Published October 29, 2025 © MIT

A portable, reliable Smart Attendance System that logs RFID/Code-based attendance to a cloud server via a 4G LTE modem — no Wi-Fi required

BeginnerFull instructions provided8 hours**1

Things used in this project

Software apps and online services

Story

📖 Project Story — B y Yarana IoT Guru

In today’s world, attendance systems are everywhere — from schools to offices, and from factories to training centers. But one problem keeps coming back: most systems depend on Wi-Fi or LAN.

Now imagine a situation where there’s no Wi-Fi connection — a construction site, a rural school, a mobile event van, or a remote research field. How will you record attendance there and send it instantly to a cloud server?

That’s exactly where this project idea was born.I wanted to build something simple, portable, and fully independent from Wi-Fi — something that can work anywhere with just a 4G SIM card.

💡 The Beginning

While experimenting with my 4G LTE development board (A7670C module) and ESP32, I thought — “why not send attendance data directly through HTTP requests over the LTE network?”

Most IoT projects use Wi-Fi or Ethernet, but mobile-based IoT (cellular IoT) is actually more powerful for outdoor or large-scale deployments. It gives the freedom to deploy your device anywhere, without relying on routers or fixed internet lines.

The concept was clear:Whenever someone taps their RFID card, the ESP32 will communicate with the 4G module, build a small JSON payload, and send it as an HTTP POST request to a PHP-based cloud API.The server will then store this data in a MySQL database, marking that person as “present” for the day.

🔧 Development Journey

At first, I began testing with an RC522 RFID reader and a simple ESP32 board. The goal was to read the card UID and display it on Serial Monitor. Once that worked, I started integrating the A7670C 4G LTE module using UART.

Getting the LTE connection stable took some effort — especially ensuring the right APN settings for the SIM card and stable power supply (cellular modules draw high current during transmission).

Once the modem responded to AT commands correctly, I integrated the TinyGSM library — this made HTTP requests super easy. Within a few lines of code, the ESP32 was successfully sending live attendance data to my web server.

On the backend, I wrote a clean and secure PHP script that receives the data, verifies the device’s API token, and inserts the attendance record into a MySQL database.It even returns a JSON response to confirm if the attendance was logged successfully.

The first time I saw "status":"success" on my Serial Monitor — it was a magical moment.The system worked completely without Wi-Fi, running only on a 4G SIM card.

🌐 How It Works (In Action)

The ESP32 waits for a card to be tapped on the RFID sensor.

• The ESP32 waits for a card to be tapped on the RFID sensor.

Once detected, it reads the UID and prepares a JSON packet with:

Device name

• Device name

API token

• API token

UID of the card

• UID of the card

Timestamp

• Timestamp
• Once detected, it reads the UID and prepares a JSON packet with:Device nameAPI tokenUID of the cardTimestamp

The LTE module connects to the internet using GPRS/4G.

• The LTE module connects to the internet using GPRS/4G.

It then sends the data as an HTTP POST request to your PHP endpoint.

• It then sends the data as an HTTP POST request to your PHP endpoint.

The PHP script validates the request, logs the entry in MySQL, and returns a success response.

• The PHP script validates the request, logs the entry in MySQL, and returns a success response.

The ESP32 gives a short beep or LED blink to confirm attendance.

• The ESP32 gives a short beep or LED blink to confirm attendance.

Every entry is instantly available on your cloud dashboard — no waiting, no syncing issues.

⚙️ Real-World Use Cases

This system can be deployed almost anywhere:

Remote schools or colleges – Teachers or students can mark attendance without Wi-Fi.

• Remote schools or colleges – Teachers or students can mark attendance without Wi-Fi.

Construction sites – Workers tap RFID tags at the gate; the data uploads instantly to the cloud.

• Construction sites – Workers tap RFID tags at the gate; the data uploads instantly to the cloud.

Corporate offices or warehouses – Real-time attendance logging with 4G backup for reliability.

• Corporate offices or warehouses – Real-time attendance logging with 4G backup for reliability.

Mobile or temporary setups – Use it in buses, event vans, or field camps where network changes frequently.

• Mobile or temporary setups – Use it in buses, event vans, or field camps where network changes frequently.

It’s a flexible, scalable solution — and you can customize it by adding:

GPS for location tracking,

• GPS for location tracking,

Camera for photo verification,

• Camera for photo verification,

Fingerprint or face sensors for biometric security.

• Fingerprint or face sensors for biometric security.

🔋 Power and Reliability

To ensure stable performance, I powered the LTE module with a 5V/2A supply, as current surges during data transmission can cause random reboots.I also implemented a retry mechanism — if the network is temporarily unavailable, the data gets queued and re-sent automatically when the connection is restored.

This makes the system more reliable and usable in real-world outdoor scenarios.

🧩 Cloud Dashboard

The backend dashboard is built with simple PHP + MySQL — it lists all attendance logs, including:

Device name

• Device name

UID

• UID

Timestamp

• Timestamp

Status (Present/Absent)

• Status (Present/Absent)

Admins can easily filter logs by date or device, and even export data to Excel (CSV) for record keeping.

This setup gives full transparency and control from anywhere — open your dashboard on a phone or laptop and instantly view who’s present.

📈 What Makes This Project Special

Unlike most IoT attendance systems that depend on routers, this version is self-sufficient.The 4G LTE module provides true portability — plug it in anywhere, power it up, and it just works.

It’s a perfect example of combining embedded electronics with real-world IoT infrastructure — all managed through a simple PHP/MySQL web backend.

And the best part? It’s cost-effective and open-source, so anyone can replicate and modify it as per their needs.

🎬 Final Thoughts

When I tested the system outdoors, miles away from any Wi-Fi, and still saw my cloud dashboard update instantly — that was the moment I realized how powerful cellular IoT really is.

This project is a big step toward offline-capable IoT systems that connect the unconnected world.Whether you’re a student, hobbyist, or engineer, this build gives you a strong foundation in:

HTTP communication via 4G,

• HTTP communication via 4G,

PHP/MySQL server integration,

• PHP/MySQL server integration,

Real-time IoT data logging,

• Real-time IoT data logging,

and creating a scalable, professional-grade IoT solution.

• and creating a scalable, professional-grade IoT solution.

💬 Created & documented by Yarana IoT GuruYouTube: Yarana IoT GuruInstagram / Hackster.io / GitHub: YaranaIoTGuru

💬 Created & documented by Yarana IoT GuruYouTube: Yarana IoT GuruInstagram / Hackster.io / GitHub: YaranaIoTGuru

Would you like me to add:

📸 I**mage captions + section titles (Step 1, Step 2… style) **for Hackster formattingor

• 📸 I**mage captions + section titles (Step 1, Step 2… style) **for Hackster formattingor

🎨 A**ttractive thumbnail + short caption for post cover **(like “4G Smart Attendance System – IoT without Wi-Fi”)

• 🎨 A**ttractive thumbnail + short caption for post cover **(like “4G Smart Attendance System – IoT without Wi-Fi”)

**Read more

Code

Credits

Thanks to Yarana IoT Guru.