JPS5953921A - Electronic control device - Google Patents

Abstract

PURPOSE:To suppress the malfunction of a system at the time of resetting, by setting forcibly an interface means which receives directly an output of a main control means, to the inactive state for a prescribed time from the time when an electric power source is turned on or the system is reset. CONSTITUTION:When an electric power source switch 3 is turned on, an electric power source for an electronic circuit, which is smoothed by a capacitor 27 through an electric power source transformer 5 and diodes 6, 7 is aroused. A constant-voltage circuit CV supplies DC constant-voltage to a main control means MCU46. Rise of power supply voltage of the MCU46 is not attained instantaneously, but a time delay is generated. On the other hand, voltage of a resetting circuit RE also rises slowly. A Zener diode 37 does not conduct until reaching breakdown voltage, and a transistor 45 remains off. Accordingly, a ground terminal 43T of a driving circuit 43 being an interface means is in a floating state, and is set forcibly to the inactive state. Therefore, a control signal of malfunction of the MCU46 is not transferred to loads 9, 16 and 20.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic control device equipped with an LSI such as a microcomputer as a main control means, and particularly relates to an improvement in control at the time of reset.

Systems that control the actual operation of consumer appliances (e.g. coolers, washing machines, etc.) using electronic control units equipped with microcomputers (hereinafter referred to as MCUs), which are LSIs, have become widespread. Made! In order to return the electronic control unit to its initial state before restarting the system, perform a system reset. Normally, a reset signal is automatically created and input to the MCU when the power is turned on.

If the reset signal input time is about 4 to 10 times the instruction cycle of 8 ICUs, the MCU
The registers and memory contents within are cleared, but what happens at the initial stage of the reset signal (within a period of 4 to 10 times the instruction cycle)? vl CU reset is insufficient and orderly signals are not output.

That is, during the above period, there is no guarantee that the MCU will operate normally, and the period will be in the so-called malfunction area. Therefore, if the electronic control device malfunctions, the equipment whose control output is manually operated may malfunction and fail to meet the specifications of the equipment.
There were some notes that could damage the system or adversely affect other peripherals.

The present invention was created in view of the above points, and aims to prevent malfunction of the system at the time of reset. The present invention provides an electronic control device that does not have the influence of

That is, the electronic control device of the present invention disables the interface means that directly receives the output of the main control means (MCU) that drives and controls the load on the equipment side for a predetermined period of time such as when the power is turned on or when the system is reset. The basic feature is that a compulsory circuit means is provided to prevent the malfunction output of the MCU from being transmitted to the equipment side at the initial stage of the reset operation.

In a preferred embodiment of the present invention, the interface means is a driver circuit, and the circuit means for forcing the circuit to be inoperable includes a transistor with a common emitter, a Zener diode whose anode is connected to the base of the transistor, and a Zener diode with an anode connected to the base of the transistor. a circuit that provides a time constant connected to the cathode of the transistor, and a grounding line that connects the ground terminal of the driver circuit to the collector of the transistor, and adjusts the time constant of the time constant circuit and the breakdown voltage of the Zener diode to an appropriate value. By selecting and making the transistor non-conductive for the predetermined time, the ground terminal of the AiJ driver circuit is forced into a floating state and the driver circuit is inactivated.

Examples will be explained below.

FIG. 1 shows the circuit and configuration of one embodiment of a fully automatic washing machine child care control device. In FIG. 1, reference numeral 9 is a motor that can be rotated in forward and reverse directions, 16 is a drain solenoid that controls the water from the washing machine, 20 is a water supply solenoid that controls water supply, and the motor 9. Drain solenoid 16. Each of the water supply solenoids 20 is a triac 10.13, 17.2.
Commercial power supply (50 or 601 (z, 100V) through 1
can be connected to

A series connection of a capacitor and a resistor (11, 12) connected in parallel with each triac 10, 13, 17.
), (14,15), (18,19), (22,23)
Both of these are intended to absorb a high forward voltage as a differential voltage applied between the terminals of the triac when the triac is turned on or commutated.

Reference numeral 47 indicates a plurality of switches provided on the switch panel of the washing machine, and by operating the switches 47, various washing conditions can be set. The setting conditions are input as electrical signals to the MCU 46, which serves as the main control means of the electronic control device. The MCU 46 is composed of a general-purpose microcomputer, microprocessor, or specially manufactured LSI, and performs calculations, timekeeping, timing control, and other processing based on a predetermined program and input conditions. The processing result is output as a control signal. In this example, a forward rotation signal for the motor 9, a reverse rotation signal for the motor 9, a control signal for the drain solenoid 16 are output as a control signal for the water supply solenoid 2o, and a control signal for the motor 9. Controls the operation of the discharge solenoid 16 and the water supply solenoid 20. The control signal is sent to the resistors 39, 40, 4], 42 via the driver circuit 43 as an interface means.
via respective Sairisk 10, 13, 17.21
given to the gate.

The driver circuit 43 is necessary to convert the voltage level of the voltage signal from the MCU 46 and apply a sufficient control voltage to the gate of the cyrisk.

In this example, as shown in the figure, an IC driver is used. 1 can include six to seven driver circuits within the IC, four of which are used.

Since these driver circuits and the MCU 46 operate on DC power, the AC power is converted into DC by the transformer 5, and the power is supplied via the DC power line DCL. Turning on the AC power Roniha Varistor 1. Two capacitors are each connected in parallel. A momentary switch 3, which is a starting switch for the washing machine, is interposed between one end of the capacitor 2 and the DC power line DCL, and a contact point of a self-holding 51J relay 4 is connected in parallel with the switch 3. ing.

A relay circuit RL is connected to the DC power line DCL.

A smoothing capacitor 2, a constant voltage circuit C, a clock circuit CL, and a reset circuit I are connected. The relay circuit RL includes a resistor 24. Relay 4 coil, transistor 25. It consists of a resistor 26, and as soon as a reset signal is input to the MCU 46 and normal operation becomes possible, a signal is applied to the base of the transistor 25 to turn on the contact of the self-holding relay 4. At this time, momentary switch 3
It is turned off. When a series of operations as a fully automatic washing machine is completed, the self-holding of the relay 4 can be released by a command from the MCU 46, and the washing machine can be automatically stopped. The constant voltage circuit C■ includes a Zener diode 28, a resistor 29. A known circuit consisting of a transistor 30 supplies a constant voltage to the electronic control wave layer. Clock circuit CL includes resistors 8.31.
It includes a transistor 32 and a resistor 33, and utilizes the frequency of the commercial power source (50 or 6Q l-1y), and inputs this as a clock to the MCU 46 to serve as the basis for timekeeping (2 minutes or 3 minutes).

The reset circuit RE automatically generates a reset signal and inputs it to the Mcu 46 when the power is turned on to this system, and also operates the driver circuit for a predetermined period of time after the power is turned on, which is a feature of the present invention. 43 not working f4g
It also constitutes circuit means for forcing J. This reset circuit RE includes a capacitor 34. Backflow prevention diode 35
．． Resistor 36, Zener diode 37. Resistance 38. It consists of a resistor 44 and a transistor 45. A Zener diode 37 is connected to the base of the emitter-grounded transistor 45.
The anode of the dimate 35 is connected, and the cathode of the dimate 35 is connected to the anode of the dimate 35. The cathode of the diode 35 is connected to the DC power line I) CL, and a series connection of a resistor 36 and a capacitor 34 is connected to the DC power line I) CL, forming a circuit that provides a time constant. And the time constant is chosen relatively large. The cathode of the Zener dimer 37 is connected to the connection point between the resistor 36 and the capacitor 34 . In this embodiment, the breakdown voltage of the Zener diode 37 is Vo (constant voltage circuit C■
voltage). The collector of the transistor 45, whose base is connected to the anode of the Zener diode, is connected to the ground terminal 43 of the driver circuit 4; It is also connected to the reset input terminal of the MCU 46.

The collector is also connected to a DC power line DCL via a collector resistor 38. Resistor 44 is connected between the base of transistor 45 and ground.

The reset operation when the power is turned on will be explained. power switch 3
When (and the panel switch 47) is turned on, the power transformer 5 is energized, and the electronic circuit power supply smoothed by the capacitor 27 is generated via the secondary-side pick-up diode 6.7 of the transformer 5. Constant voltage circuit CV is MCU46
Supplies constant DC voltage to. Here, as shown by the curve A of the curve 7 in FIG. 2, the dam of the power supply voltage of the MCU 46 is not achieved instantaneously, but a time delay occurs. The delay time is (S T )ms. time width]” is constant voltage VO
The time width S indicates the minimum time that is established and accepted as a reset signal by the MCU 46, and the time width S is a region in which the MCU 46 malfunctions even if a high-level reset signal is input.

On the other hand, the voltage of the reset circuit RE is also changed as shown by the dashed line curve B in FIG. However, it stands more gently than curve A. Since the breakdown voltage of the Zener diode 37 is set to ■0, the Zener dimate 37 is non-conductive until it reaches the breakdown voltage vO (until time [7,)], and the transistor 4
5 remains off. Therefore, driver circuit 43
The ground terminal 43T of is in a floating state and is forced into an inoperable state. On the other hand, the high level voltage that has already been established as a reset signal is input to the MCU 4.5, and the side leg signal is in a state where it can be output, and a malfunction signal is also output, but the driver circuit 43 is Since it does not operate, the malfunction control signal is not transmitted to the loads 9, 16, 20. At the moment when curve B in FIG. 2 reaches voltage vO, Zener diode 37 becomes conductive and supplies base current to transistor 45. Transistor 45 becomes conductive and its collector potential drops to approximately ground level. The ground terminal 43 T of the driver circuit 43 becomes the ground level, and the driver circuit 43
becomes active. At the same time, a low level signal is input to the reset input of the MCU 45, and the MCU 46 enters a normal operation standby state. The MCU 45 is activated and provides a control signal to the already activated driver circuit 43. Driver circuit 43
The correct control signal is sent to the triac gate.

In addition, in the above embodiment, the type that automatically generates a reset signal when the power is turned on is shown, or an independent reset circuit is provided, and a new electronic control device can be installed by changing the setting conditions using the switch 47, etc. It goes without saying that the above-mentioned disclosed technique can also be applied to devices that are actuated. In this case, the interface means is disabled for a predetermined period of time (corresponding to the technique shown in FIG. 2) from the time when the reset signal is input.

As described above, in the present invention, even if a malfunctioning control number 1 is output from the main control means (MC; U) at the initial stage of reset,
Since the interface means of the MCU is forced to be inoperable for longer than this malfunction period, it is possible to prevent erroneous operation of the system equipment at the time of reset.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a graph for explaining the operation of the embodiment. 9...Motor, 16...Drainage solenoid, 20...
・Water supply solenoid, 43...driver circuit, 43'F
...Ground terminal, 46...MCU, 34...Capacitor, 36...Resistor, 37...Zener dilade, 45...Transistor. Patent applicant: Sharp Corporation patent attorney Ao Yamaboshi and two others

Claims (2)

[Claims] (1) In an electronic control device equipped with a control means for driving and nailing a load via an interface means, circuit means is provided for forcing the interface means to be inoperable for a predetermined period of time from when the power is turned on or when the system is reset. An electronic control device characterized by: (2) The interface means is a driver circuit, and the circuit means includes a transistor with a common emitter, a Zener diode whose anode is connected to the base of the transistor, and a circuit for providing a time constant connected to the cathode of the Zener diode. , and a connection line connecting the ground terminal of the driver circuit to the collector of the transistor.