MFRC63002R datasheet(9/118 Pages) NXP

9 / 118 page

MFRC630

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Product data sheet

COMPANY PUBLIC

Rev. 3.1 — 6 September 2012

227531

9 of 118

NXP Semiconductors

MFRC630

Contactless reader IC

8.2 Timer module

Timer module overview

The MFRC630 implements five timers. Four timers -Timer0 to Timer3 - have an input

clock that can be configured by register T(x)Control to be 13.56 MHz, 212 kHz, (derived

from the 27.12 MHz quartz) or to be the underflow event of the fifth Timer (Timer4). Each

timer implements a counter register which is 16 bit wide. A reload value for the counter is

defined in a range of 0000h to FFFFh in the registers TxReloadHi and TxReloadLo. The

fifth timer Timer4 is intended to be used as a wakeup timer and is connected to the

internal LPO (Low-Power Oscillator) as input clock source.

The TControl register allows the global start and stop of each of the four timers Timer0 to

Timer3. Additionally, this register indicates if one of the timers is running or stopped. Each

of the five timers implements an individual configuration register set defining timer reload

value (e.g. T0ReloadHi,T0ReloadLo), the timer value (e.g. T0CounterValHi,

T0CounterValLo) and the conditions which define start, stop and clockfrequency (e.g.

T0Control).

The external host may use these timers to manage timing relevant tasks. The timer unit

may be used in one of the following configurations:

• Time-out counter

• Watch-dog counter

• Stop watch

• Programmable one-shot timer

• Periodical trigger

The timer unit can be used to measure the time interval between two events or to indicate

that a specific event has occurred after an elapsed time. The timer register content is

modified by the timer unit, which can be used to generate an interrupt to allow an host to

react on this event.

The counter value of the timer is available in the registers T(x)CounterValHi,

T(x)CounterValLo. The content of these registers is decremented at each timer clock.

If the counter value has reached a value of 0000h and the interrupts are enabled for this

specific timer, an interrupt will be generated as soon as the next clock is received.

If enabled, the timer event can be indicated on the pin IRQ (interrupt request). The bit

Timer(x)Irq can be set and reset by the host controller. Depending on the configuration,

the timer will stop counting at 0000h or restart with the value loaded from registers

T(x)ReloadHi, T(x)ReloadLo.

The counting of the timer is indicated by bit TControl.T(x)Running.

The timer can be started by setting bits TControl.T(x)Running and

TControl.T(x)StartStopNow or stopped by setting the bits TControl.T(x)StartStopNow and

clearing TControl.T(x)Running.

Another possibility to start the timer is to set the bit T(x)Mode.T(x)Start, this can be useful

if dedicated protocol requirements need to be fulfilled.

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