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| Remote control device for vehicles |
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| Home cleaning robot |
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Electronic control unit and method having program rewriting function
| Details |
Inventors: Hayashi, Shinnosuke; Sugai, Keiji;
Assignee: Denso Corporation (Kariya, JP)
Primary Examiner: Grant; Willaim
Assistant Examiner: Garland; Steven R.
Attorney, Agent or Firm: Nixon & Vanderhye P.C.
In an ECU for controlling an engine, a microcomputer executes a program in a mask ROM after releasing the reset, determines a signal of a specific input terminal, and switches in accordance with the foregoing determination result the self operation mode into either one of the normal mode to execute a control program in a flash ROM and the rewrite mode to update and write a data from an external unit into the ROM. A monitor circuit monitors a watchdog pulse from the microcomputer, outputs a reset pulse to the microcomputer when determining an abnormality, and alters the level of the foregoing signal to the microcomputer into the level of the normal mode into the level of the rewrite mode. |
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DETAILED DESCRIPTION The present invention has an object to provide an electronic control unit and method that can execute a data write into a rewritable nonvolatile memory without a signal line for determining the mode furnished between an external unit and the electronic control unit, even when a control program is not written into the rewritable nonvolatile memory, or when the control program stored in the rewritable nonvolatile memory becomes abnormal.
According to the present invention, a microcomputer is programmed to execute a control program composed of data stored in a rewritable nonvolatile memory, and executes a control process for controlling a control object.
A monitor circuit monitors whether an execution state of the control program by the microcomputer is normal or not.
In this electronic control unit, specially, when the monitor circuit determines that the execution state of the control program is abnormal, the microcomputer executes a rewrite process for updating to write a rewrite data transmitted from an external unit into the rewritable nonvolatile memory.
Thus, in case the control program is not yet written into the rewritable nonvolatile memory, or in case the control program stored in the rewritable nonvolatile memory becomes abnormal by any cause, the microcomputer is not able to execute the control program normally.
Therefore, in both of the foregoing cases, the monitor circuit determines the execution state by the microcomputer to be abnormal, and the microcomputer shifts the mode to the rewrite mode to execute the rewrite process.
Accordingly, although a signal line for determining the mode is not furnished between the external unit and the electronic control unit, it is possible to write a new control program and new control data into the rewritable nonvolatile memory from a state that the control program is not written into the rewritable nonvolatile memory.
When the control program stored in the rewritable nonvolatile memory is brought into an abnormal state, it is possible to rewrite the concerned control program into a program of normal contents
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Navigation and GPS 
