MFRC63002R datasheet(77/118 Pages) NXP

77 / 118 page

MFRC630

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Product data sheet

COMPANY PUBLIC

Rev. 3.1 — 6 September 2012

227531

77 of 118

NXP Semiconductors

MFRC630

Contactless reader IC

9.7.2.21

T4ReloadHi

High byte of the reload value of the 16-bit timer 4.

9.7.2.22

T4ReloadLo

Low byte of the reload value of the 16-bit timer 4.

Table 110. T4Control bits

Bit

Symbol

Description

T4Running

Shows if the timer T4 is running. If the bit T4StartStopNow is set, this

bit and the timer T4 can be started/stopped.

6T4Start

StopNow

if set, the bit T4Running can be changed.

T4AutoTrimm

If set to one, the timer activates an LPO trimming procedure when it

underflows. For the T4AutoTrimm function, at least one timer (T0 to

T3) has to be configured properly for trimming (T3 is not allowed if

T4AutoLPCD is set in parallel).

T4AutoLPCD

If set to one, the timer activates a low-power card detection

sequence. If a card is detected an interrupt request is raised and the

system remains active if enabled. If no card is detected the

MFRC630 enters the Power down mode if enabled. The timer is

automatically restarted (no gap). Timer 3 is used to specify the time

where the RF field is enabled to check if a card is present. Therefor

you may not use Timer 3 for T4AutoTrimm in parallel.

T4AutoRestart

Set to logic 1, the timer automatically restarts its countdown from

T4ReloadValue, after the counter value has reached the value zero.

Set to logic 0 the timer decrements to zero and stops. The bit

Timer4Irq is set to logic 1 at timer underflow.

T4AutoWakeUp

If set, the MFRC630 wakes up automatically, when the timer T4 has

an underflow. This bit has to be set if the IC should enter the Power

down mode after T4AutoTrimm and/or T4AutoLPCD is finished and

no card has been detected. If the IC should stay active after one of

these procedures this bit has to be set to 0.

1 to 0

T4Clk

00b - the timer input clock is the LFO clock

01b - the timer input clock is the LFO clock/8

10b - the timer input clock is the LFO clock/16

11b - the timer input clock is the LFO clock/32

Table 111. T4ReloadHi register (address 24h)

Bit

Symbol

T4ReloadHi

Access

rights

r/w

Table 112. T4ReloadHi bits

Bit

Symbol

Description

7 to 0

T4ReloadHi

Defines high byte of the for the reload value of timer 4. With the start

event the timer 4 loads the T4ReloadVal. Changing this register affects

the timer only at the next start event.

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