ST25R3916 datasheet(44/157 Pages) STMICROELECTRONICS

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Application information

ST25R3916/7

44/157

DS12484 Rev 4

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 ST25R3916/7 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 ST25R3916/7 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.

Bit rate detection mode

The Listen mode can also be started from the so-called Bit rate detection mode. In this

mode the communication mode is not fixed. This mode is activated in case of Target mode

together with bit om3 set to 1.

The other om bits define the technologies to be recognized. It is an extension of the Fixed

listen communication mode.

Once the reception of the first frame starts, the Bit rate detection mode signals an IRQ I_nfct

indicating that the bit rate has been identified and the host can retrieve the related

information by reading nfc_rate on Bit rate definition register.

When the first frame has been fully received, the host can exit the Bit rate detection mode

by setting the corresponding mode on om<3:0> bits in the Mode definition register to the

corresponding fixed listen communication mode.

ST25R3916 数据表(PDF) 44 Page - STMicroelectronics

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