AS3911 datasheet(127/149 Pages) AMSCO

127 / 149 page

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

AS3911 – 127

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

Figure 120:

Transport Frame Format According to NFCIP-1

Transport Frame for bit rate 212 and 424 kb/s has the same

format as communication frame used during Initialization and

SDD. This format is also used in FeliCa protocol (see also FeliCa

Reader Mode). In case of 106 kb/s the SB (Start byte at F0h) and

LEN (length byte) are only used in Transport Frame.

Support of Transport Frame for 106 kb/s NFCIP-1

communication is enabled by setting bit nfc_f0 in the

ISO14443A and NFC 106kb/s Settings Register.

Once this bit is set and ISO 14443A mode with bit rate 106 kb/s

is configured, the behavior of the AS3911 framing is as follows:

Transmission

In order to transmit a Transport Frame only the Transport Data

has to be put in FIFO. The number of Transport Data bytes is

defined in the Number of Transmitted Bytes Register 1 and

Number of Transmitted Bytes Register 2. Transmission is

triggered by sending direct command Transmit With CRC. First

Start byte with value F0h followed by Length byte are sent. Then

Transport Data stored in FIFO is sent, transmission is terminated

by two CRC bytes (E1 in Figure 120) which are calculated by the

AS3911. Length byte is calculated from ‘number of transmitted

bytes’. The following equation is used:

length = Transport Data length + 1 = number of transmitted

bytes +1

Reception

After transmission is done the AS3911 logic starts to parse the

receiver output to detect the start of tag reply.

Once the start of communication sequence is detected the first

byte (Start Byte with value F0h) is checked the Length byte and

Transport Data bytes are put in the FIFO. CRC bytes are internally

checked. In case the Start byte is not equal to F0h the following

data bytes are still put in FIFO, additionally a soft framing error

IRQ is set to indicate the Start Byte error.

LEN

CMD0

CMD1

Byte 0

Byte 1

Byte 2

…

Byte n

LEN

CMD0

CMD1

Byte 0

Byte 1

Byte 2

…

Byte n

Transport Data Field

Frame Format

for 106 kbps

Frame Format

for 212 kbps

and 424 kbps

AS3911 Datasheet(PDF) 127 Page - ams AG

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