AS3911 datasheet(140/149 Pages) AMSCO

140 / 149 page

AS3911 – 140

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

A p pl i c at io n I n f o r m at i o n

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 124:

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.

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. Logic 0 is used for the initially detected phase, while

logic 1 indicates inverted phase comparing to the initial phase.

End of receive is reported when the first reporting period

without sub-carrier is detected.

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

scp = 01b. With this setting the sub-carrier frequency is set to

fc/8 (1695 kHz) and the reporting period to two sub-carrier

periods (16/fc - ~1.18μs).

DatainFIFO

Inputsignal

32/fc

128/fc

AS3911 Datasheet(PDF) 140 Page - ams AG