Datasheet

PN512 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2016. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 5.2 — 16 June 2016
111352 44 of 137
NXP Semiconductors
PN512
Full NFC Forum-compliant frontend
8.2.2.8 RxSelReg
Selects internal receiver settings.
8.2.2.9 RxThresholdReg
Selects thresholds for the bit decoder.
Table 61. RxSelReg register (address 17h); reset value: 84h, 10000100b
7 6 5 4 3 2 1 0
UartSel RxWait
Access
Rights
r/w r/w r/w r/w r/w r/w r/w r/w
Table 62. Description of RxSelReg bits
Bit Symbol Description
7 to 6 UartSel Selects the input of the contactless UART
Value Description
00 Constant Low
01 Envelope signal at SIGIN
10 Modulation signal from the internal analog part
11 Modulation signal from SIGIN pin. Only valid for transfer
speeds above 424 kbit
5 to 0 RxWait After data transmission, the activation of the receiver is delayed for
RxWait bit-clocks. During this ‘frame guard time’ any signal at pin RX
is ignored. This parameter is ignored by the Receive command. All
other commands (e.g. Transceive, Autocoll, MFAuthent) use this
parameter. Depending on the mode of the PN512, the counter starts
different. In Passive Communication mode the counter starts with the
last modulation pulse of the transmitted data stream. In Active
Communication mode the counter starts immediately after the external
RF field is switched on.
Table 63. RxThresholdReg register (address 18h); reset value: 84h, 10000100b
7 6 5 4 3 2 1 0
MinLevel 0 CollLevel
Access
Rights
r/w r/w r/w r/w RFU r/w r/w r/w
Table 64. Description of RxThresholdReg bits
Bit Symbol Description
7 to 4 MinLevel Defines the minimum signal strength at the decoder input that shall be
accepted. If the signal strength is below this level, it is not evaluated.
3 - Reserved for future use.
2 to 0 CollLevel Defines the minimum signal strength at the decoder input that has to be
reached by the weaker half-bit of the Manchester-coded signal to
generate a bit-collision relatively to the amplitude of the stronger half-bit.