JP2004199310A - Operation mode setting device and setting method for electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a microcomputer itself to set a low-power-consumption mode by software without using a resistor or an external memory. <P>SOLUTION: Upon starting after a power failure or reset, the microcomputer 3 executes a self-diagnostic function. At that point, it is detected whether an interrupt is generated in a characteristic time based on a frequency of a sub oscillator 5. When the interrupt is present, it is decided that the sub oscillator 5 is present, setting of the low-power-consumption mode is set to be present. When the interrupt is absent, the setting of the low-power-consumption mode is set to be absent. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an operation mode setting device for setting whether or not to execute a low power consumption mode for guaranteeing a minimum operation in a power failure or the like in an electronic device driven and controlled by a microcomputer.
[0002]
[Prior art]
Conventionally, a microcomputer that controls an electronic device includes an oscillator that generates a clock signal. The microcomputer generates an internal clock based on the clock signal and performs various timing controls. Usually, a crystal oscillator that generates a high-frequency clock signal is used as the oscillator. This oscillator has high power consumption. Therefore, when the power supply is cut off due to a power failure or the like, the oscillator does not operate and the microcomputer does not operate. Therefore, in the event of an emergency such as a power failure, a backup power supply for backup is provided to ensure the minimum operation of the microcomputer, and a sub-oscillator operable with this power supply is provided. The sub-oscillator generates a clock signal with a lower frequency than the main oscillator and consumes less power.
[0003]
Patent Document 1 discloses that a main oscillator and a sub-oscillator are used to supply a clock signal from the main oscillator in a normal state, and to drive the sub-oscillator by a backup power supply in an emergency to generate a low-frequency clock signal. Is supplied to a microcomputer (for example, see Patent Document 1).
[0004]
In an emergency, a microcomputer that operates based on a low-frequency clock signal mainly operates a clock function, and stores a program in a RAM, which is a volatile memory in the microcomputer. The microcomputer that holds the data is driven by the power supplied from the backup power supply. As described above, in order to execute the minimum required operation of the electronic device in an emergency, the low power consumption mode needs to be set as one of the operation modes in the microcomputer.
[0005]
When the power is restored after a power failure, resetting resets various operation mode settings to the initial settings. Therefore, it is necessary to set the low power consumption mode after returning from the reset. As a setting method of the low power consumption mode, there are a method of providing a setting terminal in a microcomputer and a method of setting initial setting data in a memory.
[0006]
In the method of providing the microcomputer with the setting terminal, a terminal for determining whether the low power consumption mode is set is allocated to the terminal of the microcomputer. By reading the logical value of the terminal, the low power consumption mode is set to the presence or absence. Specifically, the logic value is set to H when the terminal of the microcomputer is connected to a power supply (5 V) via a resistor, and set to L when the terminal is connected to ground (GND). The microcomputer reads the logical value of this terminal when returning from reset. If the read logical value is H, it is determined that the low power consumption mode is set, and if the logical value is L, it is determined that the low power consumption mode is not set.
[0007]
In the method of setting the initial data in the memory, the initial setting data is allocated to an external memory such as an E2PROM. When returning from reset, the microcomputer reads the initial set values in the memory. If the initial setting value is present, it is determined that the low power consumption mode is set. If the initial setting value is not present, it is determined that the low power consumption mode is not set.
[0008]
[Patent Document 1] Japanese Patent Application Laid-Open No. 05-127772 (paragraphs 0012 to 0013, FIG. 1)
[0009]
[Problems to be solved by the invention]
Use of components for setting the operation mode, such as the above-described resistor and external memory, places a burden on the installation space and the circuit design of the board, resulting in an increase in cost. In addition, when the terminal of the microcomputer is used for the setting, the terminal is insufficient when the specification setting of the electronic device is large. In addition, the logic is easily mistaken at the time of circuit design, and mistakes are likely to occur at the time of mounting the resistor. In addition, initial setting data must be written in an external memory in advance, and mistakes are likely to occur at the time of specification determination during design or during data writing during manufacture. Therefore, if there is such a mistake, the operation mode cannot be set correctly.
[0010]
Therefore, an object of the present invention is to provide an operation mode setting device and a setting method of an electronic device that can accurately set a low power consumption mode without using a resistor, an external memory, and the like.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, in an electronic device that operates based on a clock signal of a main oscillator, a detection for detecting the presence or absence of a sub oscillator that generates a clock signal of a lower frequency than the main oscillator is performed. Means, and setting means for setting a low power consumption mode that operates based on a clock signal of the sub-oscillator when the sub-oscillator is present.
[0012]
The detecting means detects whether or not the sub oscillator is connected to the clock terminal. Based on the detection result, the setting unit determines whether the low power consumption mode is set or not. In other words, in the low power consumption mode, when the main power supply is cut off due to a power failure or the like, the backup power supply operates with less power.Therefore, a sub resonator that consumes less power than the main resonator must be used. No. Therefore, the presence of the sub-oscillator is nothing but executing the low power consumption mode. Therefore, by detecting the presence or absence of the sub-oscillator, the operation mode can be easily and definitely set.
[0013]
Here, in detecting the presence or absence of the sub-oscillator, passive means such as waiting for input of a clock signal from the sub-oscillator can be employed. That is, based on the frequency of the main oscillator, a counter is operated to measure time and detect whether there is an external interrupt. A determination means is provided for determining whether an interrupt detected at a predetermined time obtained from the frequency of the main oscillator is an interrupt from the sub oscillator. The predetermined time is a time corresponding to a specific time based on the frequency of the sub oscillator. If the predetermined time at which the interrupt occurs coincides with the specific time based on the frequency of the sub-oscillator, it can be determined that the interrupt is caused by the sub-oscillator. At this time, it is assumed that the detecting means detects the earliest interrupt at the time of startup after the power supply from the main power supply is restored or after the power supply is reset. As a result, the operation mode can be set quickly, so that other processes are not burdened.
[0014]
Further, as the detection means, the presence / absence of a sub oscillator may be actively detected, for example, the presence / absence of use of a clock terminal for the sub oscillator may be detected. As described above, if the presence or absence of the sub-oscillator is directly detected passively or actively, the conventional resistor and memory can be eliminated.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of an electronic device according to the present embodiment. The electronic device is, for example, a video device such as a video, a DVD, or a television, and includes an IC group 1 such as an audio IC and a Y / CIC, a sub-microcomputer 2, and a microcomputer 3 for controlling the driving of these.
[0016]
The main oscillator 4, the sub oscillator 5, and the memory 6 are connected to the microcomputer 3. The microcomputer 3 executes various programs according to the timing based on the clock signal generated by the main oscillator 4, and writes and reads data to and from the memory 6. The memory 6 is a non-volatile memory such as an E2PROM, and temporarily stores setting data and video data.
[0017]
The sub oscillator 5 generates a clock signal having a lower frequency than the main oscillator 4. The main oscillator 4 is a 12 MHz crystal oscillator, the sub oscillator 5 is a 32 KHz crystal oscillator, and the sub oscillator 5 has lower power consumption than the main oscillator 4.
[0018]
The electronic device is supplied with electric power from a commercial power supply or a power generator as the main power supply 7. The power supply drives the microcomputer 3, the IC group 1, the main oscillator 4, the sub oscillator 5, and the like, and the memory 6 holds data.
[0019]
Further, the electronic device has a built-in backup power supply 8 such as a capacitor and a battery. The backup power supply 8 is used in an emergency such as a power outage or a drop in power, such as when a power failure or an abnormality occurs in the main power supply 7. In an emergency, the low power consumption mode is executed. That is, when the voltage from the main power supply 7 decreases and is detected, the power supply is automatically switched to the backup power supply 8. The power from the backup power supply 8 is supplied to the microcomputer 3 and the operation is maintained. Based on the clock signal generated by the sub-oscillator 5, the microcomputer 3 performs the minimum necessary operations such as clock operation and program protection. As described above, in the low power consumption mode, the operation is performed based on the clock signal of the sub oscillator 5 by the power supply from the backup power supply 8 in an emergency.
[0020]
The microcomputer 3 sets the low power consumption mode as one of the operation modes. When there is a setting, the low power consumption mode is executed, and when there is no setting, the low power consumption mode is not executed. This setting is automatically performed at the time of startup after the main power is restored and reset, or after the microcomputer is forcibly reset to prevent runaway of the microcomputer. That is, the microcomputer 3 functions as an operation mode setting device. Here, the microcomputer 3 has a self-diagnosis function such as checking peripheral devices at startup. Using this self-diagnosis function, the microcomputer 3 detects the presence or absence of the sub-oscillator 5, and determines whether or not to set the low power consumption mode based on the result. Specifically, the microcomputer 3 includes a detecting unit that detects the earliest interrupt processing at the time of startup, a determining unit that determines whether the detected interrupt processing is an interrupt processing from the sub-oscillator 5, and a sub-oscillator. Setting means for setting the power consumption mode when there is an interrupt from the sub oscillator 5 and not setting the low power consumption mode when it is not an interrupt from the sub-oscillator 5.
[0021]
Next, a method of setting the operation mode will be described with reference to FIG. After the occurrence of a power failure, when the main power supply 7 recovers and the microcomputer 3 that has recovered from the reset starts up, it performs a self-diagnosis function and performs an operation check and the like. When setting various operation modes by the self-diagnosis function, first, an initial setting value of a high-speed counter (PWS) is set to 32 KHz corresponding to the sub-oscillator 5 as a clock source for timer interrupt processing of the self-diagnosis function. The initial setting value is previously written in the ROM in accordance with the sub-oscillator 5 to be used, and is read and set. Based on the above set value, the earliest time base in the read mode of the timer interrupt processing is set to 0.03125 sec. This time is a predetermined time corresponding to the specific time of the sub-oscillator. As a result, if there is a sub-oscillator 5, the first interrupt processing is performed by the sub-oscillator 5.
[0022]
The microcomputer 3 operates based on the clock signal of the main oscillator 4 and sequentially checks the terminal states and the interrupt occurrence status by this self-diagnosis function. When starting the confirmation, the detection time of the timer is set to, for example, 1 sec. After the start of the confirmation, it is detected whether or not there is a timer interruption process at an interval of 0.03125 sec. If there is an interrupt process to the microcomputer 3 every 0.03125 seconds, it can be recognized as the sub-oscillator 5. Therefore, the microcomputer 3 determines that the low power consumption mode is set. When there is no interrupt processing every 0.03125 seconds and the detection time of 1 second has elapsed, the microcomputer 3 recognizes that there is no sub-oscillator 5 and does not set the low power consumption mode. Therefore, by directly detecting the presence or absence of the sub oscillator, the low power consumption mode can be definitely set.
[0023]
It should be noted that the present invention is not limited to the above embodiment, and modifications and changes can be made within the scope of the present invention. For example, as a means for detecting the presence or absence of a sub-oscillator, the use status of a plurality of clock terminals of a microcomputer may be detected. Furthermore, a plurality of sub-oscillators can be provided, and operation modes assigned to the respective sub-oscillators can be similarly set. As an operation mode other than the low power consumption mode, settings such as a suspend mode and a sleep mode can be performed based on the presence or absence of a sub-oscillator. If the low power consumption mode is not required, a sub-oscillator or a backup power supply need not be provided in advance. At this time, the microcomputer detects that there is no sub-oscillator at the time of startup and sets so as not to execute the low power consumption mode.
[0024]
【The invention's effect】
As described above, according to the present invention, by determining whether or not there is a sub-oscillator, the presence or absence of the low power consumption mode can be definitely set. At this time, since the interrupt operation from the sub-oscillator is used, it is possible to cope with software. Therefore, an external memory and a resistor are not required, and the control board can be reduced in space and size.
[0025]
Further, since no setting terminal is required in the microcomputer, a low-cost microcomputer with a small number of terminals can be used. Alternatively, one extra terminal can be used for another system, and the specification of the electronic device can be given a wide range.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of an electronic device according to an embodiment of the present invention. FIG. 2 is a flowchart of a low power consumption mode setting.
1 IC group 2 Sub microcomputer 3 Micro computer 4 Main oscillator 5 Sub oscillator 6 Memory 7 Main power supply 8 Backup power supply

Claims (5)

In an electronic device that operates based on a clock signal of a main oscillator, a detection unit that detects the presence or absence of a sub oscillator that generates a clock signal having a frequency lower than that of the main oscillator; Setting means for setting a low-power-consumption mode that operates based on a slave clock signal. 2. The operation mode setting device for an electronic device according to claim 1, wherein the detection unit detects whether there is an interrupt from the sub oscillator. The backup power supply operates based on the clock signal of the main oscillator by the main power supply and generates a clock signal of a lower frequency than the main oscillator when the supply of the main power supply is interrupted. Detecting means for detecting the earliest interrupt at the time of startup; determining means for determining whether the detected interrupt is an interrupt from the sub-oscillator; Setting means for setting to execute a low power consumption mode when an interrupt is issued from an oscillator. 4. The operation mode setting device for an electronic device according to claim 3, wherein the determination means determines whether or not there is an interruption of the sub-oscillator at a predetermined time obtained from the frequency of the main oscillator. The sub-oscillator which operates based on the clock signal of the main oscillator by the main power supply and generates a clock signal having a lower frequency than the main oscillator when the supply of the main power supply is interrupted, the low power consumption mode by the backup power supply. In the electronic device that executes, it is detected whether or not there is an interrupt from the sub-oscillator at the time of startup, and when there is an interrupt at a time that matches a specific time based on the frequency of the sub-oscillator, the sub-oscillator is The operation of the electronic device is characterized in that it is determined that there is a power consumption mode, and when there is no interruption during the predetermined time, it is determined that the sub-oscillator does not exist and the low power consumption mode is not set. Mode setting method.

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