JPH1117716A - Data communication circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To share the unit of a crew protector for side crush in spite of car types and to prevent erroneous assembly by making the memory of a main control part into writable memory, composing a microcomputer of a subcontrol part of a temporary storage type memory and setting the stored data of the temporary storage type memory by reading stored data written in the writable memory. SOLUTION: All tuning constants are written and stored in a 1st ROM and each time, an ignition switch 5 is turned on, the tuning constants stored in the 1st ROM 50 are read and stored in a 2nd RAM 51 and a 3rd RAM 52. Thus, a microcomputer 14 reads a parameter from the 1st ROM 50 and transmits it to a microcomputer 28 of each crew protector for side crush. Thus, it is not necessary for the respective microcomputers of the main control part and the plural subcontrol parts to respectively have peculiar data and the hardware of the subcontrol part can be shared.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centralized control data communication circuit used for an occupant protection device having a plurality of airbags for protecting an occupant in the event of a vehicle collision.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional occupant protection device using a data communication circuit of this type of centralized control system, and its structure will be described below. That is, what is shown in FIG. 4 is the one in which the front collision occupant protection device 1, the front passenger occupant protection device 2 and the driver side occupant protection device 3 are combined using multiplex communication. The front occupant protection device 1 will be described first, and then the front passenger occupant protection device 2 will be described. Note that the driver's side passenger occupant protection device 3 is substantially the same as the passenger seat side occupant protection device 2, and a detailed description thereof will be omitted.

First, the configuration of the front collision occupant protection device 1 will be described. That is, 4 is a battery, 5 is an ignition switch, and 6 is a booster circuit, which boosts an input voltage from the battery 4 supplied through the ignition switch 5 and charges a backup capacitor 8 through a resistor 7. The boosted voltage is supplied to the passenger side side occupant protection device 2 via the first switch circuit 10 and the resistor 11 inserted in the power supply line 9 in series.
The boosted voltage is supplied to the driver's side side occupant protection device 3 via the second switch circuit 35 and the resistor 44 interposed in series. Reference numeral 13 denotes a longitudinal acceleration sensor that detects acceleration generated in the longitudinal direction of the vehicle. An acceleration signal, which is a detection signal, is supplied to the microcomputer 14.

The microcomputer 14 has a collision judgment function, and when executing the collision judgment function, the first ROM
(Abbreviation of read only memory) Reads the algorithm tuning constant for collision determination stored in 15 and executes an algorithm tuned based on the constant to make a collision determination. That is, the microcomputer 14 is shared in terms of hardware for all types of vehicles, and differs only in tuning constants related to the operation of the algorithm. For this purpose, the microcomputer 14 can cope with the collision determination of each vehicle type only by writing the tuning constant suitable for the vehicle type in the first ROM 15.
After reading the tuning constant from, the acceleration signal supplied from the longitudinal acceleration sensor 13 is calculated by a predetermined algorithm, and when it is determined that a serious collision has occurred, the third switch circuit 16 is turned on to charge the backup capacitor 8. The discharged charge is discharged to the diode 17
Discharge is performed through the switch circuit 16, and an ignition current is applied to the primer 18 and the mechanical acceleration switch 19 in series.

[0005] The microcomputer 14 comprises:
The important circuit portions of the front collision occupant protection device 1, the front passenger occupant protection device 2 and the driver side occupant protection device 3 have a failure diagnosis function. For example, the front passenger occupant protection device 2 When failure data is detected by performing multiplex communication with the microcomputer 28 via the power supply line 9 and the signal line V, a notification is made via an alarm unit (not shown). Further, the microcomputer 14 is provided for a predetermined time immediately after the ignition switch 5 is turned on (the microcomputer 28 of the side collision occupant protection devices 2 and 3 performs the initial failure diagnosis during the predetermined time). ), The first and second switch circuits 10, 35 are turned off via the signal lines X, U, and the signal line T,
The fourth switch circuit 38 is turned on through the microcomputer and the microcomputer 28 of each of the side collision occupant protection devices 2 and 3
Start the initial failure diagnosis of.

[0006] The microcomputer 14 comprises:
A request signal is transmitted to the microcomputer 28 of the passenger side side occupant protection device 2 via the signal line S, the first communication circuit 20, the switching transistor 21, the resistor 22, and the power supply line 9, and The response signal from 28 is input via the second communication circuit 20 ', the switching transistor 23, the resistor 24, the power supply line 9, and the signal line V. The microcomputer 14 is also connected to the microcomputer (not shown) of the driver's side side occupant protection device 3 via the signal line S, the first communication circuit 20, the switching transistor 25, the resistor 26, and the power supply line 12. And a response signal from a microcomputer (not shown) is input via a communication circuit, a switching transistor, a resistor, a power supply line 12 and a signal line Y in the same manner as the passenger side passenger protection device 2. I do.

Reference numeral 16 denotes a first switch circuit which is interposed between the booster circuit 6 and the primer 18 and is turned on when an ignition signal is supplied from the microcomputer 14 to turn on the primer 1
The ignition current is supplied to a series circuit composed of the motor 8 and the mechanical acceleration switch 19. When the ignition current is supplied, it goes without saying that the mechanical acceleration switch 19 is on. When a request signal is supplied from the microcomputer 14 via the signal line S, the first communication circuit 20 switches the two switching transistors 2 based on the address data attached to the request signal.
1 and 25 are selectively operated, and the request signal is transmitted via the power supply line 9 or 12 to either the passenger side passenger occupant protection device 2 or the driver side passenger occupant protection device 3. Crab is transmitted.

Reference numerals 36, 39 and 40 denote backflow preventing diodes, and reference numeral 37 denotes a resistor.

Next, the passenger-side side occupant protection device 2 will be described. Reference numeral 27 denotes the same acceleration sensor as the front-rear direction acceleration sensor 13, which is different from the front-rear direction acceleration sensor 13 in the detection direction and is mounted so as to detect the acceleration in the left-right direction of the vehicle. 28. The microcomputer 28 has a collision judging function similarly to the microcomputer 14, and based on an acceleration signal supplied from the lateral acceleration sensor 27 and a switch signal supplied from an acceleration switch 29 described later, the microcomputer 28 The magnitude of the collision from one side is determined, and when it is determined that the collision is a serious collision, the switch circuit 30 is turned on to supply an ignition current to the primer 31.

The microcomputer 28 has a diagnostic function similarly to the microcomputer 14, and
1 and the like, and based on a request signal supplied via the first communication circuit 20, the result of the diagnosis is transmitted to the second communication circuit 32 (the same as the first communication circuit 20), the power supply line 9 , Via the signal line V to the microcomputer 14 of the front occupant protection system 1. The acceleration switch 29 includes a semiconductor acceleration sensor and a comparison circuit, and outputs a switch signal when an output from the semiconductor acceleration sensor exceeds a reference value of the comparison circuit.

Reference numeral 23 denotes a switching transistor.
ON / OFF controlled by an output signal of the communication circuit 32,
It outputs signals indicating the results of various diagnoses and the like. Reference numeral 24 denotes a resistor inserted between the switching transistor 23 and the power supply line 9. The resistor 24 is connected in series with the resistor 11 via the power supply line 9, and switches the voltage on the anode side of the backflow prevention diode 33. When turned on (or when a switching transistor (not shown) formed on the output side of the first communication circuit 20 is turned on)
The input voltage is maintained at a constant voltage other than the zero level so that an input voltage can be constantly supplied to a constant voltage circuit 34 described later.

Reference numeral 35 denotes a second ROM having the same function as that of the first ROM 15. The second ROM 35 stores a collision determination algorithm tuning constant like the first ROM (abbreviation of read-only memory) 15.
Numeral 8 stores tuning constants related to calculation of an algorithm to be read and used when making a collision determination.

The power supply lines 9 and 12 are connected to each other when the front passenger occupant protection device 1 and the front passenger occupant protection device 2 are communicating with each other.
When communication is performed between the driver and the driver's seat side occupant protection device 2, the voltage waveform is as shown in FIG. That is,
In FIG. 5, the voltage V1 is, for example, a value obtained by dividing the output voltage V3 of the booster circuit 6 when the switching transistor 23 is turned on by resistors 43 and 34, and the voltage V2 is a voltage when the switching transistor 23 is turned off. It is determined by the value of the resistor 11.

Next, the operation of the above configuration will be described with reference to FIG. First, when the ignition switch 5 is turned on, the microcomputers 14 and 28 are power-on reset (step ST100), the microcomputers 14 and 28 enter a communication initial diagnosis mode in step ST110, and the front collision occupant protection device 1 becomes an assistant. It is determined whether communication is possible between the occupant protection device 2 for the seat and the occupant protection device 3 for the driver seat, whether the diagnosis function is operable, whether the collision determination function is operable, and the like. Thereafter, the microcomputers 14 and 28 proceed to step ST120, and perform a process of shifting to the next step, that is, a process such as address assignment of an internal memory. Step S
In T130, in order to output a watchdog pulse to an external watchdog timer (not shown) of the microcomputer 14, 28, the logic of the watchdog pulse output terminal is inverted every time this step is passed.
Thereafter, a normal failure diagnosis step ST14 described below.
0, proceed to collision determination step ST150,
Circular between 130 and 150.

(1) Normal failure diagnosis function (step ST1)
40) When the microcomputer 14 of the occupant protection system 1 starts operating, the microcomputer 14 connects the first and second switch circuits 10, 3 via the signal lines U, X.
5 in the off state, and the fourth signal via the signal line T.
The program of the microcomputer 14 of the front occupant protection device 14, the program of the microcomputer 28 of the front passenger occupant protection device 2, and the driver seat The program of the microcomputer of the occupant protection device 3 starts operating simultaneously and independently.

After the end of the predetermined time, the microcomputer 14 of the front collision occupant protection device 1 transmits the signal to the front passenger collision protection device 1 via the signal line S, the first communication circuit 20, and the like.
A request signal is output from the microcomputer 14 of
Response signals to the request signal are sent from the microcomputers 28 of the passenger and driver side passenger occupant protection devices 2 and 3 via the second communication circuit 32 and the switching transistor 23 to the front passenger occupant protection device 1. A response signal including a diagnosis result is transmitted to the microcomputer 14. As a result, if it is determined that an abnormality such as a failure has occurred even in a part of the entire circuit, an alarm signal is output from the microcomputer 14 of the front collision occupant protection device 1 to an alarm device (not shown). And be informed.

The microcomputer 28 in the passenger side passenger occupant protection device 2 of the two side passenger occupant protection devices that have received the request signal is, for example, a component within the passenger seat side passenger occupant protection device 2, for example, a primer. The terminal voltage of the terminal 31 is read, and the switching transistor 23 is turned on and off by the output of the second communication circuit 32, so that the microcomputer 14 of the front occupant protection device 1 is connected to the microcomputer 14 via the power supply line 9 via the signal line V. The microcomputer 14 determines whether there is a signal indicating a failure in the microcomputer 14 and, when determining that there is a signal indicating a failure, activates an alarm device (not shown). It goes without saying that the same operation is performed for the driver's side side occupant protection device 3 as well.

(2) Collision Judgment (Step ST150) After the above-mentioned various diagnoses are completed, the microcomputers 14 and 28 obtain the tuning constants from the first, second and third ROMs 15, 35 and 41 respectively connected thereto. It reads and sets the algorithm program for collision determination. Then, when the vehicle crashes forward,
When the mechanical acceleration switch 19 of the front collision occupant protection device 1 is turned on and the microcomputer 14 determines that a serious collision has occurred based on the acceleration signal from the longitudinal acceleration sensor 13, the microcomputer 14 switches the switch circuit 1.
6 is turned on, the electric charge charged in the backup capacitor 8 is supplied to the detonator 18 via the discharge diode 17 to deploy an airbag or the like, thereby protecting the occupant from a forward collision.

When the vehicle is collided with the passenger seat,
The microcomputer 28 of one of the side collision occupant protection devices, for example, the side collision occupant protection device 2 for the front passenger seat, receives a switch signal from the acceleration switch 29 and an acceleration signal from the lateral acceleration sensor 27. When it is determined that the vehicle is in a serious collision, the switch circuit 30 is turned on to supply the electric charge charged in the backup capacitor 8 to the detonator 31 via the power supply line 9 to deploy the airbag to inflate the occupant from the side collision. Protect. It goes without saying that the same operation is performed also for the driver's side side occupant protection device 2.

[0020]

However, when the occupant protection device shown in FIG. 3 is used, since the tuning constant of the collision algorithm of the microcomputer differs for each vehicle type, a predetermined tuning constant is written for each vehicle type. However, there is a problem that a unit of the side collision occupant protection device on which the read ROM is mounted must be set, and each unit must be managed and stored in a factory or the like. In addition, once an erroneous assembly is performed, the distinction becomes indistinguishable, and it has been difficult to carefully manage the erroneous assembly.

The present invention has been made in view of the above problem, and has as its object to share the unit of the side collision occupant protection device irrespective of the type of vehicle and to prevent erroneous assembly.

[0022]

According to a first aspect of the multiplex communication circuit, a microcomputer provided in each of a main control unit and a plurality of sub-control units connected to the main control unit is provided. In the data communication circuit in which multiplex communication is performed and a control signal is created by each microcomputer based on data stored in a memory provided in each of the microcomputers, the memory of the main control unit is a writable memory; The microcomputer of the sub-control unit is configured by a temporary storage type memory, and storage data of the temporary storage type memory is set by reading storage data written in the writable memory. I do.

According to a second aspect of the present invention, in the first aspect, the memory of the sub-control unit is reset when the power supply is turned off, and the microcomputer of the sub-control unit is connected to the main control unit when the power is turned on. The storage data is read from the writable memory, and the read storage data is written to the temporary storage type memory of the sub-control unit using the storage data, and the microcomputer of the sub-control unit A control signal is generated based on the control signal.

A third invention is characterized in that the stored data in the second invention is a tuning constant.

According to a fourth aspect of the present invention, the main control unit is a front collision occupant protection device that operates in a frontal collision, and the sub-control unit is a side collision occupant protection device that operates in a side collision.
The main control unit and the plurality of sub-control units are connected by signal lines, and a tuning constant used for an arithmetic algorithm of a microcomputer of the main control unit and a tuning constant used for an arithmetic algorithm of a microcomputer of the sub-control unit. And a constant stored in the memory of the main control unit, and a tuning constant stored in the memory of the main control unit when power is turned on is transmitted to the memory of the sub-control unit via the signal line. I do.

A fifth invention is characterized in that the signal line is shared with a power supply line.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. The first embodiment according to the present invention will be described with reference to FIG. 1. The same components as those of the conventional configuration already described with reference to FIG. Only different parts will be described below.

That is, in FIG. 4, tuning constants of signal processing algorithms performed by the microcomputers 14 and 28 of the front collision occupant protection device 1 and the side collision occupant protection devices 2 and 3 are respectively provided. The first, second, and third ROMs 1, 2, and 3 are stored in the first, second, and third ROMs 15, 35, and 41 when performing calculations.
5, 35 and 41 were read. On the other hand, in FIG. 1, the first ROM 15 in FIG.
In the first RAM 50, and the second ROM 35 in the second RAM 51.
Next, the third ROM 41 is replaced with the third RAM 52, and all tuning constants are written and stored in the first ROM 50. Each time the ignition switch 5 is turned on, the first R
The tuning constant stored in the OM 15 is stored in the second RAM 5
The first and third RAMs 52 are configured to read and store.

Thus, the microcomputer 14
The flowchart of step ST16 shown in FIG.
0 and ST170 are added. That is, the microcomputer 14 reads the parameters (tuning constants) from the first ROM 50 in step ST160, and transmits them to the microcomputer 28 of each side occupant protection device 2, 3 in the next step ST170.

In the above embodiment, each microcomputer 1 is used as an occupant protection device system.
The corresponding switch circuits 16 and 30 are turned on by 4 and 28 to drive the respective primers 18 and 31. However, the microcomputer 14 of the front occupant protection device 1 collectively manages the collision data. Needless to say, a system for turning on the respective switch circuits 16 and 30 as shown in FIG.

[0031]

As described above, according to the first aspect, the microcomputers of the main control unit and the plurality of sub-control units do not need to have their own data. The effect that the hardware of this can be shared is exhibited.

According to the second aspect of the present invention, since data is supplied from the main control unit to the sub-control unit when the power is turned on, the effect is obtained that the memory of the sub-control unit may be a temporary storage type inexpensive memory. You.

According to the third and fourth aspects of the invention, different tuning constants can be collectively managed for each vehicle type such as an airbag, and the effect of facilitating parts management and process management can be achieved.

According to the fifth aspect, since the signal line and the power supply line are shared, the effect of reducing the number of lines used and simplifying the wiring is exhibited.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a first embodiment in which a data communication device according to the present invention is used for an occupant protection device.

FIG. 2 is a flowchart illustrating a microcomputer of the frontal occupant protection device according to the present invention in FIG. 1;

FIG. 3 is an explanatory diagram of a circuit block according to the first embodiment in which the data communication device according to the present invention is used for another occupant protection device.

FIG. 4 is an explanatory diagram of a conventional circuit block.

FIG. 5 is an explanatory waveform diagram for explaining a communication method of the circuit block in FIG. 4;

FIG. 6 is an explanatory flowchart of a microcomputer of the conventional front occupant protection device of FIG. 4;

[Explanation of symbols]

 13, 27 Acceleration sensor 14, 28 Microcomputer 16, 10, 30, 35 Switch circuit 18, 31 Primer 20, 32 Communication circuit 21, 23, 25 Switching transistor 29 Acceleration switch 15, 35, 41 ROM 50, 51, 52 RAM

Claims (5)

[Claims] 1. A multiplex communication is performed between microcomputers provided in each of a main control unit and a plurality of sub-control units connected to the main control unit. In a data communication circuit in which a control signal is created based on data stored in a memory, a memory of the main control unit is a writable memory, and a microcomputer of the sub control unit is a temporary storage type memory. The data communication circuit is characterized in that the storage data of the temporary storage type memory is set by reading the storage data written in the writable memory. 2. The memory of the sub-control unit is reset when the power is turned off, and the microcomputer of the sub-control unit reads the stored data from the writable memory of the main control unit with the on operation. Read, and write the read storage data into a temporary storage type memory of a sub-control unit that uses the storage data, and the microcomputer of the sub-control unit generates a control signal based on the storage data. The data communication circuit according to claim 1, wherein: 3. The data communication circuit according to claim 2, wherein said stored data is a tuning constant. 4. The main control unit is a front collision occupant protection device that operates at the time of a frontal collision, and the sub-control unit is a side collision occupant protection device that operates at the time of a side collision. A plurality of sub-control units are connected by signal lines, and a tuning constant used for an arithmetic algorithm of a microcomputer of the main control unit and a tuning constant used for an arithmetic algorithm of a microcomputer of the sub-control unit are the main parameters. A data communication circuit, wherein a tuning constant stored in a memory of the control unit and stored in the memory of the main control unit when the power is turned on is transmitted to the memory of the sub control unit via the signal line. 5. The data communication circuit according to claim 4, wherein said signal line is shared with a power supply line.