RX95HF Datasheet, PDF (23/44 Pages) STMicroelectronics – Near field communication transceiver for tag emulation

RX95HF
Commands
Note:
The Management of the Analog Register Configuration register (ACC_A) is described in
Section 5.10: Write Register (WrReg) command (0x09) description.
5.10
5.10.1
Write Register (WrReg) command (0x09) description
The Write Register (WRREG) command (0x09) is used to:
 set the Analog Register Configuration address index value before reading or
overwriting the Analog Register Configuration register (ACC_A) value
 set the Analog Register Configuration register (ACC_A) value
– Bits [7:6] are ST Reserved and must be set to ‘0’
– Bits [5:4] set the Demodulator Sensitivity (‘00’ = AM 10% or ‘10’ = AM 100%)
– Bits [3:0] set the Load Modulation Index (‘0001’ = minimum load modulation, ‘0111’
= default value, ‘1111’ = maximum load modulation). The user can adjust this value
to better fit his application.
Improving RF performance
Adjusting the Load Modulation Index and Demodulator Sensitivity parameters in Card
Emulation mode helps improve application behavior.
The default value of these parameters (Table 21) is set by the PROTOCOLSELECT command,
but they can be overwritten using the Write Register (WRREG) command (0x09). Table 22
and Table 23 list possible values for the Load Modulation Index and Demodulator Sensitivity
parameters respectively.
This new configuration is valid until a new PROTOCOLSELECT or Write Register (of register
ACC_A) command is executed. Register values are cleared at power off.
Table 21. WRREG command description (Load Modulation Index and Demodulator
Sensitivity)
Direction Data
Comments
Example
Host to
RX95HF
RX95HF to
Host
0x09 Command code
0x03 or _{Length of data}
0x04
Analog Register Configuration address
0x68 _index
0x00 or Flag Increment address or not after Write
0x01 command
>>>0x0903680004
Set Analog Register Index to
0x04 (ACC_A) ⁽¹⁾
0x04
Index pointing to the Demodulator
Sensitivity and Load Modulation values in
ACC_A register (0x04) (See
Section 5.10.1)
>>>0x090468010425
Update ACC_A to 0x25
New value for Demodulator Sensitivity and
0xXX _{Load Modulation (See Section 5.10.1)}
0x00 Result code
0x00 Length of data (= RegCount)
<<<0x0000
Register written
1. This command must be executed before reading the ACC_A register (0x0903680004).
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