JPS62173511A - Reset device for microprocessor - Google Patents

Abstract

PURPOSE:To reset and restart a microprocessor in an automatic way by converting the signal received from an output port of a microprocessor into the voltage value by a pulse/voltage converting circuit and detecting a runaway by a voltage value discriminating circuit. CONSTITUTION:A microprocessor 1 contains a pulse generating means 1a and the reset terminal 1b of the processor 1 is connected to the output of a reset logic circuit 2 together with an output port 1c connected to the input of a pulse/voltage converting circuit 5. The output of the circuit 5 is connected to the circuit 2 via a voltage value deciding circuit 4. Then a power supply voltage detecting circuit 3 is connected to the circuit 2. Thus the circuit 3 detects the power supply voltage. When the processor 1 has a runaway, the signal received from the port 1c is converted into the voltage value by the circuit 5 and the circuit 4 detects the runaway. As a result, the processor 1 is automatically reset and restarted through the circuit 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a reset device for a microprocessor used to control automatic machines and the like.

Prior Art Conventionally, this type of microprocessor reset device is
Generally, as shown in FIG. 4, the power supply V of microprocessor 11. Resistor 13a and capacitor 13b connected to
The power supply voltage detection circuit 13 is composed of a series circuit of the resistor 13a and the capacitor 13b.
The connection point (point A) of the microprocessor 11 was connected to the reset terminal 11a of the microprocessor 11.

In the microprocessor reset device configured as described above, the potential at point A is zero before power is turned on, but the potential at point A is equal to the power supply voltage V. 0 rises, the potential at point A rises due to the time constant of the resistor 13a and capacitor 13b, and in a stable state of the power supply voltage co after the power is turned on, the potential at the reset terminal of the microprocessor 11 rises, and this microprocessor 11 starts working. Power supply voltage V due to disconnection of power switch or power outage. . When becomes zero, the potential of the capacitor 13b drops and the microprocessor 11 is reset and ceases to operate.

(For example, literature: Masaharu Hayause, Fundamentals of One-Chip Microcomputer and Its Application Technology, CQ Publishing, P171゜Figure 9.1) Problems to be Solved by the Invention In such a conventional configuration, it is difficult to detect the power supply voltage. Because the reset signal for the microprocessor was generated and released only by the controller, it was difficult to automatically reset and restart the microprocessor if it went out of control due to noise in the power line, etc. Ta. The present invention solves these problems,
The purpose is not only to detect the power supply voltage, but also to detect runaway of the microprocessor and automatically reset and restart the microprocessor.

Means for Solving the Problem In order to solve this problem, the present invention provides a pulse-to-voltage conversion circuit connected to the output port of the microprocessor;
A reset logic circuit that receives a signal from a voltage value discrimination circuit connected to this pulse-voltage conversion circuit and a signal from a power supply voltage detection circuit, and is connected to a reset terminal of the microprocessor and sends a reset signal, and a reset device for the microprocessor. It is composed of

With this configuration, the power supply voltage detection circuit detects the power supply voltage, and when the microprocessor goes out of control, the pulse-voltage conversion circuit converts the signal sent from the output port of the microprocessor into a voltage value, and the voltage The value discrimination circuit detects the runaway, and the reset logic circuit automatically resets and restarts the microprocessor.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 to 3. In the figure, 1 is a microprocessor with a built-in pulse generating means 1a, and the output (point E) of the reset logic circuit 2 is connected to the date reset terminal 1b of this microprocessor 1. The input (point F) of the pulse-voltage conversion circuit 6 is connected, the output of this pulse-voltage conversion circuit 5 is connected to the input of the voltage value discrimination circuit 4, and the voltage value discrimination circuit is connected to the input of the reset logic circuit 20. 4 (point B and point 0) and the power supply voltage detection circuit 3 are connected.

The reset logic circuit 2 is, for example, a logic circuit including an exclusive OR 2a, a monostable multi 2b, and an AND 2C as shown in FIG.

The output of this monostable multi 2b is designated as point D. The power supply voltage detection circuit 3 is a series circuit of a resistor 3a and a capacitor 3b as in the conventional example, and the connection point (point A) between the resistor 3a and the capacitor 3b is used as an output and connected to the reset logic circuit. The voltage value discrimination circuit 4 includes, for example, a Zener diode 4a as shown in FIG. 2, and resistors +e, 4f.
It consists of a series circuit of , a pace circuit of transistors 4a and 4g branching from each connection point, and a collector circuit. This transistor 4c has a pace circuit branched from a connection point between the Zener diode 4a and the resistor 4e through a resistor 4b, and a grounded emitter circuit having a resistor 4d connected to the collector side. Further, the transistor 4q is
It has a pace circuit whose base is connected to the connection point of the resistors 4e and 4f, and an emitter grounded circuit whose collector side is connected to the resistor 4h. The other end of the Zener diode 4a is connected to the output of the pulse-voltage conversion circuit 5 as an input to the voltage value discrimination circuit 4, and is connected to one resistor 4d, 4.
The other end of h is connected to the power supply vcc. The pulse-
The voltage conversion circuit 6 is, for example, a series circuit of a transistor 5a, a coil 6b, and a capacitor 6C, and has a DC power supply v.
Connect the collector to cc and connect the emitter and this coil 6b
, the other end of the coil 5b is connected to a capacitor 6C, and the other end of the capacitor 6C is grounded. The connection point between the capacitor 6C and the coil 6b is used as an output. The pace of the transistor 5a is determined by the input (F) of the pulse-voltage conversion circuit.
It is connected to the output port of the microprocessor 1 as a point).

In the above configuration, A, B, C before power is turned on.
.

The potentials at points D, E, and F are zero, but after the power is turned on, the potential at point A becomes V after a time t1 delay due to the time constant of the resistor 3a and capacitor 3b. reaches the same potential as C, and D
The potential at the point becomes the same potential as vcc, making the output point E of the reset logic circuit the same potential as V, and the micro C processor 1 begins to operate. This microprocessor 1 includes a pulse generating means 1 and a pulse-voltage conversion circuit 5.
A pulse shown in FIG. 3 is generated at the 0 input F point. This pulse-voltage conversion circuit 5 switches a transistor 5a by a pulse inputted to a point F, smooths it by a filter circuit of a coil 5b and a capacitor 5C, and sets a constant voltage Va [: point F to the voltage between the terminals of this capacitor 5C. Voltage va=vcC determined by the duty ratio of pulses input to
×time for which transistor 6a is conductive/(transistor 5
(the time during which transistor 5a is conductive+the time during which transistor 5a is non-conductive)] occurs. In the voltage value discrimination circuit 4, the following three combinations of outputs at point B and point 0 can occur depending on the input voltage. Assuming that the voltage at which transistor 4C conducts is v4o and the voltage at which transistor 4q conducts is 74g, 1) When va<v4o, both 4c and 4g are non-conductive11
) ■4C≦va<v4gnotki, 4c c conduction,
4q is non-conductive 111) v4g≦va, 4c and 4g are both conductive and va is 1 when the microprocessor is operating normally.
When set to satisfy the condition 1), the transistor 4c becomes conductive and the 0 point becomes zero, and the transistor 4c becomes conductive.
q is non-conducting and 6 points are V. The output point E of the reset logic circuit 2 can be kept at the same potential as ① only by the combination of the potentials of points A, B, and 0, and the microprocessor C processor 1 operates. I will continue to do so.

Next, if there is a momentary power outage (hereinafter referred to as a momentary power outage);
When the power is momentarily cut off to zero and then restored again), the potential at point A immediately becomes zero, the potential at point E also becomes zero, the microprocessor 1 is reset, and the power supply voltage rises. At the same time, the microprocessor 1 is restarted in the same way as when the power is turned on.

When the microprocessor 1 goes out of control due to external noise or the like, there are two possible cases: the transistor 6a is in a conductive state (runaway), and the transistor 5a is in a non-conductive state (runaway b).

The former is the case of 1ii), and the latter is the case of 1). In both cases, the potentials of the B point and the 0 point are equal at the same time, and the output of the exclusive OR 2a of the reset logic circuit 2 is zero. The output point of the monostable multi-circuit 2b is at time t2
becomes zero potential, and the microprocessor 1 is automatically reset and restarted.

Effects of the Invention As described above, according to the present invention, the signal of the pulse-voltage conversion circuit connected to the output port of the microprocessor, the voltage value discrimination circuit connected to this pulse-voltage conversion circuit,
A reset logic circuit is provided which receives the signal from the power supply voltage detection circuit and sends a reset signal to the microprocessor.

As a result, it is possible to not only detect the power supply voltage but also detect runaway of the microprocessor and automatically reset and restart the microprocessor.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a microprocessor reset device according to an embodiment of the present invention, FIG. 2 is a circuit diagram of the same, FIG. 3 is an operational diagram of the same, and FIG. 4 is a circuit diagram of a conventional microprocessor reset device. It is. 1...Microprocessor, 1b...
Reset @A-1-1c...Output port-2.
... Reset logic circuit, 3 ... Power supply voltage detection circuit, 4 ... Voltage value discrimination circuit, 6 ...
...Pulse-voltage conversion circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 4-
--71207°Ot, /1 2---Reta Shitozume 1r! (3-# to μ: source l town pressure machime bath 4--one voltage j! Ya j separate bath 5---heel ~/ to pressure change $2δ, Fig. 4

Claims (1)

[Claims] A pulse-to-voltage conversion circuit connected to an output port of the microprocessor, a signal from a voltage value discrimination circuit connected to the pulse-to-voltage conversion circuit, and a signal from a power supply voltage detection circuit, and connected to a reset terminal of the microprocessor. A microprocessor reset device consisting of a reset logic circuit that sends a reset signal.