Electronic control unit and method measuring and using electric power-off period
First Claim
1. An electronic control unit comprising:
- a control part which operates or stops in accordance with state of a first power voltage switched by a power supply switch; and
a timing part which operates with a second power voltage different from the first power voltage of the control part and measures time continuously irrespective of whether the control part is operating or stopped, wherein the control part determines whether the timing part has been reset by monitoring supply of the second power voltage to the timing part.
1 Assignment
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Accused Products
Abstract
In an ECU for vehicles, a clock IC operates with sub power and measures time continuously irrespective of whether a microcomputer is operating. The microcomputer determines whether the clock IC has been reset on the basis of a history indicating that the sub power has fallen below a data holding voltage of an SRAM which also operates on the sub power. Alternatively, the microcomputer determines whether the clock IC has been reset by checking data held in the SRAM. The microcomputer determines failure of a water temperature sensor from a soak time calculated from time data from the clock IC and a detection value of the water temperature sensor on restarting of the engine. When the clock IC has been reset, the microcomputer prohibits this failure determination of the water temperature sensor.
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Citations
20 Claims
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1. An electronic control unit comprising:
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a control part which operates or stops in accordance with state of a first power voltage switched by a power supply switch; and
a timing part which operates with a second power voltage different from the first power voltage of the control part and measures time continuously irrespective of whether the control part is operating or stopped, wherein the control part determines whether the timing part has been reset by monitoring supply of the second power voltage to the timing part. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An electronic control unit comprising:
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a control part which operates or stops in accordance with state of a first power voltage switched by a power supply switch; and
a timing part which measures time continuously with a second power voltage irrespective of whether the control part is operating or stopped and is initialized to a predetermined value when reset, wherein a range of time to be measured by the timing part which excludes the predetermined value is prescribed in advance, and wherein the control part determines that an abnormality has arisen in the timing part when the time of the timing part is outside the prescribed range. - View Dependent Claims (8, 9, 10, 11, 12, 14)
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13. An electronic control unit comprising:
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a control part which operates or stops in accordance with state of a first power voltage switched by a power supply switch; and
a timing part which operates with a second power voltage different from the first power voltage of the control part and measures time continuously irrespective of whether the control part is operating or stopped, wherein the control part determines whether the timing part has been reset by monitoring supply of the second power voltage to the timing part, wherein a range of time to be measured by the timing part which excludes the predetermined value is prescribed in advance, and wherein the control part determines that an abnormality has arisen in the timing part when the time of the timing part is outside the prescribed range.
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15. A method of operating an electronic control unit having a timing part continuously supplied with an electric power to measure time and a control part operable to carry out a predetermined operation when the electric power is supplied:
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storing a first time measured by the timing part when the electric power to the control part is shut off;
reading a second time measured by the timing part when the electric power to the control part is re-started;
calculating a time period from the first time to the second time to use the time period in the predetermined operation by the control part, wherein the timing part is checked by the control part with respect to operation of the timing part upon reading of the second time, and wherein the predetermined operation of the control part is prohibited when a check result indicates an abnormality of the timing part. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification