JPH08185239A - Device and method for deciding actuation - Google Patents

Abstract

PURPOSE: To conduct a self-diagnosis of whether the device is normal or not with constitution which is inexpensive in economy and simple by providing an operation holding circuit which holds a 1st state in response to a 1st level signal and is inverted from the 1st state to a 2nd state in response to a 2nd level signal. CONSTITUTION: A low-level signal L is outputted as the 1st level signal to a 1st terminal PA. At this time, a 2nd terminal PB is in a high impedance state, and consequently the 2nd terminal PB is in a low-level state. In this state, a high-level signal is outputted as the 2nd level signal to the 2nd terminal PB. Once the high-level signal is supplied to the 2nd terminal PB, a 2nd transistor(TR) Q2 turns ON and then a 1st TR Q1 also turns ON. When both the TRs Q1 and Q2 turn on, a source voltage Vcc is supplied to the 1st terminal PA through the 1st TR Q1 and a resistance R1 , and consequently the 1st terminal PA changes into the high-level state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an activation determination device and method used in combination with a microcomputer (hereinafter abbreviated as CPU).

[0002]

2. Description of the Related Art Generally, a CPU of this type is activated by turning on a power source, and starts operating in a state in which the contents of a RAM provided inside the CPU are reset. Here, this activation mode is referred to as a first activation mode, that is, a cold start mode. On the other hand, the CPU, as an external circuit, sends a reset signal to the CPU every predetermined time.
By outputting to U, CPU is reset and CP
There is a watchdog timer connected to prevent U from running out of control. In this case, the CPU starts the operation while keeping the contents of the RAM by the reset signal from the watchdog timer. Such an activation mode is referred to as a second activation mode, that is, a hot start mode, here. The hot start mode is also started by operating the reset switch.

Thus, in both start modes, the CP
Since U's internal state is different, distinguishing between
It is extremely important in managing the contents of AM.

Although a CPU for discriminating between the cold start mode and the hot start mode by a flag has been proposed, a CPU having this discriminating function is considerably expensive as compared with a CPU having no discriminating function.

On the other hand, in Japanese Patent Laid-Open No. 63-307516, in order to automatically distinguish between the cold start mode and the hot start mode, a notification signal indicating that the power is turned on is output from the time the power is turned on until the power is turned off. Circuit to
A system start-up determination circuit has been proposed in which a circuit for automatically outputting a determination signal representing the hot start mode is provided outside the CPU. This system start judgment circuit
Compared with the case of identifying both start modes by manual operation, there is an advantage that determination can be performed automatically and reliably.

[0006]

However, the system start-up determination circuit described in the above publication has a circuit for performing detection arrangement determination, such as a circuit for detecting whether power is turned on and a circuit for outputting a determination signal. Since it must be connected to the outside of the CPU, it is necessary to use a large number of expensive circuit elements, and it cannot be said that the cost is economically sufficient. Furthermore,
Since the proposed system start-up determination circuit cannot determine whether the circuit itself is operating normally, it is found that the system is insufficient in terms of reliability and safety.

An object of the present invention is to provide an apparatus and method for determining the activation of a microcomputer, which is economically economical and has a simple structure.

Another object of the present invention is to provide a start-up judging device capable of self-diagnosing whether or not it is normal.

[0009]

According to the present invention, in a start-up determining apparatus including a microcomputer which is started up in different first and second start-up modes, the microcomputer includes a first and a second. In the startup mode, the first level signal corresponding to each startup mode is output to the first terminal of the microcomputer and the first level signal is output.
After the level signal is output, a signal output means for outputting a second level signal corresponding to each start mode to a second terminal of the microcomputer is provided, and the first and second terminals are connected to the microcomputer. The first level signal is connected to a power source and is responsive to the first level signal to maintain a first state according to the first level signal, and the first level signal is responsive to the second level signal. A startup determination device having an operation holding circuit that inverts from the above state to the second state is obtained.

Further, according to the present invention, in the method for determining the activation of the microcomputer which is activated in the first and second activation modes different from each other, in the first and second activation modes, the activation mode is determined according to each activation mode. The first level signal is output to the first terminal of the microcomputer, and after the first level signal is output, the second level signal corresponding to each start mode is output.
Of software for outputting the level signal of the above to the second terminal of the microcomputer is prepared,
The operation holding circuit connected between the terminal of the second power supply and the power supply of the microcomputer in response to the first level signal and in the first state according to the first level signal. In response to the level signal of 1, the activation determination method of inverting from the first state to the second state is obtained.

[0011]

In the present invention, the software held in the CPU is provided with a function of outputting a level signal corresponding to each mode, and an operation holding circuit for holding the level signal is provided as an external circuit of the CPU. Thus, the external circuit can be simplified by combining the software and the hardware in this way. Further, by monitoring the state of the operation holding circuit by the software inside the CPU, it is possible to determine whether or not the operation holding circuit is operating normally.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a start determination device according to an embodiment of the present invention has a CPU 10.
Inside, a microprocessor (MPU) 11, a ROM 12 for storing programs, data and the like, and a RAM 13 for temporarily storing data are provided. Also, RO
The M12 and the RAM 13 are connected to the MPU 11 via the address bus AB and the data bus DB. In the illustrated ROM 12, a program as shown in FIG. 2 is added in addition to a normal program.

In FIG. 1, a power supply voltage Vcc is supplied from a power supply to the CPU 10, and a watchdog timer (WDT) 15 is connected to the CPU 10. For simplification of description, other components of the CPU 10 and other peripheral devices are omitted.

The illustrated activation determination device has an operation holding circuit 16 connected to two specific terminals of the CPU 10, here a first terminal PA and a second terminal PB.
The operation holding circuit 16 has its emitter connected to the power supply and also has the PN connected to the first terminal PA via the resistor R1.
P-transistor (hereinafter called the first transistor) Q
1 and a resistor R2 on the emitter of the first transistor Q1.
Grounded NP with collector connected through
And an N-transistor Q2 (hereinafter referred to as a second transistor). As shown in the figure, the base of the second transistor Q2 is grounded via the resistor R3 and is also connected to the second terminal PB via the resistor R4. Further, the resistors R1 and R4 are connected by a resistor R5.

On the other hand, in the ROM 12 of the CPU 10, the CP
When U10 is reset, it is reset by turning on the power (first start mode, that is, cold start mode),
Whether it is reset by the reset signal from the WDT 15 (second start mode, that is, hot start mode) is identified, a first level signal is output to the first terminal PA, and a second signal is output to the second terminal PB. A program for outputting the level signal of is stored (FIG. 2).

The operation of the activation discriminating apparatus shown in FIG. 1 will be described in more detail with reference to FIG. First, the power supply voltage V
CP in the case of cold start mode by throwing cc
The voltage of the power supply terminal of U10 is monitored by the MPU 11, and as a result, as shown in step S1 of FIG.
As a first level signal to the terminal PA of the low level signal L
Is output. At this time, the second terminal PB is in the high impedance state, and as a result, the second terminal PB is in the low level (L) state. In the state where the low level signal (L) is applied to both terminals PA and PB, the first and second terminals
Transistors Q1 and Q2 are off.

In this state, as shown in step S2,
By the program, the high level signal is output to the second terminal PB as the second level signal. Second terminal P
When a high level signal is applied to B, the second transistor Q2 turns on, and subsequently the first transistor Q1 also turns on. When both transistors Q1 and Q2 are turned on, the power supply voltage Vcc changes to the first transistor Q1 and the resistor R.
1 to the first terminal PA, and as a result,
The first terminal PA changes to the high level (H) state. First
The high level (H) state of the terminal PA of the operation holding circuit 16
Is operating normally, this state
It is held until the power supply voltage Vcc is turned off. In this way, the illustrated activation determination device can confirm the operation of the operation holding circuit.

On the other hand, in the case of the hot start mode (second startup mode) by the reset signal from the WDT 15, the high level (H) signal is applied to the first terminal PA as shown in step S1 of FIG. Is output. In this case, R
The contents of AM13 are retained as they are.

When a high level (H) signal is applied to the first terminal PA, the first and second transistors Q1 and Q2 are turned on as described above, and in this state the power supply voltage Vcc is turned off. Will be held until.
Therefore, in the hot start mode, under the control of the program, as shown in step S3, the second terminal PB
Is forced to the low level (L) state. Second terminal PB
Becomes a low level (L) state, the first and second transistors Q1 and Q2 are turned off, and the first terminal PA changes from a high level (H) state to a low level (L) state.
By detecting this change, it can be confirmed that the operation holding circuit 16 is operating normally.

After steps S2 and S3, processing operations required for the cold start mode and the hot start mode are performed under the control of the MPU 11.

As is clear from the above, the ROM
It can be seen that the program stored in 12 operates as a signal output unit for outputting the first and second level signals to the first and second terminals PA and PB.

The activation determining apparatus shown in FIG. 1 is temporarily operated after the operation in the cold start mode.
Even if a reset signal is applied from the WDT 15 to the CPU 10, the high level (H) state of the first terminal PA is maintained, which has the advantage of not being affected by the malfunction of the WDT 15.

Referring to FIG. 3, a start determination device according to another embodiment of the present invention uses a CPU as the operation holding circuit 16.
The first and second terminals PA, PB of 10 are provided with resistors R10, R
A relay 20 connected via 11 is provided. With this configuration, the same operation as in FIG. 2 can be performed.

[0024]

As described above, according to the present invention, an inexpensive and simple external circuit is added and a program is slightly added to a CPU system having no start mode determining function or a system having no backup power source. You can judge hot / cold start just by changing it. Further, since the failure of the external circuit itself connected to the outside of the CPU can be diagnosed, the reliability and safety of the system can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a startup determination device according to an exemplary embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the activation determination device in FIG.

FIG. 3 is a block diagram for explaining an activation determination device according to another embodiment of the present invention.

[Explanation of symbols]

 10 CPU 11 MPU 12 ROM 13 RAM 15 WDT 16 operation holding circuit Q1, Q2 transistors R1 to R5, R10, R11 resistance

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Ofuji 1-1-1, Shinurashima-cho, Kanagawa-ku, Yokohama, Kanagawa Prefecture NEC Robot Engineering Co., Ltd.

Claims (6)

[Claims] 1. A start-up determination device including a microcomputer activated in mutually different first and second start-up modes, wherein the microcomputer has a start-up mode in each of the first and second start-up modes. The corresponding first level signal is output to the first terminal of the microcomputer, and after the output of the first level signal, the second level signal corresponding to each start mode is output to the second terminal of the microcomputer. A signal output means for outputting is provided, and the signal output means is connected between the first and second terminals and the power supply of the microcomputer, and responds to the first level signal in response to the first level signal. While maintaining the first state,
An activation determination device, comprising: an operation holding circuit that inverts from the first state to a second state in response to the second level signal. 2. The start-up determination device according to claim 1, wherein the signal output means can confirm an inverted state of the operation holding circuit. 3. The first start mode according to claim 1, wherein the first start mode is a cold start mode when the power source is turned on, and the second start mode is a reset from an external circuit other than the power source. A start-up determination device characterized by being in a hot start mode. 4. The start-up determination device according to claim 3, wherein the external circuit is a watchdog timer. 5. The operation holding circuit according to claim 1, wherein the operation holding circuit has a first connection connected between the first terminal and the power supply.
And a base of the first transistor, the second terminal, and a second transistor connected between the ground and the start transistor. 6. A method for determining the activation of a microcomputer activated in mutually different first and second activation modes, wherein in the first and second activation modes, a first level signal corresponding to each activation mode. Is output to the first terminal of the microcomputer, and software for outputting the second level signal corresponding to each start mode to the second terminal of the microcomputer after the output of the first level signal is prepared. In addition, an operation holding circuit connected between the first and second terminals and the power supply of the microcomputer,
In response to the first level signal, the first state corresponding to the first level signal is set, and in response to the second level signal, the first state is inverted to the second state. A method for determining activation, which comprises: