ST25R3916B datasheet(46/165 Pages) STMICROELECTRONICS

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Application information

ST25R3916B ST25R3917B

46/165

DS13541 Rev 7

4.2.14

Listen mode

The ST25R3916B and ST25R3917B listen/target mode is activated by setting to 1 bit targ in

the Mode definition register. There are various target or listening modes implemented

depending on setting of the om<3:0> bits, refer to Table 25: Target operation modes.

The main modes are

•

NFCIP-1 active target

•

Passive target used for Card mode and NFCIP-1 passive target

Fixed listen communication mode

Fixed communication mode is active when one of the target modes with om3=0 is selected.

The other om bits control the type of communication.

Passive target

Communication can be performed by the host (through FIFO) or also by using automatic

responses as referred in NFCIP-1 passive target definition register.

These automatic responses include for NFC-A the complete anti-collision including SAK.

Handling of RATS and HLTA is up to the host. For NFC-F only the SENSF_REQ is handled

by sending SENSF_RES.

States of NFC-A can be handled by observing Passive target display register and Passive

target interrupt register bits I_wu_a, I_wu_a*. Direct commands Go to sense and Go to

sleep let the host influence the passive target states.

Responses to SENSF_REQ can be observed by thanks to bit I_wu_f.

The content of the automatic responses is defined by content of PT_Memory.

NFCIP-1 active target

When operating in NFCIP-1 active target mode the following settings are relevant.

•

Enable external field detector by setting bit en_fd_c in the Operation control register.

Using the field detector allows the ST25R3916B and ST25R3917B to turn on a

response field depending on nfc_ar setting in the Mode definition register.

Bits nfc_n<1:0> of the Auxiliary definition register influence the timing of Response

collision avoidance sequence.

•

The General purpose timer defines the time until RF field off after data transmission. Its

trigger sourcehas to be set to the end of transmit, according to Table 52: Trigger

sources (gptc<2:0> = 011).

•

After TARFG either I_cat or I_cac is flagged. TARFG is defined by NFC field on guard

timer register.

•

MRT starts at external field-on. NRT can be tailored by using nrt_nfc.

•

After switching off its field the ST25R3916B and ST25R3917B start the PPON2 timer

and observe the External field detector output to detect the response field. If no

external field is detected before PPON2 timer timeout, an IRQ with I_ppon2 flag is

signaled.

ST25R3916B Datasheet(PDF) 46 Page - STMicroelectronics

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