AS3909 Просмотр технического описания (PDF) - austriamicrosystems AG
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AS3909 Datasheet PDF : 77 Pages
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Application Information
An interrupt due to end of transmission is sent when RF field is
switched off.
All NFC Transmit commands are only authorized in case the ISO
mode configuration bit nfc is set and the oscillator and
regulators are running.
Mask Receive Data and Unmask Receive Data
After the direct command Mask Receive Data the signal rx_on
which enables the RSSI and AGC operation of the Receiver (see
“Receiver” on page 11) is forced to low, processing of the
receiver output by the framing block is disabled, all received
modulation is rejected. This command is useful to block receiver
and receive framing from processing the data when there is
actually no input and only a noise would be processed (for
example in case where a transponder processing time after
receiving a command from the reader is long).
The direct command Unmask Receive Data is enabling normal
processing of the received data (signal rx_on is set high to
enable the RSSI and AGC operation, the framing block is
enabled. A common use of this command is to enable again the
receiver operation after it was disabled by the command Mask
Receive Data.
Another possible use is in case one wants that the receive
processing starts immediately after the transmit command
(usually the receiver operation is enabled 40 μs after the
transmission is terminated). This is accomplished by sending
the Unmask Receive Data immediately after the end of
transmission interrupt is received.
The command Unmask Receive Data has to be used in the NFC
target mode. The sequence implemented in the AS3909/10
supposes that every action is started with a transmit command,
after sending the transmit data, the receive mode is
automatically entered to process the response. Such a
sequence is always in place in case of the ISO-14443 reader
mode and also in case of the NFCIP mode where the AS3909/10
is the initiator. In case of the NFC target mode this sequence is
started by receiving the interrogator request. After the
interrupt caused by the first initiator request command Unmask
Receive Data is sent to force the AS3909/10 in receive mode.
The commands Mask Receive Data and Unmask Receive Data are
only accepted when the Receiver is operating.
AD Convert
A/D conversion of signal on AD_IN pin is performed; result is
stored in A/D Converter Output Register (see “A/D Converter” on
page 11).
Duration time: 42μs max.
This command is accepted in any mode where the oscillator and
regulators are running.
ams Datasheet, Confidential: 2013-Oct [3-02]
AS3909/AS3910 – 31
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