JPS63185218A - Resetting device - Google Patents

Abstract

PURPOSE:To make the time when a microcomputer becomes a reset state from OFF of a power source constant, irrespective of a load variation, by connecting two photocouplers to an AC power source circuit, using one of them for a power source synchronizing signal and a reset signal, and using exclusively the other for the reset signal, in a resetting device of a microcomputer for air-conditioning. CONSTITUTION:When an AC power source is turned on, a current flows to photocouplers 2, 3 at every cycle, a signal synchronous with the power source is outputted for an interrupting signal of a microcomputer. Also, when one of the photocouplers 2, 3 is ON, a transistor (TR) 10 drives a reset use TR 14, sets it to an ON state, and subsequently, even if both the photocouplers 2, 3 become OFF and the TR 10 becomes OFF, the TR 14 does not become an OFF state due to a time constant by a resistor 13 and a capacitor 12. In such a way, a reset port of the microcomputer is fixed to an H level, and becomes a usual state. Subsequently, when the AC power source is turned OFF, no current flows to the photocouplers 2, 3, the transistors 10, 14 becomes an OFF state, and the reset port of the microcomputer also becomes an L level and becomes a reset state.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a reset device for a microcomputer used to control equipment of an air conditioner.

Conventional technology Conventionally, microcomputers 2' for air conditioning
As shown in Figure 2, the reset device for preventing residual deviation in - (hereinafter referred to as microcomputer) includes a transformer 19 that converts AC power into a low voltage, and a low voltage output from the secondary side of this transformer 19. Diode bridge 20 for full wave rectification of voltage
, a capacitor 38 for smoothing the full-wave rectified voltage, and a time constant resistor 29 for determining the reset time when the microcomputer is powered on. Capacitor 37, Zener diode 3o that determines the voltage level, and reset level ON
, a transistor 34 that determines OFF, and a transistor 33 that inverts the level of the output voltage, and is configured to be input to the reset port of the microcomputer through the transistor 33. On the other hand, from the + side of the diode bridge 20, a resistor 22 and a capacitor 21, which constitute an integrating circuit, and a transistor 26 that outputs an interrupt signal are connected, and through this transistor 26, it is connected to the interrupt board of the microcomputer. It has become. 30 in the figure is a Zener diode connected to the input side of the transistor 34.

3 ・\-2 With this configuration, by creating a half-wave voltage using one side of the diode bridge 20 and inputting this half-wave voltage to the transistor 26, a square wave synchronized with the power supply is used as an interrupt signal for the microcomputer. is output as Next, when sending a reset signal to the microcontroller, do so when the power is turned on and when the power is turned off.
There are two types of FF time. When the power is turned on, the transistor 33 is turned on depending on the time constant of the resistor 29 and capacitor 37.
and is fixed at L level. However, at a certain time, the Zener diode 3o turns on the transistor 34. This turns off the transistor 33 and fixes it at H level, releasing the reset. Next, when the power is turned off, the voltage applied to the Zener diode 30 drops, and when it falls below the Zener voltage, no current flows through the transistor 34, turning it off. As a result, the transistor 33 is turned on and L
It was fixed at a certain level, and the microcontroller formed a circuit that was in a reset state.

Problems to be Solved by the Invention In such a conventional configuration, a transformer 19, a diode bridge 20, etc. are required in order to obtain a power synchronization signal, and the circuit is complicated and the number of components increases. Also, the power is turned on.
The time it takes for the microcomputer to enter the reset state after FF is different depending on the load condition of the circuit, and the reset time is not constant. Furthermore, there was a problem in that it was difficult to reset the microcomputer in a short period of time.

The present invention solves the above conventional problems, and aims to shorten the time required for the microcomputer to enter the reset state after the power is turned off, and to make the time required for resetting constant regardless of load fluctuations. shall be.

Means for Solving the Problem In order to solve this problem, the present invention includes two photocouplers connected to an AC power source, and connects the emitter on the secondary side of each photocoupler through a diode for preventing backflow. Connect the collector of the switching transistor to the base of the reset transistor, and connect the collector side of the reset transistor to the collector side of the reset transistor for 7 hours when the power is turned on. This is the configuration of a reset device connected to a resistor for a determined time constant and a capacitor.

Effect With this configuration, when the power is on, current flows through the two photocouplers, the switching transistor is always on, and the reset port of the microcontroller is connected to H.
A level signal is output and the normal state is established. Then, when the power is turned off, current no longer flows to the two photocouplers, the switching transistors are turned off, and an L level signal is output to the reset port of the microcomputer. This will result in an operation that will result in a reset state.

Embodiment A microcomputer reset device according to an embodiment of the present invention will be described below with reference to FIG. As shown in Figure 1, the AC power supply has two photocouplers 2 and 3 connected to a current limiting resistor 1.
These photocouplers 2 and 3 are designed to detect half-cycle current of the AC power supply. The + side of a DC power supply is connected to the collector side of each secondary side of the photocouplers 2 and 3, and the resistor 4 as a load is connected to the emitter side.
, 5 are connected to each other, and are connected to the GND of the DC power supply through the resistors 4 and 5, respectively. Further, an interrupt port 6a for an interrupt signal of the microcomputer is led out from the resistor 4. The emitters of the photocouplers 2 and 3 are each connected to a current limiting resistor 8 via a backflow prevention diode 6.7, and through this resistor 8 to the base of a switching transistor 10. A current limiting resistor 11 of a reset transistor 14 is connected to the collector side of this transistor 1o, and a resistor 13. A capacitor 12 is connected to the base of the reset transistor 14. On the collector side of this reset transistor 14, there are a resistor 15 as a load, a diode 16 for discharging, and a resistor 17 for determining the reset time when the power is turned on. A capacitor 18 is connected to the reset port of the microcomputer through a resistor 1 that determines the time constant.

In the above configuration, when the AC power is turned on, current flows through the photocouplers 2 and 3 every cycle, and the secondary side transistor 10 is turned on every half cycle.

Repeat OFF. This outputs a signal synchronized with the power supply for the microcomputer's interrupt signal. In addition, when the backflow prevention diodes 6 and 7 are ON for half a cycle, one of them is in the OFF state, so the load resistors 4 and 7 of each other are in the OFF state.
This prevents current from flowing through 5. Next, when one of the photocouplers 2 and 3 is turned on, the switching transistor 10 drives the reset transistor 14 to be turned on. Next, even if both photocouplers 2 and 3 are turned OFF, the switching transistor 10 remains OFF, but the reset transistor 14 is turned off by the resistor 13.
The OFF state does not occur due to the time constant caused by the capacitor 12 and the capacitor 12. As a result, the reset port of the microcomputer is fixed at the H level and is in a normal state.

Next, when the AC power is turned off, the photocoupler 2.
No current flows through the transistor 3, and the switching transistor 10 is turned off. As a result, the reset transistor 14 is also turned off, and the reset port of the microcomputer is also brought to the L level, resulting in a reset state.

Effects of the Invention As is clear from the above description of the embodiments, according to the present invention, two photocouplers are connected to an AC power supply circuit, one photocoupler is used as a power supply synchronization signal and a reset signal, and the other photocoupler is used as a reset signal. By making it exclusive,
Regardless of load fluctuations, the time it takes for the microcomputer to enter the reset state after the power is turned off is constant, and it can be brought into the reset state even when the power is turned off for a short period of time, and the circuit has a simple configuration. This also has the effect of reducing costs.

91・-7

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram of a microcomputer reset device according to an embodiment of the present invention, and FIG. 2 is an electrical circuit diagram of a conventional microcomputer reset device. 2.3...Hotocoupler, 10.14...
Transistor, 18... Electrolytic capacitor,
16...--Discharge diode, 17...Resistor.

Claims (1)

[Claims] It has two photocouplers connected to an AC power source, the emitter of each photocoupler is connected to the base of a switching transistor via a reverse current prevention diode, and the collector of the transistor is connected to the base of a reset transistor. At the same time, the reset device consists of a time constant resistor and a capacitor connected to the collector side of this reset transistor to determine the reset time when the power is turned on.