mc68hc05p18a Freescale Semiconductor, Inc, mc68hc05p18a Datasheet - Page 54

• Manufacturer Part Number: mc68hc05p18a
• Description: Mc68hc05p18a Hcmos Microcontroller Unit
• Manufacturer: Freescale Semiconductor, Inc

Operating Modes
6.5 COP Watchdog Timer Considerations
Technical Data
NOTE:
If the 16-bit timer interrupt is enabled, it causes the processor to exit wait
mode and resume normal operation. The 16-bit timer may be used to
generate a periodic exit from wait mode. Wait mode may also be exited
when an IRQ or RESET occurs.
If port A interrupts are selected as a mask option, the processor also will
exit wait mode.
The COP watchdog timer is active in the user mode of operation when
selected by mask option. Executing the STOP instruction without
conversion to halt via mask option causes the COP to be disabled.
Therefore, it is recommended that the STOP instruction be modified to
produce halt mode via mask option if the COP watchdog timer is
enabled.
Furthermore, it is recommended that the COP watchdog timer be
disabled for applications that use the halt or wait mode for time periods
that exceed the COP timeout period.
COP watchdog timer interactions are summarized in
Stop mode selected
Halt mode selected
Halt mode selected
STOP Instruction
Freescale Semiconductor, Inc.
via mask option
via mask option
via mask option
For More Information On This Product,
Table 6-1. COP Watchdog Timer Recommendations
IF These Conditions Exist:
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Operating Modes
WAIT time MORE than
Any length WAIT time
WAIT time less than
COP timeout
COP timeout
WAIT Time
THEN the COP Watchdog
Enable or disable COP
via mask option
via mask option
via mask option
Timer Should:
Disable COP
Disable COP
Table
MC68HC05P18A
6-1.