ST25R3911B datasheet(51/116 Pages) STMICROELECTRONICS

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MIFARE™ classic compatibility

For communication with MIFARE™ classic compliant devices the bit6 and bit7 from the register 05h can be used

to enable Type A custom frames. Alternatively, the stream mode of ST25R3911B can be used to send and receive

MIFARE™ classic compliant or custom frames.

Stream mode

Stream mode can be used to implement protocols, where the low level framing needed for ISO14443 receive

coding can be used and decoded information can be put in FIFO. The main advantage of this mode over the

transparent mode is that timing is generated in the ST25R3911B therefore the external controller does not have to

operate in real time. The stream mode is selected in the Mode definition register, the operating options are

defined in the Stream mode definition register.

Two different modes are supported for tag to reader communication (Sub

‑carrier and BPSK Stream Modes).

General rule for Stream mode is that the first bit sent/received is put on the LSB position of the FIFO byte.

After selecting the stream mode the receiver and transmitter have to be configured properly (Analog Preset direct

command doesn't apply for stream mode).

Sub-carrier stream mode

This mode supports protocols where during the tag to reader communication the time periods with sub

‑carrier

signal are interchanged with time periods without modulation (like in the ISO14443A 106 kbit/s mode). In this

mode the sub

‑carrier frequency and number of sub‑carrier frequency periods in one reporting period is defined.

Sub

‑carrier frequency in the range from fc/64 (212 kHz) to fc/8 (1695 kHz) are supported.

Supported number of sub

‑carrier frequency periods in one reporting period range from two to eight.

Start of receive interrupt is sent and the first data bit is put in FIFO after the first reporting time period with

sub

‑carrier is detected. One bit of FIFO data gives information about status of input signal during one reporting

period. Logic 1 means that the sub

‑carrier was detected during reporting period, while 0 means that no

modulation was detected during reporting period. End of receive is reported when no sub

‑carrier signal in more

than eight reporting periods have been detected.

Figure 26 shows an example for setting scf = 01b and scp = 10b. With this setting the

sub

‑carrier frequency is set to fc/32 (424 kHz) and the reporting period to four sub‑carrier periods (128/fc ~106

μs).

Figure 26. Example of sub-carrier stream mode for scf = 01b and scp = 10b

Data in

FIFO

Input

signal

fc/32

fc/128

BPSK stream mode

This mode supports protocols where during the tag to reader communication BPSK code is used (like in the

ISO14443B mode).

In this mode the sub

‑carrier frequency and number of sub‑carrier frequency periods in one reporting period is

defined. Sub

‑carrier frequency in the range from fc/16 (848 kHz) to fc/4 (3390 kHz) are supported. Supported

number of sub

‑carrier frequency periods in one reporting period range from one to eight.

ST25R3911B

Application information

DS11793 - Rev 6

page 51/116

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