AS3909 datasheet(57/77 Pages) AMSCO

57 / 77 page

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

AS3909/AS3910 – 57

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

ISO-14443A SELECT SEQUENCE

In the 14443A select sequence the commands REQA (also

WUPA), ANTICOLLISION and SELECT are used. For the

commands REQA and WUPA the short frame is used, for

ANTICOLLISION the bit oriented anticollision frame is used, for

SELECT the standard frame is used. Transponder replies to

commands REQA, WUPA and ANTICOLLISION do not contain the

CRC so the configuration bit crc_rx of the Configuration Register

3 (address 03) has to be set to 1 (receive without CRC) before

these commands are sent.

REQA and WUPA

Sending of these two commands is simple since they are

implemented as the AS3909/10 direct commands (Transmit

REQA and Transmit WUPA). Procedure is the following (note that

since the ATQA response does not contain a CRC the

configuration bit crc_rx of the Configuration Register 3 (address

#03) has to be set to 1 before this procedure is started):

Send the direct command Transmit REQA (or Transmit

WUPA)

When all the data is transmitted an interrupt is sent to

inform the microcontroller that transmission is finished

(INTR due to end of transmission)

When reception of the ATQA is finished and all data is

in the FIFO an interrupt is sent to the microcontroller

(INTR due to end of receive), additionally the FIFO Status

ATQA) in the FIFO so the microcontroller can proceeded

with downloading data from the FIFO.

Sending the direct command Clear before sending Transmit

REQA and Transmit WUPA is not necessary.

ANTICOLLISION

In this command, the bit oriented anticollision frame is used.

There is no CRC, neither in the command send from PCD to PICC

(part 1 of the bit oriented anticollision frame), nor in the reply

sent from PICC to PCD (part 2 of the bit oriented anticollision

frame). Due to this configuration the bit crc_rx of the

Configuration Register 3 (address #03) has to be set to 1 before.

Sequence in case full bytes are transmitted (no collision during

the transponder response):

Send the direct command Clear

Define the number of transmitted bytes for part1 of the

bit oriented anticollision frame in the registers #0B and

#0C. Bit 0 (antcl) of register #0B has to be additionally

set to 1 to indicate that anticollision frame is sent.

Write the bytes to be transmitted in the FIFO

Send the direct command Transmit without CRC

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