AS3911 datasheet(126/149 Pages) AMSCO

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AS3911 – 126

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 Passive Communication Initiator

NFCIP-1 passive communication is equivalent to reader (PCD)

to tag (PICC) communication where initiator acts as a reader

and target acts as tag. The only difference is that in case of the

NFCIP-1 passive communication the initiator performs Initial RF

Collision Avoidance procedure at the beginning of

communication.

In order to act as NFCIP-1 passive communication initiator the

AS3911 has to be configured according to table below:

Figure 119:

Operation Mode and Bit Rate Setting for NFCIP-1 Passive Communication

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 direct command NFC Initial

Field ON is sent instead.

This command first performs the Initial RF Collision avoidance

with Collision Avoidance Threshold defined in the External Field

Detector Threshold Register. The timing of collision avoidance

is according to NFCIP-1 standard (for timing details see

Figure 37). In case collision is not detected the tx_en bit is

automatically set to switch the transmitter on. After minimum

guard time TIRFG the I_cat IRQ is sent to inform controller that

the first initiator command can be send.

From this point on communication is the same as in case of

ISO14443A (for 106 kb/s) or FeliCa (for 242 and 424 kb/s) reader

communication.

In case a presence of external field is detected an I_cac IRQ is

sent. In such case a transmission should not be performed,

command NFC Initial Field ON has to be repeated as long as

collision is not detected any more.

Initial collision avoidance is not limited to modes supported by

NFCIP-1. The initial collision avoidance according to procedure

described above can be performed before any reader mode is

started to avoid collision with an HF reader or an NFC device

operating in proximity.

Support of NFCIP-1Transport Frame Format

Figure 120 depicts the Transport Frame according to NFCIP-1

standard.

NFCIP-1 Bit Rate

[kb/s]

Operation

Mode Setting

Bit Rate for

[kb/s]

Bit Rate for Rx

[kb/s]

Comment

106

ISO14443A

fc/128 (~106)

212

FeliCa

fc/64 (~212)

In FeliCa mode data

rate is the same in

both directions

424

FeliCa

fc/32 (~424)

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