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MFRC631 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2014. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 3.3 — 4 February 2014
227433 82 of 120
NXP Semiconductors
MFRC631
High performance ISO/IEC 14443 A/B reader solution
9.8.4 Txl
9.9 CRC configuration registers
9.9.1 TxCrcPreset
Table 126. TxCon bits
Bit Symbol Description
7 to 4 OvershootT2 Specifies the length (number of carrier clocks) of the additional
modulation for overshoot prevention. Refer to Section 8.6.2.1
“Overshoot protection”
3 Cwmax Set amplitude of continuous wave carrier to the maximum.
If set, set_cw_amplitude in Register TxAmp has no influence on the
continuous amplitude.
2 TxInv If set, the resulting modulation signal defined by TxSel is inverted
1 to 0 TxSel Defines which signal is used as source for modulation
00b ... no modulation
01b ... TxEnvelope
10b ... SigIn
11b ... RFU
Table 127. Txl register (address 2Bh)
Bit 7 6 5 4 3 2 1 0
Symbol OvershootT1 tx_set_iLoad
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Table 128. Txl bits
Bit Symbol Description
7 to 4 OvershootT1 Overshoot value for Timer1. Refer to Section 8.6.2.1 “
Overshoot
protection”
3 to 0 tx_set_iLoad Factory trim value, sets the expected Tx load current. This value is
used to control the modulation index in an optimized way dependent
on the expected TX load current.
Table 129. TXCrcPreset register (address 2Ch)
Bit 7 6 5 4 3 2 1 0
Symbol RFU TXPresetVal TxCRCtype TxCRCInvert TxCRCEn
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