UPD17708 datasheet(310/356 Pages) NEC

No. de pieza	UPD17708

Descripción Electrónicos	4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DEDICATED HARDWARE FOR DIGITAL TUNING SYSTEM

PDF	356 Pages

Scroll/Zoom	100%

Fabricante Electrónico	NEC [NEC]

Página de inicio	http://www.nec.com/

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310 / 356 page

310

µPD17704, 17705, 17707, 17708, 17709

Figure 21-4. CE Reset Operation with Clock Stop Instruction

21.2.3 Cautions on CE reset

Because CE reset is effected regardless of the instruction under execution, the following points (1) and (2) must

be noted.

(1) Time to execute timer processing such as watch

When creating a watch program by using the basic timer 0 carry, the processing time of the program must be

kept to within a specific time.

For details, refer to 13.2.6 Cautions on using basic timer 0.

(2) Processing of data and flags used in program

Exercise care in rewriting the data and flags whose contents must not be changed even when CE reset is

effected, such as security code.

An example is shown below.

VDD

XOUT

BTM0CY flag

setting pulse

CE reset timer

carry counter

Set value of CE reset

timer carry counter

Normal operation

5 V

0 V

tSET

Clock stop status

Halt

status

tSET/2

STOP s instruction

Clock stop

status

released.

Oscillation

starts

CE reset

Program execution starts from address 0

CE reset signal

UPD17708 Datasheet(PDF) 310 Page - NEC