Tracking System

1. Arduino Nano: A cost-effective microcontroller for processing GPS data and managing alerts.
2. GPS Module: Captures precise latitude, longitude, and altitude coordinates via satellite signals.
3. GSM Module: Sends SMS alerts and initiates calls using a standard SIM card.
4. Trigger Button: A tactile switch to activate tracking or emergency calls.
5. Power Source: Typically a rechargeable lithium-ion battery, ensuring portability and reliability.

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How It Works

1. Initialization: The device is powered on and waits for the button to be pressed.

2. Tracking Initiation: When the button is pressed, the GPS module acquires the vehicle’s location by locking onto satellite signals. With data from at least three satellites, it can determine latitude, longitude, and altitude.

3. SMS Alert: The GSM module sends an SMS containing the GPS coordinates to the preset phone number. This message includes a link to view the location on Google Maps.

4. Extended Button Press: If the button is pressed for more than five seconds, the GSM module initiates a call to the same preset phone number, providing an additional layer of alert functionality.

5. Compact & Portable Design: The use of Arduino Nano makes the tracker lightweight and small, allowing it to be discreetly installed in any vehicle. It can be powered by a rechargeable battery, making it a wireless and mobile solution.

Related project: GPS Tracker with GSM/GPRS using blynk with SMS and calling features

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Required components

Product Name	Quantity
Arduino NANO	1	https://amzn.to/3jVNZON	https://amzn.to/3KpUQry
GPS NEO 6M Module	1	https://amzn.to/4bZa31P	https://amzn.to/4bFgyqy
SIM 800L Module	1	https://amzn.to/4iCemSV	https://amzn.to/3DBzwlu
Sim Card	1
Push button	1	https://amzn.to/3uc4gRh	https://amzn.to/3ubrLdc
10kΩ Resistor	1	https://amzn.to/3hBlqlq	https://amzn.to/3sXBKmI
5V power supply (USB or External).	1	https://amzn.to/3s1a8g3	https://amzn.to/364yInH
Few Connecting Wires		https://amzn.to/3H2BV4e	https://amzn.to/3J0WVu2

You can buy the required components from the given best buy links. We choose the components according to value for money.

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NEO-6M GPS Module: Precision Tracking for DIY Projects

 

The NEO-6M GPS module, engineered by u-blox, is a game-changer for location-based projects. Leveraging a constellation of 31 Global Positioning System (GPS) satellites, this compact powerhouse delivers real-time geographic coordinates with military-grade accuracy. Designed for seamless integration with microcontrollers like Arduino, it’s the ultimate tool for hobbyists and developers building tracking systems, drones, or IoT devices.

Key Features of the NEO-6M GPS Module

• 22 Satellite Tracking: Locks onto up to 22 satellites across 50 channels for pinpoint accuracy (within 2.5m).
• Ultra-Low Power Modes:
  • Active Mode: Draws just 45mA during operation.
  • Power-Saving Mode: Slashes consumption to 11mA, ideal for battery-powered projects.
• LED Position Fix Indicator:
  • Steady Off: Scanning for satellite signals.
  • 1-Second Blink: Successfully locked onto 3+ satellites, ready to relay coordinates.

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SIM800L GSM/GPRS Module:

The SIM800L module by SimCom bridges your projects to cellular networks worldwide. Operating at 3.4V–4.4V (compatible with LiPo batteries) and supporting 5V logic via built-in regulators, this quad-band module is a must-have for SMS alerts, voice calls, and IoT applications.

SIM800L Module Breakdown: Specs & Functionality

• Global Quad-Band Support: Works on 850/900/1800/1900MHz frequencies for cross-continent reliability.
• Antenna Flexibility: Switch between compact PCB antennas or high-gain suction cup antennas via the IPX interface.
• Auto Baud Detection: Eliminates manual configuration—plug, play, and transmit.
• LED Network Status:
  • 1-Second Blink: Powered on, searching for network.
  • 2-Second Blink: GPRS active (data transfer enabled).
  • 3-Second Blink: Network connected (SMS/call-ready).

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Circuit Diagram

After grabbing all the required components connect them according to the below circuit diagram.

 

Connect every component according to the above schematic or circuit diagram. Here we also added a li-ion 18650 battery to power the circuit remotely and a TP4056 li-ion battery charger module to charge the battery using latest USB type C cable. As we all know the battery operates between 3.7 to 4.2v which is not sufficient to power the Arduino, SIM800l and GPS module so we added MT3608 DC to DC boost converter module through which we can draw stable 5v. We also added a slide switch so we can turn On and Off the project when not in use.

If you don’t need it battery operated remove the battery, TP4056 and Mt3608 modules and directly power it from USB power supply.

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Transform Your DIY Arduino GPS Tracker into a Professional-Grade Device with PCBWay!

Bring your emergency GPS tracking system to life with PCBWay, the world’s leading PCB manufacturing and assembly service! Our platform empowers makers, engineers, and hobbyists to turn innovative prototypes—like this Arduino-based GPS tracker—into sleek, reliable devices ready for real-world use.

Why This Project is Perfect for PCBWay:

This DIY GPS tracker combines a custom PCB, GSM/GPS modules, and compact design—all areas where PCBWay excels. By partnering with it, you’ll unlock:

• High-Quality PCBs: Fabricate durable, 4-layer boards for noise reduction in GPS/GSM signal routing.
• Fast Turnaround: Receive boards in 24 hours to accelerate prototyping.
• SMT Assembly: Let they solder tiny components (e.g., SIM800L, SAM-M10Q) for flawless connections.
• 3D Printing: Encase your tracker in weatherproof ABS cases for outdoor use.

PCBWay Enhances Your Design:

1. Signal Integrity: Their Rogers 4350B substrates minimize interference between GSM/GPS antennas.
2. Miniaturization: Shrink the tracker with HDI (high-density interconnect) PCBs.
3. Battery Management: Add a PCBWay-manufactured charging circuit for safe battery operation.

Order your Custom PCB now at PCBway.com

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Upload the Program code:

After connecting everything we need to upload the program code into Arduino nano using Arduino IDE. First install the required libraries given below and then copy the below code and paste it in IDE, do some required changes and upload the code. If you don’t have have IDE check How to Install Arduino IDE on Your PC.

Required libraries:

• TinyGPS: link
• SoftwareSerial : Already included in Arduino IDE

Program code:

//DIY ARDUINO GPS tracker 2025: Sends location and SOS call [Circuitschools.com]
#include <TinyGPS.h>
#include <SoftwareSerial.h>
#include <Wire.h>

SoftwareSerial Gsm(3, 2);  // RX, TX pins for GSM module
char phone_no[] = "+91xxxxxxxx";  // Your phone number +91 is for India
TinyGPS gps;
int buttonState;
unsigned long buttonPressTime;
bool isSMSsent = false;

void setup() {
  Serial.begin(9600);
  Gsm.begin(9600);

  // Set GSM module to text mode
  Gsm.print("AT+CMGF=1\r");
  delay(100);

  // Configure the GSM module to display incoming SMS
  Gsm.print("AT+CNMI=2,2,0,0,0\r");
  delay(100);

  pinMode(13, INPUT_PULLUP);  // Set pin 13 as input for a button or sensor
}

void loop() {
  bool newData = false;
  unsigned long chars;
  unsigned short sentences = 0, failed = 0;

  // Reading GPS data
  for (unsigned long start = millis(); millis() - start < 1000;) {
    while (Serial.available()) {
      char c = Serial.read();
      Serial.print(c);  // Output GPS data to the Serial Monitor
      if (gps.encode(c)) {
        newData = true;  // Check if there is new GPS data
      }
    }
  }

  buttonState = digitalRead(13);  // Read the state of the input pin

  if (buttonState == LOW) {  // Button is pressed
    if (!isSMSsent) {
      buttonPressTime = millis();  // Record the time when the button was first pressed

      // Send SMS with GPS location
      float flat, flon;
      unsigned long age;
      gps.f_get_position(&flat, &flon, &age);

      // Check if GPS data is valid
      if (flat != TinyGPS::GPS_INVALID_F_ANGLE && flon != TinyGPS::GPS_INVALID_F_ANGLE) {
        Gsm.print("AT+CMGF=1\r");
        delay(400);
        Gsm.print("AT+CMGS=\"");
        Gsm.print(phone_no);
        Gsm.println("\"");
        Gsm.println("Emergency! this is my location!...");
        Gsm.print("http://maps.google.com/maps/?q=loc:");
        Gsm.print(flat, 6);
        Gsm.print("%2C");
        Gsm.print(flon, 6);
        delay(200);
        Gsm.println((char)26);  // End of SMS character
        delay(200);

        Serial.println("SMS Sent");
        isSMSsent = true;  // Mark SMS as sent to avoid resending
      } else {
        Serial.println("Invalid GPS data, SMS not sent.");
      }
    }

    // Check if the button is held down for more than 5 seconds
    if (millis() - buttonPressTime > 5000) {
      Serial.println("Button held for 5 seconds, making a call...");

      // Make a phone call
      Gsm.print("ATD");
      Gsm.print(phone_no);
      Gsm.println(";");
      delay(20000);  // Wait for the call to go through
      Gsm.println("ATH");  // Hang up the call
      delay(1000);

      Serial.println("Call ended");
      isSMSsent = false;  // Reset SMS sent flag for future button presses
    }
  } else {
    isSMSsent = false;  // Reset SMS sent flag when button is released
    delay(10);  // Wait before the next loop
  }

  Serial.println(failed);  // Output the number of failed GPS sentences
}

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Code Explanation: DIY Arduino GPS Tracker

This code implements a DIY GPS tracker using an Arduino, which can send location data via SMS and make an SOS call when a button is pressed. Here’s a brief overview of its functionality:

Libraries and Setup

• Libraries Used:

  • TinyGPS: For handling GPS data.
  • SoftwareSerial: To communicate with the GSM module.
  • Wire: Included but not used in this code.

• GSM Module:

  • Configured to use pins 3 (RX) and 2 (TX) for communication.
  • A phone number is defined for sending SMS.

Setup Function

• Initializes serial communication for both the Arduino and the GSM module.
• Sets the GSM module to text mode and configures it to display incoming SMS.
• Configures pin 13 as an input for a button or sensor.

Loop Function

• GPS Data Reading:

  • Continuously reads GPS data for 1 second and checks if new data is available.

• Button Press Handling:

  • Monitors the state of the button connected to pin 13.
  • If the button is pressed:
    • Records the time of the button press.
    • Retrieves the GPS coordinates (latitude and longitude).
    • If the GPS data is valid, it sends an SMS with the location link.
    • If the button is held for more than 5 seconds, it initiates a phone call to the specified number.

• SMS Sending:

  • Constructs an SMS message with the current location and sends it via the GSM module.

• Call Functionality:

  • If the button is held down for 5 seconds, it makes a call to the specified phone number and hangs up after 20 seconds.

Error Handling

• The code checks for valid GPS data before sending the SMS.
• It resets the SMS sent flag when the button is released or after a call is made, allowing for repeated use.

Output

• The code prints messages to the Serial Monitor for debugging purposes, including whether an SMS was sent or if the GPS data was invalid.

This code effectively combines GPS tracking and emergency communication features, making it suitable for personal safety applications.

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Expected Output:

When the GPS Module Receives Data

• GPS module prints raw NMEA sentences (e.g., $GPGGA, $GPRMC).
• If valid data is found, it extracts latitude and longitude.

When the Button is Pressed (Short Press)

Serial Monitor Output

Emergency! This is my location!... http://maps.google.com/maps?q=loc:37.774929%2C-122.419418 SMS Sent

SMS Received on Phone

Message from GSM Module:

Emergency! This is my location!... http://maps.google.com/maps?q=loc:37.774929%2C-122.419418

(Where 37.774929, -122.419418 is the GPS location)

When the Button is Held for 5+ Seconds (Long Press)

Serial Monitor Output

Button held for 5 seconds, making a call... Call ended

Phone Call Behavior

• Incoming call from GSM module.
• Call lasts 20 seconds, then disconnects.

When GPS Data is Unavailable

Serial Monitor Output

Invalid GPS data, SMS not sent.