JP3491358B2 - Power cut-off detection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply cutoff detection device for a control device, and more particularly to a power supply cutoff detection device for an electronic control device for controlling vehicle equipment.

[0002]

2. Description of the Related Art Conventionally, particularly in an electronic control unit (ECU) for controlling a vehicle engine and other equipment, an ECU
When the power supply to the CPU is stopped, the CPU in the ECU is reset because it does not have a power supply for power failure. Therefore from the battery E
The same phenomenon occurs even if a momentary interruption occurs due to poor contact of the power supply line to the CU, etc., and the same processing as when the ECU starts control by turning on the ignition switch (IG switch) is executed again. Therefore, controllability may deteriorate. For example, through in-vehicle LAN,
In a system that exchanges data with another ECU, an error in the transmission line is detected due to a data transmission / reception abnormality for a predetermined period. In that case, some ECU
Only when the power is momentarily cut off and transmission / reception becomes impossible, there is a problem that other ECUs judge that it is a transmission line error.

Here, by notifying the ECU of the detection of the instantaneous power failure by some means, it is possible to prevent the transmission line error from being erroneously detected. Such a detection means detects an instantaneous interruption mainly by a power supply self-holding circuit or an external interruption detection circuit provided in a power supply line, inputs the signal to the ECU, and supplies power as necessary. It prevents abnormal operation and data transfer error (for example, Japanese Patent Laid-Open No. 64-56248).

[0004]

However, in order to take measures against the slight instantaneous interruption, a complicated circuit for monitoring must be provided in addition to the control circuit body, which causes a problem of cost increase. . Therefore, an object of the present invention is to provide a device capable of detecting a power supply interruption to a control device without providing an extra circuit.

[0005]

In order to solve the above-mentioned problems, the structure of the present invention has a CPU for calculating a control amount for controlling vehicle equipment, a predetermined information stored, and after power supply is stopped. Also detects the ON state of the non-volatile memory that holds and stores the information and the external signal, starts power supply to the CPU and the non-volatile memory, and
In an electronic control device having the CPU and a power supply circuit for stopping power supply to the non-volatile memory after a predetermined period after detecting the off- state, the CPU detects the on-state of the external signal and detects the non-volatile memory. Writing a first predetermined value in a predetermined area of, while detecting the off state of the external signal to rewrite the first predetermined value of the predetermined area of the nonvolatile memory to a second predetermined value, when the power is turned on, The value written in the predetermined area of the nonvolatile memory is the first
A detection unit that detects an instantaneous power failure when it matches a predetermined value, and a unit that receives instantaneous power interruption information when it detects an instantaneous power failure.
And a process switching means for switching the processing . Further, the configuration of the related invention is such that the switching means causes the instantaneous interruption.
The process that can be switched in response to the information is that there was a momentary interruption.
It is characterized in that it is a process of transmitting to another electronic control unit . Furthermore, the electronic control unit is an engine ECU.
And the external signal is an ignition signal from an ignition switch that is turned on while the engine is running.

[0006]

In the predetermined area of the non-volatile memory provided in the microcomputer inside the ECU which is the control device of the vehicle, the first predetermined value indicating that the vehicle is in operation is set in response to the external signal being on. Then, after the external signal is turned off and the processing is normally completed, the value is set to the second predetermined value. If a momentary interruption occurs during operation, the process ends abnormally, so the value of the non-volatile memory remains at the first predetermined value, and it can be determined that the process has been forcibly ended during operation. Therefore, when the microcomputer is powered on and rises, the microcomputer refers to a predetermined area of the non-volatile memory to determine whether the previous termination is due to an abnormal termination such as an instantaneous interruption. If it is a momentary interruption, the corresponding process is executed to prevent the control from becoming unstable.

If this electronic control unit is for an engine,
The ignition switch can be used as an external signal, and the first predetermined value is set while the ignition switch is on, and when the ignition switch is off, the microcomputer continues to drive the power supply for a while and changes the value of the nonvolatile memory to the first value. 2 Replace with the specified value.

[0008]

EFFECTS OF THE INVENTION It is possible to detect the occurrence of an instantaneous power interruption without providing a circuit for detecting an instantaneous interruption outside the control unit (ECU), and the control is hardly affected during the control.
The PU can switch processing and take measures against it.
Data exchange with other ECUs etc. continues normally. Particularly in the engine ECU, since there are many exchanges of engine control signals, the configuration of the present invention makes it possible to easily prevent control disturbance due to instantaneous interruption.

[0009]

EXAMPLES The present invention will be described below based on specific examples. FIG. 1 is an overall configuration showing an electronic control unit (ECU) 1 for a vehicle engine and its peripheral circuits to which a power interruption detection method of the present invention is applied. ECU1 has an ECU
Power is input from the power supply line via the main relay 4 which is turned on and off by itself. Further, the ECU 1 is also interconnected with a transmission-dedicated ECU 5 to be controlled and a meter-related ECU 6. Then, the IG signal from the relay 3 driven by the ignition key (IG) switch 2 is input and used for control. In addition, although not shown, there are also signal lines directly controlled by the ECU 1 and lines for inputting signals from various sensors.

Inside the ECU 1, the IG signal is amplified by the buffer and the microcomputer 11 and the OR gate 12 are connected.
It is connected to the. The microcomputer 11 has a non-volatile memory 16 inside to store a specific value that means a circuit state, and to store communication data with other external ECUs 5 and 6 through a communication IC 15 inside the ECU 1.
The non-volatile memory 16 also stores other information necessary for control as necessary. The power supply circuit 14 for the microcomputer 11 receives power supply from the external main relay 4 and supplies stabilized power to the microcomputer 11. The microcomputer 11 controls the vehicle and exchanges data with other ECUs (here, the transmission ECU 5 and the meter ECU 6 are shown) through the communication IC 15. Other, directly,
The ECU may be configured to take in various sensor signals.

As a normal operation, first, when the engine of the vehicle is started by the driver of the vehicle and the IG switch 2 is turned on, the switch of the IG relay 3 is closed and the IG signal becomes Hi (active). When the IG signal becomes Hi, the transistor 13 is turned on in the ECU 1 via the OR gate 12, the main relay 4 is closed, and power is supplied to the ECU 1. After the power is supplied, the microcomputer 11 inside the ECU is activated, the microcomputer 11 recognizes Hi of the IG signal, and the microcomputer 1 outputs the output 12a (power supply delay signal) to the OR gate 12.
Set to Hi and keep the transistor 13 on.

When the engine is stopped and the IG switch 2 is turned off, the IG signal becomes Lo, so there is no direct signal to the OR gate 12, but the power supply delay signal 12a from the microcomputer 11 turns on the transistor 13. Continuing, the ECU 1 and the microcomputer 11 continue to operate with the contacts of the main relay 4 kept closed. When the microcomputer 11 finishes the necessary processing, the output 12a to the OR gate 12 is set to Lo, the transistor 13 is turned off, and the power supply to the ECU 1 and the microcomputer 11 is stopped (chart in FIG. 1 (b)). reference).

If the power supply from the main relay 4 which supplies the power supply circuit 14 to the microcomputer while the IG signal is generated causes a momentary interruption due to some reason such as a contact failure, the microcomputer For 11, the state is equivalent to the state where the power is once turned off and the power is turned on again, and since the IG signal exists, the situation is exactly the same as the state where the IG signal is first generated to start driving the ECU 1. The microcomputer 11 will be executed from the beginning of the processing program. Therefore, if it is left as it is, the control state of the ECU 1 immediately before the instantaneous interruption will be interrupted and reset, and the control of the vehicle may become unstable.

Therefore, by using the nonvolatile memory (RAMM) 16 which is a feature of the present invention, it is determined whether or not there is a momentary interruption by checking the stored value when the processing program is started up, and the momentary interruption occurs. If there is, processing for instantaneous interruption is performed. This non-volatile memory (RAMM) 16 continues to retain the stored data even when the power to the microcomputer 11 is stopped, and when the power is turned on again and the microcomputer 11 is in the operating state, A storage device in which data remains. However, when the power supply of the microcomputer 11 is stopped, the stored data cannot be read out.

(Explanation of Flowchart) The above-mentioned operation will be described with reference to the flowchart shown in FIG. The power is turned on by the IG operation, and the microcomputer 11 of the ECU 1
Starts to operate by IPL (initial program loading), the power supply delay signal 12a is first set to Hi in step 1. Then, the communication IC and the peripheral circuits are initialized (step 2). And non-volatile memory (RAMM)
It is checked whether the contents of 16 are 00 which means normal termination or not (step 3). If the contents of the non-volatile memory 16 indicate that the history is normal, nothing is done and normal processing is performed. Continue (Step 5). If the previous process was interrupted due to an abnormal termination such as power interruption,
The value of RAMM16 is different from the value of 00 for normal termination (here A
Since it is A), it is judged in step 3 that there was a momentary interruption and restarted. Then, in step 4, the battery instantaneous interruption information is set, and the fact that there is an instantaneous interruption is transmitted to other ECUs through the communication IC 15. Therefore, each of the other ECUs does not erroneously determine that it is a data transmission line error, and prevents data communication from becoming unprocessable. Then, the regular process (step 5) is continued.

The process from step 5 is a process relating to control such as exchanging data with another ECU, and a data value indicating that the process is being performed in the nonvolatile memory (RAMM) 16 while this process is being performed. Remember (AA). Therefore, in step 5, set AA in RAMM16, and in step 6
After carrying out data transmission / reception processing and other necessary processing (not shown in the flowchart) in step 8, it is judged in step 8 whether or not the IG signal is still on and maintained, and if it is maintained, the processing from step 5 is executed. repeat. If the IG signal is off, the end process is performed in step 9, and in step 10, the normal process ends in the nonvolatile memory 16.
Set 00 and set the power supply delay signal 12a in step 11.
The power is turned off at Lo and the operation of the ECU 1 is completed.

As described above, in the past, an external circuit was provided to prevent the occurrence of an abnormality due to a momentary power failure. However, in the present invention, it is possible to deal with it by simply devising the circuit inside the ECU 1, and the controllability is improved. The control system can be improved. This can also be implemented in the ECUs of other devices and the power supply circuits of other control devices.

[Brief description of drawings]

FIG. 1 is a vehicle electronic control unit (EC) to which the present invention is applied.
U) A peripheral configuration diagram and its operation chart.

FIG. 2 is a flowchart of a processing program of a microcomputer of the ECU shown in FIG.

[Explanation of symbols]

1 ECU (electronic control unit) 2 Ignition key switch (IG) 3 IG relay 4 Main relay 5 Transmission ECU 6 meter ECU 11 Microcomputer 12 OR gate (OR circuit) 12a Power supply delay signal 13 transistors 14 power supply circuit 15 Communication IC 16 Non-volatile memory (RAMM)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI H02J 1/00 308 H02J 1/00 308P (58) Fields investigated (Int.Cl. ⁷ , DB name) G01R 19/00-19 / 32 B60R 16/02 650 G05B 9/02

Claims (3)

(57) [Claims] 1. A CPU for calculating a control amount for controlling vehicle equipment, a predetermined memory, a non-volatile memory for storing and storing the information even after power supply is stopped, and an external signal. A power supply circuit that starts to supply power to the CPU and the non-volatile memory by detecting the ON state of the CPU, and stops supply of power to the CPU and the non-volatile memory after a predetermined period of time after detecting the OFF state of the external signal. In the electronic control device having :, the CPU detects an ON state of the external signal, writes a first predetermined value in a predetermined area of the nonvolatile memory, and
Writing means for detecting the off state of the external signal and rewriting the first predetermined value in the predetermined area of the non-volatile memory to a second predetermined value; and a value written in the predetermined area of the non-volatile memory when the power is turned on. Shun power when matching the first predetermined value
When a power failure is detected with the detection means that detects the power failure, the processing is performed by receiving the power failure information.
A power interruption detection device, comprising: a process switching means for switching . 2. The switching means receives the instantaneous interruption information.
The process that can be switched by
The power cutoff detecting device according to claim 1, wherein the process is a process of transmitting the power cutoff to the control device. 3. The electronic control unit is an ECU for an engine, and the external signal is an ignition signal by an ignition switch that is turned on while the engine is running. The power interruption detection device described.