Safety system challenge-and-response using modified watchdog timer

Some embodiments of the present disclosure relate to a watchdog timer having an enhanced functionality that enables the watchdog timer to monitor a process flow of the microprocessor on a task-by-task basis that enables a simple output signal to be used to determine if the watchdog timer is malfunct...

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Bibliographic Details
Main Authors BREWERTON SIMON, KNIGHT RICHARD
Format Patent
LanguageChinese
English
Published 26.03.2014
Subjects
CALCULATING
COMPUTING
CONTROL OR REGULATING SYSTEMS IN GENERAL
CONTROLLING
COUNTING
ELECTRIC DIGITAL DATA PROCESSING
FUNCTIONAL ELEMENTS OF SUCH SYSTEMS
MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS ORELEMENTS
PHYSICS
REGULATING
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Summary:Some embodiments of the present disclosure relate to a watchdog timer having an enhanced functionality that enables the watchdog timer to monitor a process flow of the microprocessor on a task-by-task basis that enables a simple output signal to be used to determine if the watchdog timer is malfunctioning. The watchdog timer has a state machine that increments a state variable from an initial value over a watchdog period. A deterministic service request, received from a microprocessor, controls operation of the watchdog timer. The deterministic service request has an indicator of a monitoring operation to be performed, a password, and an estimated state variable. A comparison element determines if the microprocessor is operating properly based upon a comparison of the received password to an expected password and the received estimated state variable to an actual state variable.
Bibliography:Application Number: CN20131417071