JPH0561572A - External power source instantaneous interruption processing device for digital computer - Google Patents

Abstract

PURPOSE:To provide the external power source instantaneous interruption processing device which restarts a processing from data before instantaneous interruption even when an external power source is instantaneously interrupted. CONSTITUTION:A ROM, RAM and power source instantaneous interruptor flag register C are connected to the CPU of the external power source instantaneous interruption processing device. A power supply holding circuit A is connected to the RAM, a power source instantaneous interruption judging circuit B is connected to the power source instantaneous interruption flag register C, and an input voltage monitor circuit D is provided. A voltage transformer E and an inside voltage monitor circuit F are connected to the input voltage monitor circuit, and a power down interrupting signal G is transmitted to the CPU. Since the inside voltage monitor circuit transmits a power on reset signal H to the CPU, the contents of data before the instantaneous interruption written in the RAM are held even when the external power source J is instantaneously interrupted and when the power source is turned on again, it is judged whether the power source is turned on by the instantaneous interruption or not. When it is caused by the instantaneous interruption, the processing is restarted from the data before the instantaneous interruption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for dealing with a momentary interruption of an external power source of a digital computer, and even if the external power source of a computer is momentarily interrupted, data written in a RAM before the momentary interruption is not destroyed. When the power is turned on again, it is judged whether or not the power is turned on again after a momentary interruption, and if it is judged that it is due to a momentary interruption, the processing is restarted from the data before the momentary interruption. External power supply interruption countermeasure device.

[0002]

2. Description of the Related Art A conventional example of a device for coping with an instantaneous interruption of an external power source of a digital computer (CPU) will be described with reference to FIG. The CPU is connected to an external power supply via a voltage converter and an internal voltage monitor, and is configured to send a CPU power down interrupt signal and a CPU power on reset signal from the internal voltage monitor to the CPU.
The CPU further includes a ROM and a RAM via the CPU bus.
Connected to. The RAM has a power supply holding circuit. At this point, the external power is turned on and the power is turned on.
In the reset procedure, specific data on a predetermined ROM is written to a specific address of RAM, and after the power is momentarily cut off and supplied again, this specific data is not destroyed. (Or the content of this specific data is not changed) to determine whether or not there is a power interruption. This program is as shown in FIG.
In this conventional example, when the external power supply to the CPU is momentarily cut off, the internal voltage monitor circuit detects it and sends a power down interrupt signal. When it is detected by the internal voltage monitor, the CPU is not already supplied with the normal specified voltage. Therefore, at this time, the CPU runs out of control because it cannot maintain the normal execution state.
There was a problem of destroying AM data. Also, R
Address data set in AM (there are several types)
Only by checking only, it is not guaranteed that all the data in RAM is the same as before the power interruption, and in some cases, even if the address data for determining the power interruption is correct, other data However, there was a problem that it was different from that before the power interruption.

In the case of the conventional example described above, the power supply is momentarily cut off,
Until the power is supplied again, the R
Even if the contents of the data stored in AM are retained,
RAM data is destroyed due to CPU runaway,
Alternatively, it is impossible to determine whether or not there is an instantaneous interruption only by checking a part of the data in the RAM and confirming that these data are the same as before the instantaneous interruption.

[0004]

SUMMARY OF THE INVENTION According to the present invention, even if the external power supply is interrupted, the contents of the data written in the RAM before the interruption is retained without being destroyed, and when the power is turned on again, the power supply concerned is retained. It is intended to provide an external power interruption protection device for a digital computer that accurately determines whether the input is due to an instantaneous interruption, and if it is an interruption, restarts the processing from the data before the interruption. is there.

[0005]

An external power supply interruption countermeasure device for a digital computer CPU is provided with a CPU, and a CPU is connected to a ROM, a RAM and a power interruption flag register, and the RAM is provided with a power supply holding circuit. Is connected, and a power interruption detection circuit is connected to the power interruption flag register, and it is equipped with an input voltage monitor circuit. The input voltage monitor circuit sends a CPU power down interrupt signal to the CPU A voltage converter is connected to the voltage monitor circuit and an internal voltage monitor circuit is connected to the voltage converter. The internal voltage monitor circuit is a CPU.
By sending a CPU power-on-reset signal to the CPU, even if the external power supply is interrupted, the contents of the data written in the RAM before the interruption is retained without being destroyed, and the power is turned on again. Whether or not the power-on is due to a momentary interruption is accurately determined, and if it is a momentary interruption, the processing is restarted from the data before the momentary interruption.

[0006]

Embodiments of the present invention will be described with reference to FIGS. The external power supply is first connected to the input voltage monitor circuit. The input voltage monitor circuit is connected to the CPU and sends the CPU power down interrupt signal to the CPU, and is also connected to the voltage converter. The voltage converter is then connected to an internal voltage monitor circuit, which is further configured to connect to and send a CPU power-on reset signal to it. CP
ROM and RAM are connected to U via a CPU bus, and the RAM is equipped with a power supply holding circuit. A power supply interruption flag register is further connected to the CPU, and a power supply interruption detection circuit is connected to this register.

The CPU is a general-purpose central processing unit, and the CPU bus is also general-purpose. ... Structure 1 ROM is a read-only memory that incorporates the following two programs: Structure 2 CPU power-on output from the internal voltage monitor circuit
After receiving the reset signal and CPU power-on reset, first input the value of the power interruption flag register, and if it is judged as an interruption, clear only a part of the RAM area and restart the computer promptly. If you execute the procedure described above and do not determine that there is an instantaneous interruption, it is determined that the power was turned on normally, and the clearing and initialization of all RAMs and other procedures are executed. The CPU power down interrupt signal which is the output of the monitor circuit is received, and the CPU power down interrupt signal is input for the permissible interruption time T0 during the power down interrupt procedure, and it is determined that the power is not down. If this is not the case, execute the procedure to restart the computer immediately. Write signal performs permanently waiting process until no longer a power-down, the CPU is a program that allows the CPU does not access the RAM prior to runaway, quite independently of the RAM C
Program composed of PU internal register and ROM ... Structure 7 RAM is a general-purpose random access memory, and this RAM has a permissible interruption time T0 after the external power supply is cut off.
It has a power supply holding circuit that holds the power supply to this RAM until the time elapses, and holds the contents of the data written here ... Configuration 3 After the external power supply is cut off The power interruption judgment circuit that determines whether or not the permissible interruption time T0 has passed, and the high level during the time within the permissible interruption time T0 after receiving the output of this judgment circuit, and the low level during other periods. It is equipped with a power interruption flag register that is a level ... Configuration 4 An input voltage monitor circuit and an internal voltage monitor circuit are connected to a general-purpose voltage converter, where the input voltage monitor circuit is an external power source. Is below the specified voltage value. If it is below the specified voltage value, a power down interrupt signal is generated to the CPU. The internal voltage monitor circuit outputs the voltage converter. Inside It is determined whether or not the voltage is equal to or lower than a specified voltage value, and when the voltage is equal to or lower than the specified voltage value, a power-on reset signal is generated to the CPU ... Configuration 5 Next, the present invention The operation of the device for coping with the instantaneous interruption of the external power supply of the digital computer will be described. First, referring to FIG. 5, here, the instantaneous interruption is classified into three cases regarding the duration.

Case 1 A case where even a momentary interruption is not reached. The input voltage monitor circuit detects that the external power supply voltage 28V is below the abnormality detection threshold level V1 = 20V, but the internal voltage monitor circuit detects that the abnormality detection threshold level is 4.6V. The case where the external power supply voltage returns to V1 = 20V or more, which is the abnormality detection threshold level, without breaking.

Case 2 The external voltage monitor circuit interrupts V1 which is the abnormality detection threshold level, and the internal voltage monitor circuit also interrupts 4.6V which is the abnormality detection threshold level, and the allowable interruption time T0 = 250 m. The external power supply voltage reaches V1 which is the abnormality detection threshold level in less than a second.
= Case of returning to 20V or more.

Case 3 The external voltage monitor circuit interrupts V1 which is the abnormality detection threshold level, and the internal voltage monitor circuit also interrupts 4.6V which is the abnormality detection threshold level, and the instantaneous interruption is T0 = 250 msec. After the voltage exceeds the threshold, the external power supply voltage is the abnormal detection threshold level V1 = 20V
Case to return to above.

In FIG. 5, V2 is an external voltage when the internal voltage monitor circuit detects an abnormality. Description of Case 1. It is detected by the input voltage monitor circuit that the external power supply is momentarily cut off and the abnormality detection threshold level V1 = 20 V is exceeded. As a result, a power down interrupt signal is sent to the CPU. Where CP
U initiates the power down interrupt process shown in FIG. Case 1 is a case where the external power supply voltage is restored before the internal voltage monitor circuit falls below the abnormality detection threshold level of 4.6 V.
The ER continuously performs the procedure of restarting the computer immediately after TIMER counts 0 to ensure that it is not power down.

Description of Case 2. External power supply is shown in Figure 6.
It is detected by the input voltage monitor circuit that a momentary disconnection occurs at the point D, and the error detection threshold level V1 = 20V has been diminished.
It is the same as in case 1 up to where the power down interrupt signal is sent. After that, more time has passed and the internal voltage monitor circuit
Since the external power supply voltage still does not return to the normal level even when the level of 4.6 V is interrupted, the internal voltage monitor circuit powers on the CPU at F in FIG.
Send a reset signal. In case 2, the external power supply voltage returns to the normal level at the point G before T0 = 250 msec from the point D in FIG. 6 and the input voltage monitor circuit detects the abnormality detection threshold at the point in FIG. 6H. After the level of 20 V is exceeded, the internal voltage monitor circuit further reaches the abnormality detection threshold level at I in FIG.
The power-on reset is released at J in FIG. 6 when 50 msec has passed after exceeding 6V. By this, C
PU is the power of the configuration 6 of FIG.
Start the on-reset program. At this time, the power interruption detection circuit is capable of holding the power interruption flag register at a high level for 250 msec. Therefore, the power interruption flag register is 250 m from A in FIG. It goes without saying that the high level is maintained until the second passes. This time measurement is accurate (actually, considering the safety factor, it is set to a value of about 90 percent of 250 msec), and during this 250 msec, the RAM is guaranteed the data written therein by the power supply holding circuit. The Rukoto. In this case, it is determined that the power supply has been cut off instantaneously, and the computer is immediately restarted.

Description of Case 3. The difference from Case 2 in this case is that the external power supply recovers to the normal level when the instantaneous interruption exceeds not this time T0 = 250 msec but this time. In this case, case 2
Unlike the above, when the CPU is released from the power-on reset and started, that is, when the power-on reset program of FIG. = 250 msec is exceeded, the instantaneous power failure flag register is set to a low level, the power supply holding circuit can no longer maintain the potential for holding the data in the RAM, and the contents of the RAM are destroyed. After all, power
In the on-reset program, the power interruption flag register is at a low level, that is, there is no interruption, so all RAM
To start the normal startup procedure when the power is turned on.

[0014]

As described above, the external power interruption protection device for a digital computer according to the present invention comprises a power interruption detection circuit, and a power interruption flag register is interposed between this and the CPU. Furthermore, by providing an input voltage monitor circuit and using its output as a CPU power-down interrupt signal different from the CPU power-on reset signal, even if the external power supply is interrupted, it is written to the RAM before the interruption. If the power is turned on again, it can be accurately determined whether the power was turned on due to a momentary interruption, and if it is a momentary interruption, the data before the interruption can be processed. It was possible to restart.

[Brief description of drawings]

FIG. 1 is a block diagram of an external power interruption protection device for a digital computer according to the present invention.

FIG. 2 is a diagram showing a program stored in a ROM shown in FIG.

FIG. 3 is a block diagram of a conventional example of an external power interruption protection device for a digital computer.

FIG. 4 is a diagram showing a program of a conventional example.

FIG. 5 is a diagram showing a case of power interruption.

FIG. 6 is a diagram showing an example of a power cutoff timing chart.

Claims (1)

[Claims] 1. An external power interruption protection device for a digital computer CPU, comprising a CPU, wherein the CPU is connected to a ROM, a RAM and a power interruption flag register via a CPU bus, and the RAM holds power. The circuit is connected, the power interruption detection circuit is connected to the power interruption flag register, and the input voltage monitor circuit is provided.
The input voltage monitor circuit sends a CPU power down interrupt signal to the CPU, the input voltage monitor circuit is connected to the voltage converter, and the voltage converter is connected to the internal voltage monitor circuit. Circuit is C
The CPU power-on reset signal is sent to the PU, and the power interruption detection circuit outputs the CPU power-down interrupt signal sent as a result of the momentary interruption of the external power supply and the internal voltage output from the voltage converter falls below the specified value. Based on the CPU power-on reset signal sent out as a result, it is determined whether or not the permissible interruption time after a momentary interruption has passed, and the power interruption flag register receives the output of the power interruption determination circuit and receives an interruption. Is high level during the momentary interruption allowable time, and keeps low level during the other period, and the power supply holding circuit is from the momentary interruption of the external power supply until the momentary interruption allowable time elapses. RA while the power interruption flag register is high
The power supply to M is retained to retain the contents of the data written in it. The ROM outputs the CPU power down interrupt signal, the CPU power on reset signal, and the power interruption detection circuit. A device for dealing with instantaneous interruption of external power supply of a digital computer, which deals with instantaneous interruption based on the above.