Computer monitoring system for indicating abnormalities in execution of main or interrupt program segments
First Claim
1. A system for monitoring program execution in a digital computer adapted to perform a main routine and at least one interrupt routine in response to an interrupt command signal generated during execution of the main routine in response to the occurrence of a particular event, said system comprising:
- (a) first means including said digital computer for providing a decision signal with first and second levels, said digital computer being adapted to provide a transition of the signal to the first level upon termination of the main routine and to provide a transition of the signal to the second level upon beginning of the interrupt routine;
(b) means for developing a predetermined reference time period;
(c) means for measuring a period of time during which said decision signal is held without transition at either the first or second levels; and
(d) second means for generating a signal indicative of a fault condition in said digital computer in response to the decision signal being held without transitions at either the first level or the second level for a time greater than the reference time period.
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Abstract
A watchdog-type fail-safe system monitors program execution by a computer used, e.g., in controlling operation of an automative vehicle engine. The system includes a control unit, with a microprocessor; and a memory, which stores program segments. These segments include a main routine for performing a background job (BGJ), and a plurality of interrupt routines for handling event generated interrupts. Completion of the BGJ causes transition of an emergency decision signal, provided by the control unit, to a first level. Initiation of a particular first interrupt routine causes transition of the decision signal to a second level. Abnormalities in program execution may result in non-transition of the decision signal. If there is non-transition of the decision signal for greater than a predetermined reference time period, a fault condition signal is generated. This may initiate various emergency procedures, e.g., stopping or resetting the computer, and visual or audio alarms. Detectable abnormalities include; non-return to the BGJ from any one of the interrupt routines; non-completion of the BGJ due to an excessive number of interrupts, as might occur due to unusally high engine speed; or non-advancement to processing of an interrupt, even though the control unit accepted a valid interrupt demand, as might occur due to temporary troubles in vibration susceptible signal lines between the computer and engine.
80 Citations
8 Claims
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1. A system for monitoring program execution in a digital computer adapted to perform a main routine and at least one interrupt routine in response to an interrupt command signal generated during execution of the main routine in response to the occurrence of a particular event, said system comprising:
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(a) first means including said digital computer for providing a decision signal with first and second levels, said digital computer being adapted to provide a transition of the signal to the first level upon termination of the main routine and to provide a transition of the signal to the second level upon beginning of the interrupt routine; (b) means for developing a predetermined reference time period; (c) means for measuring a period of time during which said decision signal is held without transition at either the first or second levels; and (d) second means for generating a signal indicative of a fault condition in said digital computer in response to the decision signal being held without transitions at either the first level or the second level for a time greater than the reference time period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification