CLRC632 Datasheet, PDF (87/163 Pages) NXP Semiconductors – Multiple Protocol Contactless Reader IC

Philips Semiconductors
Multiple Protocol Contactless Reader IC
9.2 Implementation of the Timer Unit
9.2.1 BLOCK DIAGRAM
The following block diagram shows the timer module.
Product Specification Rev. 3.0; May 2003
CL RC632
TStartTxBegin
TxBegin Event
TStartTxEnd
TxEnd Event
TAutoRestart
TRunning
RxEnd Event
TStopRxEnd
RxBegin Event
TStopRxBegin
13.56 MHz
TReloadValue [7:0]
TStartNow
TStopNow
QS
QR
parallel in
start counter /
parallel load
stop counter
Counter Module
(x <= x-1)
TPreScaler [4:0]
Clock
Divider
>clock
parallel out
to Parallel Interface
TimerValue [7:0]
Counter = 0 ?
to Interrupt Logic: TimerIRq
Figure 9-1: Timer Module Block Diagram
The timer unit is designed in a way, that several events in combination with enabling flags start or stop the
counter. For example, setting the bit TStartTxBegin to 1 enables to control the receiving of data using the
timer unit. In addition, the first received bit is indicated by TxBeginEvent. This combination starts the counter
at the defined TReloadValue.
The timer stops either automatically if the counter value is equal to zero, or if a defined stop event happens.
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