68HC705BD7 datasheet(42/85 Pages) FREESCALE

Part #	68HC705BD7

Description	SPECIFICATION REV 2.0 (General Release)

PDF	85 Pages

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Manufacturer	FREESCALE [Freescale Semiconductor, Inc]

Direct Link	http://www.freescale.com

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SECTION 6: OPERATING MODES

Page 32

GENERAL RELEASE SPECIFICATION

MC68HC05BD7 Rev. 2.0

6.7

COP Watchdog Timer Considerations

The COP Watchdog Timer is always enable in MC68HC05BD7. It will reset the MCU when

it times out. For a system that must have intentional uses of the WAIT Mode, care must be

taken to prevent such situations from happening during normal operations by arranging

timely interrupts to reset the COP Watchdog timer.

Figure 6-2: WAIT Flowcharts

1.Fetch Reset Vector

2.Service Interrupt

a.Stack

b.Set I-Bit

c.Vector to Interrupt Routine

Internal

COP

RESET?

External Oscillator Active,

and Internal

Timer Clock Active

Restart

Internal Processor Clock

Stop Internal Processor Clock,

Clear I-Bit in CCR

External

H/W

Interrupt?

External

RESET?

WAIT

Internal

Interrupt?

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68HC705BD7 Datasheet(PDF) 42 Page - Freescale Semiconductor, Inc