AS3911 datasheet(128/149 Pages) AMSCO

128 / 149 page

AS3911 – 128

ams Datasheet, Confidential: 2013-Oct [2-03]

A p pl i c at io n I n f o r m at i o n

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 121:

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” on page 53).

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” on

page 51), 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. The tx_en bit and therefore

switching on of the transmitter is controlled by NFC Field ON

commands. Switching off the field is performed automatically

after a message has been sent. The General Purpose and

No-response Timer Control Register is used to define the time

during which the field stays switched on after a message has

been transmitted.

NFCIP-1 Bit Rate

[kb/s]

Initiator

Operation

Mode Setting

Bit Rate for

[kb/s]

Bit Rate for Rx

[kb/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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