JPH02254516A - Resetting device for microcomputer - Google Patents

Abstract

PURPOSE:To cope with many kinds of purposes while using by providing a voltage detecting means which detects the circuit voltage of the device to reset a microcomputer, and switching its detection position to plural circuit voltage positions in accordance with purposes. CONSTITUTION:A microcomputer 1 used for device control, a voltage detecting means 2 which detects the circuit voltage of the device to reset the microcomputer 1, and a switching means 3 which switches the detection position of this voltage detecting means to plural circuit voltage positions in accordance with purposes are provided. Consequently, the detection position is switched to a proper detection position by the switching means when it is necessary to change the reset voltage or timing in accordance with a peripheral circuit. Thus, the principal circuit is shared to cope with requests of different reset detection positions by easy switching in the device where the peripheral circuit is changed to cope with many kinds of purposes.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to power reset of a microcomputer used for controlling equipment.

2. Description of the Related Art In recent years, technology for using microcomputers has advanced, and microcombiators are often used to control devices. In equipment that uses a microcomputer, it is necessary to operate the microcomputer only when the circuit voltage of the equipment is within the guaranteed operating voltage of the microcomputer, and the means to do so is to detect the circuit voltage and reset the microcomputer. Power reset is used. The detection position of the circuit voltage for power reset was determined individually depending on the characteristics of the circuit of the device.

Problems to be Solved by the Invention However, in order to improve development efficiency and production efficiency, the main circuit is the same but the peripheral circuits are changed to support a wide variety of products. There were cases where this occurred.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide a computer-based device that can be used for a wide variety of products while maintaining a common main circuit by selecting a power reset detection position.

Means for Solving the Problems In order to achieve the above object, the microcomputer reset device of the present invention includes a microcomputer used for controlling equipment, and a voltage that detects the circuit voltage of the equipment and resets the microcomputer. This configuration includes a detection means and a switching means that allows the detection position of the voltage detection means to be switched to a plurality of circuit voltage positions depending on the purpose.

Operation The present invention has the above-described configuration, and even if it becomes necessary to change the reset voltage or timing due to circumstances in the peripheral circuit, it is possible to switch to an appropriate detection position using the switching means, and it is possible to use a common main circuit for a wide variety of products. It makes it possible to respond.

Embodiment Figure 1 is a configuration diagram showing an embodiment of the present invention, in which 1 is a microcomputer used to control equipment, 2 is a voltage detection means for detecting the circuit voltage of the equipment, and 3 is a voltage detection position of the voltage detection means 2. This is a switching means that enables switching.

The power outage detection circuit 4 is a peripheral circuit, and may or may not be necessary depending on the characteristics of the device.If the function of the device is simple and power outage detection is unnecessary, the power outage detection circuit 4 is omitted and the switching means 3 The internal contact of is located at position A, and the output voltage of the 12V three-terminal regulator 15 is detected at the position. If the minimum input and output voltage of the 5V three-terminal regulator 6 is 3■,
If the microcomputer 1 is reset when the output voltage of the three-terminal regulator 5 is 8V, the microcomputer 1 will work only in a state where the operating voltage of 5V is guaranteed. Assuming that the voltage detected by the voltage detection means 2 is 3V, the above condition is satisfied by setting the ratio of the dividing resistors R and R1 to 5=3.

If the function of the device is complex and it is not desired to reset the microcomputer 1 even in the event of a power outage, a power outage detection circuit 4 is incorporated as a peripheral circuit. The power failure detection circuit 4 puts the microcomputer 1 into stop mode when the output voltage of the three-terminal regulator 5 drops to 8V. The microcomputer 1 that has entered the stop mode restarts from the state before the stop mode when the power is restored again while retaining the memory contents. In stop mode, the power consumption of the microcomputer 1 is low and the guaranteed operating voltage is 3V, lower than during normal operation. However, if the power outage becomes long and the voltage of the power backup capacitor 7 drops below 3V, , the microcomputer l needs to be reset. Therefore, in this case, the internal contact of the switching means 3 is set to the B position.

According to the configuration of the above embodiment, the switching means 3 can be connected to an appropriate detection position for the detection position of the voltage detection means 2, which differs depending on the presence or absence of the power failure detection circuit 4, which is a peripheral circuit.

Effects of the Invention As described above, in the microcomputer reset device of the present invention, the main circuit is common and only a simple changeover can be made to meet the requirements for different reset detection positions in devices that are compatible with a wide variety of products by changing the peripheral circuits. This has the advantage of improving equipment development efficiency and production efficiency.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a microcomputer reset device in an embodiment of the present invention. 1...Microcomputer, 2...
Voltage detection means, 3...Switching means.

Claims (1)

[Claims] A microcomputer used to control the equipment, a voltage detection means for detecting the circuit voltage of the equipment and resetting the microcomputer, and a detection position of the voltage detection means capable of being switched to a plurality of circuit voltage positions according to the purpose. A microcomputer reset device equipped with a switching means.