MC68HC05RC17 Datasheet, PDF (52/128 Pages) Freescale Semiconductor, Inc – General Release Specification

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Freescale Semiconductor, Inc.
5.5.2.4 COP Watchdog Timer Considerations
The COP watchdog timer is active in all modes of operation if enabled
by a mask option. If the COP watchdog timer is selected by a mask
option, any execution of the STOP instruction (either intentionally or
inadvertently due to the CPU being disturbed) causes the oscillator to
halt and prevents the COP watchdog timer from timing out. If the COP
watchdog timer is selected by a mask option, the COP resets the MCU
when it times out. Therefore, it is recommended that the COP watchdog
be disabled for a system that must have intentional uses of the wait
mode for periods longer than the COP time out period.
The recommended interactions and considerations for the COP
watchdog timer, STOP instruction, and WAIT instruction are
summarized in Table 5-1.
Table 5-1. COP Watchdog Timer Recommendations
IF the Following Conditions Exist:
Wait Time
Wait Time Less than COP Time Out
Wait Time More than COP Time Out
Any Length Wait Time
THEN the COP Watchdog Timer
Should Be:
Enable or Disable COP by Mask Option
Disable COP by Mask Option
Disable COP by Mask Option
General Release Specification
MC68HC05RC17 — Rev. 2.0
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