MC68HC05P9ACDW FREESCALE [Freescale Semiconductor, Inc], MC68HC05P9ACDW Datasheet - Page 52

• Manufacturer Part Number: MC68HC05P9ACDW
• Description: HCMOS Microcontroller Unit
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Resets and Interrupts
COP Watchdog
Reset
Low-Voltage Protection
52
A timeout of the COP watchdog generates a COP reset. The COP
watchdog is part of a software error detection system and must be
cleared periodically to start a new timeout period. To clear the COP
watchdog and prevent a COP reset, write a logic 0 to bit 0 (COPC) of the
COP register at location $1FF0.
A drop in power supply voltage below the minimum operating V
voltage is called a brownout condition. A brownout while the MCU is in a
non-reset state can corrupt MCU operation and necessitate a power-on
reset to resume operation.
The best protection against brownout is an undervoltage sensing circuit
that pulls the RESET pin low when it detects a low-power supply voltage.
The undervoltage sensing circuit may be made of discrete components
or an integrated circuit can be used.
For information about brownout and the COP watchdog, see the
Computer Operating Properly Watchdog
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
Resets and Interrupts
section.
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