Development of RFID/NFC based access control system
Author: Darko Topić
Subject: Advanced Programmable Electronic Systems
Mentor: Assoc. prof. Matej Rojc, PhD
Degree: 2
Date: 2018
DKUM: DARKO TOPIĆ
The master thesis describes the development of NFC/RFID access control system based on the ARM platform. The goal of this thesis is to develop a smart NFC access control system used for accessing an elevator, where users could use only NFC tags to access a specific floor.
The master thesis describes the development of NFC/RFID access control system based on the ARM platform. The access control system is widely used in different applications. The goal of this thesis is to develop a smart NFC access control system used for accessing an elevator, where users could use only NFC tags to access a specific floor. The design of the proposed NFC access control system is based on the ARM platform, while the developed NFC antenna guarantees wide scanning range. At the end of the thesis the results are presented.
The thesis also describes the conditions for accessing and writing data to MIFARE Classic 4K card blocks, as well as the conditions for accessing and reading data from these blocks. Access conditions are defined by 4 syllables (6, 7, 8 and 9). By using 3 (6, 7 and 8) syllables, keys for reading data from MIFARE card blocks are defined, as well as keys for writing data to MIFARE card blocks. The 9th syllable is actually a USER syllable and does not affect the access conditions. The three MIFARE cards for the proposed system thus contain different data in their data blocks, as well as different A and B keys in the “Sector Trailer” blocks. Two of them contain the same access bits. Only one MIFARE card has different access bits written. The fourth MIFARE card contains both the default data as well as the default A and B keys and bits to access the “Sector Trailer” blocks in the data blocks.
The thesis also presents a measurement procedure for measuring the characteristics of an NFC antenna. We also measured the magnitude of the magnetic field that can be generated by an NFC antenna. The field strength was checked at 0 cm and at 10 cm. The peak voltage measured with the oscilloscope was thus 8.32 V in the first case, and 124 mV in the second case. Furthermore, the signal frequency was 13.59 MHz, so we can confirm that the NFC antenna also resonates at the appropriate frequency, since NFC technology also works at this frequency.
In the thesis, we described in detail each part (theory, hardware and software development) that make up the proposed RFID/NFC based access control system. In this respect, we have introduced RFID and NFC technologies in more detail and also highlighted the main differences between them. In addition, we have introduced in detail the MIFARE technology and CAN protocol, since without them the proposed system would not work. Tests and measurements have proven that the NFC antenna is properly designed and operates to 13.56 MHz specifications. We further demonstrated that the NFC antenna can successfully scan MIFARE cards up to a distance of 5 cm. When developing code for the MIFARE card, the most difficult problem was determining the A and B keys in the PN7462 EEPROM NFC microcontroller. After analyzing the documentation of MIFARE cards, it turned out that MIFARE cards support an efficient encryption system. In this regard, it was also necessary to set access bits. In the assignment, we also demonstrated that the proposed system allows flexible and correct access control to the floors of any building, with the main elevator control panel receiving relevant user information and permitted access via the CAN bus. As soon as the user approaches the NFC card with the NFC reader inside the elevator, the elevator can automatically take it to the corresponding floor.
In the future, we will be adding some more “improvements”. The prototype of the elevator access control system using NFC cards showed that the system can also work with any other device operating at 13.56 MHz. Nowadays, people use mobile phones that already support NFC technology. The idea, then, is to develop a mobile application for the Android platform that would also allow the user to select the required floor and gain access simply by bringing the NFC mobile phone closer to the reader in the elevator. Such a mobile phone solution could be an even more practical solution.
Discussion and Results
