Vehicle control device

• US 6,081,755 A
• Filed: 11/25/1997
• Issued: 06/27/2000
• Est. Priority Date: 07/24/1997
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Fujimoto, Takanori
• Primary Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US08/978,626
• Time in Patent Office: 945 Days
• Field of Search: 701/1, 701/29, 701/33, 701/35, 701/115, 340/825.31, 340/825.44, 340/825.69, 73/117.3, 123/396, 714/31, 714/46
• US Class Current: 701/1
• CPC Class Codes: B60R 16/0315 using multiplexing techniques multiplexing for transmission of signals G08C15/00; multiplexing for electrical communication in general H04J
• CPC Class Codes: F02D 41/2487 Methods for rewriting
• CPC Class Codes: F02D 41/249 Methods for preventing the loss of data
• CPC Class Codes: G05B 19/0426 Programming the control sequence
• CPC Class Codes: G05B 2219/23214 Checksum CRC
• CPC Class Codes: G05B 2219/23324 Separate update program onboard
• CPC Class Codes: G05B 2219/23333 Modify program and store it
• CPC Class Codes: G05B 2219/23337 Modify if history of program coincides with history of modifying data
• CPC Class Codes: G05B 2219/23338 Transfer modified program from ram to eprom, flash

Abstract

A vehicle control device has an PROM with a first and second memory area. The contents of the PROM are updated by erasing locations for a vehicle control program, writing part of the vehicle control program into the PROM, checking for abnormalities in the writing process, and then writing the remaining part of the vehicle control program into the PROM only when the result of writing the part first is determined not to have been abnormal. This determination may be based on a checksum, of the program codes that were expected to have been written into the first memory area as the first part of the vehicle control program, compared with the checksum of the program codes actually written. In the event of an abnormality, only the part of the vehicle control program first written is in the PROM, and the area in which the remaining part of the vehicle control program would have been written remains erased. The remaining part of the vehicle control program is a part of the program necessary for proper functioning, such as the reset vector. If the reset vector of the vehicle control program is used as the remaining part, and the remaining part is not written due to the detection of an abnormality, then any attempt to execute the abnormally updated control program will result in performance that is manifestly abnormal and easy to detect in subsequent production steps.

Claims

1. An apparatus for updating a memory with a vehicle control program, wherein said memory has memory locations for storing said vehicle control program, said apparatus comprising:

a vehicle control program adapted to perform an arithmetic process, on the basis of a vehicle drive state, to output a vehicle control amount;

said vehicle control program comprising a part of said vehicle control program to be written first, and a remaining part of said vehicle control program, wherein said part to be written first defines first write data, and said remaining part defines second write data;

means for erasing said memory locations;

first writing means for writing, after said means for erasing erases said memory locations, in one or more of said memory locations, said first write data, said one or more of said memory locations defining a first set of said memory locations;

collating means for making a determination whether said writing of said first write data was abnormally performed; and

second writing means for writing, only when said determination indicates said writing of said first write data was not abnormally performed, said second write data in a second set of said memory locations, one or more of said second memory locations being different from said first set of said memory locations;

wherein, when said determination indicates said writing of said first write data was abnormally performed, said second writing means does not write said second write data in said second set of said memory locations.

2. The apparatus for updating a vehicle control program in a memory, as a set forth in claim 1, wherein:

said first set of memory locations define a first contiguous memory area for storing said part of said vehicle control program to be written first;

said second set of memory locations define a second contiguous memory area for storing said remaining part of said vehicle control program;

said vehicle control program requires the presence of said remaining part of said vehicle control program in order to perform said arithmetic process in a manner that outputs said vehicle control amount with a normal value; and

said collation means makes said determination by comparing a value determined based on said writing of said first write data with an expected value.

3. The apparatus for updating a vehicle control program in a memory, as set forth in claim 2, wherein said value determined based on said writing of said first write data is a checksum of program codes written in said first set of memory locations, and wherein said expected value is a checksum of program codes of said first write data.

4. The apparatus for updating a vehicle control program in a memory, as set forth in claim 2, wherein said second contiguous memory area is a memory area in which execution of said vehicle control program is started first.

5. The apparatus for updating a vehicle control program in a memory, as set forth in claim 2, wherein said memory having said memory locations is an electrically programmable nonvolatile memory.

6. The apparatus for updating a vehicle control program in a memory, as set forth in claim 1, further comprising said memory being a component of a vehicle control device, and wherein said first write data and said second write data are written to said memory from a device external to said vehicle control device containing said memory, and wherein said writing of said first write data and said writing of said second write data are performed in response to a command received external to said vehicle control device.

7. The apparatus for updating a vehicle control program in a memory, as set forth in claim 1, wherein said memory having said memory locations is an electrically programmable nonvolatile memory.

8. A method of storing a vehicle control program in a memory, wherein said memory has memory locations for storing said vehicle control program, said method comprising:

providing a vehicle control program adapted to perform an arithmetic process, on the basis of a vehicle drive state, to output a vehicle control amount;

determining, for said vehicle control program, a part of said vehicle control program to be written first, and a remaining part of said vehicle control program, wherein said part to be written first defines first write data, and said remaining part defines second write data;

erasing said memory locations;

then

writing, in one or more of said memory locations, said first write data, said one or more of said memory locations defining a first set of said memory locations;

then

making a determination whether said writing of said first write data was abnormally performed; and

only when said determination indicates said writing of said first write data was not abnormally performed, writing said second write data in a second set of said memory locations, one or more of said second memory locations being different from said first set of said memory locations.

9. The method of storing a vehicle control program in a memory, as a set forth in claim 8, wherein:

said first set of memory locations define a first contiguous memory area for storing said part of said vehicle control program to be written first;

said second set of memory locations define a second contiguous memory area for storing said remaining part of said vehicle control program;

said remaining part of said vehicle control program is required by said vehicle control program to perform said arithmetic process to output said vehicle control amount with a normal value;

said vehicle control program requires the presence of said remaining part of said vehicle control program in order to perform said arithmetic process in a manner that outputs said vehicle control amount with a normal value; and

said determination is performed by comparing a value determined based on said writing of said first write data with an expected value.

10. The method of storing a vehicle control program in a memory, as set forth in claim 9, wherein said value determined based on said writing of said first write data is a checksum of program codes written in said first set of memory locations, and wherein said expected value is a checksum of program codes of said first write data.

11. The method of storing a vehicle control program in a memory, as set forth in claim 9, wherein said second contiguous memory area is a memory area in which execution of said vehicle control program is started first.

12. The method of storing a vehicle control program in a memory, as set forth in claim 9, wherein said memory having said memory locations is an electrically programmable nonvolatile memory.

13. The method of storing a vehicle control program in a memory, as set forth in claim 8, wherein said first write data and said second write data are written to said memory from a device external to a vehicle control device containing said memory, and wherein said writing of said first write data and said writing of said second write data are performed in response to a command received external to said vehicle control device.

14. The method of storing a vehicle control program in a memory, as set forth in claim 8, wherein said memory having said memory locations is an electrically programmable nonvolatile memory.