MFRC522 datasheet(22/109 Pages) NXP

22 / 109 page

112132

Product data sheet

Rev. 3.2 — 22 May 2007

22 of 109

NXP Semiconductors

MFRC522

Contactless Reader IC

9.2.1.13

ControlReg

Miscellaneous control bits.

Table 30:

Description of WaterLevelReg bits

Bit

Symbol

Description

7 to 6

Reserved for future use.

5 to 0

WaterLevel

This register defines a warning level to indicate a FIFO-buffer over- or

underflow:

The bit HiAlert in Status1Reg is set to logic 1, if the remaining

number of bytes in the FIFO-buffer space is equal or less than the

defined number of WaterLevel bytes.

The bit LoAlert in Status1Reg is set to logic 1, if equal or less than

WaterLevel bytes are in the FIFO.

Remark: For the calculation of HiAlert and LoAlert see Section 9.2.1.8

“Status1Reg”.

Table 31:

ControlReg register (address 0Ch); reset value: 10h

Bit

Symbol

TStopNow

TStartNow

RxLastBits

Access

Rights

RFU

Table 32:

Description of ControlReg bits

Bit

Symbol

Description

TStopNow

Set to logic 1, the timer stops immediately.

Reading this bit will always return 0.

TStartNow

Set to logic 1 starts the timer immediately.

Reading this bit will always return 0.

5 to 3

Reserved for future use.

2 to 0

RxLastBits

Shows the number of valid bits in the last received byte. If 0, the

whole byte is valid.

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