AS3910-BQFP AMSCO [austriamicrosystems AG], AS3910-BQFP Datasheet - Page 21

• Manufacturer Part Number: AS3910-BQFP
• Description: 13.56 MHz RFID Reader IC, ISO-14443 A/B
• Manufacturer: AMSCO [austriamicrosystems AG]

AS3910
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
Table 9. Direct Commands
8.10.1 Set Default
This direct command puts the AS3910 in the same state as power-up initialization. All registers are initialized to the default state. Please note
that results of different calibration and adjust commands are also lost. This direct command is accepted in all operating modes.
8.10.2 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).
8.10.3 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).
8.10.4 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.
Actual implementation in the AS3910 is the following:
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.
www.austriamicrosystems.com/HF_RFID_Reader/AS3910
010100
010101
010110
011000
011001
011010
010111
011100
Guard time after sending
Code
response or request
Active guard time
Active delay time
Initial guard time
Initial delay time
RF waiting time
Parameter
Calibrate modulation depth
Check antenna resonance
Transparent mode
Calibrate antenna
Adjust regulators
Clear Squelch
Command
Clear RSSI
Squelch
Symbol
T
T
T
T
T
T
ARFG
RWF
IRFG
ADT
GAS
IDT
Value
37.76
5.11
302
151
84
65
Performs gain reduction based on the current noise level.
Resumes gain settings which were in place before sending Squelch command
Adjusts supply regulators according to the current supply voltage level
Starts sequence which activates the TX, measures the modulation depth and
adapts it to comply with the specified modulation depth
Starts the sequence to adjust parallel capacitances connected to TRIMx pins so
that the antenna LC is in resonance.
Measurement of antenna LC tank resonance to determine whether calibration is
needed.
Clears RSSI bits and restarts the measurement
Enter in Transparent mode
Revision 2.3
Unit
ms
µs
µs
µs
µs
µs
T
GAS
after sending a response or request. This time is not
is the time during which RF field stays switched on
Comments
Response RF Collision Avoidance
Response RF Collision Avoidance
specified in the ISO/IEC 18092.
Initial RF Collision Avoidance
Initial RF Collision Avoidance
Note
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