System Protection Modules

COP
The Computer Operating Properly (COP) watchdog timer is designed to detect software errors. When the COP is being used, the user's software is responsible for regularly resetting the COP timer; if this does not happen, the CPU assumes there is a problem and resets to a known condition. It's typically used to prevent CPU runaway.

LVR
The low voltage reset (LVR) circuit monitors the operating voltage of the MCU and forces a reset of the MCU if the voltage drops below a predefined minimum. MCUs can continue to operate below the specified minimum voltage rating but may experience unpredictable operation before they fail. The LVR circuit places the MCU in the reset state before any unpredictable behavior can occur.

LVI
The low voltage interrupt (LVI) circuit monitors the operating voltage of the MCU and generates an interrupt to the MCU if the voltage drops below a predefined minimum. MCUs can continue to operate below the specified minimum voltage rating but may experience unpredictable operation before they fail. The LVI circuit generates an interrupt where software can cause an orderly shutdown before unpredictable behavior can occur.

LVPI
The low voltage program inhibit (LVPI) circuit monitors the operating voltage of the MCU and inhibits programming of the MCU if the voltage drops below a predefined minimum. MCUs can continue to program below the specified minimum voltage rating but may experience unpredictable operation before programming fails. The LVPI circuit inhibits programming before any unpredictable behavior can occur.

last update: 10JUL1997