CN110657458B

CN110657458B - Electronic control device, semiconductor integrated circuit device for electronic control, and gas stove

Info

Publication number: CN110657458B
Application number: CN201910578094.3A
Authority: CN
Inventors: 濑川智贵
Original assignee: Mitsumi Electric Co Ltd
Current assignee: Mitsumi Electric Co Ltd
Priority date: 2018-06-28
Filing date: 2019-06-28
Publication date: 2023-07-25
Anticipated expiration: 2039-06-28
Also published as: JP2020003128A; KR102650821B1; CN110657458A; KR20200001980A; JP7116304B2

Abstract

The invention provides an electronic control device, a semiconductor integrated circuit device for electronic control and a gas stove, which have a watchdog function with strong electromagnetic noise resistance. In an electronic control device including a plurality of semiconductor integrated circuit devices and generating and outputting a control signal for a device to be controlled, each of the plurality of semiconductor integrated circuit devices has a function of outputting a clock signal of a predetermined frequency and a function of determining a frequency or a period of the clock signal input from another semiconductor integrated circuit device, and the plurality of semiconductor integrated circuit devices monitor the clock signal input from the other semiconductor integrated circuit device.

Description

Electronic control device, semiconductor integrated circuit device for electronic control, and gas stove

Technical Field

The present invention relates to a technique for mutually monitoring watchdog (watch dog) signals between a microcomputer and a plurality of semiconductor devices such as analog front ends (analog front ends), and for example, to a technique effective for use in an electronic control device of a device generating relatively large electromagnetic noise such as a gas cooker and an electronic control IC (semiconductor integrated circuit) constituting the electronic control device.

Background

Conventionally, as an example of an electronic control device having a function of a dongle, a control device for a gas range has been provided. The gas range includes an ignition circuit (igniter) and generates relatively large electromagnetic noise when the igniter discharges, which may cause program runaway of the microcomputer, and a watchdog function is provided to prevent program runaway. In the electronic control device of the gas range, the invention has been proposed in which the power supply to the solenoid valve is shut off when the pulse period of the clock signal for the watchdog is shorter than the normal range, except when the clock signal for the watchdog is not present (patent document 1).

Patent document 2 describes the following invention: a safety circuit is provided, and the 2 safety control units monitor each other for abnormality, and when abnormality is detected, the safety circuit cuts off power supply to the solenoid valve.

The invention described in patent document 2 is an invention in which safety control units are mutually monitored for abnormality in addition to the double operation of the safety control units based on the combustion temperature sensor, and is not an invention in which the main control unit and the safety control unit mutually monitor for abnormality.

The invention described in patent document 1 is effective for preventing erroneous operation of a control device caused by runaway of a microcomputer in an electronic control system. On the other hand, an electronic control device of a gas range may be constituted by a microcomputer and an analog front end IC for processing signals of a sensor for detecting flame and temperature. In such a case, since there is a possibility that the control device may malfunction due to the runaway of the analog front end IC, it is necessary to monitor the operation of the analog front end IC to prevent the runaway.

Conventionally, a technique for mutually monitoring a watchdog clock signal in a system including a plurality of ICs has been known (patent document 3). However, conventionally, a microcomputer and other ICs having a function of outputting a clock signal for a watchdog generally include an oscillation circuit having an external oscillator such as a crystal oscillator for generating an operation clock signal, and generate the clock signal for the watchdog based on a clock signal generated by dividing the oscillation signal of the oscillation circuit.

Since the oscillator such as a crystal oscillator has high impedance, noise is likely to be mixed in an external terminal to which the oscillator is connected, and the function of the watchdog may be impaired due to the noise mixed in the external terminal. In particular, in the electronic control device of the gas range, it is known that relatively large electromagnetic noise is generated at the time of discharge of the igniter, and therefore, there are the following problems: the possibility of damaging the watchdog function by mixing electromagnetic noise into the external terminal to which the vibrator is connected increases.

Patent document 1: japanese patent laid-open No. 2017-133757

Patent document 2: japanese patent laid-open publication 2016-01807

Patent document 3: japanese patent laid-open No. H06-4353

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a gas stove electronic control device including a microcomputer and a plurality of semiconductor devices such as analog front ends, which can detect erroneous operation by monitoring for runaway and cut off an electromagnetic valve. Another object of the present invention is to provide an electronic control device having a watchdog function with high electromagnetic noise resistance, and an electronic control IC and a gas range constituting the electronic control device.

In order to achieve the above object, the present invention provides an electronic control device including a plurality of semiconductor integrated circuit devices each having a function of outputting a clock signal of a predetermined frequency and a function of determining a frequency or a period of the clock signal inputted from another semiconductor integrated circuit device, and generating and outputting a control signal for a device to be controlled,

the plurality of semiconductor integrated circuit devices are configured to mutually monitor the clock signals input from the other semiconductor integrated circuit devices.

According to the above configuration, since the clock signals are monitored with each other, it is possible to detect the situation when any one of the semiconductor integrated circuit devices is out of control.

Here, it is preferable that one of the plurality of semiconductor integrated circuit devices is a microcomputer, a clock signal of a predetermined frequency outputted from the microcomputer is generated by a watchdog function,

the semiconductor integrated circuit device other than the microcomputer is configured to include an oscillation circuit that generates a clock signal of a predetermined frequency, and to output the clock signal based on the oscillation signal generated by the oscillation circuit as an abnormality monitoring clock signal.

According to this configuration, the electronic control device can be designed efficiently by utilizing the watchdog function provided in the microcomputer.

Further, the semiconductor integrated circuit device other than the microcomputer is preferably configured to include: an oscillation circuit that generates a clock signal of a predetermined frequency without using a vibrator; a counting circuit capable of counting the number of clock signals input from other semiconductor integrated circuit devices; and a comparison circuit that compares the value counted by the counting circuit with a predetermined determination value, wherein the counting circuit performs a counting operation based on the clock signal generated by the oscillation circuit, and outputs an abnormality signal when the value counted by the counting circuit exceeds the predetermined determination value.

According to this configuration, the counter circuit performs a counting operation based on the clock signal generated by the oscillation circuit without using the oscillator, and determines the presence or absence of an abnormality based on the count value, so that it is possible to prevent erroneous determination by avoiding an abnormality of the clock signal due to noise from the outside, and to improve noise tolerance of the semiconductor integrated circuit device.

The gas cooker of another invention of the present application is configured to include: an electronic control device having the above-described configuration; a gas burner; an ignition unit disposed in the vicinity of the gas burner for igniting the gas; a gas adjusting valve and a solenoid valve provided in the middle of a gas pipe connected to the gas burner; and a switching circuit for turning on/off the energization of the electromagnetic valve, wherein the switching circuit is controlled based on the abnormality signal and an abnormality signal generated by detecting a watchdog function of the microcomputer, and the electromagnetic valve is closed when any one of the abnormality signals is output.

According to this configuration, since the microcomputer and the semiconductor integrated circuit device constituting the electronic control device monitor the clock signals from each other, if any one of them is out of control, the out of control can be detected, and the supply of the gas can be shut off by closing the electromagnetic valve, so that the safety of the gas cooker can be improved.

Another aspect of the present invention provides an electronic control semiconductor integrated circuit device comprising:

an output terminal that outputs a signal for controlling an ignition unit disposed in the vicinity of the gas burner;

an input terminal for receiving a clock signal supplied from another semiconductor integrated circuit device;

a communication circuit for transmitting and receiving data to and from the other semiconductor integrated circuit device;

a first oscillation circuit that generates a clock signal required for an operation of the communication circuit using a vibrator;

a second oscillation circuit that generates a clock signal of a predetermined frequency without using a vibrator;

a counting circuit capable of counting the number of clock signals input from the input terminal of the other semiconductor integrated circuit device;

a comparison circuit for comparing the value counted by the counting circuit with a predetermined determination value,

the counting circuit performs a counting operation based on the clock signal generated by the second oscillation circuit, and outputs a signal indicating an abnormality when the value counted by the counting circuit exceeds the predetermined determination value.

According to this configuration, the counter circuit performs a counting operation based on the clock signal generated by the oscillation circuit without using the oscillator, and determines the presence or absence of an abnormality based on the count value, so that it is possible to prevent occurrence of an abnormality in the clock signal due to noise from the outside, to thereby prevent erroneous determination, and to improve noise tolerance of the semiconductor integrated circuit device. Further, since the oscillator circuit is provided with the clock signal necessary for the operation of the communication circuit by using the oscillator, the oscillation frequency of the oscillator circuit can be easily made higher than the oscillation frequency of the oscillator circuit without using the oscillator, and data transmission and reception with other semiconductor integrated circuit devices can be performed at high speed by using the clock signal of high frequency in the communication circuit.

According to the present invention, in a gas stove electronic control device including a microcomputer and a plurality of semiconductor devices such as analog front ends, it is possible to detect erroneous operation by monitoring for runaway and to cut off an electromagnetic valve. Further, there are effects that an electronic control device having a watchdog function having high resistance to electromagnetic noise, an electronic control IC constituting the electronic control device, and a gas cooker can be realized.

Drawings

Fig. 1 is a circuit configuration diagram showing an embodiment of the electronic control device for a gas range according to the present invention.

Fig. 2 is a block diagram showing a specific configuration example of an analog front end IC (AFE-IC) of the embodiment.

Fig. 3 is a circuit diagram showing a specific example of a watchdog circuit provided in the AFE-IC.

Fig. 4 (a) and (B) are flowcharts showing an example of the sequence of ignition switch processing of a Microcomputer (MCU) and an AFE-IC.

Fig. 5 (a) and (B) are flowcharts showing an example of the procedure of initial setting processing of a Microcomputer (MCU) and an AFE-IC.

Fig. 6 is a circuit configuration diagram showing a first modification of the electronic control device for a gas range according to the embodiment.

Fig. 7 is a circuit configuration diagram showing a second modification of the electronic control device for a gas range according to the embodiment.

Fig. 8 (a) and (B) are block diagrams showing another embodiment of the electronic control device for a gas range according to the present invention.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Fig. 1 shows a schematic configuration of an embodiment of an electronic control device for a gas range according to the present invention. In fig. 1, a portion enclosed by a dash-dot line a is a gas range electronic control device 10. The portion surrounded by the chain line B is a gas range 20, and fig. 2 shows a range burner 21 as a main component, a fire power adjusting solenoid valve 23 provided in the middle of a gas pipe 22, and a fail-safe valve 24 constituted by the solenoid valve.

A thermocouple 25 for detecting a flame, a thermistor 26 for detecting a temperature of a bottom portion of a cooking appliance such as a pot or frying pan carried on a stove portion above the stove burner 21, and an igniter 27 for ignition are disposed near the stove burner 21. Attached with reference numeral 28 is an ignition switch for energizing the igniter 27. The electromagnetic valve 23 for adjusting the flame may be configured to include a motor, and the gas flow rate may be adjusted by changing the valve angle by the motor, or may be configured to adjust the gas flow rate by driving and controlling an openable/closable electromagnetic valve by a PWM (pulse width modulation) system.

The electronic control device 10 for a gas range of the present embodiment is composed of a microcomputer (hereinafter referred to as an MCU) 11 and an analog front end IC (hereinafter referred to as an AFE-IC) 12 for detecting signals from sensors such as a thermocouple 25 and a thermistor 26, and is provided with, as peripheral devices, a current switching transistor 13 for causing an igniter 27 to flow a current, a buzzer 14 for emitting an alarm sound, a driving circuit 15 for driving a electromagnetic valve 23 for adjusting the fire, and a transistor switching circuit 16 for operating a safety valve 24. In addition, a battery 17 is provided for supplying a power supply voltage to the AFE-IC 12. The supply voltage of the MCU11 can also be supplied from the battery 17.

The oscillator 18 is connected to the AFE-IC12 as an external element in order to generate a clock signal of a predetermined frequency by an internal oscillation circuit. Although not shown, the MCU11 similarly includes an internal oscillation circuit and an external terminal for connecting the oscillator in order to generate a system clock signal for use in the chip. The MCU11 may also be of the form: the portable electronic device is provided with an input terminal for receiving an externally generated clock signal, and operates by the externally supplied clock signal. Attached with reference numeral 19 is an LED (light emitting diode) as an indicator lamp for indicating that a power supply voltage (battery voltage) is supplied or turned on, or for indicating an abnormality of the stove.

The MCU11 and the AFE-IC12 each have a function of generating a watchdog clock signal or an abnormality monitoring clock signal and a function of monitoring a watchdog clock input from the outside. The AFE-IC12 is provided with a terminal CLKO that outputs a clock signal generated internally as an abnormality monitoring clock, and a terminal WDI that inputs a watchdog clock WDP from the MCU 11. The MCU11 is configured to receive an input of the abnormality monitoring clock WCK from the AFE-IC12 through any one general-purpose IO port (input/output port) GPIO, and to output the watchdog clock WDP from the other general-purpose IO port GPIO.

By mutually monitoring the generated watchdog clock WDP and abnormality monitoring clock WCK in this way, when the other IC is out of control, the out of control condition can be detected. The AFE-IC12 is provided with a terminal OUT that outputs a signal when an abnormality of the watchdog clock WDP is detected, and the MCU11 outputs an abnormality signal from the general-purpose IO port GPIO when an abnormality of the abnormality monitoring clock WCK is detected. The input of the clock WCK to which the general purpose IO port GPIO is to be used by the MCU11 can be freely set by an internal user program, and the clock WDP and the abnormality signal can be outputted.

The AFE-IC12 is provided with an external terminal for inputting a chip selection signal CS from the MCU11, a synchronous clock signal SCK for serial communication, serial data SDATA, and an external terminal SOUT for outputting serial data to the microcomputer 11. The AFE-IC12 is configured to transmit temperature data detected based on signals from the sensors such as the thermocouple 25 and the thermistor 26 from the external terminal SOUT to the MCU 11.

The AFE-IC12 is provided with an input terminal SW for receiving a signal from the ignition switch 28, a terminal IG for outputting a signal for operating the igniter 27, and a terminal BZ for outputting a signal for sounding the buzzer 14.

On the other hand, the MCU11 is provided with a function of generating a signal for operating the solenoid valve 23 and outputting the signal through the general purpose IO port GPIO.

The transistor switch circuit 16 is supplied with an abnormality signal of a watchdog clock and an abnormality monitoring clock outputted from a terminal OUT of the AFE-IC12 and a general purpose IO port GPIO of the MCU11 to control the safety valve 24. That is, the clock abnormality signal is a signal for operating the safety valve 24.

The transistor switching circuit 16 includes 2 PNP bipolar transistors TR1 and TR2 connected in series, resistors Rb1 and Rb2 connected to the bases of the respective transistors, and resistors Re1 and Re2 connected between the emitter bases, and an emitter terminal of the transistor TR1 is connected to a power supply voltage terminal VCC.

As a result, the transistors TR1 and TR2 normally flow a collector current, and the solenoid of the relief valve 24 is energized to be excited, thereby controlling the valve to an open state. As a result, the fuel gas is supplied to the solenoid valve 23 through the relief valve 24. Then, when a detection signal indicating an abnormal high level of the watchdog clock is output from any one of the terminal OUT of the AFE-IC12 and the general purpose IO port GPIO of the MCU11, the transistor TR1 or TR2 is turned off. As a result, the energization to the relief valve 24 is cut off to demagnetize the solenoid, thereby controlling the valve to the closed state. Therefore, the safety valve 24 is shut off and the safety function of not supplying fuel gas to the solenoid valve 23 is activated.

Further, 2 resistors R1 and R2 connected in series with transistors TR1 and TR2 are provided between the transistor switching circuit 16 and the safety valve 24, and the potential of the connection node between the resistors R1 and R2 is inputted to the analog input terminal ain of the AFE-IC12, so that the AFE-IC12 can detect the state of the safety valve 24 from the input potential of the terminal. Specifically, if the input potential of the terminal ANIN is high, it can be detected that the relief valve 24 is open, and if the input potential of the terminal ANIN is low, it can be detected that the relief valve 24 is closed.

Fig. 2 shows a specific circuit configuration example of the AFE-IC12 according to the above embodiment. As shown in fig. 2, the AFE-IC12 includes: a power supply voltage detection circuit 31 that detects a decrease in battery voltage applied to a power supply voltage terminal VCC; an ignition switch input circuit 32 that receives a signal from the ignition switch 28; a regulator circuit 33 that generates and outputs a bias voltage for activating the thermistor 26 and a power supply voltage for internal circuits; a power-on reset circuit 34 that generates a power-on reset signal that resets the inside when the power is turned on.

The AFE-IC12 further includes: a thermistor switching circuit 35 for switching a voltage dividing resistance value connected in series with a plurality of (5 in the drawing) thermistors 26 that detect temperature; an AD conversion circuit 36 that converts the detection voltage of the thermistor into a digital code; a multiplexer 37a that supplies a detection voltage of one detection unit of the plurality of thermistors 26 and the power supply voltage detection circuit 31 for detecting the temperature of the bottom of the cooking appliance or the like to the AD conversion circuit 36; a multiplexer 37b that selects one detection signal from among a plurality (6 in the figure) of thermocouples 25; and an amplifier 38 that amplifies the selected detection signal. The signals amplified by the amplifier 38 and input to the common analog input terminals AIN1 to AIN4 are supplied to the AD conversion circuit 36 via the multiplexer 37a and converted into digital signals.

The AFE-IC12 includes: a serial interface circuit 39 for performing serial data communication with the microcomputer 11; an oscillation circuit 40 that generates a clock signal of the serial interface circuit 39, and the oscillation circuit 40 is connected to the external vibrator 18. The AFE-IC12 further includes: a sequencer 41 for operating the internal circuits of the chip in a predetermined order; control logic 42 that generates an internal control signal based on the instruction code of the sequencer 41 and the digital code from the AD conversion circuit 36; a timer circuit 43 that performs a timer operation based on a clock signal from the oscillation circuit 40; and a relief valve control circuit 44 that generates a signal for operating the relief valve 24.

The AFE-IC12 includes: an internal oscillation circuit (oscillation circuit not using a vibrator) 45 configured by a ring oscillator or the like for generating a clock signal of a predetermined frequency, and a watchdog circuit 46 that operates based on the clock signal generated by the internal oscillation circuit 45.

In contrast to the oscillation frequency of the oscillation circuit 40 being set to a high value, for example, several hundreds kHz to several MHz, the oscillation frequency of the internal oscillation circuit 45 is set to a low value, for example, several tens kHz to several tens kHz.

In the AFE-IC12 of the present embodiment, the internal oscillation circuit 45 that generates a signal of a predetermined frequency without using an external vibrator generates a clock signal for the watchdog function, and the elements constituting the internal oscillation circuit 45 and the wiring for transmitting the clock signal are covered with the plastic cladding, so that even when relatively large electromagnetic noise is generated at the time of discharging the igniter 27, there is little possibility that the electromagnetic noise is mixed into the internal oscillation circuit 45 and the watchdog function is impaired. That is, it is possible to realize a gas stove electronic control device including a clock monitoring circuit having high noise resistance.

In addition, even in the case where the discharge electrode of the igniter 27 is located at a position distant from the AFE-IC12, since the high voltage cable is disposed in the gas range case, in the case where the external vibrator is used, there is a possibility that noise generated at the time of ignition from the high voltage cable may adversely affect the internal circuit of the AFE-IC12 to cause malfunction at the external terminal of the connection vibrator, but in the AFE-IC12 of the present embodiment, the watchdog circuit 46 operates in accordance with the clock signal generated by the internal oscillation circuit 45, and thus malfunction due to noise at the time of discharge of the igniter 27 can be avoided.

Fig. 3 shows a specific circuit configuration example of the watchdog circuit 46 of the present embodiment.

As shown in fig. 3, the watchdog circuit 46 of the present embodiment includes: an edge detection circuit 51 that detects a rising edge or a falling edge of the clock signal generated by the internal oscillation circuit 45; an edge detection circuit 52 that detects an edge of a watchdog clock WDP input from the MCU11 to the terminal WDI; a W/D counting circuit 53 that counts the number of edge detections of the watchdog clock WDP; comparison circuits 55A and 55B for comparing the value counted by the W/D counting circuit 53 with the determination value (maximum value) and the determination value (minimum value) set in the registers 54A and 54B; an OR gate 56 that obtains a logical sum of outputs of the comparison circuits 55A, 55B; and a test circuit 57 for testing the operation of the circuit.

In the registers 54A and 54B, a count value corresponding to the allowable maximum frequency of the watchdog clock WDP and a count value corresponding to the allowable minimum frequency are set as determination values. The watchdog circuit 46 operates in accordance with a control signal of the control logic 42, and supplies the output of the OR gate 56 to the control logic 42, and when an abnormality is detected, the control logic 42 operates so as to output a signal for shutting off the safety valve 24 to the safety valve control circuit 44. The W/D counter circuit 53 is configured to be able to write a value by the test circuit 57 in the test mode.

As shown in fig. 3, the W/D counter circuit 53 operating based on the clock signal from the internal oscillation circuit (internal OSC) 45 counts the watchdog clock WDP input to the terminal WDI for a predetermined time (for example, 1 second) and converts the counted time to a pulse frequency, and when it is determined that the frequency is not in the range of 1kHz to 10Hz, it is determined that there is an abnormality in the watchdog clock WDP.

When it is determined that there is an abnormality, the safety valve control register clears all bits, thereby outputting a signal (abnormality signal) for shutting off the safety valve 24, and for example, sets 1 to the abnormality flag of the watchdog status register. By transmitting the bit of the watchdog status register to the MCU11, the MCU11 can be made aware of an abnormality of the watchdog clock WDP.

The watchdog circuit 46 of the present embodiment includes: a frequency divider circuit for generating a clock signal to an oscillator circuit (OSC) 40Frequency division is carried out; and a buffer 59 for outputting the divided signal from the terminal CKLO to the outside of the chip as an abnormality detection clock WCK. By inputting the abnormality detection clock WCK to the MCU11 and monitoring it by a program, the MCU11 can detect an abnormality in the operation of the AFE-IC 12. The clock signal generated by the internal oscillation circuit (internal OSC) 45 may be outputted to the outside of the chip as the abnormality detection clock WCK.

Next, a sequence of ignition switch processing performed by the Microcomputer (MCU) 11 as a master IC and the analog front end IC (AFE-IC) 12 as a slave IC when the ignition switch 28 is operated in the gas range electronic control device shown in fig. 1 will be described with reference to the flowchart of fig. 4. Fig. 4 (a) is a flowchart of the MCU11, and (B) is a flowchart of the AFE-IC 12.

When the ignition switch 28 is turned on and an on signal of the ignition switch 28 is input to the Microcomputer (MCU) 11, the ignition switch process shown in fig. 4 is started, and first, a setting instruction (command code) for instructing initial setting is transmitted from the MCU11 to the AFE-IC12, and the initial setting process is executed by the AFE-IC12 (steps S11, S12). The specific contents of this initial setting process will be described in detail with reference to fig. 4.

When the initial setting is completed, the MCU11 transmits a start command for starting the sequencer to the AFE-IC12, and the AFE-IC12 receives the start command and performs the start processing of the sequencer (steps S12 and S22). Thus, abnormality monitoring for determining abnormality of the watchdog clock WDP is started. Then, the MCU11 determines whether or not ignition is successful by, for example, reading a status register in the AFE-IC12 (step S13), and transitions to the sleep state when it is determined that ignition is successful (yes).

On the other hand, when the reception and start-up process of the timer start-up instruction is completed (step S22), the AFE-IC12 turns on the current switching transistor 13 for causing the current to flow through the igniter 27, starts discharging the igniter 27 (step S23), and thereafter turns on the transistor TR1 of the switching circuit 16 to open the relief valve 24, thereby starting the supply of the fuel gas (step S24).

Next, the electromotive force of the thermocouple 25 is read to determine whether or not a flame is detected (step S25). Then, when a flame is detected, it is determined that ignition is successful, the discharge of the igniter 27 is stopped (step S26), and when a flame is not detected, the abnormality process of shutting off the safety valve 24 is executed (step S30).

When the discharge of the igniter 27 is stopped in step S26, the routine proceeds to step S27, where it is determined whether or not the battery voltage is equal to or higher than a set value, and if not, an abnormality process of shutting off the safety valve 24 is executed (step S30). If the battery voltage is equal to or higher than the set value, the routine proceeds to step S28, where the detection voltage of the thermistor 26 is read, and it is determined whether or not the detection voltage is equal to or higher than the set value, and if the detection voltage is not equal to or higher than the set value, the abnormality processing for shutting off the safety valve 24 is executed (step S30). Then, when the detected voltage of the thermistor 26 is equal to or higher than the set value, the flow proceeds to step S29, and the electromotive force of the thermocouple 25 is read to determine whether or not a flame is detected, that is, whether or not the stove burner 21 is not turned off, and when the flame is not detected, the abnormality processing of the shut-off relief valve 24 is executed (step S30). When a flame is detected, the process returns to step S27, and the above-described process is repeated.

Next, specific steps of the initial setting process (steps S11, S12) of each of the master IC (MCU 11) and the slave IC (AFE-IC 12) will be described with reference to the flowchart of fig. 5.

As shown in fig. 5, when the initial setting process is started, first, the MCU11 performs initial setting of the general-purpose port (i.e., input/output port), and transmits a setting instruction (command code) for instructing initial setting of the general-purpose port of the AFE-IC, such as the validity/invalidity of the abnormality monitoring clock output, the validity/invalidity of the interrupt output, the validity/invalidity of the igniter control output, and the validity/invalidity of the buzzer control output, to the AFE-IC12, and the AFE-IC12 performs setting of the port received (steps S31, S41).

Next, the generation and output of the watchdog clock WDP is started at the MCU11 (step S32), and the generation and output of the abnormality monitoring clock WCK is started at the AFE-IC12 (step S42). Then, a setting command for instructing the initial setting of the watchdog circuit 46 is transmitted from the MCU11 to the AFE-IC12, and the setting command is received and set by the AFE-IC12 (steps S33 and S43), and the monitoring of the abnormality monitoring clock WCK from the AFE-IC12 is started at the MCU11 (step S34).

Then, a setting command for instructing the initial setting of the AD conversion circuit 36 is transmitted from the MCU11 to the AFE-IC12, and the setting command is received and set by the AFE-IC12 (steps S35 and S44).

Then, a setting command for instructing the initial setting of the thermistor switching circuit 35 is transmitted from the MCU11 to the AFE-IC12, and the setting command is received and set by the AFE-IC12 (steps S36 and S45). Further, a setting command for instructing the initial setting of the power supply voltage detection circuit 31 and a setting command for instructing the setting of the determination value to the registers 54A, 54B of the watchdog circuit 46 are transmitted from the MCU11 to the AFE-IC12 (steps S37, 38), and the AFE-IC12 receives the setting command and performs setting (steps S46, S47).

(modification)

Next, a modification of the electronic control device for a gas range according to the above embodiment will be described with reference to fig. 6 and 7. Fig. 6 shows a first modification, fig. 7 shows a second modification, and the same or corresponding components and circuits are given the same reference numerals, and overlapping description is omitted.

As shown in fig. 6, in the first modification, the switching circuit 16 is constituted by the transistor TR1 and the OR gate G1, and the signals from the MCU11 and the AFE-IC12 are input to the input terminal of the OR gate G1, instead of the switching circuit 16 constituted by the transistors TR1 and TR2 connected in series, which operates the safety valve 24. The MCU11 and AFE-IC12 function as in FIG. 1.

The OR gate G1 of fig. 6 can be constituted by a diode OR circuit, for example. The diode OR circuit is composed of 2 diodes having cathode terminals connected to each other, and can reduce the number of constituent elements compared with the switching circuit 16 of fig. 1.

As shown in fig. 7, the second modification is to package the MCU11 and the AFE-IC12 in one package PK to constitute one semiconductor device. Further, the circuits of the MCU11 and the AFE-IC12 may be formed on one semiconductor chip, and may be configured as one system LSI.

Fig. 8 shows a second embodiment of the electronic control device for a gas range according to the present invention.

The present embodiment is used for a case where an electronic control device is configured by 3 ICs, and as a specific example of such a configuration, a control device including the MCU11, AFE-IC12, and power supply control IC61 is considered, for example.

In such a control device, as shown in fig. 8 (a), watchdog clocks WDP1 and WDP2 are output from 2 general-purpose I/O ports of the MCU11, input to the AFE-IC12 and the power supply control IC61, respectively, are monitored by a watchdog circuit W/D inside the chip, and abnormality monitoring clocks WCK are output from the AFE-IC12 and the power supply control IC61, respectively, and input to the MCU11, and are monitored.

As shown in fig. 8 (B), the watchdog clock WDP1 may be output from the general-purpose I/O port of the MCU11 and input to the AFE-IC12, the abnormality monitoring clock WCK1 may be output from the AFE-IC12 and input to the power supply control IC61, and the abnormality monitoring clock WCK2 may be output from the power supply control IC61 and input to the MCU11 to monitor each other. The same manner of thinking can be applied to a case where the electronic control device is configured by 4 or more ICs.

The invention proposed by the present inventors is specifically explained above according to the embodiments, but the invention is not limited to the above-described embodiments. For example, in the above embodiment, the comparison circuits 55A and 55B are provided and the value counted by the W/D counter circuit 53 is compared with the determination values (maximum value and minimum value) set in the registers 54A and 54B, but only one of the registers and the comparison circuits may be provided. In the above embodiment, the value counted by the W/D counter circuit 53 is compared with the determination value (maximum value) and the determination value (minimum value) set in the registers 54A and 54B, but the value may be compared with the determination value set in advance as a fixed value instead of the value set in the registers.

In the above embodiment, the watchdog circuit 46 determines the presence or absence of an abnormality based on the frequency of the watchdog clock WDP from the MCU, but the period of the WDP may be counted and the presence or absence of an abnormality may be determined based on the length of the period.

As described above, the AFE-IC12 includes the serial interface circuit 39 for performing serial data communication with the microcomputer 11, and the oscillation circuit 40 for generating a clock signal of the serial interface circuit 39, and the external vibrator 18 is connected to the oscillation circuit 40. The AFE-IC12 includes a timer 41 for operating the internal circuits of the chip in a predetermined order, a control logic 42 for generating an internal control signal based on the instruction code of the timer 41 and the digital code from the AD conversion circuit 36, a timer circuit 43 for performing a timer operation based on the clock signal from the oscillation circuit 40, and a safety valve control circuit 44 for generating a signal for operating the safety valve 24, and the autonomous abnormality monitoring operation is performed by the timer operation of the AFE-IC12, but the AFE-IC12 of the present configuration may perform the abnormality monitoring operation based on the instruction from the microcomputer 11 generated by the manual operation.

In the above-described embodiment, the case where the invention proposed by the inventor is applied to the electronic control device of the gas cooker in the application field as the background of the invention has been mainly described, but the invention is not limited to this, and the invention can be applied to an electronic control system of a device that is liable to generate noise such as a microwave oven for cooking food, an in-vehicle engine control system, and the like.

Description of the reference numerals

11: a Microcomputer (MCU); 12: analog front end IC (AFE-IC); 13: a current switching transistor; 14: a buzzer; 15: a driving circuit; 16: a transistor switching circuit; 20: a gas range; 21: a stove burner; 23: a solenoid valve for adjusting the fire power; 24: a safety valve; 25: a thermocouple; 26: a thermistor; 27: an igniter for ignition; 28: an ignition switch; 45: an internal oscillation circuit; 46: a watchdog circuit.

Claims

1. An electronic control device which includes a plurality of semiconductor integrated circuit devices and generates and outputs a control signal for a device to be controlled,

each of the plurality of semiconductor integrated circuit devices has a function of outputting a clock signal of a predetermined frequency and a function of determining a frequency or a period of the clock signal inputted from the other semiconductor integrated circuit device,

the plurality of semiconductor integrated circuit devices are configured to mutually monitor the clock signals input from the other semiconductor integrated circuit devices,

one of the plurality of semiconductor integrated circuit devices is a microcomputer that generates a clock signal of a predetermined frequency output from the microcomputer by a watchdog function,

2. The electronic control device according to claim 1, wherein,

the semiconductor integrated circuit device other than the microcomputer includes:

an oscillation circuit that generates a clock signal of a predetermined frequency without using a vibrator;

a counting circuit capable of counting the number of clock signals input from other semiconductor integrated circuit devices; and

the counting circuit performs a counting operation based on the clock signal generated by the oscillation circuit, and outputs an abnormal signal when the value counted by the counting circuit exceeds the predetermined determination value.

3. A gas cooker is characterized by comprising:

the electronic control device of claim 2;

a gas burner;

an ignition unit disposed in the vicinity of the gas burner for igniting the gas;

a gas adjusting valve and a solenoid valve provided in the middle of a gas pipe connected to the gas burner; and

a switch circuit for switching on and off the energization to the electromagnetic valve,

the switch circuit is controlled based on the abnormality signal and an abnormality signal generated by detecting a watchdog function of the microcomputer, and the electromagnetic valve is closed when any one of the abnormality signals is output.

4. An electronic control semiconductor integrated circuit device, comprising:

a counting circuit capable of counting the number of clock signals input from the other semiconductor integrated circuit device to the input terminal;