AS3911 datasheet(149/159 Pages) AMSCO

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ams Datasheet

Page 149

[v2-11] 2016-Jun-13

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AS3911 − Application Information

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).

Figure 128:

Example of BPSK Stream Mode for scf = 01b and scp = 01b

Reader to Tag Communication in Stream Mode:

Reader to tag communication control is the same for both

stream modes. Reader to tag coding is defined by data put in

FIFO. The stx bits of Stream Mode Definition Register define the

Tx time period during which one bit of FIFO data define the

status of transmitter. In case the data bit is set to logic 0 there

is no modulation, in case it is logic 1 the transmitted carrier

signal is modulated according to current modulation type

setting (AM or OOK). Transmission in stream mode is started by

sending direct commands Transmit Without CRC or Transmit

With CRC.

Figure below depicts an example for setting stx = 000b. With

this setting the Tx time period is defined to 128/fc (~9,44μs).

Figure 129:

Example of Tx in Stream Mode for stx = 000b and OOK Modulation

Data in FIFO

Input signal

8/fc

16/fc

Data in FIFO

Output signal

128/fc

AS3911 Datasheet(PDF) 149 Page - ams AG