sri512 STMicroelectronics, sri512 Datasheet - Page 11

• Manufacturer Part Number: sri512
• Description: 13.56-mhz Short-range Contactless Memory Chip With 512-bit Eeprom And Anti-collision Functions
• Manufacturer: STMicroelectronics

SRI512
3.2
3.2.1
3.2.2
Output data transfer from the SRI512 to the Reader (Answer
Frame)
The data bits issued by the SRI512 use back-scattering. Back-scattering is obtained by
modifying the SRI512 current consumption at the antenna (load modulation). The load
modulation causes a variation at the reader antenna by inductive coupling. With appropriate
detector circuitry, the reader is able to pick up information from the SRI512. To improve load-
modulation detection, data is transmitted using a BPSK encoded, 847 kHz subcarrier
frequency ƒ
Figure 7.
Character transmission format for Answer Frame
The character format is the same as for input data transfer
frames are made up of an SOF, data, a CRC and an EOF
transfer, if an error occurs, the reader does not issue an error code to the SRI512, but it
should be able to detect it and manage the situation. The data transfer rate is
106 Kbits/second.
Answer Start Of Frame
The SOF described in
Figure 8.
followed by 10 ETUs at logic-0
followed by 2 ETUs at logic-1
Data Bit to be Transmitted
847kHz BPSK Modulation
Generated by the SRI512
ETU
s
Wave transmitted using BPSK subcarrier modulation
Answer Start Of Frame
as shown in
to the Reader
0
b0
b1
0
Figure 8
Or
Figure
0
b2
is composed of:
7, and as specified in the ISO 14443-2 Type B Standard.
0
During a One-bit Data Transfer Time (1/106kHz)
b3
0
b4
BPSK Modulation at 847kHz
0
b5
0
b6
(Figure
(Figure
0
b7
b8
0
10). As with an input data
4). The transmitted
0
b9
Data transfer
1
b10
ai07665
AI10797
b11
1
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