JPH11141393A - Memory rewriting device for controlling vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate diagnosis results having abnormality from being deleted and prevent a state not diagnosing a diagnostic system rightly by prohibiting the data rewrite for a control memory, when a diagnostic result having abnormality is stored in a memory target to be rewritten. SOLUTION: In a step 1, whether a rewrite demand signal of a control memory is received or not is judged. In forward to a step 2, a diagnostic result stored in the memory or a target to be rewritten is observed. If just one abnormality is found in the diagnostic results, it is forwarded to steps 4, 5, and after an output signal saying that there is abnormality in the diagnosis result is transmitted to an external tool, it is checked whether an output demand of the diagnosis result having abnormality is received or not. Then, it is forwarded to a step 6 and a rewrite prohibition signal is sent to the external tool. When the output demand of the diagnosis result having the abnormality is received from the external tool, it is forwarded to a step 7 and the diagnosis result having the abnormality is sent without any omission.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a memory rewriting device for a control unit mounted on a vehicle.

[0002]

2. Description of the Related Art In a control unit composed of a CPU, a memory, and an input / output device, it has conventionally been necessary to replace the memory itself in order to change the contents of the control memory. By using a erasable and writable memory, it is not necessary to replace the control memory, and the cost can be reduced (see Japanese Patent Application Laid-Open No. 7-287605).

[0003]

By the way, in a vehicle equipped with a diagnostic system, if an abnormality occurs in a sensor, an actuator, or a wire harness of the engine control system during traveling, the control unit diagnoses the abnormality and stores it in a memory (RAM). ), The abnormality warning lamp is turned on to notify the driver, and the contents of the failure diagnosis are recorded in the backup memory as necessary so that they are not erased even if the ignition key switch is turned off.

An OBDI (On Board Diameter) submitted by the California Bureau of Atmospheric Resources (CARB) in North America
In gnostics version I), a device for purifying exhaust gas (O2
Obligation for failure diagnosis of sensors, EGR valves, etc.) and warning display to the driver from 1988 model cars, OB
DII will further expand the content of failure diagnosis such as monitoring of the three-way catalyst's purification rate and misfire,
ty of Automotive Enginieers), a 1994 model car has specified that the contents of diagnosis can be monitored using a data communication method standardized by the Automobile Enginieers. And stored in a memory (RAM).

However, when rewriting the control memory, the entire memory is often erased. Therefore, when the diagnostic result when there is an abnormality is stored in the memory to be rewritten, the diagnostic result when there is an abnormality is stored. However, if new information (a diagnostic result is obtained even when there is an abnormality) is written after the erase, it means that the diagnostic system has not correctly diagnosed.

Accordingly, the present invention is to prevent a diagnosis system from being diagnosed incorrectly by confirming a diagnosis result when rewriting a control memory and prohibiting rewriting when there is an abnormality in the diagnosis result. With the goal.

[0007]

According to a first aspect of the present invention, there is provided a control unit having a control memory including a memory electrically erasable and writable by an external tool, and permission of data rewriting to the control memory from the external tool. Means for performing a determination, in a vehicle control memory rewriting device in which data rewriting to the control memory is executed only when rewriting is permitted, a diagnosis result when there is an abnormality is stored in a memory to be rewritten. Means for judging whether there is an error or not, and means for prohibiting data rewriting to the control memory when a diagnosis result when there is an abnormality is stored in the memory to be rewritten.

According to a second aspect of the present invention, when a diagnostic result in the case where there is an abnormality based on the determination result in the first aspect is stored in a memory to be rewritten, the diagnostic result is displayed on an external tool.

In the third invention, when there is an instruction to erase the diagnosis result when there is an abnormality in the first invention, the prohibition of data rewriting for the control memory is released, and the data rewriting for the control memory is performed.

In the fourth invention, when there is an instruction to erase the diagnosis result when there is an abnormality in the second invention, the prohibition of data rewriting on the control memory is released and the data rewriting on the control memory is performed.

[0011]

According to the first aspect of the present invention, the rewriting of data in the control memory is prohibited when the diagnosis result in the case of an abnormality is stored in the memory to be rewritten. The result is not erased, thereby preventing a situation in which the diagnostic system does not correctly diagnose.

In the second invention, the reason why the data rewriting to the control memory is prohibited is clarified by looking at the diagnosis result when there is an abnormality represented by the external tool.

According to the third aspect, it is possible to rewrite data in the control memory after understanding that there is an abnormality in the diagnosis result.

According to the fourth aspect, it is possible to rewrite the data in the control memory after understanding the contents of the diagnosis result when there is an abnormality.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a system configuration, and 1 is an engine control unit (hereinafter referred to as ECM).

In the ECM 1 including a CPU, a memory, and an input / output device, the CPU performs various controls according to a control program. For example, as a mechanism for automatically controlling the idle speed to a target value according to the operating conditions, an auxiliary air passage bypassing the throttle valve is provided.
An auxiliary air valve driven by a signal from ECM1 is interposed, and the opening of the auxiliary air valve is controlled by a step motor.
The idle speed is controlled so as to match the target value.

In the ECM 1, when an abnormality occurs in a sensor, an actuator, or a wire harness of the engine control system during traveling, the abnormality is self-diagnosed, the result is stored in a memory, and an abnormality warning lamp is turned on. The information is stored in the backup memory as needed so that the driver is notified or the contents of the fault diagnosis are not erased even if the ignition key switch is turned off.
In a vehicle compatible with OBDII, the ECM1 performs a failure diagnosis conforming to OBDII, and stores the diagnosis result in a memory (RAM) as a diagnosis code.

By constructing the control memory with a flash memory (an electrically erasable and writable memory), a bug (error) is found in the idle speed control program after writing the control program in the flash memory. In this case, as shown in FIG.
An external tool 2 is connected to the ECM 1 and rewrite data of the control memory is sent from the external tool 2 to enable rewriting of the control memory inside the ECM 1.

Similarly to the ECM 1, the external tool 2 for rewriting the control memory is also composed of a CPU, a memory, and an input / output device, and is loaded with control memory rewrite data (a control program after removing bugs). External tool 2
Is connected to the ECM1 via the communication line when the control memory is rewritten, and the control memory is rewritten as shown in FIG. Both the ECM 1 and the external tool 2 have communication devices, and both exchange data by serial communication.

This rewriting of the control memory can be performed without removing the ECM 1 from the vehicle while keeping the engine stopped.
This is performed with the engine key switch turned on.

In this case, when the diagnosis result in the case where there is an abnormality is stored in the memory to be rewritten, the diagnosis result up to the case where there is an abnormality is erased.
If new information (a diagnostic result becomes normal by initialization) is written, the diagnostic system is not correctly diagnosed.

In order to cope with this, in the first embodiment of the present invention, when a diagnosis result when there is an abnormality is stored in a memory to be rewritten, a rewrite inhibition signal is transmitted to the external tool 2 and The diagnosis result having the abnormality is displayed on the external tool 2.

This control will be described in more detail.

FIG. 2 is a communication sequence showing the exchange of signals between the external tool 2 and the ECM 1.

When rewriting the control memory, first,
Security communication is performed with M1. Security communication is the exchange of cryptography before rewriting memory so that it is not easy for anyone other than manufacturers and dealers in the market to rewrite various types of memory, including control memory. . Specifically, the external tool 2 sends a rewrite prevention release request to the ECM 1, and if this is a legitimate request, the ECM 1
The security communication is terminated by sending back the rewrite prevention release, and the ECM 1 is unlocked (that is, the rewrite prevention is released).

When the external tool is not a legitimate external tool, the exchange of encryption is not established, so that the ECM 1 does not enter the unlocked state but remains in the locked state (rewrite preventing state).

When the security communication is completed, the external tool 2 sends a request for rewriting the control memory to the ECM 1. In response to the request from the external tool 2, the ECM 1 receives a control memory rewrite request and performs a rewrite process.

The processing in the ECM 1 will be described with reference to the flowchart of FIG.

In FIG. 3, first, at step 1, it is determined whether or not a rewrite request signal for the control memory has been received. If a rewrite request signal has been received, the process proceeds to step 2 to check the diagnostic result stored in the memory to be rewritten. If there is no abnormality in the diagnosis result, the process proceeds to step 3, and a rewrite permission signal is transmitted to the external tool 2 as in the conventional case.

On the other hand, if there is any abnormality in the diagnosis result, the process proceeds from step 2 to steps 4 and 5, and after transmitting a target output signal having the diagnosis result to the external tool 2, the abnormality is detected. Check whether a request to output a diagnostic result in a certain case has been received. Immediately after receiving the rewrite request signal in step 1, the request for outputting the diagnosis result is not issued. On the other hand, when a request for output of a diagnosis result in the case of an abnormality is received from the external tool 2,
Proceeding to step 7, the diagnosis result when there is an abnormality is transmitted without omission. Step 8, which has been skipped, will be described later.

Next, the reception of the rewrite permission signal of the control memory and the predetermined processing executed by the external tool 2 will be described with reference to the flowchart of FIG.

In FIG. 4, first, at step 11, it is checked whether or not a rewrite permission signal for the control memory has been received from the ECM1. If the rewrite permission signal has been received, the process proceeds to step 12, and the rewrite data is transmitted to the ECM 1 as in the related art.

When the ECM 1 receives the rewrite data of the control memory, it rewrites the control memory. For example, in the case of the idle speed control described above, the entire control program after correcting the error by this rewrite becomes E
It is stored in the control memory of CM1.

When the rewriting is completed, the state is switched from the unlocked state to the locked state, and the end of the rewriting is sent back to the external tool 2. In response to this transmission, the external tool 2 confirms that the rewriting of the control memory has been completed, and the communication sequence ends.

On the other hand, when the rewrite permission signal has not been received, the process proceeds to steps 13 and 14 to determine whether the rewrite prohibition signal of the control memory has been received, and whether the diagnosis result in the case of abnormality has been received. to decide.

As a result, if the rewrite prohibition signal has been received and the diagnosis result in the case where there is an abnormality has not been received, the process proceeds to step 15 and the output of the diagnosis result in the case where there is an abnormality is requested to the ECM 1. When the result of the diagnosis when there is an abnormality is received, the process proceeds to step 16 and the result of the diagnosis when there is an abnormality is displayed on the display device of the external tool 2 without omission. Steps 17, 18, and 19 for which the description has been skipped will be described later.

As described above, when the ECM 1 receives the rewrite request signal from the external tool 2 after the security communication for executing the memory rewrite is established, the diagnosis result when there is an abnormality is stored in the memory to be rewritten. It is checked whether or not the data is stored. If the diagnosis result is stored when there is an abnormality, a rewrite prohibition signal is transmitted to the external tool 2. Since an output request is issued to the ECM 1 and the diagnosis result sent from the ECM 1 when there is an abnormality is displayed on the external tool 2, when the control memory is rewritten, up to the diagnosis result when there is an abnormality. Is not erased, thereby preventing a situation in which the diagnostic system does not correctly diagnose.

However, after confirming the diagnosis result in the case of abnormality with an external tool, there is a case where it is desired to rewrite the control memory.

In order to respond to this, steps 17, 18, and 19 are added in FIG. 4 and step 8 is added in FIG. In other words, even if the external tool has received the diagnosis result when there is an abnormality, and there is an instruction to delete the diagnosis result, the process proceeds from step 17 to steps 18 and 19 in FIG. The memory rewrite inhibition release signal is transmitted to the ECM1, and the diagnosis result is not displayed. On the other hand, on the ECM 1 side, even if there is an abnormality in the diagnosis result, when this rewrite inhibition release signal is received, the control memory is rewritten, so that the process proceeds from step 2 and step 8 in FIG. Send the permission signal to the external tool.

This makes it possible to rewrite data in the control memory after understanding the contents of the diagnosis result when there is an abnormality.

In the embodiment, the case where the ECM 1 makes a diagnosis and the diagnosis result is stored in the memory to be rewritten has been described. However, the automatic transmission control control unit makes a diagnosis concerning the transmission control, and the diagnosis is performed. The present invention can be applied to a case where the result is stored in a memory to be rewritten. Furthermore, the control unit is not limited to these, and the present invention can be applied if a predetermined control unit performs a diagnosis related to a predetermined control and the diagnosis result is stored in a memory to be rewritten. Needless to say, there is.

[Brief description of the drawings]

FIG. 1 is a control system diagram of a first embodiment.

FIG. 2 is a communication sequence diagram of the first embodiment.

FIG. 3 is a flowchart illustrating a process at the time of receiving a control memory rewrite request.

FIG. 4 is a flowchart illustrating a process at the time of receiving a control memory rewrite permission.

[Explanation of symbols]

 1 ECM 2 External tool

Claims (4)

[Claims] A control unit having a control memory including a memory electrically erasable and writable by an external tool; and a means for determining permission of rewriting data in the control memory from the external tool,
In a vehicle control memory rewriting device in which data rewriting to a control memory is performed only when rewriting is permitted, a means for determining whether a diagnosis result when there is an abnormality is stored in a memory to be rewritten, Means for prohibiting rewriting of data in the control memory when a diagnosis result when there is an abnormality from the determination result is stored in a memory to be rewritten. 2. The method according to claim 1, wherein when a diagnosis result when there is an abnormality based on the determination result is stored in a memory to be rewritten, the diagnosis result is displayed on an external tool. Memory rewriting device for vehicle control. 3. The method according to claim 1, wherein when there is an instruction to erase the diagnosis result when there is an abnormality, the prohibition of data rewriting on the control memory is released and the data rewriting on the control memory is performed. Vehicle rewrite device for vehicle control. 4. The method according to claim 2, wherein when there is an instruction to delete the diagnosis result when there is an abnormality, the prohibition of data rewriting on the control memory is released and the data rewriting on the control memory is performed. Vehicle rewrite device for vehicle control.