ST25R3911B datasheet(52/116 Pages) STMICROELECTRONICS

52 / 116 page

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. Logic 0 is used for the initially detected phase, while logic 1 indicates inverted phase

comparing to the initial phase.

End of receive is reported when the first reporting period without sub

‑carrier is detected.

Figure 27 shows an example for setting scf = 01b and scp = 01b. With this setting the sub

‑carrier frequency is set

to fc/8 (1695 kHz) and the reporting period to two sub

‑carrier periods (16/fc ~1.18 μs).

Figure 27. Example of BPSK stream mode for scf = 01b and scp = 10b

Data in

FIFO

Input

signal

fc/8

fc/16

Reader to Tag communication in stream mode

Reader to tag communication control is the same for both stream modes. Reader to tag coding is defined by data

put in FIFO. The stx bits of Stream mode definition register define the Tx time period during which one bit of FIFO

data define the status of transmitter. In case the data bit is set to logic 0 there is no modulation, in case it is logic 1

the transmitted carrier signal is modulated according to current modulation type setting (AM or OOK).

Transmission in stream mode is started by sending direct commands Transmit Without CRC or Transmit With

CRC.

Figure 28 shows an example for setting stx = 000b. With this setting the Tx time period is defined to 128/fc (~9,44

μs).

Figure 28. Example of Tx in stream mode for stx = 000b and OOK modulation

Data in

FIFO

Input

signal

fc/128

1.3

Registers

The 6-bit register addresses below are defined in hexadecimal notation. The possible addresses range from 00h

to 3Fh.

There are two types of registers implemented in the ST25R3911B:

•

Configuration registers

•

Display registers

The configuration registers are used to configure the ST25R3911B. They can be read and written (RW) through

the SPI. The display registers are read only (R); they contain information about the ST25R3911B internal state.

ST25R3911B

Registers

DS11793 - Rev 6

page 52/116

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