JP3082525B2 - Control 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 control device capable of quickly transferring data from a main control circuit to a sub control circuit when a backup power supply operates.

[0002]

2. Description of the Related Art An airbag control device 1 shown in FIG. 5 is a device for deploying an airbag 2 in the event of a vehicle collision to protect an occupant. When the amount of change in speed and the impact force within a certain period of time exceed respective predetermined threshold levels, it is determined that a collision has occurred, and a deployment signal is sent to the drive circuit 5 to ignite and detonate the detonating element 6. The configuration is such that the airbag 2 is deployed by pressure. Usually, the main control circuit 3 periodically performs a collision determination by a timer interrupt, and allocates the remaining time to an abnormality diagnosis of the power supply circuit 7, the drive circuit 5, or the detonating element 6. In this configuration, the sub control circuit 8 monitors the operation of the main control circuit 3, particularly the presence or absence of runaway.

The power supply circuit 7 has a battery power supply 7a as a main power supply. However, in the event that the battery power supply 7a is disconnected from the main control circuit 3 or the sub control circuit 8, the power supply circuit 7 is backed up to the battery power supply 7a. The power supply 7b is connected in parallel, and the backup power supply 7b is always kept on standby in case of emergency. The backup power supply 7b includes a backup capacitor C connected to the charging resistor R and a rapid discharging diode D connected in parallel to the charging resistor R.
When the output voltage of the battery power supply 7a decreases, the backup capacitor C discharges and supplies a power supply current to the main control circuit 3 and the sub control circuit 8. Da is the battery power 7
a backflow prevention diode provided on the output side of
Is a constant voltage circuit that stabilizes the output of the power supply circuit 7 and sends it out to the main control circuit 3 and the sub control circuit 8. When the battery power supply 7a is damaged due to the collision, and the ignition power and the circuit operation current must be supplied only by the backup power supply 7b, the main control circuit which consumes a large amount of current compared to the sub-control circuit 8 No. 3 shifts from the previous operation mode to the stop mode with the least current consumption. At the same time as the main control circuit 3 shifts to the stop mode, if the power supply voltage is sufficient, the operation performed by the main control circuit 3 is limited by the sub-control circuit 8 so that the data before and after the collision can be reduced. It was useful for records etc.

Further, in order to ensure data exchange between the main control circuit 3 and the sub control circuit 8, when data is transferred from the main control circuit 3 to the sub control circuit 8, it is synchronized with data transmission. A data set signal is sent to the sub-control circuit 8 and the sub-control circuit 8 captures the level inversion of the data set signal and switches to the data reception mode, after which the data supplied from the main control circuit 3 is received. Was. However, the judgment of the level inversion of the data set signal is
In order to avoid malfunction due to external noise such as ignition noise, the determination is performed according to predetermined determination software.For example, the data set signal is sampled at a predetermined cycle, and the signal level of the continuously collected data set signal is a certain number of samples. When it was found that the data set signal was inverted, the level inversion of the data set signal was recognized.

[0005]

When the sub-control circuit 8 receives the data sent from the main control circuit 3, the data set output in synchronization with the data is transmitted to the sub-control circuit 8. Since the switching to the data reception mode is performed by determining the signal level inversion by software processing, the battery power supply 7a is damaged when a collision accident occurs, for example, and the backup power supply 7b
When the output voltage of the power supply circuit 7 that relies solely on the power supply falls below the specified voltage, the main control circuit 3 that has performed the collision determination almost simultaneously with the occurrence of the collision immediately before the transition to the stop mode in response to the decrease in the power supply voltage, Even when data such as collision determination data and abnormality diagnosis data are transferred to the sub-control circuit 8, the sub-control circuit 8 determines the data set signal by software processing. Important data representing the operation history could not be received as quickly as possible. In other words, while the power supply circuit 7 is operating normally, the data reception method by software processing suitable for eliminating the influence of noise can be achieved by using the backup power supply 7b having a limited power supply capacity to uselessly consume unnecessary current. In such a case, the determination of the data set signal is likely to be too redundant. In such an emergency, the conventional airbag control device 1 that follows the same data reception method as in the normal case has a large size for the backup power supply 7b. A backup capacitor C having a large capacity is required, and it is difficult to reduce the size or the cost of the entire device including the power supply circuit 7.

[0006]

Means for Solving the Problems To solve the above problems,
In this invention, the external power supply and the backup power supply are parallel.
The power supply circuit connected in a row and the airbag
Drive circuit and acceleration sensor for detecting vehicle acceleration
Connected to the drive circuit and the acceleration sensor,
Generates an airbag deployment signal based on the signal from the speed sensor.
Output to the drive circuit, and the output voltage of the power supply circuit is
Execute the required operation program if the specified voltage or higher
In the operation mode, the output voltage satisfies the specified voltage.
When there is no main system, shift to stop mode with reduced current consumption
Control circuit and the main control circuit.
Receive data transmitted in synchronization with the data set signal
A control device comprising:
Determine whether the output voltage of the source circuit is equal to or higher than the specified voltage
A voltage comparing means, and a connection to the main control circuit and the sub control circuit.
Data write or read
A volatile memory; and
Output voltage of the power supply circuit based on the determination result of the comparing means.
Is higher than the specified voltage, the data set signal
Based on the level transition of the leading edge or trailing edge of the
Receiving data transmitted from the main control circuit,
When the output voltage of the power supply circuit is less than the specified voltage,
Is based on the edge detection result of the data set signal.
Before receiving the data transmitted from the main control circuit.
Writing to the non-volatile memory. This departure
According to the embodiment described above, the power supply circuit in which an external power supply and a backup power supply are connected in parallel, and an operation mode for executing a required operation program when an output voltage of the power supply circuit is equal to or higher than a specified voltage, When the voltage is less than the specified voltage, the main control circuit shifts to a stop mode in which current consumption is suppressed, and when the output voltage of the power supply circuit is equal to or higher than the specified voltage, the main control circuit synchronizes with the data set signal. The data to be transmitted and received is determined by determining the leading edge or trailing edge of the data set signal from a level transition for a certain period of time, monitoring the operation of the main control circuit, and adjusting the output voltage to the specified voltage. If not, a leading edge or a trailing edge of the data set signal is determined by edge detection, the data is received by interruption, and a limited complementing operation is performed in place of the main control circuit. Characterized by comprising a control circuit.

Further, according to the present invention, when the output voltage of the power supply circuit is equal to or higher than a specified voltage, the sub-control circuit converts the diagnostic data output by the main control circuit into an edge at the leading edge of the data set signal. In addition to receiving and judging by detection, data indicating the end of diagnosis output from the main control circuit that has received the signal indicating the diagnosis result is received by judging the trailing edge of the data set signal from the level transition for a certain period. It is characterized by the following.

[0008]

According to the present invention, an external power supply and a backup power supply are used.
The power supply circuit connected in parallel and the airbag
Drive circuit and acceleration sensor for detecting vehicle acceleration
Connected to the drive circuit and the acceleration sensor,
Generates an airbag deployment signal based on the signal from the speed sensor.
Output to the drive circuit, and the output voltage of the power supply circuit is
Execute the required operation program if the specified voltage or higher
In the operation mode, the output voltage satisfies the specified voltage.
When there is no main system, shift to stop mode with reduced current consumption
Control circuit and the main control circuit.
Receive data transmitted in synchronization with the data set signal
A control device comprising:
Determine whether the output voltage of the source circuit is equal to or higher than the specified voltage
A voltage comparing means, and a connection to the main control circuit and the sub control circuit.
Data write or read
A volatile memory; and
Output voltage of the power supply circuit based on the determination result of the comparing means.
Is higher than the specified voltage, the data set signal
Based on the level transition of the leading edge or trailing edge of the
Receiving data transmitted from the main control circuit,
When the output voltage of the power supply circuit is less than the specified voltage,
Is based on the edge detection result of the data set signal.
Before receiving the data transmitted from the main control circuit.
By writing to the non-volatile memory, current consumption during the operation of the backup power supply is suppressed, and the size and cost of the backup power supply are reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit configuration diagram showing an embodiment of an airbag control device to which the control device of the present invention is applied, and FIG. 2 is a flowchart for explaining a data receiving operation of the sub control circuit shown in FIG. .

An airbag control device 11 shown in FIG. 1 determines an collision of a vehicle based on an acceleration sensor 4 provided in a vehicle interior and a signal from the acceleration sensor 4, and issues an airbag deployment signal together with a collision recognition. A main control circuit 12, a sub-control circuit 13 for monitoring the operation of the main control circuit 12, and a memory 1 in which processing data is written by one of the main control circuit 12 and the sub-control circuit 13 when a collision occurs
4 and the like constitute a main part for collision determination. As the memory 14, an EEPROM is used, which requires some power for writing data, but keeps the written data once without supplying power. Battery power supply 7a
Supplies power to each unit in the device 11 and charges the backup power supply 7b to maintain a standby state, and forms the power supply circuit 7 together with the backup power supply 7b as in the related art.

Reference numeral 15 denotes a voltage comparator provided between the power supply circuit 7 and the main control circuit 12 and the sub control circuit 13. The voltage comparator 15 monitors the output voltage of the power supply circuit 7 and guarantees the operation mode to the main control circuit 12. The threshold value of the output voltage of the power supply circuit 7 is determined based on the specified voltage Va. Main control circuit 12 and sub control circuit 13
Switches the operation mode according to the threshold value determination output of the voltage comparator 15 as described later.

The main control circuit 12 operates in accordance with an operation program mainly including a main routine based on abnormality diagnosis, and a timer interrupt routine for giving priority to an almost periodic interrupt request and performing collision determination according to a predetermined algorithm. I do. The main routine includes a step of performing abnormality diagnosis, a step of transferring diagnostic data to the memory 14 in response to a write request, and a step of communicating internal information to the outside in response to a request from an external checker (not shown). If the power supply voltage is sufficient when a collision occurs, the collision determination data and the abnormality diagnosis data are written into the memory 14 by themselves, and the collision determination data and the abnormality diagnosis data are stored in the sub-control circuit 13 when the power supply voltage is equal to or lower than the specified voltage Va. And a step of transmitting diagnostic data to the sub-control circuit 13.

The timer interrupt routine includes a step of transmitting a one-shot pulse to the sub control circuit 13 every time an interrupt occurs, and a step of sampling a signal from the acceleration sensor 4 and performing a collision determination according to a predetermined collision determination algorithm. And The timer interrupt interval is determined in consideration of the sampling period required by the collision determination algorithm performed by the digital signal processing and the processing speed of the main control circuit 12, but here, the integrated value of the acceleration signal and the time until the collision is reached. The method employs a method for determining the change in impact energy on a two-dimensional map, and therefore requires a slightly longer determination time than the conventional simple determination method.

The sub-control circuit 13 includes a step of monitoring whether the main control circuit 12 is interrupted by a timer at a predetermined period, a step of determining whether there is an abnormality from the diagnostic data transmitted by the main control circuit 12, and a step of Sometimes, when the collision determination data or the abnormality diagnosis data is transferred from the main control circuit 12, a step of writing the collision determination data or the abnormality diagnosis data into the memory 14 instead of the main control circuit 12 is included. The abnormality diagnosis data includes short-circuit and open of the detonating element 6,
Are short-circuited and opened by an impact sensor (not shown) which is connected in series and mechanically closed with a relatively small impact, an abnormal voltage of the battery power supply 7a, an abnormal voltage of the backup power supply 7b, and the like. The diagnostic data is sequentially taken into the main control circuit 12 according to a predetermined sequence.

As mentioned above, the operation modes of the main control circuit 12 and the sub-control circuit 13 differ depending on the level of the power supply voltage with respect to the specified voltage Va.
Is in an operation mode for executing a required operation program when the output voltage of the power supply circuit 7 is equal to or higher than the specified voltage Va. When the power supply voltage is lower than the specified voltage Va, the operation mode shifts to a stop mode in which current consumption is suppressed. On the other hand, the sub control circuit 13
When the output voltage of the power supply circuit 7 is equal to or higher than the specified voltage Va, the data transmitted by the main control circuit 12 in synchronization with the data set signal is converted by software into level inversion at the leading edge and the trailing edge of the data set signal. Determined and received by
The operation of the main control circuit 12 is monitored. On the other hand, when the power supply voltage is less than the specified voltage Va, the data is received by detecting the level inversion of the leading edge and the trailing edge of the data set signal by hardware, and the data is limitedly supplemented in place of the main control circuit 12. Perform the action. As an edge detection hardware, an analog type edge detection circuit (not shown) or the like is used, and such an edge detection circuit is connected to a data set signal input port and an interrupt port.

The data receiving operation of the sub control circuit 13 is shown in FIG.
As shown in (1), the receiving method differs depending on the magnitude relationship between the power supply voltage and the specified voltage Va. First, in the determination step (101), the receiving method is selected based on the output of the voltage comparator 15. Here, suppose that the output voltage of the power supply circuit 7 is the specified voltage Va.
If so, as shown in step (102), the data to be transmitted by the main control circuit 12 in synchronization with the data set signal is determined by software for level inversion at the leading edge and trailing edge of the data set signal. I do. This software discriminates the level of a data set signal between high and low for a specified number of samples, that is, for a predetermined period. When the same level exceeding a predetermined number is continuously obtained after level inversion, the level is set. It is programmed to determine the reversal. Thus, when it is found in step (103) that the level of the data set signal has been continuously inverted at the leading edge and trailing edge, in the next step (104), the data transmitted by the main control circuit 12 is transmitted to the sub-control circuit. 13 receives. In this case, since the level inversion of the data set signal is determined by software that monitors the level transition for a certain period including the level inversion point, avoid erroneous determination due to sudden and non-persistent external noise such as ignition noise. Can be.

On the other hand, when the power supply voltage is lower than the prescribed voltage Va, as shown in step (105), the level inversion of the leading edge and the trailing edge of the data set signal is detected by hardware, that is, the edge is detected. To detect. in this case,
If the cause of the power supply voltage drop is due to a collision, the effects of ignition noise etc. are not considered.Also, even if a collision has not occurred, urgent situations can be determined by the analog type edge detection circuit. The level inversion of the data set signal can be quickly detected. And
When it is determined in step (106) receiving the edge detection result that the level of the leading edge and the trailing edge of the data set signal has been inverted, in the next step (107)
The sub-control circuit 13 receives data transmitted by the main control circuit 12 through an interrupt operation. Therefore, the main control circuit 12
Is transmitted by the sub-control circuit 13 in the shortest time. The sub-control circuit 13 that has received the data writes the received data to the memory 14 in place of the main control circuit 12 in step (108). In this case, the current consumption of the sub-control circuit 13 is smaller than that of the main control circuit 12, so that the load on the backup power supply 7a is small, and no write leakage occurs.

As described above, the airbag control device 11
Immediately after the main control circuit 12 shifts to the stop mode in response to the decrease in the power supply voltage, when the data such as the collision determination data and the abnormality diagnosis data is transferred to the sub control circuit 13, the sub control circuit 13 The main control circuit 12 transmits the signal so as to switch the level inversion of the leading edge portion and the trailing edge portion to the determination using the edge detection circuit instead of the redundant determination process up to that point, and to shift to the interrupt operation immediately after the determination. Data can be received immediately. For this reason, important data indicating the operation history before and after the fluctuation of the power supply voltage can be received as quickly as possible, and required data can be received efficiently by using a backup power supply having a limited power supply capacity. Therefore, a large-capacity backup capacitor is not required for the backup power supply, and the entire control device 11 including the power supply circuit 7 can be reduced in size and cost.

The main control circuit 12 and the sub control circuit 13
Are connected to the voltage comparators 15 that monitor the output voltage of the power supply circuit 7 and determine the threshold value based on the specified voltage Va, so that both the control circuits 12 and 13 can quickly switch the operation mode according to the power supply voltage. Possible, sub-control circuit 1
3 indicates that even after the main control circuit 12 has shifted to the stop mode,
When it is detected from the output of the voltage comparator 15 that the power supply voltage has recovered to the specified voltage Va or more, a reset signal for urging the main control circuit 12 to return to the operation mode can be issued. Since the threshold level set in the voltage comparator 15 can be freely and accurately changed in accordance with the discharge characteristics of the above, it is possible to flexibly respond to the device configuration.

Further, the power supply circuit 7 is provided with a backup power supply 7b at a safe place sufficiently away from the battery power supply 7a so that even if the battery power supply 7a is damaged due to an accident or the like, the backup power supply 7b is not damaged at the same time. By doing so, the main control circuit 12 and the sub control circuit 13 are reliably supported by the backup power supply 7b when the battery power supply 7a is invalidated, and the airbag control device 11
Proper function maintenance is possible.

In the airbag control device 11, the sub control circuit 13 monitors the operation of the main control circuit 12, which is the main subject of collision determination, so that an abnormal operation of the main control circuit 12 is detected at an early stage, and a collision occurs. In this case, one of the main control circuit 12 and the sub-control circuit 13 stores the processing data in the memory 14, so that the risk of the processing progress at the time of occurrence of a collision being dispersed can be dispersed. In addition, the collision determination and the abnormality diagnosis, which are very important for the airbag 2, are periodically prioritized by the timer interrupt for the collision determination, and the abnormality diagnosis is continuously performed using the other time. The required algorithm required for the collision determination can be surely digested within the timer interrupt period, and the sub-control circuit 13 can detect the operation abnormality of the main control circuit 12 by monitoring the timer interrupt. Meanwhile, the main control circuit 12
Since the sub-control circuit 13 is in charge of the substantial diagnosis of the diagnostic data collected by the sub-controller, the burden on the main control circuit 12 can be reduced. Furthermore, for a difference in current consumption based on a difference in the amount of work between the main control circuit 12 and the sub-control circuit 13, the battery power supply 7a cannot be obtained with the occurrence of a collision, or a backup power supply 7b instead of the battery power supply is used. However, when the power supply voltage becomes insufficient, switching from data writing by the main control circuit 12 to data writing by the sub-control circuit 13 allows
You can save as much data as possible with less power.

In the above embodiment, when the output voltage of the power supply circuit 7 is higher than the specified voltage Va, the main control circuit 12
Is configured to receive the diagnostic data output by judging the leading edge and trailing edge of the data set signal from the level transition for a certain period. For the purpose of introducing a bidirectional communication relationship, different meanings are given to the leading edge and the trailing edge of the data set signal, and the detection method on the side of the sub-control circuit 13 is changed to the leading edge and the trailing edge of the data set signal. It is also possible to make different.

The airbag control device 21 shown in FIG.
The main control circuit 12 collectively manages the output of the voltage comparator 15,
If the power supply voltage is lower than the specified voltage Va, the main control circuit 12 transmits a memory write request signal to the sub-control circuit 13, and both control circuits 12, 13 use the memory write request signal as a starting point for an emergency. The time axis is unified so that they can be handled simultaneously. Furthermore, in order to establish a more advanced two-way communication relationship between the main control circuit 12 and the sub-control circuit 13,
The sub control circuit 13 that has received the diagnostic data
Is provided with a signal line for transmitting a data receive signal. Here, the bidirectional communication relationship means that, for example, when the output voltage of the power supply circuit 7 is equal to or higher than the specified voltage Va, the data set signal falls when the diagnostic data is transmitted from the main control circuit 12 to the sub-control circuit 13. Further, when the main control circuit 12 receives the data indicating the diagnosis result returned from the sub-control circuit 13 and transmits the data indicating the end of the diagnosis to the sub-control circuit 13, the diagnostic data and the diagnostic data are raised. Data indicating the diagnosis result and data indicating the end of the diagnosis are exchanged in accordance with a certain sequence, and the leading edge and the trailing edge of the data set signal are set at a predetermined timing according to the bidirectional communication procedure. Invert the level.

More specifically, data reception is performed by the sub-control circuit 13 in accordance with the procedure shown in FIG. First, when the output voltage of the power supply circuit 7 is equal to or higher than the specified voltage Va, the diagnostic data output by the main control circuit 12 is received by judging the leading edge of the data set signal by edge detection. That is, step (202) following step (201),
At (203), the fall of the data set signal is determined by edge detection, and together with the fall, diagnostic data is received from the main control circuit 12 at step (204).

Upon receiving the diagnostic data, the sub-control circuit 13
The data receive signal falls and the main control circuit 12 is diagnosed based on the diagnostic data. In the case of the embodiment,
The diagnostic data includes a passing point flag inserted at an appropriate position in a program to be digested by the timer interrupt operation of the main control circuit 12, that is, the main control circuit 12 passes a required passing point while performing a given job step by step. Is used. The sub-control circuit 13 compares the passing point flag received at the time of the previous diagnosis with the passing point flag received at the time of the current diagnosis, and determines the presence or absence of an abnormality according to whether or not the passing points indicated by the two flags have an appropriate continuous relationship. . Here, if the passing points indicated by both flags do not have an appropriate continuous relationship, an abnormality determination is made in a determination step (205), and if there is no abnormality, a data receive signal is turned on in a subsequent step (206). Lower. Therefore, the main control circuit 12 can recognize that it is normal by the falling edge of the data receive signal, and can resume the interrupted operation during the diagnosis period.

In this embodiment, the leading edge of the data set signal is determined not by observing the level transition during a certain period but by edge detection. The main control circuit 1 which outputs the diagnostic data and requests the sub-control circuit 13 for the diagnosis
In contrast, the diagnosis data can be received as early as possible, and the diagnosis result can be sent back as quickly as possible, thereby minimizing the operation interruption period of the main control circuit 12 due to the diagnosis waiting. Although the edge detection method is said to be relatively vulnerable to extraneous noise, here, the leading edge and the trailing edge of the data set signal are not determined by edge detection, but the trailing edge is determined as described later. Is adopted by determining the level transition during a certain period, so that the diagnosis time can be shortened and the communication reliability can be made compatible as long as the noise environment is not bad.

In step (206), the sub control circuit 13, which has transmitted the data receive signal to the main control circuit 12,
The fact that the main control circuit 12 has started the data set signal after receiving the data receive signal is determined in step (20).
In 7), the trailing edge of the data set signal is determined and detected from the level transition for a certain period. Then, when it is determined in the judgment step (208) that the data set signal has risen, as shown in step (209), the sub control circuit 13 receives the diagnosis end data output from the main control circuit 12, The main control circuit 12 is diagnosed based on the diagnosis end data. Then, if there is no abnormality, a step (211) following the determination step (210)
, The data receive signal is started, and all the one-time diagnostic operations are completed. If an abnormality is found from the diagnosis end data, an abnormality determination is made as in step (205). At the time when the main control circuit 12 raises the data set signal, the operation of the main control circuit 12 has already ended, and therefore, the emphasis should be placed on reliably determining the trailing edge of the data set signal. Therefore, although somewhat redundant, a method of judging and detecting level inversion at a trailing edge of the data set signal from a level transition for a certain period is advantageous. That is, in this case, the end transition of one diagnosis is ensured by eliminating the external noise and the confusion with the data set signal indicating the next diagnosis request by the level transition determination method instead of the edge detection determination method. Can be detected.

On the other hand, when the output voltage of the power supply
When the value is less than a, the main control circuit 12 that has received the output of the voltage comparator 15 causes the memory write request signal to fall, so that the process immediately proceeds from the determination step (201) to the interrupt step (212) and thereafter. Here, similarly to the above embodiment, the memory write data output from the main control circuit 12 is received by determining the leading edge of the data set signal by edge detection. That is, in steps (212) and (213) subsequent to step (201), the falling edge of the data set signal is determined by edge detection, and together with the falling edge determination, the data receive signal falls in step (214). In step (214), the sub-control circuit 13 that has received the memory write data and transmitted the data receive signal to the main control circuit 12
Detects that the main control circuit 12 has started the data set signal after receiving the data receive signal in the following step (215) by determining the trailing edge of the data set signal by edge detection. Then, when it is determined in the determination step (216) that the data set signal has risen, the data receive signal rises as shown in step (217).

The main control circuit 12, having learned that the transfer of the memory write data to the sub-control circuit 13 is performed according to a predetermined sequence by the rise of the data receive signal, The aforementioned memory write request signal rises. Therefore, in the determination step (218), the sub-control circuit 1 that has learned that the memory write request signal has risen
3 writes the received data in the memory in step (219).

As described above, the airbag control device 21
Data transfer and abnormality diagnosis can be performed between the main control circuit 12 and the sub control circuit 13 with more advanced bidirectional communication, and at the same time, the bidirectional communication performed between the main control circuit 12 and the sub control circuit 13 can be performed. It is possible to achieve a good balance between shortening of communication time and securing of reliability.

[0031]

As described above, according to the present invention, a power supply in which an external power supply and a backup power supply are connected in parallel is provided.
A power supply circuit, a drive circuit of an airbag deploying means,
An acceleration sensor that detects acceleration,
Connected to the speed sensor and based on the signal from the acceleration sensor
Output an airbag deployment signal to the drive circuit
If the output voltage of the power supply circuit is higher than the specified voltage,
It is in the operation mode to execute the operation program and its output
Reduced current consumption when voltage is less than specified voltage
The main control circuit that shifts to the stop mode and the main control circuit
Connected to a data set signal from the main control circuit.
And a sub-control circuit for receiving data to be transmitted.
In the control device, the output voltage of the power supply circuit is higher than the specified voltage
Voltage comparing means for determining whether or not the main control circuit and the sub-control
Connected to a circuit to write or read data
The sub control circuit has a voltage ratio
The output voltage of the power supply circuit is regulated based on the determination result of the comparing means.
If the voltage is higher than the constant voltage, the leading edge of the data set signal or
Based on the level transition of the trailing edge for a certain period, the main control circuit
From the power supply circuit,
If the voltage is below the specified voltage, the edge of the data set signal
Data sent from the main control circuit based on the
Data is received and written to nonvolatile memory.
And the output voltage of the power supply circuit drops below the specified voltage
In addition, the sub-control circuit transmits data transmitted from the main control circuit.
Receive and write to nonvolatile memory as soon as possible
Can be. As a result, the secondary control circuit can be used without wasting the life of the backup power supply with limited power supply capacity.
Can receive required data transmitted from the main control circuit within a limited period, so that a large-capacity backup capacitor is not required for the backup power supply, and the entire control device including the power supply circuit can be downsized. And excellent effects such as cost reduction are possible.

Further, according to the present invention, when the output voltage of the power supply circuit is equal to or higher than a specified voltage, the sub-control circuit outputs the diagnostic data output by the main control circuit to the leading edge of the data set signal. In addition to receiving and judging by detection, data indicating the end of diagnosis output from the main control circuit that has received the signal indicating the diagnosis result is received by judging the trailing edge of the data set signal from the level transition for a certain period. With this configuration, even when the power supply circuit is at or above the specified voltage and the main control circuit is operating in the normal operation mode, the diagnostic data is output together with the leading edge of the data set signal and a diagnosis request is issued to the sub control circuit. By receiving diagnostic data as soon as possible and sending back the diagnostic results to the main control circuit that has performed the diagnostics, the operation interruption period of the main control circuit due to waiting for diagnosis can be minimized. When the main control circuit that has received the diagnosis result outputs data indicating the end of diagnosis together with the trailing edge of the data set signal, the main control circuit has already completed the operation interruption period. The method focuses on the reliable determination of the trailing edge of the data set signal, and adopts a method of detecting the level inversion at the trailing edge of the data set signal, which is somewhat redundant, so that extraneous noise and the next transmission will be transmitted. The confusion with the data set signal indicating the diagnosis request can be eliminated, the end of one diagnosis can be reliably detected, and the time and reliability of the bidirectional communication performed between the main control circuit and the sub control circuit can be reduced. There is an effect that it is possible to balance the securing of the properties in a well-balanced manner.

Further, the main control circuit and the sub control circuit are connected to voltage comparators for monitoring the output voltage of the power supply circuit and determining the threshold value based on the specified voltage, so that both control circuits correspond to the power supply voltage. The operation mode can be quickly switched, and the sub-control circuit detects that the power supply voltage has recovered to the specified voltage or more from the output of the voltage comparator even after the main control circuit has shifted to the stop mode. A reset signal that prompts the circuit to return to the operation mode can be issued, and the threshold level set in the voltage comparator can be freely and accurately changed according to the discharge characteristics of the backup power supply. It is possible to achieve an effect that a flexible response can be made in accordance with the requirements.

Furthermore, when the power supply circuit is charged by a battery power supply as an external power supply and the battery power supply and the output voltage of the battery power supply falls below the charging voltage,
Since the backup power supply supplies the power supply current instead of the battery power supply, it is backed up in a safe place sufficiently away from the battery power supply so that the backup power supply will not be damaged if the battery power supply is damaged due to an accident. By providing the power supply, the main control circuit and the sub-control circuit are reliably supported by the backup power supply when the battery power supply is invalidated, and the functions of the control device can be maintained.

In addition, the main control circuit operates in accordance with an operation program mainly including a main routine based on abnormality diagnosis and a timer interrupt routine which performs priority processing by an almost regular interrupt request and determines an event according to a predetermined algorithm. An operation program that operates and includes a step of monitoring whether or not a main control circuit is interrupted by a timer at a predetermined period, and a step of determining whether there is an abnormality from diagnostic data transmitted by the main control circuit. , The priority of the event judgment should be periodically processed by timer interrupt for two very important items, event judgment and abnormality diagnosis, and the abnormality diagnosis should be continuously performed using other time This ensures that the required algorithm required for event determination is digested within the timer interrupt period. In addition, the sub control circuit determines whether the main control circuit is continuously performing the collision judgment operation by monitoring the timer interrupt, so that an abnormality in the main control circuit can be detected at an early stage. It works.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of an airbag control device to which a control device of the present invention is applied.

FIG. 2 is a flowchart for explaining a data receiving operation of a sub control circuit shown in FIG. 1;

FIG. 3 is a circuit diagram showing another embodiment of the airbag control device to which the control device of the present invention is applied.

FIG. 4 is a flowchart for explaining a data receiving operation of the sub-control circuit shown in FIG. 3;

FIG. 5 is a circuit diagram showing an example of a conventional airbag control device.

[Explanation of symbols]

 Reference Signs List 7 power supply circuit 7a battery power supply (external power supply) 7b backup power supply 11, 21 airbag control device 12 main control circuit 13 sub-control circuit 14 memory 15 voltage comparator

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G05B 9/02 B60R 21/32 G06F 1/28

Claims (5)

(57) [Claims] 1. A and the external power supply and a backup power supply circuit power supply and are connected in parallel, driving for deployment means for an air bag
Circuit, an acceleration sensor for detecting the acceleration of the vehicle,
Connected to the drive circuit and the acceleration sensor.
The airbag deployment signal is driven based on the signal from the sensor
Circuit, and the output voltage of the power supply circuit
Operation mode to execute the required operation program
The output voltage is lower than the specified voltage.
Main control circuit shifts to stop mode with reduced current consumption
Is connected to the main control circuit, and data is transmitted from the main control circuit.
A secondary receiver that receives data transmitted in synchronization with the
A control circuit comprising: a control circuit configured to determine whether an output voltage of the power supply circuit is equal to or higher than the specified voltage.
Another voltage comparing means, and a data comparing means connected to the main control circuit and the sub-control circuit.
The non-volatile memory to which writing or reading is performed is
The sub-control circuit is provided based on a determination result of the voltage comparing means.
There are, when the output voltage of the power supply circuit is not less than the prescribed voltage
Is a period of the leading edge or trailing edge of the data set signal.
Transmitted from the main control circuit based on the level transition between
Received data, and the output voltage of the power supply circuit is less than the specified voltage
Based on the edge detection result of the data set signal
Before receiving the data transmitted from the main control circuit.
Writing to a non-volatile memory . 2. The sub-control circuit, when an output voltage of the power supply circuit is equal to or higher than a specified voltage, judges diagnostic data output by the main control circuit by detecting a leading edge of the data set signal by edge detection. Receiving the signal indicating the end of the diagnosis output from the main control circuit that has received the signal indicating the diagnosis result, and determining and receiving the trailing edge of the data set signal from the level transition for a predetermined period. The control device according to claim 1, wherein 3. The power supply circuit according to claim 1 , wherein
Is connected the the serial main control circuit to the sub-control circuit, according to claim 1, wherein monitoring the output voltage of the power supply circuit, wherein the specified voltage is a voltage comparator for threshold determination on the basis of the
The control device as described. 4. The power supply circuit includes: a battery power supply as an external power supply; and a power supply current charged by the battery power supply, and when the output voltage of the battery power supply falls below the charged voltage, the power supply current replaces the battery power supply. 2. The control device according to claim 1, further comprising a backup power supply for supplying the power. 5. An operation program mainly comprising: a main routine based on abnormality diagnosis; and a timer interrupt routine that performs priority processing by an almost periodic interrupt request and determines an event according to a predetermined algorithm. The sub-control circuit includes a step of monitoring whether or not the main control circuit is interrupted by a timer at a predetermined cycle, and a step of determining whether there is an abnormality from the diagnostic data transmitted by the main control circuit. 2. The control device according to claim 1, wherein the control device operates according to an operation program.