MFRC522 datasheet(23/109 Pages) NXP

23 / 109 page

112132

Product data sheet

Rev. 3.2 — 22 May 2007

23 of 109

NXP Semiconductors

MFRC522

Contactless Reader IC

9.2.1.14

BitFramingReg

Adjustments for bit oriented frames.

9.2.1.15

CollReg

Defines the first bit collision detected on the RF interface.

Table 33:

BitFramingReg register (address 0Dh); reset value: 00h

Bit

Symbol

StartSend

RxAlign

TxLastBits

Access

Rights

wr/w

RFU

r/w

Table 34:

Description of BitFramingReg bits

Bit

Symbol

Description

StartSend

Set to logic 1, the transmission of data starts.

This bit is only valid in combination with the Transceive command.

6 to 4

RxAlign

Used for reception of bit oriented frames: RxAlign defines the bit position

for the first bit received to be stored in the FIFO. Further received bits are

stored at the following bit positions.

Example:

RxAlign = 0:

the LSB of the received bit is stored at bit 0, the second

received bit is stored at bit position 1.

RxAlign = 1:

the LSB of the received bit is stored at bit 1, the second

received bit is stored at bit position 2.

RxAlign = 7:

the LSB of the received bit is stored at bit 7, the second

received bit is stored in the following byte at bit position 0.

This bits shall only be used for bitwise anticollision at 106 kbit/s. In all

other modes it shall be set to 0.

Reserved for future use.

2 to 0

TxLastBits

Used for transmission of bit oriented frames: TxLastBits defines the

number of bits of the last byte that shall be transmitted. A 000b indicates

that all bits of the last byte shall be transmitted.

Table 35:

CollReg register (address 0Eh); reset value: XXh

Bit

Symbol

Values

AfterColl

-CollPos

NotValid

CollPos

Access

Rights

r/w

RFU

Table 36:

Description of CollReg bits

Bit

Symbol

Description

ValuesAfterColl

If this bit is set to logic 0, all receiving bits will be cleared after a

collision. This bit shall only be used during bitwise anticollision at

106 kbit/s, otherwise it shall be set to logic 1.

Reserved for future use.

CollPosNotValid

Set to logic 1, if no collision is detected or the position of the collision

is out of the range of bits CollPos.

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