AS3911 datasheet(136/159 Pages) AMSCO

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[v2-11] 2016-Jun-13

AS3911 − Application Information

CRC bytes are internally checked. In case the Start byte is not

equal to F0h the following data bytes are still put in FIFO,

additionally a soft framing error IRQ is set to indicate the Start

Byte error.

NFCIP-1 Active Communication Initiator

During NFCIP-1 active communication both, initiator and target

switch on its field when transmitting and switch off its field

when receiving. In order to operate as NFCIP-1 active

communication initiator the AS3911 has to be configured

according to table below (bit targ in the Mode Definition

Figure 124:

Operation Mode and Bit Rate Setting for NFCIP-1 Active Communication Initiator

After selecting the NFCIP-1 active communication mode the

Receiver and Transmitter have to be configured properly. This

configuration can be done automatically by sending direct

command Analog Preset (see Analog Preset).

During NFCIP-1 active communication the RF Collision

avoidance and switching on the field is performed using ‘NFC

Field ON’ commands (see NFC Field ON Commands), while the

sending of message is performed using Transmit commands as

in the case of reader communication. Alternatively the

Response RF Collision Avoidance sequence is started

automatically when the switching off of target field is detected

in case the bit nfc_ar in the Mode Definition Register is set.

When NFCIP-1 mode is activated the External Field Detector is

automatically enabled by setting bit en_fd in the Auxiliary

Display Register. The Peer Detection Threshold is used to detect

target field. During execution of ‘NFC Field ON’ commands, the

Collision Avoidance Threshold is used.

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.

NFCIP-1

Bit Rate [kbit/s]

Initiator

Operation

Mode Setting

Bit Rate for Tx

[kbit/s]

Bit Rate for Rx

[kbit/s]

Comment

106

NFCIP-1 active

communication

fc/128 (~106)

For all NFCIP-1

communication,

data rate is the same

in both directions.

212

NFCIP-1 active

communication

fc/64 (~212)

424

NFCIP-1 active

communication

fc/32 (~424)

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