CLRC663 datasheet(14/177 Pages) NXP

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NXP Semiconductors

CLRC663

High performance multi-protocol NFC frontend CLRC663 and CLRC663 plus

8.2.1 Timer modes

8.2.1.1 Time-Out- and Watch-Dog-Counter

Having configured the timer by setting register T(x)ReloadValue and starting the counting of Timer(x) by setting

bit TControl.T(x)StartStop and TControl.T(x)Running, the timer unit decrements the T(x)CounterValue Register

beginning with the configured start event. If the configured stop event occurs before the Timer(x) underflows

(e.g. a bit is received from the card), the timer unit stops (no interrupt is generated).

If no stop event occurs, the timer unit continues to decrement the counter registers until the content is zero and

generates a timer interrupt request at the next clock cycle. This allows indicating to a host that the event did not

occur during the configured time interval.

8.2.1.2 Wake-up timer

The wake-up Timer4 allows to wake-up the system from standby after a predefined time. The system can be

configured in such a way that it is entering the standby mode again in case no card had been detected.

This functionality can be used to implement a low-power card detection (LPCD). For the low-power card

detection, it is recommended to set T4Control.T4AutoWakeUp and T4Control.T4AutoRestart, to activate

the Timer4 and automatically set the system in standby. The internal low frequency oscillator (LFO) is

then used as input clock for this Timer4. If a card is detected, the host-communication can be started. If bit

T4Control.T4AutoWakeUp is not set, the CLRC663 will not enter the standby mode again in case no card is

detected but stays fully powered.

8.2.1.3 Stop watch

The elapsed time between a configured start- and stop event may be measured by the CLRC663 timer unit. By

setting the registers T(x)ReloadValueHi, T(x)ReloadValueLo the timer starts to decrement as soon as activated.

If the configured stop event occurs, the timer stops decrementing. The elapsed time between start and stop

event can then be calculated by the host dependent on the timer interval TTimer:

(1)

If an underflow occurred which can be identified by evaluating the corresponding IRQ bit, the performed time

measurement according to the formula above is not correct.

8.2.1.4 Programmable one-shot timer

The host configures the interrupt and the timer, starts the timer and waits for the interrupt event on pin IRQ.

After the configured time, the interrupt request will be raised.

8.2.1.5 Periodical trigger

If the bit T(x)Control.T(x)AutoRestart is set and the interrupt is activated, an interrupt request will be indicated

periodically after every elapsed timer period.

8.3 Contactless interface unit

The contactless interface unit of the CLRC663 supports the following read/write operating modes:

• ISO/IEC14443 type A and MIFARE Classic

• ISO/IEC14443B

CLRC663

All information provided in this document is subject to legal disclaimers.

Product data sheet

Rev. 5.3 — 3 January 2024

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