JPS6253848B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reset device for setting an electronic circuit such as a microcomputer to an initial state.

In devices that use a microcomputer, it is necessary to reset the microcomputer and return the program to its initial state before starting operation.

For this reason, conventionally, as shown in Fig. 1, the reset terminal 1a of the microcomputer 1 is connected between the power supply line 2 and the ground, and connected to the connection point between the resistor R and the capacitor C.
While the potential at the reset terminal 1a rises instantaneously as shown in Figure 2a, the potential at the reset terminal 1a rises slowly according to the time constant determined by the resistor R and capacitor C as shown in Figure 2b. The microcomputer 1 uses the rise time difference between the potentials a and b to momentarily set the reset terminal 1a to the "L" level.
I am trying to reset it. However, in this case, malfunctions occur due to so-called chattering, where the voltage drops once when the power is turned on.
It may not be possible to reset reliably.

In order to prevent this, a manually operated reset button is provided, which closes the reset switch and connects the reset terminal 1a of the microcomputer 1 to a predetermined potential point (for example, ground). However, especially if the device has a memory function, there is a risk that the stored contents will be erased if the reset button is pressed by mistake, so it is necessary to place the reset button in a location that is difficult to operate, such as on the back of the device. This results in the inconvenience of forgetting the reset operation itself.

Of course, as shown in FIG. 3, the microcomputer 1 has three reset terminals 1a, 1b, 1c.
are provided, and these three reset terminals 1a, 1b,
It is also conceivable to connect three reset switches 3, 4, and 5 to 1c so that the reset is applied only when these three switches are closed at the same time. In this way, even if the reset buttons for switches 3, 4, and 5 are placed on the front of the device, there is no risk of erroneous operation, and it is also possible to prevent forgetting to reset them. , 5, a new problem arises in that a special program must be installed to identify the open and closed states of the terminals.

The present invention provides a reset device that solves these problems.

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 4, S ₁ to _{S 5} are command switches for giving predetermined commands such as writing and reading data to the microcomputer 1, and among these, switches S ₁ , S ₃ , and S ₅ are interlocked with each other. It consists of two circuit switches S _1-1 , S _1-2 , S _3-1 , S _3-2 , S _5-1 , and S _5-2 . One of these switches S _1-1 ,
S _3-1 and S _5-1 operate as switches for giving predetermined commands like the other command switches S ₂ and S ₄ ,
The other switches S _1-2 , S _3-2 , and S _5-2 are connected in series between the reset terminal 1a of the microcomputer 1 and ground.

In the above configuration, if the switches S ₁ to S ₅ are individually closed, a predetermined command can be given to the microcomputer 1, and the switches S ₁ , S ₃ , S ₅
Only when both are closed at the same time, the reset terminal 1a is connected to ground, and the microcomputer 1 is reset.

As described above, according to the present invention, (1) Since the reset can be performed by manual operation of the switch, the reset operation can be performed more reliably than when the power supply is turned on.

(2) Since the reset point of the electronic circuit is directly connected to a predetermined potential point to apply a reset, there is no need for a program to identify the open/closed states of multiple switches.

(3) Since the reset is activated only when multiple switches are closed at the same time, there is no risk of accidentally resetting or forgetting to reset even if the reset button is provided on the front of the device.

(4) Since the reset switch is interlocked with the command switch, the reset button can also be used as the command button, which is advantageous in terms of mounting space for parts.

This excellent effect can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional example, FIG. 2 is an explanatory diagram of its operation, FIG. 3 is a circuit diagram of another conventional example, and FIG. 4 is a circuit diagram of an embodiment of the present invention. 1...Microcomputer, 1a...Reset terminal, 2...Power line, _S1-1 , S2, _{S3-1 , S4} , _S5-1
...Command switch, _S1-2 , _S3-2 , _S5-2 ...Reset switch.

Claims (1)

[Claims] 1. An electronic circuit configured to reset the circuit network to an initial state when a reset point in the circuit network is connected to a predetermined potential point, and a plurality of command switches that command the electronic circuit to perform predetermined operations;
A reset device comprising a plurality of reset switches interlocked with the plurality of command switches, the plurality of reset switches being connected in series between a reset point in the circuit network and the predetermined potential point.