AS3956 datasheet(44/107 Pages) AMSCO

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[v1-11] 2018-Nov-14

AS3956 − Detailed Description

Tunneling Mode

Tunneling mode enables transparent data transfer between

NFC device and MCU. In this mode, the internal EEPROM cannot

be accessed via RF and any type of data received will be

forwarded to MCU when the tag is in SELECTED state. An error

during the reception will trigger a corresponding interrupt. In

this mode the MCU shall take care for the correct response. For

this purpose, the MCU may issue an ACK or a different type NAK

response using implemented commands.

By enabling this mode, the MCU can emulate NFC type 2 tags,

NFC type 4 tags, ISO14443A Level 3 cards, ISO14443A Level 4

cards, and also implement higher level protocols such as

[PHDC].

Tunneling mode can be configured by setting Configuration

Byte IC_CFG2 in EEPROM or the corresponding register

( IC Configuration Register 2).

This mode also allows access to the internal EEPROM via the SPI

/ I²C during RF communication.

The basic assumption of Tunneling mode is that MCU is

responsible for generating the response and that AS3956 takes

care of the response synchronization over RF. For this reason,

AS3956 has a possibility to transmit ACK and NACK by issuing

a direct command (see section Direct Commands). The MCU can

also transmit data by writing the data into the buffer and issuing

a Transmit command. The implementation of Tunneling mode

also requires the handling of the SLP_REQ command since all

the received data in SELECTED state are stored in the buffer and

will not be processed by AS3956. This also implies that MCU has

to take care of correct transition of the tag into SLEEP or SENSE

state by using one of the three available commands Go To Sleep,

Go To Sense and Go To Sense / Sleep.

AS3956 Folha de dados(PDF) 44 Page - ams AG