CN110657458A

CN110657458A - Electronic control device, semiconductor integrated circuit device for electronic control, and gas range

Info

Publication number: CN110657458A
Application number: CN201910578094.3A
Authority: CN
Inventors: 濑川智贵
Original assignee: Sanmei Electric Co Ltd
Current assignee: Sanmei Electric Co Ltd
Priority date: 2018-06-28
Filing date: 2019-06-28
Publication date: 2020-01-07
Anticipated expiration: 2039-06-28
Also published as: JP2020003128A; KR102650821B1; KR20200001980A; CN110657458B; JP7116304B2

Abstract

The invention provides an electronic control device, a semiconductor integrated circuit device for electronic control, and a gas range, which have a watchdog function with strong electromagnetic noise resistance. In 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 input from another semiconductor integrated circuit device, and the plurality of semiconductor integrated circuit devices mutually monitor the clock signal input from another semiconductor integrated circuit device.

Description

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

Technical Field

The present invention relates to a technique for mutually monitoring watchdog signals between a microcomputer and a plurality of semiconductor devices such as analog front end (analog front end), and for example, relates to a technique effectively used for an electronic control device of a device that generates relatively large electromagnetic noise such as a gas range, and an electronic control IC (semiconductor integrated circuit) constituting the electronic control device.

Background

Conventionally, a gas range control device has been provided as an example of an electronic control device having a dongle function. The gas range includes an ignition circuit (igniter) and generates relatively large electromagnetic noise when the igniter is discharged, which may cause a program of the microcomputer to be out of control. An invention has been proposed in which, in the electronic control device for a gas range, power supply to the solenoid valve is cut off when the pulse cycle of the watchdog clock signal is shorter than a normal range, in addition to the absence of the watchdog clock signal (patent document 1).

Patent document 2 describes the following invention: a safety circuit is provided, and 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 based on combustion temperature sensors are duplicated and the safety control units monitor each other for abnormalities, and is not an invention in which a main control unit and a safety control unit monitor each other for abnormalities.

The invention described in patent document 1 is effective for preventing an erroneous operation of a control device due to runaway of a microcomputer in an electronic control system. On the other hand, an electronic control device for a gas range may be composed of a microcomputer and an analog front-end IC that processes signals from sensors for detecting flame and temperature. In such a case, there is a possibility that the control device malfunctions due to runaway of the analog front end IC, and therefore, it is necessary to prevent runaway by monitoring the operation of the analog front end IC.

Conventionally, in a system including a plurality of ICs, a watchdog clock signal is mutually monitored (patent document 3). However, a microcomputer and other IC having a function of outputting a watchdog clock signal in the related art generally have an oscillation circuit having an external oscillator such as a crystal oscillator for generating an operation clock signal, and generate the watchdog clock signal from a clock signal generated by dividing the oscillation signal of the oscillation circuit.

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

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

Patent document 2: japanese patent laid-open publication No. 2016-011807

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

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above-mentioned problems, and an object thereof is to enable mutual monitoring of runaway to detect a malfunction and cut off an electromagnetic valve in an electronic control device for a gas range including a microcomputer and a plurality of semiconductor devices such as analog front ends. 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 is 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 input 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 monitor the clock signal input from another semiconductor integrated circuit device with each other.

According to the above configuration, since the clock signals are mutually monitored, it is possible to detect a situation in which any one of the semiconductor integrated circuit devices is out of control.

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

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

With this configuration, the electronic control device can be designed efficiently by using the watchdog function of the microcomputer.

Preferably, 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 counter circuit capable of counting the number of clock signals input from another semiconductor integrated circuit device; and a comparison circuit that compares a value counted by the counter circuit with a predetermined determination value, wherein the counter circuit performs a counting operation based on the clock signal generated by the oscillator circuit, and outputs an abnormality signal when the value counted by the counter 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 oscillator circuit not using the oscillator, and determines the presence or absence of an abnormality based on the count value, so that it is possible to avoid an abnormality in the clock signal due to external noise, prevent erroneous determination, and improve the noise resistance of the semiconductor integrated circuit device.

A gas range according to another aspect of the present invention includes: an electronic control device having the above-described configuration; a gas burner; an ignition unit disposed in the vicinity of the gas burner and configured to ignite the gas; a gas regulating valve and an electromagnetic valve provided in a gas pipe connected to the gas burner; and a switching circuit for turning on/off the energization to the electromagnetic valve, the switching circuit being controlled based on the abnormality signal and an abnormality signal generated by detection of a watchdog function of the microcomputer, and the electromagnetic valve being 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 mutually monitor the clock signal from each other, if any one of them is out of control, the out of control can be detected, and the supply of gas can be shut off by closing the electromagnetic valve, so that the safety of the gas range can be improved.

Another semiconductor integrated circuit device for electronic control according to the present invention includes:

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 that transmits and receives data to and from other semiconductor integrated circuit devices;

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

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

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

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

the counter circuit performs a counting operation based on the clock signal generated by the second oscillation circuit, and outputs a signal indicating an abnormality when a value counted by the counter 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 oscillator circuit not using the oscillator, and determines the presence or absence of an abnormality based on the count value, so that it is possible to avoid occurrence of an abnormality in the clock signal due to external noise, prevent erroneous determination, and improve noise resistance of the semiconductor integrated circuit device. Further, since the oscillator circuit is provided to generate the clock signal necessary for the operation of the communication circuit using the oscillator, the oscillation frequency of the oscillator circuit can be easily made higher than the oscillation frequency of the oscillator circuit not 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 having a high frequency in the communication circuit.

According to the present invention, in the electronic control device for a gas range including a microcomputer and a plurality of semiconductor devices such as analog front ends, runaway can be mutually monitored to detect a malfunction and cut off the solenoid valve. Further, the electronic control device having the watchdog function having a high resistance to electromagnetic noise, the electronic control IC constituting the electronic control device, and the gas range can be realized.

Drawings

Fig. 1 is a circuit configuration diagram showing an embodiment of an 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) according to 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 the ignition switch processing of the Microcomputer (MCU) and the AFE-IC.

Fig. 5 (a) and (B) are flowcharts showing an example of the procedure of the initial setting process of the Microcomputer (MCU) and the 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 configuration diagrams showing another embodiment of the electronic control device for a gas range according to the present invention.

Detailed Description

Preferred embodiments of the present invention will be described below 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 chain line a is a gas range electronic control device 10. The portion enclosed by the chain line B is a gas range 20, and fig. 2 shows a range burner 21 as a main component, a heating power adjusting solenoid valve 23 provided in the middle of a gas pipe 22, and a fail-safe relief valve 24 formed of a solenoid valve.

A thermocouple 25 for detecting flame, a thermistor 26 for detecting the temperature of the bottom of a cooking utensil such as a pot or a frying pan, which is placed on the cooker part above the cooker burner 21, and an ignition igniter 27 are disposed in the vicinity of the cooker burner 21. Attached to the reference numeral 28 is an ignition switch for energizing the igniter 27. The fire power adjusting solenoid valve 23 may be configured to include a motor, and the gas flow rate may be adjusted by changing the angle of the valve by the motor, or may be configured to adjust the gas flow rate by driving and controlling an openable and closable solenoid valve in a PWM (pulse width modulation) system.

The gas range electronic control device 10 of the present embodiment is composed of a microcomputer (hereinafter referred to as MCU)11 and an analog front end IC (hereinafter referred to as AFE-IC)12 for detecting signals from sensors such as a thermocouple 25 and a thermistor 26, and includes, as peripheral devices, a current switching transistor 13 for passing a current to an igniter 27, a buzzer 14 for emitting an alarm sound, a drive circuit 15 for driving a heating power adjustment solenoid valve 23, and a transistor switching circuit 16 for operating a safety valve 24. Further, a battery 17 for supplying a power supply voltage to the AFE-IC12 is provided. The power supply voltage of the MCU11 can also be supplied from the battery 17.

In order to generate a clock signal of a predetermined frequency by an internal oscillation circuit, the oscillator 18 is connected as an external element to the AFE-IC 12. Although not shown, the MCU11 similarly includes an internal oscillation circuit and an external terminal for connecting a transducer in order to generate a system clock signal used inside the chip. The MCU11 can also be of the form: the clock signal generator includes an input terminal for receiving an externally generated clock signal, and operates by the clock signal supplied from the outside. Attached to reference numeral 19 is an LED (light emitting diode) as an indicator light for indicating that a power supply voltage (battery voltage) is supplied or turned on, or that an abnormality of the range is present.

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, provided inside the chip. The AFE-IC12 is provided with a terminal CLKO for outputting an internally generated clock signal as an abnormality monitoring clock, and a terminal WDI for inputting 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 via any one general-purpose IO port (input/output port) GPIO and output the watchdog clock WDP from the other general-purpose IO port GPIO.

By monitoring the watchdog clock WDP and the abnormality monitoring clock WCK generated in the respective units in this manner, if the other IC is out of control, the out-of-control situation can be detected. The AFE-IC12 is provided with a terminal OUT for outputting a signal when an abnormality of the watchdog clock WDP is detected, and the MCU11 is configured to output an abnormality signal from the general IO port GPIO when an abnormality of the abnormality monitoring clock WCK is detected. The MCU11 can be freely set by an internal user program, which general IO port GPIO is used to receive the input of the clock WCK and output the clock WDP and the exception signal.

The AFE-IC12 is provided with an external terminal for inputting the chip select signal CS from the MCU11, the synchronous clock signal SCK for serial communication, and the serial data SDATA, and an external terminal SOUT for outputting the 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 to the MCU11 from the external terminal SOUT.

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 the terminal OUT of the AFE-IC12 and the general IO port GPIO of the MCU11, and controls the safety valve 24. That is, the clock abnormality signal is a signal for operating the safety valve 24.

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

Accordingly, the transistors TR1 and TR2 normally flow a collector current, and energize the solenoid of the relief valve 24, thereby opening the valve. As a result, the solenoid valve 23 is supplied with gas through the relief valve 24. When a high-level detection signal indicating an abnormality of the watchdog clock is output from either one of the terminal OUT of the AFE-IC12 and the general IO port GPIO of the MCU11, the transistor TR1 or TR2 is turned off. As a result, the energization of the relief valve 24 is cut off to demagnetize the solenoid, thereby controlling the valve to the closed state. Therefore, a safety function of shutting off the safety valve 24 without supplying the gas to the electromagnetic valve 23 is activated.

Further, 2 resistors R1 and R2 connected in series to the 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 input to the analog input terminal ANIN of the AFE-IC12, and the AFE-IC12 can detect the state of the safety valve 24 from the input potential of the terminal. Specifically, it can be detected that the relief valve 24 is opened if the input potential of the terminal ANIN is high, and that the relief valve 24 is closed if the input potential of the terminal ANIN is low.

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 the battery voltage applied to the 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; and a power-on reset circuit 34 that generates a power-on reset signal for resetting the inside when the power is turned on.

The AFE-IC12 includes: a thermistor switching circuit 35 for switching the voltage dividing resistance value connected in series to a plurality of (5 in the figure) thermistors 26 for detecting temperature; an AD conversion circuit 36 that converts the detection voltage of the thermistor into a digital code; a multiplexer 37a for supplying 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 utensil to the AD conversion circuit 36; a multiplexer 37b that selects one detection signal from among a plurality of (6 in the figure) thermocouples 25; and an amplifier 38 for amplifying the selected detection signal. The signal amplified by the amplifier 38 and the input signals 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 codes.

The AFE-IC12 includes: a serial interface circuit 39 that performs serial data communication with the microcomputer 11; and an oscillation circuit 40 for generating a clock signal of the serial interface circuit 39, wherein the external oscillator 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 from the instruction code of the timer 41 and the digital code from the AD conversion circuit 36; a timing circuit 43 that performs a timing operation based on a clock signal from the oscillation circuit 40; and a safety valve control circuit 44 that generates a signal for operating the safety valve 24.

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

The oscillation frequency of the oscillation circuit 40 is set to a high value such as several hundred kHz to several MHz, for example, while the oscillation frequency of the internal oscillation circuit 45 is set to a low value such as several kHz to several tens kHz, for example.

In the AFE-IC12 of the present embodiment, since 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 clad, even if a relatively large electromagnetic noise is generated at the time of discharge of 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 an electronic control device for a gas range including a clock monitoring circuit having high noise resistance.

Further, even when 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 of using the external vibrator, noise generated when the ignition is performed from the high-voltage cable may have a bad influence on the internal circuit of the AFE-IC12 at the external terminal to which the vibrator is connected, and cause an erroneous operation, in the AFE-IC12 of the present embodiment, the watchdog circuit 46 operates based on the clock signal generated by the internal oscillation circuit 45, and therefore, an erroneous operation due to noise when the igniter 27 discharges can be avoided.

Fig. 3 shows a specific circuit configuration example of the watchdog circuit 46 according to 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 counter circuit 53 that counts the number of edge detections of the watchdog clock WDP; comparison circuits 55A and 55B that compare the value counted by the W/D counter 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 the logical sum of the outputs of the comparison circuits 55A and 55B; and a test circuit 57 for testing the operation of the circuit.

In addition, the registers 54A and 54B set, as determination values, a count value corresponding to the allowable maximum frequency and a count value corresponding to the allowable minimum frequency of the watchdog clock WDP. The watchdog circuit 46 operates in accordance with a control signal of the control logic 42, supplies an 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, which operates in accordance with a clock signal from the internal oscillator circuit (internal OSC)45, counts the watchdog clock WDP input to the terminal WDI for a predetermined time (for example, 1 second), converts the count into a pulse frequency, and determines that there is an abnormality in the watchdog clock WDP when the frequency is determined to be out of the range of 1kHz to 10Hz, for example.

When it is determined that there is an abnormality, all bits of the safety valve control register are cleared, and a signal (abnormality signal) for cutting off the safety valve 24 is output, and, for example, 1 is set to an abnormality flag of the status register for watchdog. 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 dividing circuit for dividing the clock signal generated by the oscillation circuit (OSC)40Carrying out frequency division; and a buffer 59 for outputting the frequency-divided signal to the outside of the chip from a terminal CKLO as an abnormality detection clock WCK. The abnormality detection clock WCK is input to the MCU11 and monitored by a program, whereby the MCU11 can detect an operation abnormality of the AFE-IC 12. Further, 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, the 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 electronic control device for a gas range 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 processing shown in fig. 4 is started, and first, a setting command (command code) for commanding initial setting is transmitted from the MCU11 to the AFE-IC12, and the AFE-IC12 executes the initial setting processing (steps S11 and S12). The details 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 to the AFE-IC12 to start the timer, and the AFE-IC12 receives the start command and performs the timer start processing (steps S12 and S22). This starts anomaly monitoring for determining an anomaly of the watchdog clock WDP. Then, the MCU11 determines whether or not ignition is successful by reading a status register in the AFE-IC12 (step S13), for example, and shifts to a sleep state when it is determined that ignition is successful (yes).

On the other hand, when the reception of the sequencer activation command and the activation processing (step S22) are completed, the AFE-IC12 turns on the current switching transistor 13 for causing the current to flow through the igniter 27 to start the discharge of the igniter 27 (step S23), and then turns on the transistor TR1 of the switching circuit 16 to open the safety valve 24 to start the supply of the gas (step S24).

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

After the discharge of the igniter 27 is stopped in step S26, the process proceeds to step S27, where it is determined whether or not the battery voltage is equal to or greater than a set value, and if not, an abnormal process for shutting off the safety valve 24 is executed (step S30). When the battery voltage is equal to or higher than the set value, the process proceeds to step S28, where the detection voltage of the thermistor 26 is read, whether or not the battery voltage is equal to or higher than the set value is determined, and if the battery voltage is not equal to or higher than the set value, an abnormality process for shutting off the safety valve 24 is executed (step S30). Then, when the detected voltage of the thermistor 26 is read and is equal to or higher than the set value, the process 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 extinguished is determined, and when a flame is not detected, an abnormality process for shutting off the safety valve 24 is performed (step S30). When the flame is detected, the process returns to step S27 to repeat the above process.

Next, the specific steps of the initial setting processing (steps S11 and S12) of the master IC (MCU11) and the slave IC (AFE-IC12) will be described with reference to the flowchart of fig. 5.

As shown in fig. 5, when the initial setting process is started, the MCU11 initially sets a general-purpose port (i/o port), transmits a setting command (command code) to the AFE-IC12 to command the initial setting of the general-purpose port of the AFE-IC, such as enabling/disabling of the abnormality monitoring clock output, enabling/disabling of the interrupt output, enabling/disabling of the igniter control output, and enabling/disabling of the buzzer control output, and the AFE-IC12 sets the received port (steps S31 and S41).

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

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

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

(modification example)

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 denoted by the same reference numerals, and redundant description thereof is omitted.

As shown in fig. 6, in the first modification, the switching circuit 16 is configured by a transistor TR1 and an OR gate G1, and the switching circuit 16 configured by series-connected transistors TR1 and TR2 for operating the safety valve 24 is replaced by inputting signals from the MCU11 and the AFE-IC12 to the input terminal of the OR gate G1. The functions of the MCU11 and AFE-IC12 are the same as in FIG. 1.

The OR gate G1 of fig. 6 may be formed of, for example, a diode OR circuit. The diode OR circuit is composed of 2 diodes having cathode terminals coupled to each other, and the number of components can be reduced as compared with the switching circuit 16 of fig. 1.

As shown in fig. 7, the second modification is a semiconductor device in which the MCU11 and the AFE-IC12 are packaged in one package PK. Further, the MCU11 and AFE-IC12 may be formed as a single system LSI by forming the circuits on a single semiconductor chip.

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

The present embodiment is applied to a case where an electronic control device is configured by 3 ICs, and a specific example of such a configuration is a control device including the MCU11, the AFE-IC12, and the power supply control IC 61.

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, are input to the AFE-IC12 and the power control IC61, respectively, are monitored by the watchdog circuit W/D inside the chip, and are also monitored by an abnormality monitoring clock WCK output from the AFE-IC12 and the power control IC61, respectively, and are input to the MCU 11.

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 for mutual monitoring. The same concept 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 has been specifically described above based on the embodiments, but the present invention is not limited to the above embodiments. For example, in the above embodiment, 2 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 circuit may be provided. In the above embodiment, the example in which 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 has been described, but the value may be compared with the determination value set in advance as a fixed value, instead of the value set in the register.

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 may count the period of the WDP and determine the presence or absence of an abnormality based on the length of the period.

As described above, the AFE-IC12 includes the serial interface circuit 39 that performs serial data communication with the microcomputer 11, and the oscillation circuit 40 that generates a clock signal for the serial interface circuit 39, and the external oscillator 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 internal control signals based on the command 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 performs an autonomous abnormality monitoring operation by the timer operation of the AFE-IC12, but the AFE-IC12 of the present configuration may perform an abnormality monitoring operation based on a command from the microcomputer 11 generated by a 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 range as the application field of the background of the invention has been mainly described, but the invention is not limited to this, and can be applied to an electronic control system of a device which is likely to generate noise, such as a microwave oven for cooking food, or a vehicle-mounted engine control system.

Description of the reference numerals

11: a Microcomputer (MCU); 12: an analog front end IC (AFE-IC); 13: a current switching transistor; 14: a buzzer; 15: a drive circuit; 16: a transistor switch circuit; 20: a gas range; 21: a stove burner; 23: an electromagnetic 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 having a predetermined frequency and a function of determining a frequency or a period of the clock signal input from another semiconductor integrated circuit device,

2. The electronic control device according to claim 1,

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,

3. The electronic control device according to claim 2,

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 counter circuit capable of counting the number of clock signals input from another semiconductor integrated circuit device; and

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

4. A gas range is characterized by comprising:

the electronic control device of claim 3;

a gas burner;

an ignition unit disposed in the vicinity of the gas burner and configured to ignite the gas;

a gas regulating valve and an electromagnetic valve provided in a gas pipe connected to the gas burner; and

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

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

5. A semiconductor integrated circuit device for electronic control, comprising: