Error detection/correction and fault detection/recovery – Data processing system error or fault handling – Reliability and availability
Patent
1997-11-18
2000-03-07
Beausoliel, Jr., Robert W.
Error detection/correction and fault detection/recovery
Data processing system error or fault handling
Reliability and availability
714 24, 714 25, 714 32, 714 27, 714724, 714725, G06F 1124
Patent
active
060354216
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a system for testing a computer installed in a controller.
BACKGROUND OF THE INVENTION
Processor errors in controllers that control or regulate functions that are critical with regard to safety must be detected by monitoring. The controllers with safety functions are conventionally used for anti-lock control systems, traction control systems and/or driving dynamics control systems. Self-test, plausibility monitoring and watchdog methods are known for use in single-computer controllers.
Methods and measuring equipment for measuring the quiescent current (IDDQ) are used for manufacturer testing of CMOS components (integrated circuits, IC). The testing is described, for example, in the article "Parallel heiBt schnell", (Parallel means fast) Markt und Technik, Wochenzeitung fur Elektronik (Market and Technology, Weekly Journal of Electronics), no. 36 of Sep. 1, 1995, page 58. The background of the quiescent current test is that in a digital CMOS component in a purely static logic, almost the entire power loss occurs in its interior during switching operations. In an idle state, the current flow is limited to tiny leakage currents and currents due to pull-up or pull-down resistance at the inputs and external loads at the output drivers. Many manufacturing-related errors lead to increased conductivity between the positive and negative power supply voltage. If such defective regions (point errors) in a circuit are activated, it leads to a sudden increase in current consumption. Such errors can be detected by a highly precise measurement of current consumption during the test procedure and comparison with suitable setpoints. Such a quiescent current measurement is utilized in the production of CMOS components to sort out the defective components after the manufacturing process.
Utilizing the above described controllers with safety functions, it is customary to provide two computers that check on each other mutually by parallel computing and/or plausibility tests to increase reliability. Cost considerations suggest using only one computer in these controllers.
The object of the present invention is to increase the reliability in operation with a control unit having safety functions.
SUMMARY OF THE INVENTION
The present invention provides a system for testing a computer installed in a controller. A power supply unit is provides supply power to the control unit and to the computer. In addition, the test results may be displayed and/or means may be provided for shutting down the system controlled and/or regulated by the controller. The control unit contains means that can bring the computer into certain operating modes. In addition, sensing means are provided to detect the current or voltage in the computer's power supply circuit, whereupon the current or voltage detected is compared in comparing elements with at least one preset threshold value. To activate the display and/or the cut-off, there are actuators that cause an error to be displayed, if applicable, depending on the result of the comparison, or cause all or part of the system to be shut down in reaction to such an error.
The system according to the present invention has the advantage that a multitude of possible errors in a computer can be detected by a simple measurement of current or voltage. The quiescent current measurement known in the production of computer components is used during normal operation of a computer built into a controller. The system according to the present invention can detect the most common errors in the computer module with a few test steps. Such errors include lock-up errors (stuck at), bridge errors (bridging) and/or interrupt errors (stuck open).
In particular, the combination of the quiescent current measurement according to the present invention with an optimized self-test program yields an error coverage that is adequate for safety-critical applications with regard to the most important errors in computer modules, in particular CMOS processors. The advantage of th
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"Parallel means fast", Market and Technology, Weekly journal of Electronics, No. 36, Sep. 1, 1995, p. 58*.
Harter Werner
Henno Christiane
Beausoliel, Jr. Robert W.
Hamdan Wasseem H.
Robert & Bosch GmbH
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