ST6255B View Datasheet(PDF) - STMicroelectronics

Part Name

Description

MFG CO.

ST6255B

8-BIT OTP/EPROM MCUs WITH A/D CONVERTER, AUTO-RELOAD TIMER, EEPROM AND SPI

STMicroelectronics 

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ST62T55B ST62T65B/E65B

DIGITAL WATCHDOG (Cont’d)

These instructions test the C bit and Reset the

MCU (i.e. disable the Watchdog) if the bit is set

(i.e. if the Watchdog is active), thus disabling the

Watchdog.

In all modes, a minimum of 28 instructions are ex-

ecuted after activation, before the Watchdog can

generate a Reset. Consequently, user software

should load the watchdog counter within the first

27 instructions following Watchdog activation

(software mode), or within the first 27 instructions

executed following a Reset (hardware activation).

It should be noted that when the GEN bit is low (in-

terrupts disabled), the NMI interrupt is active but

cannot cause a wake up from STOP/WAIT modes.

Figure 14. A typical circuit making use of the

EXERNAL STOP MODE CONTROL feature

SWI TCH

NMI

I/O

Figure 15. Digital Watchdog Block Diagram

RESET

VR02002

Q

RSFF

S

R

-27

DB1.7 LOAD SET

DB0

8

WRITE

RESET

DATA BUS

-28

SET

-12

OSCILLATOR

CLOCK

V A00 010

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