JPH0537256Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to an improvement of a state determination device using a microcomputer.

[Technical background of the invention] Conventionally, as a state determination device using a microcomputer, one end is connected to +Vs at the input port IN of the microcomputer 1, as shown in FIG.
Connect the connection point between the resistor 2 and the contact switch 3 in a series circuit consisting of the resistor 2 connected to the terminal and the contact switch 3 whose one end is grounded, and turn on the contact switch 3.
A known device is known in which the state of the contact switch 3 is determined by taking in a contact signal generated from the connection point by the off-operation from the input port IN via the signal line L and the inverter 4. In addition,
The contact switch 3 operates by detecting an abnormal state of the device controlled by the microcomputer 1. For example, if the device is a combustion device, it is a switch for detecting an earthquake. It is turned on and turned off when an abnormal condition occurs.

Therefore, the microcomputer 1 inputs the level state of the input port IN as shown in FIG.
If the level is L level, it is determined that the contact switch 3 is on and in a normal state, and the process moves to the next sequence. If the level is H level, the contact switch 3 is turned off. When it is determined that an abnormal state has occurred, the system jumps to an abnormal sequence and performs control to deal with the abnormal state. For example, in the case of a combustion device, the control to deal with this abnormal state is control to stop the combustion operation.

[Problems in the Background Art] However, in this conventional device, if an accident occurs such as, for example, the line L provided inside the microcomputer 1 is broken at a location A, the input level to the inverter 4 becomes unstable, and this Therefore, for example, if the microcomputer 1 reads the output of the inverter 4 as H level, that is, reads the level of the input port IN as L level, an abnormal condition occurs and the contact switch 3 turns OFF. However, the microcomputer 1 determines that the system is in a normal state, and for example, in a combustion system, even if an earthquake occurs, a fire extinguishing operation is not performed, which is a very important mistake.

[Purpose of the invention] This invention was devised to solve this problem, and even if an accident occurs in which the internal signal line is disconnected, the abnormal state can be reliably determined. The purpose of this invention is to provide a state determination device using a microcomputer.

[Summary of the invention] This invention is based on a microcomputer that can set input/output ports to high and low levels by turning on and off the transistors housed inside, and a control system using this microcomputer. The microcomputer is equipped with a contact switch that operates by detecting an abnormal state of the device being operated, and a contact signal generation circuit that supplies a contact signal generated in response to the operation of the contact switch to an input/output port. On, off control,
The normal and abnormal states of the control device are determined by taking in the level states of the input/output ports when they are on and off, respectively.

[Embodiment of the invention] An embodiment of the invention will be described below with reference to the drawings.

As shown in Figure 1, this is done by connecting the connection point between a normally closed contact switch 12, which turns off when an abnormal condition such as an earthquake is detected, and a resistor 13 to the input/output port I/O of the microcomputer 11. There is. The other end of the contact switch 12 is connected to the +Vs terminal via a resistor 14, and the other end of the resistor 13 is grounded. The contact switch 12, the resistor 1
The series circuits 3 and 14 constitute a contact signal generation circuit. Resistance value R1 of the resistors 13 and 14
The relationship between 3 and R14 is R13≫R14. The microcomputer 11 is an N-MOS
The transistor 16 has one end connected to the signal line L connected between the input/output port I/O and the input terminal of the inverter 15, and has the other end grounded. There is. The transistor 16 is turned on and off by a signal from an output latch 17 controlled by the CPU.

The microcomputer 11 performs program control as shown in FIG. 2 based on built-in program data. That is,
The transistor 16 is turned off by the signal from the output latch 17, and the input/output port I/O is set to H level. In this state, input the level signal of the input/output port I/O. If the level signal is at the H level, then the transistor 16 is turned on by the signal from the output latch 17 to set the input/output port I/O to the L level. In this state, input the level signal of the input/output port I/O. If the level signal is at L level, the process moves to the next sequence. Also, if the level signal is at L level when the input/output port I/O is set to H level, or the level signal is at H level when the input/output port I/O is set to L level, Determine that an abnormal condition has occurred and jump to the abnormal sequence. By executing this abnormal sequence, if it is a combustion device, extinguishing control is performed.

With this configuration, when the transistor 16 is turned off and the input/output port I/O is set to the H level, when the H level signal is input, the contact switch 12 is in the on state and the device operates normally. judge that it is. Further, when the L level signal is input, it is determined that the contact switch 12 is in the OFF state and an abnormal state of the device is detected, and the abnormality sequence is executed. Next, transistor 16
When the input/output port I/O is turned on and the input/output port I/O is set to L level, if an L level signal is input, it is determined that the circuit is working normally, and if an H level signal is input, the signal line L is It is determined that there is a disconnection or the transistor 16 has failed and is in an open state at the location (b), and an abnormality sequence is executed. Incidentally, even if the signal line L is disconnected at a point C or D, the abnormality sequence is immediately executed in almost the same state as if the contact switch 12 were turned off.

Not only can it be determined whether the device is normal or abnormal based on the off state or on state of the contact switch 12, but also the abnormal state of the port due to disconnection of the signal line L or failure of the transistor 16 can be determined.
It is possible to reliably deal with abnormal occurrences. Therefore, when this is applied to a combustion device, it is possible to reliably extinguish a fire in the event of an earthquake or the like, and it is also possible to reliably extinguish a fire in the event of a circuit abnormality, thereby improving safety.

Next, another embodiment of this invention will be described with reference to the drawings. Note that the same parts as in the above embodiment are given the same reference numerals, and detailed explanations will be omitted.

First, in the circuit shown in FIG. 3, a resistor 18 is inserted in place of the resistor 14 in FIG. 1 between the connection point between the contact switch 12 and the resistor 13 and the input/output port I/O to form a contact signal generation circuit. It is composed of

In this case as well, the normal state and abnormal state can be determined by program control similar to the case shown in FIG. Therefore, in this case as well, the same effects as in the above embodiment can be obtained.

The circuit shown in FIG. 4 is a contact signal generating circuit in which one end of a contact switch 12 is connected to the +Vs terminal via a resistor 19 with a high resistance value, and the other end is grounded via a resistor 20 with a low resistance value. The connection point between the resistor 19 and the contact switch 12 is connected to the input/output port I/O. Further, as the microcomputer 11, a P-MOS type is used. This microcomputer 11
In this case, a transistor 21 having one end connected to the +Vs terminal and the other end connected to the signal line L is used, and the transistor 21 is turned on and off by a signal from the output latch 17.

In this embodiment, by carrying out program control in which the levels are exactly reversed from those in Fig. 1, i.e., in the flow chart of Fig. 2, it is possible to reliably distinguish between normal and abnormal states in the same manner as in the previous embodiment, and therefore it is possible to obtain the same effects as in the previous embodiment.

Furthermore, in the device shown in FIG. 5, the positions of the contact switch 12 and the resistor 13 in FIG.

Similar to the program control shown in Fig. 4, this odor can also be controlled in normal and abnormal states by performing the program control shown in Fig. 1, that is, the program control with the level exactly reversed in the flowchart shown in Fig. 2. As in the previous embodiment, the determination can be made reliably. Therefore, in this case as well, the same effects as in the above embodiment can be obtained.

[Effects of the invention] As detailed above, according to this invention, the above conditions can be determined by the operation of the contact switch when the circuit is normal, and even if an accident occurs in which the internal signal line is disconnected. It is possible to provide a state determination device using a microcomputer that can reliably determine abnormal states.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of this invention, FIG. 2 is a flowchart showing program control in the same embodiment, and FIGS. 3 to 5 are circuit diagrams showing other embodiments of this invention. Figure 6 is a circuit diagram showing a conventional example, and Figure 7 is a circuit diagram showing a conventional example.
The figure is a flowchart showing program control in the conventional example. 11...Microcomputer, 12...Contact switch, 13, 14...Resistor, 16...Transistor, 17...Output latch.

Claims (1)

[Scope of utility model registration request] A microcomputer that can set input/output ports to high and low levels by turning on and off the transistors housed inside, and detects abnormal conditions in devices controlled by this microcomputer. and a contact signal generation circuit that supplies a contact signal generated in accordance with the operation of the contact switch to the input/output port, and the microcomputer controls the transistor on and off. A state determination device using a microcomputer, characterized in that it determines whether a control device is in a normal or abnormal state by reading the level state of the input/output port when it is on or off, respectively.