AS3911 datasheet(121/149 Pages) AMSCO

121 / 149 page

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

AS3911 – 121

Appl icatio n I n f o rm a t i o n

Set the antcl bit in the ISO14443A and NFC 106kb/s

Settings Register. This needs to be set before sending

the REQA (or WUPA). As a result of setting this bit, the

AS3911 will not trigger a framing error if in case the

collision occurs in the ATQA or during anticollision

procedure.

Note(s): This bit must be set to one for REQA, WUPA and

ANTOCOLLISION commands, for other commands it has to be

zero)

Review and set the value for Mask Receive Timer

the ISO14443A. And set the No-response Timer Register

1&No-response Timer Register 2 according to the

requirements. This is typically larger than the FDT.

Note(s): AS3911 offers the resolution of n/2 (64/fc - half steps)

compared to n (128/fc) as mentioned in 14443A so that the

receiver can be unmasked n/2 step before the actual

transmission from the PICC). According to ISO 14443A the FDT

must be 1236/fc if last transmitter bit if 1 or 1172/fc if last

transmitter bit is 0. As a simple rule one can follow the following.

Figure 116:

Selection of MRT & NRT for a given FDT

The receiver and transmitter operation options related

to operation mode have to be defined. This is done

automatically by sending the direct command Analog

Preset. If different options are required apart from those

defined by Analog Preset, then such options must be

additionally set by writing the appropriate registers.

Set rx_en and tx_en in the Operation Control Register.

RFID protocols usually require that the reader field is

turned on for a while before sending the first command

(5 ms for ISO14443). General purpose timer can be used

to count this time.

PCD to PICC

FDT

MRT < FDT – 64/fc

NRE > FDT + 64/fc

PICC to PCD

AS3911 Datasheet(PDF) 121 Page - ams AG