JPH05333963A - Electronic controller containing power-on reset circuit - Google Patents

Abstract

PURPOSE:To prevent the malfunction of an electronic controller when a clock oscillation signal of a prescribed oscillation frequency is not outputted from a clock oscillation circuit in a normal way. CONSTITUTION:When the voltage applied to a microcomputer 2 reaches 90-95% of the set voltage, a voltage monitoring circuit 6 outputs a reset release signal. A clock counter 9 starts to count the clock oscillation frequency of the clock oscillation signal of a clock oscillation circuit 3. When the count value of the counter 9 reaches a fixed level, the reset release signal is outputted for the program of the microcomputer 2. Thus, the reset state of the program is released and the microcomputer 2 actuates the program in a normal way. When the circuit 3 has no output, the reset state of the microcomputer 2 is not released and therefore, the microcomputer 2 does not work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic control device used in a control system such as an anti-skid brake control system or a traction control system mounted on a vehicle or the like, and more particularly to monitoring a voltage applied to the electronic control device. Then, the present invention relates to an electronic control device provided with a power-on reset circuit which outputs a program reset release signal when the applied voltage reaches a set voltage.

[0002]

2. Description of the Related Art Generally, an anti-skid brake control (hereinafter, also referred to as ABS control) system, when it detects that a wheel tends to lock during braking, weakens the braking force of the wheel to eliminate the lock tendency. After that, by increasing the braking force again, the system controls the steering of the vehicle and controls the braking so that the braking distance is as short as possible.

In such an anti-skid brake control system, calculation is performed based on the wheel speed to determine whether or not the wheel tends to lock during braking, and the lock tendency of the wheel is determined based on the result of the determination. There is provided an electronic control device equipped with a computer such as a microcomputer that outputs a control signal to a modulator that adjusts the brake pressure so as to cancel the brake pressure.

In such an electronic control unit, not only the power-on voltage does not reach the set voltage immediately after the power is turned on, but the peripheral circuits of the electronic control unit are not completely stable. Moreover, the operation of the mechanical part of the electronic control unit is not completely stable. If the program of the electronic control unit is operated in such a state, the ABS control system may malfunction.

Therefore, it is necessary to operate the program after the applied voltage becomes completely the set voltage, the peripheral circuits become completely stable, and the operation of the mechanical portion becomes completely stable. For this,
Conventionally, the electronic control unit is provided with a power-on reset circuit, and the power-on reset circuit monitors the state of the applied voltage, the peripheral circuit and the mechanical portion.

As an example of a conventional power-on reset circuit, there is a power-on reset circuit as shown in FIG. 4, for example. As shown in FIG. 4, the electronic control unit 1 includes a microcomputer 2 and an X'ta of the microcomputer 2.
The clock oscillator circuit 3 connected to the l terminal, the stabilizing power source 5 provided in the connecting circuit between the battery 4 and the input terminal V _CC of the microcomputer 2, and the stabilizing power source 5 and the microcomputer 2. The voltage monitoring circuit 6 is provided in the connection circuit with the reset terminal RST. Then, the reset terminal RS of the microcomputer 2
A power-on reset circuit 7 is configured by T and the voltage monitoring circuit 6.

Then, when the voltage monitoring circuit 6 monitors the input voltage of the microcomputer 2 and determines that the input voltage has reached 90 to 95% of 5 Volt which is the set voltage, the voltage monitoring circuit 6 causes the microcomputer 2 to operate. It is designed to release the reset of the program.

Another example of the power-on reset circuit is a power-on reset circuit as shown in FIG.
In contrast to the voltage monitoring circuit 6 in the conventional power-on reset circuit 7 described above, as shown in FIG. 5, the power-on reset circuit 7 includes a series circuit of a resistor R and a capacitor C between the stabilizing power source 5 and the ground. In addition to being provided, the resistor R and the capacitor C are connected to the reset terminal RST of the microcomputer 2 via the buffer 8.

The voltage applied to the microcomputer 2 charges the capacitor C, and the resetting of the program of the microcomputer 2 is delayed after the power is turned on based on the time constant of the circuit CR including the capacitor C and the resistor R. It is supposed to be released.

[0010]

In the conventional electronic control unit 1 as described above, the clock oscillation circuit 3 for generating a reference time for program control of the microcomputer 2 is activated at the same time when the microcomputer 2 is powered on. And starts to output a clock oscillation signal. Then, in order for the program of the microcomputer 2 to operate normally, it is necessary that the clock oscillation circuit 3 outputs a clock oscillation signal of a predetermined oscillation frequency (for example, 4 MHz). That is, if the program of the microcomputer 2 is operated in a state where the clock oscillation signal of the predetermined oscillation frequency is not normally output from the clock oscillation circuit 3 due to a failure of the clock oscillation circuit 3 or the like, the electronic control unit 1 will be erroneous. It may operate.

However, in the conventional electronic control unit 1, since it is not monitored whether the clock oscillation signal of the predetermined oscillation frequency is normally output from the clock oscillation circuit 3, the clock oscillation as described above is performed. There is a problem that the malfunction of the electronic control unit 1 due to the failure of the circuit 3 or the like cannot be reliably prevented.

The present invention has been made in view of such a problem, and an object thereof is to provide an electronic control unit when a clock oscillation signal of a predetermined oscillation frequency is not normally output from the clock oscillation circuit. It is an object of the present invention to provide an electronic control device provided with a power-on reset circuit capable of preventing a malfunction of the device.

[0013]

In order to solve the above-mentioned problems, the invention of claim 1 performs a predetermined calculation and outputs a control signal based on the calculation result, and a microcomputer of this microcomputer. At the same time when the power is turned on, a clock oscillation circuit that creates a reference time for program control of the microcomputer, a stabilizing power supply that supplies a predetermined turn-on voltage to the microcomputer, and a program reset release signal after a predetermined time has elapsed after the power was turned on And a power-on reset circuit for outputting to the microcomputer, the clock oscillation circuit between the power-on reset circuit and the microcomputer according to the reset release signal of the power-on reset circuit. Of the clock oscillation signal output from Start the cement, said feeding a reset release signal to the microcomputer Kyusuru clock counter is characterized in that provided when the count reaches a predetermined value.

According to a second aspect of the present invention, the power-on reset circuit monitors at least the applied voltage supplied from the stabilized power supply to the microcomputer, and when the applied voltage reaches a predetermined ratio of the set voltage. , A voltage monitoring circuit that outputs the reset release signal.

According to a third aspect of the present invention, the power-on reset circuit is composed of a capacitor that stores electricity via a resistor at least by a supplied voltage supplied from the stabilized power source to the microcomputer. Is reset to a constant value, the reset release signal is output to the clock counter.

Further, in the invention of claim 4, the clock counter is fed from the time when the reset release signal from the power-on reset circuit is input between the clock counter and the microcomputer. The microcomputer is provided with a count time monitoring circuit that counts the time until the reset release signal is input and does not output the reset release signal to the microcomputer when the count time deviates from a reference value. .

[0017]

In the electronic control device having the power-on reset circuit according to the present invention having such a configuration, the reset release signal of the program is output from the power-on reset circuit to the clock counter after a lapse of a predetermined time after power-on. .. The reset release signal causes the clock counter to start counting the clock oscillation signal output from the clock oscillation circuit, and when the count number reaches a constant value, sends the reset release signal to the microcomputer. ..

Therefore, when the clock oscillation signal is not normally output from the clock oscillation circuit, the reset release signal is not sent to the microcomputer, so that the program operation of the microcomputer is held in a stopped state. This prevents a malfunction of the microcomputer when the clock oscillation signal is not normally output from the clock oscillation circuit.

Further, in the present invention, the count time monitoring circuit determines the time from the input of the reset release signal from the power-on reset circuit to the input of the reset release signal sent from the clock counter. When the count is performed and the count time deviates from the reference value, the reset release signal is not output to the microcomputer.

Therefore, by checking the count time of the clock oscillation signal output from the clock oscillation circuit, when the oscillation frequency of the clock oscillation signal is abnormal, the program operation of the microcomputer will not be performed, and the microcomputer will not operate. The malfunction of the computer is prevented.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a view similar to FIG. 4, showing an embodiment of a power-on reset circuit of an electronic control unit in an anti-skid brake control system according to the present invention. The same components as those of the conventional electronic control device described above are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, in this embodiment, the power-on reset circuit 7 of the conventional electronic control unit 1 shown in FIG. 4 is used.
A clock counter 9 is provided in a connection circuit between the voltage monitoring circuit 6 and the reset terminal RST of the microcomputer 2. The clock counter 9 is connected to the clock signal output terminal CLK of the microcomputer 2.
From this clock signal output terminal CLK, the clock oscillation signal of the clock oscillation circuit 3 is output to the clock counter 9.

In the present embodiment thus constructed, the voltage monitoring circuit 6 outputs a signal when the voltage applied to the microcomputer 2 reaches 90% to 95% of 5 Volt which is the set voltage. With this output signal, the clock counter 9 starts counting the clock oscillation frequency of the clock oscillation signal of the clock oscillation circuit 3, and when the count number reaches a constant value (for example, 2 ¹⁵ ), the reset of the program of the microcomputer 2 is released. Output a signal. As a result, the reset of the program of the microcomputer 2 is released, and the microcomputer 2 operates the program normally.

Therefore, when the clock oscillation circuit 3 is not outputting normally, the reset of the program of the microcomputer 2 is not released, so that the microcomputer 2 does not operate the program and keeps it in the stopped state. As a result, malfunction of the electronic control unit 1 is prevented.

FIG. 2 is a view similar to FIG. 5, showing another embodiment of the present invention. As shown in FIG. 2, in this embodiment, the connection circuit between the buffer 8 of the power-on reset circuit 7 and the reset terminal RST of the microcomputer 2 of the conventional electronic control unit 1 shown in FIG. Similarly to the above, a clock counter 9 is provided, and the clock counter 9 is connected to the clock signal output terminal CLK of the microcomputer 2.

In this embodiment thus constructed, the capacitor C starts charging when the power is turned on. When the amount of electricity stored in the capacitor C reaches a constant value, a signal is input to the clock counter 9. With this signal, the clock counter 9 starts counting the clock oscillation frequency of the clock oscillation signal from the clock oscillation circuit 3 as in the above-described embodiment, and the count number is a constant value (for example, 2 ¹⁵ ).
Then, the reset release signal of the program of the microcomputer 2 is output. The other operation and effect of this embodiment are the same as those of the above-mentioned embodiment, so that the description thereof will be omitted.

FIG. 3 is a view similar to FIG. 1, showing still another embodiment of the present invention. As shown in FIG. 3, in this embodiment, a count time monitoring circuit 10 is provided in a connection circuit between the clock counter 9 of the embodiment shown in FIG. 1 and the reset terminal RST of the microcomputer 2. Further, the count time monitoring circuit 10 is connected to the voltage monitoring circuit 6, so that the signal from the voltage monitoring circuit 6 is not only input to the clock counter 9 but also to the count time monitoring circuit 10. It has become.

In this embodiment thus constructed, the voltage applied to the microcomputer 2 is, for example, 5 Volt 9 which is a set voltage, as in the embodiment shown in FIG.
At 0 to 95%, the voltage monitoring circuit 6 outputs a signal to the clock counter 9 and the count time monitoring circuit 10. With this output signal, the clock counter 9 starts counting the clock oscillation frequency of the clock oscillation signal of the clock oscillation circuit 3, and at the same time, the count time monitoring circuit 10 starts the clock from the time when the signal from the voltage monitoring circuit 6 is input. The time until the output signal of the counter 9 is input is monitored. Then, the count time monitoring circuit 1
0 does not output a reset release signal to the microcomputer 2 when the count time deviates from the reference time. In the present embodiment, when a plurality of microcomputers are used, the count time may be monitored by another microcomputer.

In each of the above-mentioned embodiments, the case where the present invention is applied to the electronic control unit in the ABS control system has been described, but the present invention is not limited to this and, for example, traction control. It can be applied to other electronic control devices including the electronic control device in the system.

[0030]

As is apparent from the above description, according to the electronic control device provided with the power-on reset circuit according to the present invention, when the clock oscillation signal is not normally output from the clock oscillation circuit, Since the reset release signal is not sent, the malfunction of the microcomputer when the clock oscillation signal is not normally output from the clock oscillation circuit can be reliably prevented.

According to the present invention, when the time from the input of the reset release signal from the power-on reset circuit to the input of the reset release signal sent from the clock counter deviates from the reference value. Since the reset release signal is not output to the microcomputer, the malfunction of the microcomputer when the oscillation frequency of the clock oscillation signal is abnormal can be prevented.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of an electronic control device including a power-on reset circuit according to the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit diagram showing still another embodiment of the present invention.

FIG. 4 is a circuit diagram showing an example of an electronic control device including a conventional power-on reset circuit.

FIG. 5 is a circuit diagram showing another example of an electronic control device including a conventional power-on reset circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electronic control device, 2 ... Microcomputer, 3 ... Clock oscillation circuit, 4 ... Battery, 5 ... Stabilized power supply, 6 ...
Voltage monitoring circuit, 7 ... Power-on reset circuit, 8 ... Buffer, 9 ... Clock counter, 10 ... Count time monitoring circuit, R ... Resistor, C ... Capacitor

Claims (4)

[Claims] 1. A microcomputer that performs a predetermined operation and outputs a control signal based on the result of the operation, and a clock oscillation circuit that creates a reference time for program control of the microcomputer at the same time when the power of the microcomputer is turned on. An electronic control device comprising: a stabilized power supply for supplying a predetermined turn-on voltage to the microcomputer; and a power-on reset circuit for outputting a reset release signal of a program to the microcomputer after a lapse of a predetermined time after the power is turned on. Between the power-on reset circuit and the microcomputer, counting of the clock oscillation signal output from the clock oscillation circuit is started by the reset release signal of the power-on reset circuit, and the count number becomes a constant value. When the reset solution Electronic controller having a power-on reset circuit, characterized in that the signal of the feed to the microcomputer Kyusuru clock counter is provided. 2. The power-on reset circuit monitors at least a supply voltage supplied from the stabilized power supply to the microcomputer, and outputs the reset release signal when the supply voltage reaches a predetermined ratio of a set voltage. An electronic control device comprising a power-on reset circuit according to claim 1, wherein the electronic control device comprises an output voltage monitoring circuit. 3. The power-on reset circuit is composed of at least a capacitor that stores electricity via a resistor by a supplied voltage supplied from the stabilized power supply to the microcomputer, and the amount of electricity stored in the capacitor has a constant value. At this time, the reset release signal is output to the clock counter, and the electronic control device comprising the power-on reset circuit according to claim 1. 4. The reset release signal sent from the clock counter is input between the clock counter and the microcomputer when the reset release signal from the power-on reset circuit is input. 4. A count time monitoring circuit is provided for counting the time up to the time when the count time deviates, and not outputting the reset release signal to the microcomputer when the count time deviates from a reference value. An electronic control device comprising the power-on reset circuit according to any one of claims 1.