AS3909 Просмотр технического описания (PDF) - austriamicrosystems AG
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AS3909 Datasheet PDF : 77 Pages
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Application Information
Clear
This direct command stops all current activities (transmission
or reception) and clears FIFO. It also clears Collision and
Interrupt Registers. This command has to be sent first in a
sequence preparing a transmission (except in case of direct
commands Transmit REQA and Transmit WUPA).
Transmit Commands
All Transmit commands (Transmit with CRC, Transmit without
CRC, Transmit REQA and Transmit WUPA) are only accepted in
case the Transmitter is enabled (bit tx_en is set).
NFC Transmit Commands
The NFC transmit commands (NFC transmit with Initial RF
Collision Avoidance, NFC transmit with Response RF Collision
Avoidance, NFC transmit with Response RF Collision Avoidance
with n=0) are used to transmit requests and responses in the
NFC mode. Before actual transmission the RF Collision
avoidance with Collision avoidance threshold defined in the
NFCIP Field Detection Threshold Register is performed.
In the command NFC transmit with Response RF Collision
Avoidance n is randomly set in a range from 0 to 3, while in the
command NFC transmit with Response RF Collision Avoidance
with n=0 it is set to 0. In case collision is detected during the RF
Collision Avoidance the transmission is not done and an
interrupt is sent with flag INTR due to NFC event.
The NFC transmit commands switch on and off the transmission
block, setting the Operation control bit tx_en in the NFC mode
is not allowed.
Timing of the NFC transmit commands is according to the
ISO/IEC 18092 standard. For some timings the ISO/IEC 18092
specifies a range.
Figure 21:
NFC P2P Timings Implemented in AS3909/10
Symbol
Parameter
TIDT
TRWF
TIRFG
TADT
TARFG
Initial delay time
RF waiting time
Initial guard time
Active delay time
Active guard time
Value
302
37.76
5.11
151
84
TGAS
Guard time after sending
response or request
65
Unit
μs
μs
ms
μs
μs
μs
Note
Initial RF Collision Avoidance
Initial RF Collision Avoidance
Response RF Collision Avoidance
Response RF Collision Avoidance
TGAS is the time during which RF field stays
switched on after sending a response or
request. This time is not specified in the
ISO/IEC 18092.
AS3909/AS3910 – 30
ams Datasheet, Confidential: 2013-Oct [3-02]
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