JPH06204856A - Count value setting circuit - Google Patents

Abstract

PURPOSE:To provide a count value setting circuit for monitoring writing data in respect to a counter circuit for changing various count values in a data processor. CONSTITUTION:The count value setting circuit is constituted of a counter 1 for starting count from set data, an initial data part 2 having initial data for the counter 1, a set point monitoring part 3 for judging the validity/invalidity of set data outputted from a central processing unit (CPU) 7, a data setting part 4 for writing set data outputted from the CPU 7 based upon a judged result outputted from the monitoring part 3, and a switching control part 5 for sending a switching signal to a switch 6 when data to be written in the setting part 4 are correct and controlling switching so that the initial data outputted from the initial data part 2 are switched to the set data outputted from the setting part 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a count value setting circuit for changing various count values in a data processing device.

With the increase in reliability of computer systems incorporating a central processing unit in recent years, a reference count timer is configured by hardware, and various counters are provided in order to suppress software runaway. When the count value of is fixed, it becomes difficult to divert it to another device having different specifications. Therefore, it is important to generalize the counter circuit.

[0003]

2. Description of the Related Art Since the function of a counter in a conventional data processing device is designed with a constant count value in the device, the counter circuit part must be changed when it is diverted to another device. .

Alternatively, there is a method of using a dedicated programmable timer semiconductor integrated circuit (for example, one that writes a count value from a central processing unit), but in this method, the count value must be written.

[0005]

Therefore, in the prior art, (1) the count value is fixed in the case of the counter design. (2) If a semiconductor integrated circuit is used, the count value must always be written, but if the count value is written incorrectly, there is a problem that the device malfunctions.

It is an object of the present invention to provide a count value setting circuit which has an initial value as a count value, can be reset if necessary, and always monitors write data at the time of resetting.

[0007]

To achieve the above object, as shown in FIG. 1, counting is started from preset data in a count value setting circuit which constitutes a peripheral circuit of the central processing unit 7. Counter 1 to perform, and the counter 1
An initial data part 2 having initial data for the above, a set value monitoring part 3 for judging whether the setting data output from the central processing unit 7 to the counter 1 is correct, and outputting the judgment result, and the set value monitoring part. On the basis of the determination result from 3, the data setting unit 4 in which the setting data output from the central processing unit 7 is written, and the switching signal is sent to the switch 6 when the data written in the data setting unit 4 is correct. ,
A switching control unit 5 for controlling the initial data output from the initial data unit 2 to be switched to the setting data output from the data setting unit 4 is provided, and the count value from the central processing unit 7 is provided to the counter 1 It is configured so that an arbitrary count timer can be obtained by writing to the.

[0008]

According to the present invention, as shown in FIG. 1, the count of the counter 1 is started by the initial data held in the initial data section 2, and when the count value of the counter 1 is changed, the central processing unit 7 is used. Write the setting data output to the counter 1 to the data setting unit 4, and when the setting value monitoring unit 3 determines whether the setting data is correct and correct and switches the setting data, the switching control unit 5 switches to the switching unit 6. A signal is sent, and the initial data from the initial data unit 2 is switched to the setting data from the central processing unit 7 and sent to the counter 1.

Therefore, the counter 1 can start counting from the initial data and can be reset by arbitrary setting data.

[0010]

EXAMPLE An example of the present invention will be described below with reference to FIG. FIG. 2 is a diagram showing the configuration of a circuit according to an embodiment of the present invention, and shows a counter peripheral circuit of the data processing device.

In the figure, 1a is a watchdog timer counter (WDT counter) which is a kind of the counter 1, and the WDT counter 1a is initialized by a reset signal sent from the central processing unit 7 in a constant cycle.

Reference numeral 2 denotes an initial data section which has initial data such that the WDT counter 1a can be immediately activated when the power is turned on. Reference numeral 3 is a set value monitoring unit that determines whether the setting data is correct or incorrect and outputs a permission / prohibition signal. Reference numeral 4 is a data setting unit in which the setting data is written.

Further, 5 is a switching control section for outputting a switching signal when correct setting data is written in the data setting section 4, and 6 is for switching between data from the initial data section 2 and data from the data setting section 4. This is a switching device. A central processing unit 7 manages the entire circuit.

In this embodiment, instead of the counter 1 shown in FIG. 1, a WDT counter 1a for monitoring the runaway of the software of the central processing unit 7 is used. If the central processing unit 7 does not reset the WDT counter 1a within a fixed period, the WDT counter 1a counts over and notifies the central processing unit 7 of an interrupt signal.

In the initial state, the setting data of the WDT counter 1a is defined by the initial data section 2, and unless resetting is performed, the initial data sent from the initial data section 2 is used as the count value of the WDT counter 1a. Used.

Next, when changing the setting data of the WDT counter 1a, the central processing unit 7 writes the changed setting data to the data setting section 4 via the bus. However, when a write signal is applied from the central processing unit 7 to the set value monitoring unit 3, the set value monitoring unit 3 monitors the setting data to be written from the central processing unit 7 to the data setting unit 4, and if it is determined to be correct, A write enable signal is sent to the data setting unit 4, and the setting data from the central processing unit 7 is sent to the data setting unit 4
Write in.

If the wrong setting data is stored in the central processing unit 7,
Is written in the data setting section 4, the set value monitoring section 3 sends a write inhibit signal to the data setting section 4,
It is protected so that erroneous setting data cannot be written in the data setting unit 4.

When the set value monitoring section 3 determines that the change setting data has a correct count value, the switching control section 5 sends a switching signal to the switch 6 to transmit data to the WDT counter 1a. Switch.

[0019]

As is apparent from the above description, according to the present invention, the initial data is used as the count value even when the count value is not set, and the count value can be reset. Therefore, the versatility of the device can be increased, and the effect that it greatly contributes to the efficiency of the development of the computer system is exerted.

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit of a principle configuration of the present invention.

FIG. 2 is a diagram showing a configuration of an embodiment circuit of the present invention.

[Explanation of symbols]

 1 is a counter 2 is an initial data unit 3 is a set value monitoring unit 4 is a data setting unit 5 is a switching control unit 6 is a switching unit 7 is a central processing unit

Claims (1)

[Claims] 1. A counter for starting counting from preset data in a count value setting circuit constituting a peripheral circuit of a central processing unit (7).
(1), the initial data section (2) having the initial data for the counter (1), and whether the setting data output from the central processing unit (7) to the counter (1) is correct A set value monitoring unit (3) that outputs a result, and a data setting unit (4) in which the setting data output from the central processing unit (7) is written based on the judgment result from the set value monitoring unit (3) When the data written in the data setting section (4) is correct, a switching signal is sent to the switch (6), and the initial data output by the initial data section (2) is output from the data setting section (4). A switching control unit (5) for controlling switching to output setting data is provided, and the count value from the central processing unit (7) is stored in the counter.
A count value setting circuit characterized in that an arbitrary count timer can be obtained by writing in (1).