mc68hc05l25 Freescale Semiconductor, Inc, mc68hc05l25 Datasheet - Page 33

• Manufacturer Part Number: mc68hc05l25
• Description: M68hc05 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

COP Watchdog Timer Considerations
If time base interrupts are enabled, a time base interrupt will cause the processor to exit the wait mode
and resume normal operation. The time base may be used to generate a periodic exit from the wait mode.
The wait mode also may be exited when an external interrupt (IRQ) or reset occurs.
3.4 COP Watchdog Timer Considerations
The COP watchdog timer is active in all modes of operation if enabled by a TBCR2 select bit. If the COP
watchdog timer is selected by the TBCR2 bit, any execution of the STOP instruction (either intentional or
inadvertent due to the CPU being disturbed) will cause the oscillator (OSC) to halt and thus the COP
watchdog timer will not time out if driven from OSC. Thus for applications that require use of COP
watchdog from OSC, STOP instruction must be disabled, or COP must be driven from XOSC.
If the COP watchdog timer is selected by the TBCR2 select bit, the COP will reset the MCU when it times
out. Therefore, it is recommended that the COP watchdog should be disabled for a system that must
have intentional uses of the wait or stop modes for periods longer than the COP timeout period.
MC68HC05L25 Data Sheet, Rev. 3.1
Freescale Semiconductor
33