Build an ESP32 GPS Tracker : No Wi-Fi? No Problem | Details

Why GSM Instead of Wi-Fi?

Wi-Fi trackers only work when connected to a network.
The SIM800L connects to the 2G GSM network, so it works even in remote areas.
Perfect for tracking vehicles, delivery packages, or outdoor assets.

What You’ll Need

ESP32 development board
SIM800L GSM module
NEO-6M GPS module
2 LEDs (5 mm)
2 × 470Ω resistors
Breadboard and jumper wires

Optional: a Li-ion or LiPo battery for powering the GSM module.

Component Notes

ESP32 – Main controller
SIM800L – Provides GSM/GPRS cellular connectivity (3.7–4.2V)
NEO-6M – Receives GPS coordinates from satellites (3.3–5V)
LEDs – Show GPS fix and data send status

Setting Up GeoLinker Cloud

GeoLinker is CircuitDigest’s free cloud platform for IoT visualization.

Steps to get your API key:

Go to CircuitDigest Cloud.
Click Login and create a free account if you don’t have one.
Once logged in, go to My Account → Generate API Key.
Copy the API key and use it in your Arduino code.

Each key can handle around 10,000 GPS data points before renewal.

Circuit Connections

SIM800L TX → ESP32 GPIO18
SIM800L RX → ESP32 GPIO19
NEO-6M TX → ESP32 GPIO16
NEO-6M RX → ESP32 GPIO17
GPSFix LED → ESP32 GPIO23
DataSent LED → ESP32 GPIO32

The SIM800L should be powered at 3.7–4.2V. Use a separate Li-ion cell, a LiPo, or a buck converter from 5V.

Arduino Code Overview

We’ll use the GeoLinker Arduino Library to handle GPS parsing, GSM communication, and cloud upload.

Include the library:

#include <GeoLinker.h>

GPS Configuration:

HardwareSerial gpsSerial(1);
#define GPS_RX 16
#define GPS_TX 17
#define GPS_BAUD 9600

GSM Configuration:

HardwareSerial gsmSerial(2);
#define GSM_RX 18
#define GSM_TX 19
#define GSM_BAUD 9600

Network and Cloud Setup:

const char* apn = "yourAPN";
const char* apiKey = "yourAPIkey";
const char* deviceID = "ESP32_Sim800L";

LEDs:

const int DataSent_LED = 32;
const int GPSFix_LED = 23;

GeoLinker Initialization:

GeoLinker geo;

void setup() {  Serial.begin(115200);  gpsSerial.begin(GPS_BAUD, SERIAL_8N1, GPS_RX, GPS_TX);  gsmSerial.begin(GSM_BAUD, SERIAL_8N1, GSM_RX, GSM_TX);
  pinMode(DataSent_LED, OUTPUT);  pinMode(GPSFix_LED, OUTPUT);
  geo.begin(gpsSerial);  geo.setApiKey(apiKey);  geo.setDeviceID(deviceID);  geo.setNetworkMode(GEOLINKER_CELLULAR);  geo.setModemCredentials(apn, nullptr, nullptr);  geo.beginModem(gsmSerial, -1, -1, true);  geo.setUpdateInterval_seconds(30);
}

Main Loop:

void loop() {  uint8_t status = geo.loop();
  if ((status != STATUS_GPS_ERROR) && (status != STATUS_PARSE_ERROR))    digitalWrite(GPSFix_LED, HIGH);  else    digitalWrite(GPSFix_LED, LOW);
  if (status == STATUS_SENT) {    digitalWrite(DataSent_LED, HIGH);    delay(1000);    digitalWrite(DataSent_LED, LOW);  }
}

That’s all you need. The library manages all the background work automatically.

Testing and Debugging

When you power it up:

SIM800L LED (1s blink): Not connected to network
SIM800L LED (3s blink): Connected and ready
SIM800L LED (fast blink): Data transmission active
NEO-6M LED: Starts blinking when GPS lock is achieved

Once both modules are active, open the GeoLinker dashboard to see your live location updates in real time.

Pro tip: test outdoors for a faster GPS fix.

Common Issues

No GPS Lock?

Move outdoors or near a window
Wait 2–10 minutes for a cold start
Check antenna and power supply
Verify UART baud rate (9600)

SIM800L not connecting?

Ensure 3.7–4.2V power supply
Check SIM card is active with a 2G data plan
Try Airtel, Vi, or BSNL in India (avoid Jio or 4G-only SIMs)

Data not uploading?

Double-check API key and APN
Verify GSM signal strength
Check serial monitor for error messages

Power Optimization Tips

Use ESP32 deep sleep between updates
Lower GPS update rate
Turn off GSM module when idle
Use efficient DC-DC converters
Log data locally when offline

Final Notes

This ESP32 GPS Tracker with SIM800L is a solid weekend build that blends hardware tinkering with IoT connectivity. It’s easy to modify, and the GeoLinker platform takes care of all the backend work.

Project Details