UHF RFID Based Door Lock

In this device we have designed a door lock using the ultra-high frequency antenna and RFID technology. This device can detect the RFID tags in the range of 8 meters. The device only supports to UHF RFID tags and can detect the tag even if it is in the wallet inside the back pocket of the user. The device is powered by 18650 batteries and can provide a backup of around 24 hours without electricity. This report details the design, development, and testing phases of the project.
The UHF antenna is installed outside the door to detect the RFID tags. As the tag is detected, the lock is opened for a couple of seconds. Once the door is locked again, it will not be unlocked by the RFID tag, considering the person is leaving the building or apartment.

01. Devoforge Expertise

Devoforge specializes in end-to-end product development, including:

  1. Embedded system design
  2. RFID-based access control systems
  3. Custom PCB design and optimization
  4. Prototype development and testing
  5. Battery-powered system design
  6. 3D enclosure design and fabrication
  7. International PCB manufacturing coordination
  8. Full system assembly and validation

In this project, we developed a complete UHF RFID-based door locking system, covering everything from proof-of-concept to final production-ready hardware.

02. Client Requirements

The client required:

  1. A UHF RFID-based door lock system
  2. Detection range up to 8 meters
  3. Capability to detect UHF RFID tags even inside a wallet or back pocket
  4. Automatic unlocking when tag is detected
  5. Lock should open for a few seconds and automatically re-lock
  6. The same tag should not immediately re-trigger unlocking after exit
  7. Battery backup of approximately 24 hours
  8. Custom enclosure design
  9. Complete PCB design and manufacturing
  10. Full system testing and validation

03. Proposed Solution

We proposed a multi-stage development process:

  1. Proof-of-concept using Arduino platform
  2. Prototype validation with UHF antenna module
  3. Custom PCB design and optimization
  4. Battery backup integration using 18650 Li-ion cells
  5. Professional PCB manufacturing from JLC PCB (China)
  6. Custom 3D-printed enclosure
  7. Final assembly and real-world testing

04. Implemented Solution

We successfully implemented:

  1. A UHF RFID-based door lock system
  2. 8-meter detection range
  3. Reliable detection even when tag is inside a wallet
  4. Intelligent lock timing logic
  5. 6 × 18650 Lithium-Ion battery backup system
  6. Custom-designed PCB with optimized layout
  7. 3D-printed durable enclosure
  8. Fully assembled and tested working unit

The system unlocks the door for a few seconds upon tag detection and prevents immediate re-triggering when the user exits.

05. Our Process

At Devoforge, we follow a structured product development lifecycle:

Step 1
Initial Proof of Concept

The first circuit was designed using:

  • Arduino
  • MFRC522 RFID Reader
  • L298N Motor Driver
  • Solenoid Lock

This prototype demonstrated basic RFID-based lock control.

Step 2
UHF Prototype Development

A second prototype was built on a dotted PCB board using:

  • Arduino Nano
  • L298N driver
  • UHF antenna module

Range testing was performed by mounting the antenna above a door.

Step 3
Custom PCB Development

After successful prototype validation:

  • A custom PCB was designed
  • All possible optimizations were reviewed
  • A handmade PCB model was fabricated and tested in-house
Step 4
Battery Backup Integration

To ensure operation during electricity failure:

  • 6 × 18650 Lithium-Ion batteries were selected
  • Designed to provide approximately 24 hours of backup
Step 5
Final PCB Manufacturing

After verification:

  • Final PCB designed considering JLC PCB inventory
  • Manufactured in China
  • Delivery time: 25 days
Step 6
Testing & Validation

The PCB and UHF module were assembled inside the enclosure and connected to the lock.

Comprehensive functional testing was conducted including:

  • Lock timing behavior
  • Tag detection reliability
  • Battery backup duration test

All systems performed as expected.

06. 3D Enclosure Design

The enclosure was custom-designed and 3D printed in Pakistan to:

  1. Securely house PCB and UHF module
  2. Provide structural durability
  3. Maintain aesthetic appeal
  4. Support wall/door mounting

07. Circuit Design

The system evolved from:

  1. Arduino + MFRC522 (concept stage)
  2. Arduino Nano + UHF module (prototype stage)
  3. Fully custom PCB (production stage)

The final PCB integrates:

  1. UHF module communication
  2. Lock control circuit
  3. Battery management
  4. Power regulation
  5. Motor driving circuitry

08. Challenges

  1. Transitioning from HF RFID to long-range UHF system
  2. Optimizing antenna positioning for 8m detection
  3. Ensuring detection inside wallet/back pocket
  4. Preventing immediate re-trigger unlocking
  5. Designing stable 24-hour battery backup
  6. Optimizing PCB according to JLC PCB inventory
  7. 25-day manufacturing lead time

09. Revisions

  1. Initial MFRC522 replaced with UHF system
  2. Improved PCB layout after handmade model testing
  3. Optimized battery configuration
  4. Firmware logic refined for exit condition handling
  5. Mechanical alignment adjustments during enclosure integration

10. Final Version (Result)

The final system:

  1. Detects UHF RFID tags up to 8 meters
  2. Detects tags inside wallets or pockets
  3. Unlocks door for predefined time
  4. Prevents immediate re-trigger unlocking
  5. Provides ~24-hour battery backup
  6. Uses custom professional PCB
  7. Fully enclosed in durable 3D-printed body

The device is now ready for deployment and provides a secure, efficient, and modern access control solution.

11. Future Upgrades

Potential improvements include:

  1. Cloud-based access management
  2. Access log recording
  3. Mobile app integration
  4. WiFi / Ethernet connectivity
  5. Remote access management
  6. Encrypted tag authentication
  7. Weatherproof enclosure (IP-rated)
  8. Low-battery monitoring system

Interested in Similar Project?

If you are looking to develop:

  1. RFID-based access systems
  2. Smart door locks
  3. Custom embedded hardware
  4. Industrial IoT devices
  5. Battery-powered electronics
  6. Complete product development solutions

We provide full-cycle development from concept to production-ready hardware.

Contact us today to discuss your project requirements.

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