MC68HC705BD3 FREESCALE [Freescale Semiconductor, Inc], MC68HC705BD3 Datasheet - Page 88

• Manufacturer Part Number: MC68HC705BD3
• Description: High-density complementary metal oxide semiconductor (HCMOS) microcontroller unit
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

10
10.3
The COP watchdog timer is always enabled in MC68HC05BD3. 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.
10-2
COP Watchdog Timer Considerations
Stop internal processor clock,
Internal Timer Clock Active
External oscillator active
Clear I bit in CCR
Internal COP
External H/W
interrupt?
External
Internal
reset?
reset?
reset?
Figure 10-1 WAIT Flowchart
WAIT
and
N
N
N
N
LOW POWER MODES
Y
Y
Y
Y
1. Fetch reset vector
2. Service interrupt
a. Stack
b. Set I bit
c. Vector to interrupt routine
Restart internal
processor clock
or
MC68HC05BD3
TPG