RFID, Radio Frequency Identification Chip Technology Details

Radio Frequency Identification (RFID) Chip Technology Analysis

Giant companies such as Intel, Microsoft, IBM, NEC, Hitachi, Symbol, etc. have all poured great enthusiasm on RFID technology. American IC manufacturers such as TI and Intel are all investing heavily in RFID chip development in the RFID field. IBM, Microsoft and others are also actively developing corresponding software and systems to support the application of RFID, while Philip Electronics is the RFID chip manufacturing industry. Leading producer. Therefore, this article takes Mifare lS50 produced by Philips as an example to analyze the structure of RFID card and the communication and storage technology of its chip. The unique MIFARE RF (radio frequency) contactless interface standard of the RFID chip of this card has been formulated as the international standard ISO / IEC 14443 TYPE A standard, and its application is very wide.


RFID (Radio Frequency Identification) technology is praised by the global high-tech field as the most promising technology with the most market prospects, the most changing human lifestyle and the appearance of high-tech industry.

 

What are some RFID Tecchnology Companies?

Intel, Microsoft, IBM, NEC, Hitachi, Symbol and other giant enterprises have poured great enthusiasm for RFID technology. American IC manufacturers such as TI and Intel are all investing heavily in RFID chip development in the RFID field.

IBM, Microsoft and others are also actively developing corresponding software and systems to support the application of RFID, while Philip Electronics is the RFID chip manufacturing industry leading producer.

Therefore, this article takes Mifare lS50 produced by Philips as an example to analyze the structure of RFID card and the communication and storage technology of its chip.

The unique MIFARE RF (radio frequency) contactless interface standard of the RFID chip of this card has been formulated as the international standard ISO / IEC 14443 TYPE A standard, and its application is very wide.

 

L Mifare lS50 Card Structure and Main Features

Mifare 1 S50 card is a non-contact IC card, also known as RFID card (radio frequency card). RFID card is a new technology that has developed vigorously in recent years in the world.

He successfully combined radio frequency identification technology and IC card technology to solve the problem of no power supply and contactless use in the card, which is in the field of electronic devices. A big breakthrough.

 

The electrical part of the Mifare 1S50 card consists of only one antenna and one RFID chip. Among them, the antenna is a coil with only a few windings, and it is encapsulated in an ISO card.

The data storage period is 10 years, which can be rewritten 100,000 times and read unlimitedly. The communication between the card and the reader uses the internationally-secured DES and RES security cross algorithm, which has extremely high security performance.

 

Its main features are  as follows:

Working frequency: 13.56 MHz

Communication rate: 106 kb / s

Anti-collision: multiple cards can be processed at the same time

Reading and writing distance: within 100 mm (related to the shape of the antenna) can easily and quickly transfer data

Handshake half-duplex communication method

 

In the wireless communication process, the following mechanisms are used to ensure data integrity and anti-collision mechanism:

  • Each block has 16-bit CRC error correction
  • Each byte has parity
  • Check the number of bits
  • Use coding to distinguish between "1" and "0" Or no information
  • Channel monitoring (through protocol sequence and bit stream analysis)
  • Support multi-card operation
  • Material: PVC
  • Size: conform to ISO10536 standard
  • No battery: wirelessly transfer data and energy
  • Chip processing technology: using high-speed CMOS E2PROM process
  • Security: 3 mutual authentications (ISO / IEC DIS 9798-2). All data is encrypted during communication to prevent signal interception. Each sector has independent passwords
  • Each card has a 32-bit globally unique serial number. Transmission Mima protection.
  • Support one card multi-purpose storage structure
  • Typical transaction process "100 ms
  • 2 Mifare 1S50 card RFID chip internal structure
  • The chip of Mifare 1S50 card is composed of RF-Interface (radio frequency interface) and Digtal SecTIon (digital module)

 

The RF interface part is composed of rectifier, voltage regulator, POWER ON RESET (POR) module, clock regenerator, modulator / demodulator and other parts.


There are 4 main functions:

(1) Provides the energy required for the operation of each part of the internal circuit of the RFID chip.

 

(2) Provide the POR signal to make each part of the circuit start synchronously.

 

(3) Extract the clock signal required by the circuit for normal operation from the carrier wave.

 

(4) Demodulate the commands and data on the carrier for digital module processing and modulate the data to be sent.

 

The digital module is mainly composed of the following parts:

ATR (Answer to Request) module: when the card is within the working range of the reader's antenna, when the reader sends a Request all (or: Requested) command to the card. This module of the chip starts, thereby establishing and reading and writing device, the first step of communication.

 

Anti-Collision module

to prevent cards from overlapping. The specific principle is as follows: If there are multiple cards within the working range of the reader antenna, the module of the chip starts, the reader first communicates with all the cards, obtains the serial number of each card, and then, according to the serial number Select a card.

Radio Frequency Identification Technology

Select Application module: Confirm the selection of the card.

Authentication & Access Control module: After the card confirmation is selected, start this module to perform mutual authentication between the card and the reader.

Only through mutual authentication can further operations be carried out.

 

Control & Arithmetic Unit module: This module is the control center of the whole chip, and the central processing unit built in the chip.

 

RAM: Cooperate with Control & Arithmetic Unit to temporarily store the operation results.

If there is data to be stored in E2PROM, then take out the data and store it in E2PROM.

If there is data to be transferred to the reader, take out the data and let the RF interface circuit process.

It is transmitted to the reader via the antenna on the card.

 

ROM: The necessary program instructions required for the operation of the fixed card.

 

Crypto Unit: This module completes the data encryption and password protection.

E2PROM Interface: This module is the interface circuit of E2PROM.

E2PROM Memory: E2PROM memory.

3 Mifare 1S50 card RFID chip communication technology

 

The communication rate between the card and the reader is 106 kb / s. When transmitting signals from the card to the reader, the subcarrier frequency used is 847 kHz (fc / 16), using Manchester encoding, on-off keying (OOK) modulated signal.

The reader transmits signals to the card at that time, the RF carrier frequency used was 13.56 MHz, using synchronous timing and improved: Miller coding method, ASK (Amplirude Shift Keying) signal with a modulation depth of 100%.

 

Miller coding uses any edge in half a bit period to represent binary 1, and the level unchanged in the next period represents binary O.

If a series of O is continuous, a level change occurs at the beginning of the O bit period. The improved Miller coding is a modification of the Miller coding, and each edge is replaced by a groove.

The Manchester encoding method uses a negative edge of half a bit period to represent a binary 1, and a positive edge of a half bit period to represent a binary 0. Figure 2 is the result of 10100110 using Manchester, Millerm Modified Miller encoding.


Radio Frequency Identification (RFID) chip technology

 

4 Mifare 1S50 card RFID chip supports one card multi-purpose storage technology

 

The E2PROM Memory capacity in the chip is 8 kh, which is divided into 16 sectors, each sector is 4 blocks (block 0 - block 3), that is, the entire E2PROMMemory is 64 blocks, the block number addressing is 0 - 63, each Block 16 bytes (0 - 15 B), one block is an access unit. Block 0 of each sector (Note: The exception is block 0 of sector 0, which is used to store the manufacturer's code, which has been solidified and cannot be rewritten. Among them: the 0th to 4th bytes are the serial number of the card. The 5th byte is the sequence.

The check code of the number. The 6th byte is the capacity of the card "SIZE" byte. The 7th and 8th bytes are the type byte of the card, that is, the Tag type byte. Other bytes are defined by the manufacturer), block 1.

Block 2 is a data block, used to store user data. Block 3 of each sector is a control block of each sector, used to store password A (0 - 5 bytes), access control (6 - 9 bytes) , Password B (10 ~-15 bytes).

 

In access control, each block (block 0, 1, 2, 3) is determined by 3 control bits for the operation authority of the data block or control block, the control bit representation is "CXxy". Among them: CX represents the control bit number (X can be 1, 2 or 3, for example: C1 represents the first control bit). z represents the sector. y represents the block number.

For example: "C2x1" indicates the second control bit of a sector block 1). The position of the 3 control bits in the access control byte (that is, the 6th to 9th bytes in each sector block 3.

(Note: "_b" in the table means inversion. For example: the 6th word When "1" is stored in bit7 of the section, C2x3 = 0; and B represents the spare bit.

Control bits control each sector data block (block 0, 1 or 2).

 

In block 3, the initial value of the access control 4B (manufacturer's initial value) is "FF 07 80 69".


The initial value of the 3-bit control bits of each block is as follows:

C1x0 C2x0 C3x0 = 000 , C1x1 C2x1 C3x1 = 000, C1x2 C2x2 C3x2 = 000, C1x3 C2x3 C3x3 = 001.

It can be inferred that after verifying Password A or Password B in the initial state. Perform operations such as reading, writing addition, subtraction, and initialization on data blocks 0 to 2.

After verifying password A or B, you can write password A. Yes Read and write control bits, can read and write password B, but can not read password A.

 

There are two application methods for the data block in the chip. One is for general data storage, direct reading and writing. Another usage is as a numeric block, which can be used for initialization, addition, subtraction, and reading operations.

The application system is equipped with corresponding functions to complete the corresponding functions.

 

In summary, the E2PROM Memory in the chip of the Mifare 1S50 card is divided into 16 sectors. They do not interfere with each other. Each sector can be set with its own different password and access control as required (no manufacturer’s Initial value).

Therefore, each sector can be independently applied to an application to realize "one card", for example: transportation card, campus card, enterprise card, family payment card, etc.

 

Important on RFID

RFID card is the product of the combination of radio frequency identification technology and IC technology. Compared with the contact IC card, it does not need to contact the reader when it is used. It is convenient and fast to operate, has high reliability and long service life. Fortunately, there is an anti-collision mechanism that can be used for one card.


At present, RFID cards have shown their bright application prospects in China's electronic ID cards, urban public transport payment, license and commodity anti-counterfeiting, special equipment strong inspection, security management, animal and plant electronic identification, modern logistics management, etc. Great efforts to develop RFID chips.

 

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