PN512_11 Datasheet, PDF (80/125 Pages) NXP Semiconductors – Transmission module Integrated data mode detector

NXP Semiconductors
PN512
Transmission module
12. Analog interface and contactless UART
12.1 General
The integrated contactless UART supports the external host online with framing and error
checking of the protocol requirements up to 848 kBd. An external circuit can be connected
to the communication interface pins MFIN and MFOUT to modulate and demodulate the
data.
The contactless UART handles the protocol requirements for the communication
protocols in cooperation with the host. Protocol handling generates bit and byte-oriented
framing. In addition, it handles error detection such as parity and CRC, based on the
various supported contactless communication protocols.
Remark: The size and tuning of the antenna and the power supply voltage have an
important impact on the achievable operating distance.
12.2 TX driver
The signal on pins TX1 and TX2 is the 13.56 MHz energy carrier modulated by an
envelope signal. It can be used to drive an antenna directly using a few passive
components for matching and filtering; see Section 15 on page 92. The signal on pins TX1
and TX2 can be configured using the TxControlReg register; see Section 9.2.2.5 on
page 36.
The modulation index can be set by adjusting the impedance of the drivers. The
impedance of the p-driver can be configured using registers CWGsPReg and
ModGsPReg. The impedance of the n-driver can be configured using the GsNReg
register. The modulation index also depends on the antenna design and tuning.
The TxModeReg and TxSelReg registers control the data rate and framing during
transmission and the antenna driver setting to support the different requirements at the
different modes and transfer speeds.
Table 152. Register and bit settings controlling the signal on pin TX1
Bit
Bit
Bit
Bit
Envelope Pin
Tx1RFEn Force InvTx1RFOn InvTx1RFOff
TX1
100ASK
GSPMos GSNMos Remarks
0
X^[1]
X^[1]
X^[1]
X^[1]
X^[1] X^[1]
X^[1]
not specified if RF is
switched off
1
0
0
0
1
X^[1]
0
RF pMod
nMod
100 % ASK: pin TX1
1
RF pCW
nCW
pulled to logic 0,
independent of the
X^[1]
0
RF pMod
nMod
InvTx1RFOff bit
1
RF pCW
nCW
1
1
X^[1]
0
0
pMod
nMod
1
RF_n pCW
nCW
[1] X = Do not care.
PN512
Product data sheet
COMPANY PUBLIC
All information provided in this document is subject to legal disclaimers.
Rev. 3.7 — 18 May 2011
111337
© NXP B.V. 2011. All rights reserved.
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