Electronic control unit for a vehicle
First Claim
1. An electronic control unit for a vehicle having equipment, the control unit comprising:
- a microcomputer for controlling the equipment;
a first power supply circuit that starts supplying the microcomputer with operating power when a predetermined switch signal is applied from an outside, and stops supply of the operating power when the predetermined switch signal disappears;
a timer for counting time after the switch signal disappears, and for starting up the first power supply circuit when the counted time reaches a predetermined time;
a volatile memory for storing control data to be used for controlling the equipment;
a second power supply circuit for supplying the timer and the volatile memory with operating power even after the switch signal disappears; and
a nonvolatile memory for storing the control data stored in the volatile memory,wherein, when the counted time reaches the predetermined time, the microcomputer starts operating with the operating power supplied from the first power supply circuit, writes the control data stored in the volatile memory into the nonvolatile memory, stores the written data in the nonvolatile memory, and thereafter stops the power supply from the second power supply circuit to the volatile memory.
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Accused Products
Abstract
In an electronic control unit for a vehicle, control data is stored in a volatile memory until a predetermined time passes after an ignition switch is turned off. This makes it possible to greatly reduce the frequency at which data is written into a nonvolatile memory. When the predetermined time has passed after the ignition switch is turned off, the control data stored in the volatile memory is written into the nonvolatile memory. Thereafter, the power supply from a power supply circuit to the volatile memory is stopped. Consequently, it is possible to store the control data reliably in either the volatile memory or the nonvolatile memory. It is also possible to reduce the dark current in the volatile memory.
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Citations
11 Claims
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1. An electronic control unit for a vehicle having equipment, the control unit comprising:
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a microcomputer for controlling the equipment; a first power supply circuit that starts supplying the microcomputer with operating power when a predetermined switch signal is applied from an outside, and stops supply of the operating power when the predetermined switch signal disappears; a timer for counting time after the switch signal disappears, and for starting up the first power supply circuit when the counted time reaches a predetermined time; a volatile memory for storing control data to be used for controlling the equipment; a second power supply circuit for supplying the timer and the volatile memory with operating power even after the switch signal disappears; and a nonvolatile memory for storing the control data stored in the volatile memory, wherein, when the counted time reaches the predetermined time, the microcomputer starts operating with the operating power supplied from the first power supply circuit, writes the control data stored in the volatile memory into the nonvolatile memory, stores the written data in the nonvolatile memory, and thereafter stops the power supply from the second power supply circuit to the volatile memory. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification