Texas Instruments TRF7970A Instruction Manual page 57

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6.14.3 Detailed Register Description
6.14.3.1 Main Configuration Registers
6.14.3.1.1 Chip Status Control Register (0x00)
Function: Control of Power mode, RF on/off, AGC, AM/PM, Direct Mode
Default: 0x01, preset at EN = L or POR = H
Bit Name
1 = Standby Mode
B7 stby
0 = Active Mode
1 = Direct Mode 0 or 1
B6 direct
0 = Direct Mode 2 (default)
1 = RF output active
B5 rf_on
0 = RF output not active
1 = half output power
B4 rf_pwr
0 = full output power
1 = selects Aux RX input
B3 pm_on
0 = selects Main RX input
1 = AGC on
B2 agc_on
0 = AGC off
1 = Receiver activated for
external field measurement
B1 rec_on
0 = Automatic Enable
1 = 5 V operation
B0 vrs5_3
0 = 3 V operation
6.14.3.1.2 ISO Control Register (0x01)
Function: Controls the selection of ISO Standard protocol, Direct Mode and Receive CRC
Default: 0x02 (ISO15693 high bit rate, one subcarrier, 1 out of 4); it is preset at EN = L or POR = H
Bit Name
B7 rx_crc_n CRC Receive selection
B6 dir_mode Direct mode type selection
B5 rfid RFID / Reserved
B4 iso_4 RFID / NFC Target
B3 iso_3 RFID / NFC Mode
(1) Only applicable to ISO-14443A and ISO-15693
Copyright © 2011–2014, Texas Instruments Incorporated
Table 6-25. Chip Status Control Register (0x00)
Function
Standby mode keeps all supply regulators, 13.56-MHz SYS_CLK oscillator
running. (typical start-up time to full operation 100 µs)
Active Mode (default)
Provides user direct access to AFE (Direct Mode 0) or allows user to add their
own framing (Direct Mode 1). Bit 6 of ISO Control register must be set by user
before entering Direct Mode 0 or 1.
Uses SPI or parallel communication with automatic framing and ISO decoders
Transmitter on, receivers on
Transmitter off
TX_OUT (pin 5) = 8-Ω output impedance P = 100 mW (20 dBm) at 5 V,
P = 33 mW (+15 dBm) at 3.3 V
TX_OUT (pin 5) = 4-Ω output impedance P = 200 mW (+23 dBm) at 5 V,
P = 70 mW (+18 dBm) at 3.3 V
RX_IN2 input is used
RX_IN1 input is used
Enables AGC (AGC gain can be set in register 0x0A)
AGC block is disabled
Forced enabling of receiver and TX oscillator. Used for external field
measurement.
Allows enable of the receiver by Bit 5 of this register (0x00)
Selects the V
Table 6-26. ISO Control Register (0x01)
Function
0 = RX CRC (CRC is present in the response)
1 = no RX CRC (CRC is not present in the response)
0 = Direct Mode 0
1 = Direct Mode 1
0 = RFID Mode
1 = NFC or Card Emulation Mode
RFID: See
application
NFC:
0 = target
1 = initiator
NFC:
0 = passive mode
1 = active mode
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SLOS743K – AUGUST 2011 – REVISED APRIL 2014
Description
voltage range
IN
Description
Table 6-27 for B0:B4 settings based on ISO protocol desired by
TRF7970A
TRF7970A
(1)
Detailed Description 57