AS3911 datasheet(148/159 Pages) AMSCO

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[v2-11] 2016-Jun-13

AS3911 − Application Information

After selecting the stream mode the Receiver and Transmitter

have to be configured properly (Analog Preset direct command

doesn't apply for stream mode).

Sub-Carrier Stream Mode:

This mode supports protocols where during the tag to reader

communication the time periods with sub-carrier signal are

interchanged with time periods without modulation (like in the

ISO14443A 106 kbit/s mode). In this mode the sub-carrier

frequency and number of sub-carrier frequency periods in one

reporting period is defined. Sub-carrier frequency in the range

from fc/64 (212 kHz) to fc/8 (1695 kHz) are supported.

Supported number of sub-carrier frequency periods in one

reporting period range from two to eight.

Start of receive interrupt is sent and the first data bit is put in

FIFO after the first reporting time period with sub-carrier is

detected. One bit of FIFO data gives information about status

of input signal during one reporting period. Logic 1 means that

the sub-carrier was detected during reporting period, while 0

means that no modulation was detected during reporting

period. End of receive is reported when no sub-carrier signal in

more than eight reporting periods have been detected.

Figure below depicts an example for setting scf = 01b and

scp = 10b. With this setting the sub-carrier frequency is set to

fc/32 (424 kHz) and the reporting period to four sub-carrier

periods (128/fc - ~106 μs).

Figure 127:

Example of Sub-Carrier Stream Mode for scf = 01b and scp = 10b

BPSK Stream Mode:

This mode supports protocols where during the tag to reader

communication BPSK code is used (like in the ISO14443B mode).

In this mode the sub-carrier frequency and number of

sub-carrier frequency periods in one reporting period is

defined. Sub-carrier frequency in the range from fc/16 (848 kHz)

to fc/4 (3390 kHz) are supported. Supported number of

sub-carrier frequency periods in one reporting period range

from one to eight.

DatainFIFO

Inputsignal

32/fc

128/fc

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