AS3911 datasheet(119/149 Pages) AMSCO

119 / 149 page

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

AS3911 – 119

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

When all the data is transmitted an interrupt is sent to

inform the microcontroller that the transmission is

finished (IRQ due to end of transmission)

After the transmission is executed, the AS3911 receiver

automatically starts to observe the RFI inputs to detect a

transponder response. The RSSI and AGC (in case it is enabled)

are started. The framing block processes the sub-carrier signal

from receiver and fills the FIFO with data. When the reception

is finished and all the data is in the FIFO an interrupt is sent to

the microcontroller (IRQ due to end of receive), additionally the

FIFO Status Register 1 and FIFO Status Register 2 display the

number of bytes in the FIFO so the microcontroller can

proceeded with downloading the data.

In case there was an error or bit collision detected during

reception, an interrupt with appropriate flag is sent.

Microcontroller has to take appropriate action.

Transmit and Receive in case data packet is longer than FIFO:

In case a data packet is longer than FIFO the sequence explained

above is modified.

Before transmit the FIFO is filled. During transmit an interrupt

is sent when remaining number of bytes is lower than the water

level (IRQ due to FIFO water level). The microcontroller in turn

adds more data in the FIFO. When all the data is transmitted an

interrupt is sent to inform the microcontroller that transmission

is finished.

During reception situation is similar. In case the FIFO is loaded

with more data than the receive water level, an interrupt is sent

and the microcontroller in turn reads the data from the FIFO.

When reception is finished an interrupt is sent to the

microcontroller (IRQ due to end of receive), additionally the

FIFO Status Register 1 and FIFO Status Register 2 display the

number of bytes in the FIFO which are still to be read out.

Anticollision – ISO 14443A

Note(s): For this section, it is assumed that there are more than

one ISO/IEC 14443A PICC in the reader’s RF field and all are

compatible to ISO/IEC 14443 up to level 4.

This section highlights on a procedure of performing

anticollision with AS3911 for ISO14443A tags. After an

ISO14443 type A tag enters in the reader field, the reader has

to perform a selection process which brings it into the

PROTOCOL state in which the actual application implemented

in the tag can be executed. This selection process is described

in the ISO/IEC 14443-3. The Figure 115 depicts the states which

a tag and a reader have to pass through to enter the protocol

state.

AS3911 Datasheet(PDF) 119 Page - ams AG

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