AS3909 datasheet(67/77 Pages) AMSCO

67 / 77 page

ams Datasheet, Confidential: 2013-Oct [3-02]

AS3909/AS3910 – 67

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

Active Receive – Use in ISO-14443B

Anticollision

Usually the microcontroller does not need information about

beginning of the transponder message, it gets an interrupt once

reception is finished or earlier in case the transponder message

is longer than the FIFO.

In some cases the information about the fact that the receiver

is already processing a message from the transponder is useful.

The bit rx_act in the FIFO Status Register (address 09) provides

this information. This bit is set to 1 when start of the

transponder message is detected and stays high until the end

of reception.

This information can be used to speed up the ISO-14443B

anticollision procedure when more slots are used. In case there

is no message in a certain slot the reader does not have to wait

the time message ATQB takes before sending the next

Slot-MARKER command, it can send it as soon as it is clear that

there is no answer in that particular slot. The microcontroller

can obtain this info by reading the rx_act flag at the time the

receiver should already be processing the ATQB message. In

case rx_act flag is set to one the receiver is processing a message

and the microcontroller has to wait for the end of receive

interrupt, in opposite case when the rx_act flag is set to zero

there is no ATQB message in that particular slot and the next

Slot-MARKER command can be sent immediately.

ISO-14443B, Reduction of TR0 and TR1 and

Suppression of EOF/SOF in PICC Response

The ISO-14443-3 standard, chapter 7.10.3 Coding of Param 1

defines possibility to reduce the TR0 and TR1 and suppress the

EOF/SOF in PICC response.

Note(s):The AS3909/10 Receiver and Framing blocks do not

support the reduction of TR0 and TR1 and suppression of

EOF/SOF. In case default settings of these parameters are

changed, the framing block will not be able to decode the PICC

response.

Test Pins

Pins TEST and TIO are used to test the AS3909/10. Pin TEST is a

digital pin with pull down, it is used to enter the test mode, pin

TIO is used in test mode as a digital IO, in normal mode it is in

tristate. It is recommended to connect pin TEST to VSS and to

leave pin TIO open.

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