ST25R3911B datasheet(42/116 Pages) STMICROELECTRONICS

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FeliCa™ transmission

In order to transmit FeliCa™ frame only the Payload data is put in the FIFO. The number of Payload bytes is

defined in the Number of transmitted bytes register 1 and Number of transmitted bytes register 2. Preamble length

is defined by bits f_p1 and f_p0 in the ISO14443B and FeliCa settings register, default value is 48 bits, but other

options are possible.

Transmission is triggered by sending direct command Transmit With CRC. First preamble is sent, followed by

SYNC and Length bytes. Then Payload stored in FIFO is sent, transmission is terminated by two CRC bytes that

are calculated by the ST25R3911B. Length byte is calculated from ‘number of transmitted bytes’. The following

equation is used:

length = payload length + 1 = number of transmitted bytes +1

FeliCa™ reception

After transmission is done the ST25R3911B logic starts to parse the receiver output to detect the Preamble of

FeliCa™ tag reply.

Once the Preamble (followed by the two SYNC bytes) is detected the Length byte and Payload data are put in the

FIFO. CRC bytes are internally checked.

1.2.19

NFCIP-1 operation

The ST25R3911B supports all NFCIP-1 initiator modes and active communication target modes. All NFCIP-1 bit

rates (106, 212 and 424 kbit/s) are supported.

NFCIP-1 passive communication Initiator

NFCIP-1 passive communication is equivalent to reader (PCD) to tag (PICC) communication where initiator acts

as a reader and target acts as tag. The only difference is that in case of the NFCIP-1 passive communication the

initiator performs Initial RF Collision Avoidance procedure at the beginning of communication.

In order to act as NFCIP-1 passive communication initiator the ST25R3911B has to be configured according to

Table 15.

Table 15. Operation mode/bit rate setting for NFCIP-1 passive communication

NFCIP-1 bit rate

(kb/s)

Operation mode

setting

Bit rate

for Tx (kb/s)

Bit rate

for Rx (kb/s)

Comments

106

ISO14443A

fc/128 (~106) fc/128 (~106) -

212

FeliCa™

fc/64 (~212)

In FeliCa Mode data rate is the same in both

directions

424

fc/32 (~424)

Initial set-up of the Operation control register before the start of communication is the same as in case of reader

to tag communication, with the exception that the transmitter is not enabled by setting the tx_en bit. The direct

command NFC Initial Field ON is sent instead.

This command first performs the Initial RF Collision Avoidance with Collision Avoidance Threshold defined in the

External field detector threshold register. The timing of Collision Avoidance is according to NFCIP-1 standard (for

timing details see Table 10. Timing parameters of NFC Field ON commands). In case collision is not detected the

tx_en bit is automatically set to switch the transmitter on. After minimum guard time TIRFG the I_cat IRQ is sent to

inform controller that the first initiator command can be sent.

From this point on communication is the same as for ISO14443A (for 106 kb/s) or for FeliCa™ (for 242 and 424

kb/s) reader communication.

In case a presence of external field is detected an I_cac IRQ is sent. In such case a transmission should not be

performed, command NFC Initial Field ON has to be repeated until collision is not detected anymore.

Initial Collision Avoidance is not limited to modes supported by NFCIP-1. The initial Collision Avoidance according

to procedure described above can be performed before any reader mode is started to avoid collision with an HF

reader or an NFC device operating in proximity.

ST25R3911B

Application information

DS11793 - Rev 6

page 42/116

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