sri4k STMicroelectronics, sri4k Datasheet - Page 11

• Manufacturer Part Number: sri4k
• Description: 13.56 Mhz Short-range Contactless Memory Chip With 4096-bit Eeprom And Anticollision Functions
• Manufacturer: STMicroelectronics

SRI4K
3.2
3.2.1
3.2.2
Output data transfer from the SRI4K to the Reader (answer
frame)
The data bits issued by the SRI4K use retro-modulation. Retro-modulation is obtained by
modifying the SRI4K 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 SRI4K. 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 SRI4K, 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.
ETU
–
–
Data Bit to be Transmitted
847kHz BPSK Modulation
Generated by the SRI4K
0
followed by 10 ETUs at logic-0
followed by 2 ETUs at logic-1
b0
s
Wave transmitted using BPSK subcarrier modulation
Answer start of frame
as shown in
to the Reader
0
b1
0
b2
Figure 8
Or
Figure
0
b3
is composed of:
7, and as specified in the ISO 14443-2 Type B Standard.
During a One-bit Data Transfer Time (1/106kHz)
b4
0
0
b5
BPSK Modulation at 847kHz
0
b6
0
b7
(Figure
(Figure
0
b8
0
b9
10). As with an input data
4). The transmitted
1
b10
Data transfer
1
b11
AI10881
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