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 103 of 137
NXP Semiconductors
PN512
Full NFC Forum-compliant frontend
18.3.1.8 Transceive
This command continuously repeats the transmission of data from the FIFO buffer and the
reception of data from the RF field. The first action is transmit and after transmission the
command is changed to receive a data stream.
Each transmit process must be started by setting the BitFramingReg register’s StartSend
bit to logic 1. This command must be cleared by writing any command to the
CommandReg register.
Remark: If the RxModeReg register’s RxMultiple bit is set to logic 1, the Transceive
command never leaves the receive state because this state cannot be cancelled
automatically.
18.3.1.9 AutoColl
This command automatically handles the MIFARE activation and the FeliCa polling in the
Card Operation mode. The bit Initiator in the register ControlReg has to be set to logic 0
for correct operation. During this command also the mode detector is active if not
deactivated by setting the bit ModeDetOff in the ModeReg register. After the mode
detector detects a mode, all the mode dependent registers are set according to the
received data. In case of no external RF field the command resets the internal state
machine and returns to the initial state but it will not be terminated. When the command
terminates the transceive command gets active.
During protocol processing the IRQ bits are not supported. Only the last received frame
will serve the IRQ’s. The treatment of the TxCRCEn and RxCRCEn bits is different to the
protocol. During ISO/IEC 14443A activation the enable bits are defined by the command
AutoColl. The changes cannot be observed at the register TXModeReg and RXModeReg.
After the Transceive command is active, the value of the register bit is relevant.
The FIFO will also receive the two CRC check bytes of the last command even if they
already checked and correct, if the state machine (Anticollision and Select routine) has to
not been executed and 106 kbit is detected.
During Felica activation the register bit is always relevant and is not overruled by the
command settings. This command can be cleared by software by writing any other
command to the CommandReg register, e.g. the idle command. Writing the same content
again to the CommandReg register resets the state machine.