Texas Instruments TRF7970A Manual page 71

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6.15.3.3.7 NFC Low Field Level Register (0x16)
Table 6-51 describes the NFC Low Field Level register.
Function: Defines level for RF collision avoidance
Default: 0x00 at POR = H and EN = L.
Bit Name
B7 Clex_dis Disable clock extractor
B6 Hash6 N/A
B5 Hash5 N/A
B4 Hash4 N/A
B3 Hash3 N/A
B2 Rfdet_I2
RF field level for RF
B1 Rfdet_I1
collision avoidance
B0 Rfdet_I0
6.15.3.3.8 NFCID1 Number Register (0x17)
This register is used to hold the ID of the TRF7970A for use during card emulation and NFC peer-to-peer
target operations.
The procedure for writing the ID into register 0x17 is the following:
1. Write bits 5, 6, and 7 in register 0x18 to enable SDD anticollision (bit 5), and set bit 6 and 7 to select
the ID length of 4, 7, or 10 bytes.
2. Write the ID into register 0x17. This should be done using write continuous mode with 4, 7, or 10 bytes
(according to what was set in register 0x18 bits 6 and 7).
6.15.3.3.9 NFC Target Detection Level Register (0x18)
Table 6-52 describes the NFC Target Detection Level register.
Function: Defines level for RF wake up, enables automatic SDD and gives NFCID size. This register is supplied by Vin to ensure data
retention during complete power down.
Default: 0x00 at POR on Vin (not POR based on V
Bit Name
B7 Id_s1
NFCID1 size used in 106-
kbps passive target SDD
B6 Id_s0
B5 Sdd_en
B4 N/A
Extended range for RF
B3 Hi_rf
measurements
B2 Rfdet_h2 RF field level required for
system wakeup. If all bits
B1 Rfdet_h1
are 0, then the RF level
B0 Rfdet_h0 detection is off.
Copyright © 2011–2017, Texas Instruments Incorporated
Table 6-51. NFC Low Field Level Register (0x16)
Function
NFC passive 106-kbps and ISO/IEC 14443 A card emulation
Comparator output is displayed in B6 of the NFC Target Protocol register
(0x19)
Table 6-52. NFC Target Detection Level Register (0x18)
) and not reset at EN = 0
DD_X
Function
Automatic SDD using internal state machine and ID stored in the NFCID1
Number register (0x17)
Comparator output is displayed in B7 of the NFC Target Protocol register
(0x19)
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SLOS743L – AUGUST 2011 – REVISED MARCH 2017
Description
Description
Id_s1 Id_s0
0 0
0 1
1 0
1 1
TRF7970A
TRF7970A
NFCID1 Size
(bytes)
4
7
10
Not allowed
Detailed Description 71