UPD17217GT datasheet(38/84 Pages) NEC

Part #	UPD17217GT

Description	4-BIT SINGLE-CHIP MICROCONTROLLER FOR SMALL GENERAL-PURPOSE INFRARED REMOTE CONTROL TRANSMITTER

PDF	84 Pages

Scroll/Zoom	100%

Manufacturer	NEC [NEC]

Direct Link	http://www.nec.com/

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38 / 84 page

µPD17215, 17216, 17217, 17218

6.3

Operation Timing for Watchdog Timer

The basic interval timer can be used as a watchdog timer.

Unless the watchdog timer is reset within a fixed time*, it judges that “the program has hung up”, and the

µPD17215 is

reset. It is therefore necessary to reset through programming the watchdog timer with in a fixed time.

The watchdog timer can be reset by setting WDTRES to 1.

*: Fixed time: approx. 340 ms (at 4 MHz)

Coutions 1:

The watchdog timer cannot be reset in the shaded range in Fig. 6-2. Therefore, set WDTRES

before both the fx/2

21 and fx/220 signals go high.

Refer to 9. RESET for the WDOUT pin function.

Fig. 6-2

Watchdog Timer Operation Timing

f /2

INTBTM (f /2 )

WDOUT

WDTRES

Watchdog timer

reset signal

WDOUT output goes low

if WDTRES is not set

Setting WDTRES at

this timing is invalid

f /2

UPD17217GT Datasheet(PDF) 38 Page - NEC