JPH03230229A - Abnormality detection system of microcomputer - Google Patents

Abstract

PURPOSE:To decrease the number of terminals by setting the format of data which are sent between microcomputers and allowing one computer to detect abnormality of the other microcomputer according to the necessary detection time required to receive data with set data length. CONSTITUTION:When the microcomputers 31 and 32 which perform arithmetic operation associatively with each other transmit data, the transmission format of the data length, etc, of the data to be sent is previously set and the data are transmitted. One microcomputer 31 detects the time required to receive data sent from the other microcomputer 32, compares the necessary detection time for the data with the previously set data length with the reference transmis sion time required to send data with the data length, and detects the abnormal ity such as the runaway of the other microcomputer 32 according to the compari son result. Consequently, the need for signal terminals dedicated for the abnor mality detection is eliminated and the number of terminals of the microcomputers 31 and 32 is decreased.

Description

[Detailed Description of the Invention] Overview In control, etc. where multiple microcomputers cooperate to perform arithmetic operations, the format of data to be transmitted from the sub-microcomputer to the main microcomputer is set in advance, and the format of data to be transmitted from the sub-microcomputer to the main microcomputer is By comparing the transmission station time required per unit data length of data transmitted to the main microcomputer with the standard transmission time, the main microcomputer can determine whether an abnormality such as runaway has occurred in the sub microcomputer. To detect.

This allows the terminals for data transmission and reception and the terminals for abnormality detection to be shared, thereby reducing the number of terminals of the microcomputer.

INDUSTRIAL APPLICATION FIELD The present invention relates to a microcomputer abnormality detection method that is suitably implemented in a so-called multi-CPU type control device using a plurality of microcomputers, such as a control device for an internal combustion engine of an automobile.

BACKGROUND OF THE INVENTION FIG. 5 is a block diagram showing the electrical configuration of a control device 1 in which a typical prior art microcomputer abnormality detection method is used. This control device 1 is used, for example, to control fuel injection and ignition timing of an internal combustion engine of an automobile.

This control device 1 includes two microcomputers 2.
3 are provided, and these microcomputers 2
．． Sensors 5a, 5 3 detect intake air temperature, cooling water temperature, etc. input via the analog/digital converter 4.
b) Detection results and input interface times l! Sensors 7a, 7 for crank angle, vehicle speed, etc. input via 86
Based on the detection result of step b, etc., calculation operations are performed in cooperation with each other, and the fuel injection amount, ignition timing, etc. are calculated. The calculation result is outputted to an actuator 8 such as a fuel injection valve or an igniter via an output interface circuit 7.

Main microcomputer 2 and sub microcomputer 3
means line 11. (The arithmetic data is transmitted and received via the line 13, and the arithmetic operation is performed in cooperation with each other as described above.The terminal p1 of the sub-microcomputer 3 is connected to the terminal p2 of the main microcomputer 2 via the line so-called watchdog control (hereinafter referred to as WDC)
The main microcomputer 2 detects runaway of the sub microcomputer based on this WDC signal, and when runaway is detected, the main microcomputer 2 detects runaway of the sub microcomputer via line p4. A reset signal is output to the computer 3.

Further, a runaway detection circuit 9 is provided in connection with the main microcomputer 2, and this runaway detection circuit 9 detects the main microcomputer based on the WDC signal inputted from the main microcomputer 2 via the line r5. 2 runaway detection is performed, and when runaway is detected, line r6 is detected.
Outputs a reset signal via.

Problems to be Solved by the Invention In the prior art described above, the microcomputer 32 has a dedicated signal terminal pt for transmitting and receiving the WDC signal.
It is necessary to provide p2. On the other hand, as the control device 1 becomes more sophisticated, there has been a demand for a reduction in the number of terminals of the microcomputer 2.3.

An object of the present invention is to provide a microcomputer in which a plurality of microcomputers cooperate to perform arithmetic operations, in which one microcomputer can detect an abnormality in the other microcomputer without providing a dedicated terminal. The purpose of this invention is to provide an anomaly detection method.

Means for Solving the Problems The present invention provides a microcomputer abnormality detection method in which a plurality of microcomputers cooperate to perform arithmetic operations and one microcomputer detects an abnormality in the other microcomputer. The computer transmits data with a predetermined data length, and the one microcomputer detects the time required to receive the data with the predetermined data length, and calculates the detection time and the data with the predetermined data length. This is a microcomputer abnormality detection method characterized by comparing the reference transmission time required for transmission of one microcomputer with a reference transmission time, and detecting an abnormality in the other microcomputer based on the comparison result.

According to the present invention, when transmitting data between a plurality of microcomputers that cooperate to perform arithmetic operations, the data transmission format such as the data length of the data to be transmitted is set in advance. conduct. One microcomputer detects the time required to receive the data transmitted from the other microcomputer, and determines the time required for detecting data of the preset data length and transmission of data of the data length. Based on the comparison result, an abnormality such as runaway of the other microcomputer is detected.

Therefore, there is no need to provide a dedicated signal terminal for abnormality detection, and the number of terminals of the microcomputer can be reduced.

Embodiment FIG. 1 is a block diagram showing the electrical configuration of a control device 11 for an internal combustion engine in which a microcomputer abnormality detection method according to an embodiment of the present invention is used.

This control device 11 controls intake air temperature, intake pressure, cooling water temperature,
The fuel injection amount and ignition timing are calculated based on the detection results of various sensors 12 to 19 such as throttle valve opening, crank angle, and vehicle speed, and the calculation results are applied to actuators 21 and 22 such as fuel injection valves and igniters. Output to.

The control device W11 includes two microcomputers 31.
32 are provided, and these microcomputers 31 and 32 cooperate to perform the arithmetic operation. The detection results of the sensors 12 and 13 are sequentially converted into digital data by the analog/digital converter 33 and read into the main microcomputer 31, and the detection results of the sensors 14 and 15 are read into the input interface circuit 34. are read sequentially via .

Similarly, the sensor 16 is sent to the sub microcomputer 32.
．． The detection results of sensors 18 and 17 are sequentially digitally converted and read by the analog/digital converter 35, and the detection results of sensors 18 and 19 are input to the input interface circuit 3.
6 are read sequentially.

Arithmetic data is transmitted from the main microcomputer 31 to the sub microcomputer 32 via a line 111, and from the sub microcomputer 32 to the main microcomputer 31 via a line 112.

In this way, the microcomputers 31 and 32 perform calculation operations while converting mutual calculation data, and output the calculation results to the individually provided actuators 21 and 22 via the output interface circuits 37 and 38. do.

The main microcomputer 31 detects the runaway of the sub microcomputer 32 based on the data input via the line n12 as described later, and when it is detected that the sub microcomputer 32 has runaway, Outputs a reset signal.

Further, a runaway detection circuit 40 is provided in association with the main microcomputer 31, and the main microcomputer 31 supplies the runaway detection circuit 40 with a WDC signal having a predetermined constant cycle via a line 114. The runaway detection circuit 4o detects the runaway of the main microcomputer 31 based on the input WDC signal.
If the signal is not detected for a predetermined period of time or longer, it is determined that there is a runaway, and a reset signal is output via line 115.

FIG. 2 is a diagram showing the data transmission format between the microcomputers 31 and 32. The data to be transmitted is composed of a start bit Da, data bits DO to D7, and an end bit Db. Data bits DO~D7
is transmitted every predetermined time W1, for example, every 4 m5ec. Further, the data length per unit data, that is, the time T1 from the fall of the start bit Da to the fall of the next start bit Dal is set in advance.

Therefore, if an abnormality such as runaway occurs in the sub microcomputer 32, the data transmission time per unit data length changes. Utilizing this, the main microcomputer 31 first detects the detection time Tla per unit data length of data input from the sub microcomputer 32 via the line N12. next,
The detection time Tla is determined by the sub-microcomputer 3.
Runaway detection of the sub microcomputer 32 is performed based on whether or not the reference transmission time α, which is set based on the required detection time in the normal state of No. 2, is greater than or equal to β, and less than or equal to β.

FIG. 3 is a flowchart for explaining the data transmission operation of the sub microcomputer 32. step n
At step n2, an initialization operation is performed, and at step n2, only one bit of data is transmitted at the timing of the predetermined time W1. In step n3, data bit DO~
It is determined whether or not all the dot data of D7 has been transmitted. If not, the process returns to step n2, and when the transmission is completed, the process moves to step n4.

In step n4 or n5, the data to be transmitted next is
When the data is read from the analog/digital converter 35 or the input interface circuit 36, the process returns to step n2.

In this way, the read data is transmitted over the predetermined time Tl. Note that the transmission operation of the main microcomputer 31 is also performed in the same procedure as the transmission operation of the sub microcomputer 32.

FIG. 4 is a flowchart for explaining the data receiving operation of the main microcomputer 31. step m
In Step 1, an initialization operation is performed, and in Step m2, data sampling is performed every 2m5ee so as to be at the center timing of the data transmission time W1 per unit bit. In step m3, the data sampled in step m2 is stored in a register, and in step m4, it is determined whether all data bits DO to D7 have been received, and if not, the process returns to step m2. , if so, the process moves to step m5.

In step m5, the detection required time Tla from the start bit Da to the start bit Dal of the next data is calculated based on the data reception results in steps m2 to m4. In step m6, it is determined whether the time Tla obtained in step m5 is greater than or equal to the predetermined reference transmission time α and less than β. If so, step m7 determines whether the sub microcomputer 32 is normal. If it is determined that there is, the process moves to another operation, and if not, it is determined in step m8 that the sub microcomputer 32 is abnormal, and after a fail-safe operation such as outputting the reset signal is performed in step m9, Move on to other actions.

As described above, in the control device 11 according to the present invention, the main microcomputer 31 receives data transmitted from the sub-microcomputer 32 in a predetermined format, and based on the received data, receives data per unit data length. Time T1a required for detection of Yuko
Abnormality detection is performed based on whether la is greater than or equal to the reference transmission time α and less than β, which is set within a predetermined range from the transmission time T1 during normal operation of the sub microcomputer 32. computer 3
1. There is no need to provide a dedicated signal terminal for abnormality detection at 32, and the number of terminals can be reduced.

Effects of the Invention As described above, according to the present invention, the format of data to be transmitted between a plurality of microcomputers that cooperate to perform arithmetic operations is set in advance, and one microcomputer transmits data of a predetermined data length. Since abnormality detection is performed in the other microcomputer based on the detection time required to receive data from the other microcomputer, abnormality detection can be performed without providing a dedicated signal terminal, reducing the number of microcomputer terminals. can do.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the electrical configuration of a control device 11 in which an abnormality detection method according to an embodiment of the present invention is used, and FIG. 2 shows a microcomputer 31.3211 in the control device 11.
3 is a flowchart for explaining the data transmission operation of the microcomputer 31, 32, and FIG. 4 is a diagram showing the data transmission format of the main microcomputer 31.
FIG. 5 is a flowchart for explaining the data reception operation of the control device 1 in which the conventional abnormality detection method is used.
FIG. 2 is a block diagram showing the electrical configuration of FIG. 11... Control device, 12-19 Sensor, 2122.
・・Actuator, 31.32 ・Microcomputer, 40・・Runaway detection circuit

Claims (1)

[Claims] In a microcomputer abnormality detection method in which a plurality of microcomputers cooperate to perform arithmetic operations and one microcomputer detects an abnormality in the other microcomputer, the other microcomputer is determined in advance. The one microcomputer detects the time required to receive the data of the predetermined data length, and calculates the detection time and the time required to transmit the data of the predetermined data length. An abnormality detection method for a microcomputer, characterized by comparing the transmission time with a reference transmission time and detecting an abnormality in the other microcomputer based on the comparison result.