KR920004384B1 - Protection circuit for run-away of mpu - Google Patents

Abstract

The circuit for preventing run away resets the microprocessor instantaeously in the case of false operation of the microprocessor and reconstructs the microprocessor to guarantee the continuous control of equippment. The circuit includes a key scan signal discriminator (41) to detect the run away of microprocessor, and a reset and return unit (42) for resetting and returning the microprocessor when the microprocessor runs away.

Description

Run Away Prevention Circuit of Microprocessor

1 is a block diagram of a circuit of the present invention.

2 is a circuit diagram of the present invention.

(A)-(k) is an operation waveform diagram of each part of the circuit of this invention.

4 is a voltage waveform across a resistor (R ₁ ) at initial power-up.

5 is a block diagram of a congestion prevention circuit of a conventional microprocessor.

6 is a circuit diagram of a square wave checking unit and a power element driving unit connected to a conventional microprocessor.

* Explanation of symbols for main parts of the drawings

1: power supply 2: power on reset circuit

3: microprocessor 4: congestion prevention circuit portion

5: display unit 6: key input unit

7: external device driving unit 8: external device

9: interrupt signal generating circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a run-away prevention circuit for safely operating all electronic and electrical products controlled by a microprocessor. In particular, the present invention relates to control of a device when a microprocessor is runaway in a device using high frequency and high voltage. The invention relates to a microprocessor congestion prevention circuit that is capable of preventing accidental damage to human life or property.

In the related art, 'Applicant's method and apparatus for preventing runaway of a microprocessor' of Patent Publication No. 87-1728 previously proposed by the present applicant is a relay (RY), a ROM for storing a program, and various controls as shown in FIG. RAM to record information, square wave check unit 2, power element driver 3, control unit 10, key control unit 11, display unit 12, register 13 for storing a predetermined word, relay drive generation The signal unit 14, the runaway control signal unit 15, the flag state converter 16, and the runaway detector 17 are connected to each other, and the square wave check unit 2 connected to the microprocessor 1 is included. ) And the power element driver 3 include a DC blocking capacitor C ₂ , a diode D ₁ , a resistor R _1- R ₃ , a switching transistor T ₃ , and a transistor ( T ₁ , T ₂ ), resistors (R _4- R ₇ ) and condensers (C ₁ ), respectively. The operation relationship of is as follows.

First, the transistor T ₃ is turned off by the DC blocking capacitor C ₂ as the 'high' signal is continuously output from the output port RP thereof when the microprocessor 1 is in an abnormal runaway state. Since (T ₁ , T ₂ ) are also off, the relay RY is also off, which stops powering the load. However, such a configuration cuts off the power supplied to various loads when a malfunction occurs, but the microprocessor remains in a malfunction state, and thus the device cannot be operated again before unplugging the power supply to the microprocessor.

If the power supplied to the microprocessor by the relay RY is cut off at the same time, an initial power supply capable of supplying power to the microprocessor must be added when the unit is restarted, and the equipment used must be continuously restricted. (E.g., automatic exhaust system) has a problem that can not be controlled again after a malfunction.

The present invention adds a runaway prevention circuit portion consisting of a kisscan signal determination portion and a reset and return portion to a conventional power-on reset circuit portion in order to solve such a conventional problem, if the microprocessor malfunctions, Set it up and restore it so that the microprocessor can always control the device and safely operate any equipment that must be continuously controlled under any circumstances (e.g. mine exhaust, toxic gas chamber switchgear and microwave oven). An object of the present invention is to provide a congestion prevention circuit of a microprocessor capable of preventing damage to human life and products. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

As shown in Figs. 1 and 2, the circuit of the present invention includes a power supply unit 1, a power-on reset circuit unit 2, a microprocessor 3, a display unit 5, a key input unit 6, and an external device. In a control circuit using a microprocessor in which the device driver 7, the external device 8, and the interrupt generator circuit 9 are connected to each other, a kisscan signal determination unit 41 having an input terminal connected to an output terminal of the key input unit 6 is provided. And the power-on reset circuit unit 2 through the congestion prevention circuit unit 4 including the reset and return unit 42, but the kisscan signal determination unit 41 may include a diode D ₈ , D ₉ , and a resistor. (R ₅ -R ₉ ), condensers (C ₁ , C ₂ ) and transistors (T ₃ , T ₄ ), and the reset and return unit 42 includes resistors (R ₁₀ , R ₁₁ ) and condensers ( C ₃₎ to the hayeoseo wareul connection configuration, in which reference numeral PT is a power transformer, the relay RY, a diode D ₁ -D ₁₁ is, T _1, T _2, T ₄ is Transitive Emitter, a capacitor C _{4, R 1 -R 4, R 12} -R 17 is a resistor, the Zener diode ZD is _1, V _SS, V _DD is a power supply terminal, RESET is a reset terminal, IN ₁ -IN ₄ are key scan Input terminal, DRI is the external device control terminal, SC _1- SC ₄ is the kisscan terminal, INT is the interrupt terminal.

The operation and effect of the circuit of the present invention configured as described above will be described with reference to FIGS. 3 (a)-(k) and 4.

First, when the initial power source AC is applied to the power transformer PT of the power supply circuit 1 and the power-on reset circuit unit 2, the rectifier diodes ZD are rectified by direct current through the rectifying diodes D ₁ and D ₂ . ₁ ), in which the current does not flow in the zener diode ZD _{1 in the period of} 0 <t <t ₀ (see FIG. 4), the transistor T ₁ is turned off and the transistor T ₂ is turned on. The processor 3 is reset so that the program counter in the microprocessor 3 returns to the initial start address.

Afterward, when t> t ₀ , a current flows in the zener diode ZD ₁ , and thus the transistor T ₁ is turned on and the transistor T ₂ is turned off to reset the microprocessor 3. The processor 3 executes the program from the first address.

At this time, when an interrupt signal is generated by the interrupt signal generation circuit unit 9, the microprocessor 3 recognizes this and executes an interrupt routine program. Therefore, a scan signal of a square wave is generated to generate a kisscan terminal SC ₁ of the microprocessor 3. SC ₄ is applied to the key input device 6, the display portion 5 and the runaway prevention circuit portion 4, respectively.

In addition, the output waveforms of the kisscan terminals SC ₁ -SC ₂ of the microprocessor 3 are output in the normal state as in the T ₁ section of (c)-(f) of FIG. That is, in the T ₁ -T ₂ section, the kisscan signal is not generated, and the DC signal is output by being pulled up or pulled down.

Accordingly, in the normal state, the transistor T ₃ is turned on when the scan signal of the point A of the congestion prevention circuit part 4 is 'high', and the transistor T ₃ is turned off when the scan signal at the point A is 'high'. Will be repeated.

Accordingly, the capacitor C ₂ in the charge / discharge circuit composed of the resistors R ₈ and R ₉ and the capacitor C ₁ is charged with a negative charge to maintain a constant value, so that the transistor T ₄ is kept on and P _{Since the} point ₄ is a 'high' signal, the 'high' signal is also applied to the emitter terminal of the transistor T _{2 in the} power-on reset circuit 2 so that the transistor T ₂ remains in an off state. Will continue.

However, if the microprocessor 3 is in a congested state, even if an interrupt signal is generated, the interrupt routine is not performed. Therefore, a scan signal is not output from the kisscan terminals SC _{1 to} SC ₄ of the microprocessor 3, and thus a DC voltage is output. A DC voltage is supplied to the point A of the runaway prevention circuit section 4.

Therefore, since the DC voltage is cut off by the DC blocking capacitor C ₁ , the transistor T ₃ remains off, and since the transistor T ₄ is also turned off, the point P ₄ is low (ie, V). _DD voltage) signal is applied. At this time, the potential at the point P ₅ goes from 'high' (ie, ground potential) to 'low' and then returns to 'high' again.

That is, the instantaneous voltage drop of the P ₄ that is so passed through the condenser (C _3), but P ₄ dots continued while maintaining the DC power supply (V _DD) voltage is a DC voltage is blocked by the capacitor (C ₃₎ back to 'high' To return.

Therefore, since the transistor T ₂ of the power-on reset circuit unit 2 is turned off and then turned off again, the microprocessor 3 resets and then releases the program counter to reset the program. Go back to the first address and execute main program again.

In addition, the main program clears the RAM in which the data recorded by the first user is stored so that each output terminal is 'low', and then the external device control terminal DR of the microprocessor 3 in order to cut off the power supplied to all external devices. ₁ ) 'LOW' signal is output, so relay RY is turned off to cut off power supplied to external devices.

Therefore, the microprocessor 3 is restored to its original function after the runaway, and always remains in a user controllable state. In addition, since the interrupt program does not execute the interrupt routine when the microprocessor 3 is congested, the scan signal does not come out so that the voltage of the kisscan terminals SC _1- SC ₄ of the microprocessor 3 is pulled up or pulled down. In this case, when the microprocessor 3 operates normally, the kisscan signal of the square wave is output through the kisscan terminals SC ₁ -SC ₄ , so that the congestion state of the microprocessor can be detected.

On the other hand, of the 3a turn will showing the voltage of the P ₁ point, (b) turning will showing an interrupt signal, (h) turning will showing the base voltage of the transistor (T _3), (i) turning the transistor (T ₃₎ The collector voltage is shown, and (k) shows the reset signal of the microprocessor 3.

As described above, according to the present invention, when a microprocessor malfunctions, the chip is instantly reset and then restored so that the microprocessor can always keep the other device in a controlled state. When applied to the exhaust system of the mine or the opening and closing device of the toxic gas chamber that should be controlled, it is possible to prevent the damage of life, property and products in advance.

Claims (1)

Power supply unit 1, power-on reset circuit unit 2, microprocessor 3, display unit 5, key input unit 6, external device driver 7, external device 8 and interrupt generating circuit unit 9 In the control circuit using a microprocessor connected to the configuration, the congestion prevention circuit portion (4) consisting of a kisscan signal determination unit 41 and the reset and return unit 42, the input terminal is connected to the output terminal of the key input unit (6) The power-on reset circuit unit 2 is connected to the circuit board, but the kisscan signal determination unit 41 includes a diode D ₈ , D ₉ , a resistor R _5- R ₉ , and a capacitor C ₁ , C ₂ . And the transistors T ₃ and T ₄ connected to each other, and the reset and return unit 42 connects the resistors R ₁₀ and R ₁₁ to the capacitor C ₃ . A) prevent circuit.

Images