JPH03186940A - Method for inspecting type of microcomputer - Google Patents

Abstract

PURPOSE:To eliminate a process for displaying a type in a microcomputer by discriminating the type of the microcomputer which cannot apparently be discriminated through the use of the function of the microcomputer. CONSTITUTION:Four kinds of microcomputers 2A-2D in which storage constant are different are assumed as one example. They are used as the microcomputer 2 and they cannot apparently be discriminated. Thus, THW and THA are used as inspection analog signals and the values are respectively set. Respective microcomputers 2A-2D recognize the combination of THW and THA, which are set for the types for themselves by characteristic inspection programs. When the microcomputer 2A can recognize that THW=0V and THA=0V, an output OK which is that a result is good is outputted from a discrimination terminal VF, and an output NG which is that the result is not good is outputted if it cannot recognize it. Consequently, it can be judged that ECU mounts the mistaken microcomputer when NG is outputted in such inspection. Thus, the process for displaying the type in the microcomputer is eliminated.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for testing the type of a microcomputer that cannot be determined from its appearance, the purpose of this method is to easily determine the type without adding any hardware configuration. An input terminal that inputs an analog signal, an A/D converter that converts the analog signal into a digital signal, a microcomputer that takes in the digital signal and performs predetermined processing, and a test terminal that puts the microcomputer into test mode. and a determination terminal for outputting an inspection result of the microcomputer, in which the microcomputer is equipped with a type-specific inspection program, and the nuclear inspection program allows the microcomputer to output the inspection result from the input terminal. The value of the input test analog signal is checked, and the result is outputted from the discrimination terminal.

[Industrial application field]

The present invention relates to a method for inspecting the type of microcomputer that cannot be determined from its appearance.

Even if automotive electronic control units share the same hardware configuration with a microcomputer (hereinafter referred to as microcomputer) and an A/D converter mounted on the board, they differ only by changing the constants used in the microcomputer's program. It can also be applied to car models, so they may actually be manufactured that way. In such a case, it would be a problem to manufacture an electronic control unit equipped with a microcomputer with different constants for the requested vehicle type, so it is necessary to check this before shipping.

[Conventional technology]

The electronic control unit (ECU) used in vehicles includes
There are types for engine control, speed change control, constant speed driving control, etc., and these are configured with a small number of parts by using a microcomputer. This microcomputer is mounted on the ECU base board together with an A/D converter for inputting analog signals and a driver for driving the load.

ECLJs with the same purpose can often be used with other car models by sharing not only the hardware configuration but also most of the microcomputer programs. The simplest method is to simply change the constants stored in the microcontroller to match the characteristics of each vehicle type. However, even if the microcomputers have different internal constants, they cannot be distinguished visually, so if you mistakenly manufacture an ECU with a microcontroller for a different car model, the vehicle equipped with this will not be able to obtain sufficient control performance. Sometimes.

For this reason, conventionally, a unique product number indicating the type (separate from the one indicating the microcontroller model) was printed on the surface of the microcontroller in which the program was stored, and this was read visually or optically to determine the microcontroller type. ing.

[Problem to be solved by the invention]

However, the conventional type determination method requires a step of printing a product number indicating the type in addition to the original process of manufacturing the ECU, which has the disadvantage of increasing manufacturing costs. Furthermore, since the display check is performed in a separate system from other electrical tests, there is a drawback that a series of tests cannot be performed continuously.

The present invention makes it possible to easily determine the type of microcomputer by utilizing the functions of the microcomputer without adding any hardware configuration.

[Means to solve the problem]

The present invention includes an input terminal for inputting an external analog signal;
An A/D converter that converts the analog signal into a digital signal, a microcomputer that takes in the digital signal and performs predetermined processing, a test terminal that puts the microcomputer into an inspection mode, and a test terminal that outputs the inspection results of the microcomputer. In the method for testing the type of a microcomputer of an electronic control unit, the microcomputer is equipped with a type-specific testing program, and the testing program determines the value of the testing analog signal input from the input terminal. The device is characterized in that it is checked and the result is outputted from the determination terminal.

[Effect]

In the present invention, a type-specific inspection program is built into the microcomputer in advance, but this can be written at the same time as other programs, so no special process is required. Furthermore, an analog signal for inspection is used, but this can also be input from an existing input terminal, so there is no need to add a special terminal. The value of this test analog signal is confirmed by a test program, and if it is appropriate, it can be determined that the type of microcomputer is compatible with the ECU installed in the vehicle.

Existing test terminals for starting this inspection program and discrimination terminals for outputting confirmation results can be used.
No additional hardware is required.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention, and shows an outline of an ECU. This ECLJ has an A/D converter 1 and a microcomputer 2 mounted on a board, and is also provided with an input terminal IN, a test terminal T, and a discrimination terminal (service check terminal) VF as external terminals. An analog signal is input from the input terminal IN, and this is converted into a digital signal (AD value) by the A/D converter 1 and taken into the microcomputer 2. Taking child fuel injection control as an example, the analog signal includes water temperature T.
HW, intake air temperature THA, intake pipe negative pressure P0, etc. are inputted from input terminals IN, ~IN, respectively. The microcomputer 2 can select and import these AD values.

In the normal control mode, the microcomputer 2 adjusts the fuel injection fit (time) while referring to the values of each input, but when a similar microcomputer inspection start signal is input to the test terminal T, it enters the inspection mode and runs the built-in inspection program. Run it and check the values of the inputs.

-As an example, four types of microcontrollers with different memory constants2
Assuming A to 2D. These are all ECUs shown in Figure 1.
It is used as the microcomputer 2 of the microcomputer 2, but it cannot be distinguished from the outside, so T' HW and T are used as analog signals for inspection.
Use HA and set the values as shown in the table below.

Table 1 THW (water temperature) + TlIA (intake temperature) changes depending on the ambient temperature and engine condition, but the range of change is limited during normal operation. The values of THW and THA shown in Table 1 are special values set outside this normal operating range. This value of 5V, OV is set to 4 types of microcontroller 2A as shown in Table 1.
- Combine 2D to differentiate.

Each microcomputer 2A to 2D has a TH set for its own type.
The combination of W and THA is confirmed using a unique inspection program. Then, microcontroller 2A has THW=OV, THA=OV
If it is confirmed that the result is OK, an OK output is output from the determination terminal VF, and if it is not confirmed, an NG output is output from the result stand. The same applies to the other microcomputers 2B to 2D. When an NG is output in such a test, the EC
It can be determined that U has the wrong microcontroller installed.

By using three types of analog signals THW, THA, and Pi, eight types of microcontrollers can be identified. FIG. 2 shows an outline of the inspection method at this time. ECU from inspection equipment
O) After setting up the test pins at each terminal I Nl to I Ns, T, and V F, start the test in step S1. Turn on the power supply. Then, in step s2, set the test pin to the test terminal T! !
Similar microcomputer inspection start signal (here Ov at a constant cycle)
Input the duty multiplied signal that repeats 5V and start the microcomputer's inspection program to set it to inspection mode. In the following step S3, from the input terminals IN, ~IN, T HW,
Each test value of T HA and P r - is input, and it is determined from the level outputted to the terminal VF whether it is NG or OK (step S4). If it is OK, the next test is performed in step S5. If it is NG, the continuation of the inspection is stopped in step S6. It is best to perform this similar microcomputer test at the beginning of all test items.

FIG. 3 is a time chart showing the state of each part during the above-mentioned similar microcomputer inspection. THW (water temperature) and THA
(Intake air temperature) is expected to vary from 85°C to -30°C, and will be set to 0°C at the time of inspection. On the other hand, P, (intake pipe negative pressure) will change from 0PEN (open) to 0 Hg. Assume that the range is F, and during the test, set the value to 0.Some of these values are in the normal variation range, but when combined, they become inputs that are difficult to generate during normal operation.During the test, turn off the test terminal T. ON from
The result is read from the discrimination terminal VF.

Note that the test terminal T provided for checking the operation of the ECU can also be used. This check outputs a normal code from the diagnosis display output terminal W when the ECU is normal, and a normal code from the diagnosis display output terminal W.
This is to output an abnormality code when the CU is abnormal.

〔Effect of the invention〕

As described above, according to the present invention, the type of the microcomputer, which is indistinguishable in appearance, is determined using the functions of the microcomputer, so a separate step of displaying the type on the microcomputer is not necessary. Furthermore, since the type determination 0 can be performed electrically, there is an advantage that it can be performed in the same preparation state as other electrical tests.

[Brief explanation of drawings]

FIG. 1 is a constituent country showing an embodiment of the present invention, FIG. 2 is a flowchart showing the inspection procedure of the present invention, and FIG. 3 is a time chart showing the inspection conditions of the present invention. In the figure, l is an A/D converter, 2 is a microcomputer, ECU is an electronic control unit, IN is an input terminal, T is a test terminal, and VF is a discrimination terminal. Applicant Fujitsu Ten Ltd.

Claims (1)

[Claims] 1. An input terminal (IN) for inputting an external analog signal; an A/D converter (1) for converting the analog signal into a digital signal; A microcomputer type test for an electronic control unit comprising: a microcomputer (2) that performs a test; a test terminal (T) that sets the microcomputer in test mode; and a discrimination terminal (VF) that outputs a test result of the microcomputer. In the method, a type-specific test program is built into the microcomputer, the test program checks the value of the test analog signal input from the input terminal (IN), and the result is sent from the discrimination terminal (VF). A microcomputer type inspection method characterized by outputting.