Rainbow Electronics AT88RF1354 - Manual (Page 27)

13.56 MHz Type B RF Reader
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8547A −RFID−10/08
Appendix A. The ISO/IEC 14443 Type B RF Signal Interface
A.1. RF Signal Interface
The AT88RF1354 RF communications interface is compliant with the ISO/IEC 14443 part 2 and part 3 Type B
signaling requirements when used exactly as described in the AT88RF1354 reference design application notes.
Type B signaling utilizes a 10 % amplitude modulation of the RF field for communication from the reader to the card
with NRZ encoded data. Communication from card to reader utilizes BPSK load modulation of an 847.5 khz
subcarrier with NRZ-L encoded data. The 13.56 MHz RF magnetic field is continuously on for Type B
communications.
A.2. Data Format
Data communication between the card and reader is performed using an LSB first data format. Each byte of data is
transmitted with a 0b start bit and a 1b stop bit as shown in Figure A-1. The stop bit, start bit, and each data bit are
each one elementary time unit (ETU) in length (9.4395 microseconds).
Each byte transmission consists of a start bit, 8 data bits (LSB first), and a stop bit. Each byte may be separated from
the next byte by extra guard time (EGT). The EGT may be zero or a fraction of an ETU. EGT cannot exceed 19
microseconds for data transmitted by the PICC. EGT for data transmitted by the AT88RF1354 PCD is zero ETUs.
The position of each bit is measured relative to the falling edge of the start bit.
Figure A-1. Byte transmission format requirements for Type B communications.
Byte Format
Start LSB MSB
One byte transmission is 10 ETUs long plus EGT
b0 b1 b2 b3 b4 b5 b6 b7
Stop EGT
All bit timing is measured from the falling edge of the start bit.
Bit transitions should occur within (n ± 0.125) ETU of thefalling edge of start bit.
Despite the fact that data transmissions occur LSB first, all of the commands, data, and CRC bytes in ISO/IEC 14443
and in this specification are listed in the conventional manner, with MSB on the left and LSB on the right.