4282 datasheet(10/69 Pages) RENESAS

10 / 69 page

Rev.1.33

Mar 18, 2004

page 10 of 67

4282 Group

Fig. 12 Auto-reload function

TIMERS

The 4282 Group has the programmable timer.

• Programmable timer

The programmable timer has a reload register and enables

the frequency dividing ratio to be set. It is decremented from a

setting value n. When it underflows (count to n + 1), a timer 1

underflow flag is set to “1,” new data is loaded from the reload

FF16

0016

n: Counter initial value

Count starts

Reload

1st underflow

2nd underflow

n+1 count

Time

A skip instruction is executed

Timer 1 underflow flag “1”

“0”

The 4282 Group timer consists of the following circuit.

• Timer 1 : 8-bit programmable timer

• Timer 2 : 8-bit programmable timer

These timers can be controlled with the timer control registers

V1 and V2.

Each timer function is described below.

Table 3 Function related timer

Circuit

Timer 1

Timer 2

14-bit timer

Structure

8-bit programmable

binary down counter

8-bit programmable

binary down counter

14-bit fixed frequency

Count source

• Carrier wave output (CARRY)

• Bit 5 of watchdog timer

• f(XIN)

• f(XIN)/2

• Instruction clock

Frequency

dividing ratio

1 to 256

16384

Use of output signal

• Carrier wave output control

• Carrier wave output

• Watchdog timer

• Timer 1 count source

Control

4282 Datasheet(PDF) 10 Page - Renesas Technology Corp

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