JPS6029403B2 - Timed circuit control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control circuit using a microcomputer or the like, and particularly to a control method for a timer circuit that performs processing having a timer element.

Processing that has a timed element does not necessarily require instantaneous processing, for example, when protecting equipment, but rather for a certain period of time (in milliseconds) after the microcomputer detects an abnormal signal. , seconds, minutes, etc.) has elements such as starting processing and applying protective actions if an abnormality continues.

FIG. 1 is a block diagram showing a conventional example. First, FIG. 1 will be explained. 1 microprocessor (hereinafter simply referred to as ``MPU''), 2 read-only memory (hereinafter simply referred to as ``ROM'') that stores programs, and 3 random memory that temporarily stores data. access·
Memory (hereinafter simply referred to as "RAM"), and 4, 5,
A timer No. 6 and an input/output circuit No. 7 are connected by a bus line 20, and timer outputs No. 4, 5, and 6 are connected to three interrupt terminals A, B, and C of the MPUI, respectively.

Now, the operation shown in FIG. 1 will be described.

The MPUI executes the program written in the ROM2.

Detectors 8, 9, and 10 detect the state of the monitored device, and monitor each of them via the input/output circuit 7.

If the detector 8 or the M-circle UI detects an abnormality that requires processing with a timed element, the timer 4 is set to a predetermined time.

Here, if another abnormality that requires processing with a timed element again within a predetermined time is detected, for example, by the detector 9, an unused A predetermined time is set in the timer 5. If these abnormalities continue for a predetermined period of time, the equipment will be protected.This will require the MPUI to perform an interrupt process using the output of the timer, that is, the output after a predetermined period of time set in the timer. protection processing is performed on the controlled objects 11, 12, 13, etc. Therefore, in FIG. 1, a timer or the like is required to perform processing that has a timed element.

Although there are only three timers, one timer is required for each increase in the number of processes, and since there is a limit to the number of interrupt input terminals for MPUI, the number of interrupt input terminals is limited. This means that processing with time-limited elements is no longer possible.

Furthermore, if the interrupt input terminal of the MPUI is used only for processing that has this time-limited element, the interrupt cannot be used for other processing, making it impossible to perform processing that requires a long time. Further, each time the number of processes having a time limit element increases, the number of timers 4, 5, and 6 increases, wiring becomes complicated, and costs increase.

The present invention was devised to solve these problems, and is capable of processing processes with many timed elements, reduces costs by reducing the number of circuit elements used, and is capable of processing processes with many timed elements. The purpose of the present invention is to provide a time limit circuit control method that can improve processing efficiency by opening the MPUI's interrupt input terminal to other processes even if the number of processes increases beyond the MPUI's interrupt input terminal. shall be. Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a block diagram of an embodiment of the present invention, in which the same reference numerals as in FIG. 1 indicate the same elements, and the block diagram is the same as in FIG. 1 except that one timer 4 is provided.

Now, the operation with respect to FIG. 2 will be explained.

The MPUI executes the program written in the ROM2, but here, when the MPUI detects a request signal for processing with a timed element from the input/output circuit 7, the R
The MPUI determines which process is requested among the processes with various timed elements prepared in OM2, and also sends the count value up to the time when the process with that timed element is started to the timer 4. The program to set (this is called the "timer set program") and the timer 4
A separate program (referred to as an "interrupt service program") is prepared in the ROM 2 to determine the interrupt signal MPUI output by the CPU when the count ends and to start interrupt processing.

Here, while the MPUI is executing the normal routine of the program in the ROM 2 and periodically checking the signals of the input/output circuit 7, the MPUI receives a request signal for a process having a time element from the input/output circuit 7. If detected, the normal routine branches to the timer set program,
The starting address of the processing program having the designated time element and the address of the ROM 2 storing the count value up to the time when the processing program having the designated time element is to be started are determined.

A processing program start address with a specified time element,
Set the address of ROM2 that stores the count value up to the time to start the processing program with the specified time element to M.
Once the PUI has determined, the MPUI will use the ROM2 address.
The start address and count value of the processing program having the specified time element are read, the former is stored at a predetermined address in the RAM 3, and the latter is set in the timer 4.

When the counter of timer 4 ends, M is output from timer 4.
An interrupt signal is input to the PUI, and the MPUI executes the interrupt service program.

When the interrupt service program ends, the MPUI sets the return address to the start address of the processing program having the designated time element stored in the RAM 3, and starts executing the processing program having the designated time element. here,
When the MPUI detects a request signal for processing having a second time element from the input/output circuit 7 while the timer 4 is counting,
The count value of timer 4 at the current time (that is, the remaining time of the time count, which is written as tc) and the count value up to the start time of the processing program with the time element requested by the process with the second time element. (In other words, this is the time count value that was requested later, and this is written as tW), and the subtraction of tW-tc is executed. The result is negative (tW<
tc), the timer 4 stops counting, writes the value of tW to the timer 4, and starts counting.

The result of the subtraction is inverted and stored in a predetermined address in RAM3 (hereinafter, the address in RAM3 where the count value is stored is referred to as the "timer address"), and the first time element stored in RAM3 is (Hereinafter, the address in RAM3 that stores the start address of the processing program that has a time element will be referred to as a "pointer")
Regarding the program start address of the second program that requests a process with a timed element, the priority order is reversed such that the latter becomes the pointer address and the former becomes the pointer address + 2 addresses. If the result is positive (tw>tc), the count of timer 4 continues, the subtraction result is stored in the timer address of RAM 3, and the start address of the processing program having the second time element is stored in the pointer address + 2 address. Make it have priority after the processing program with the first timed element.

Here, when timer 4 finishes counting and outputs an interrupt signal to MPUI, the interrupt service program is executed,
The start address of the processing program with the time element indicated by the pointer address is set as the return address from the interrupt service program, the count value stored at the timer address is set to timer 4, and the count value stored at the pointer address + 2 is set. Move the start address of the processing program that has the timed element stored in it to the pointer address, branch to the previously set return address, that is, the processing program that has the timed element stored at the pointer address, and start processing. do.

Here, when the MPUI detects a process that has the third time element while counting the timer, the process program that has the first time element that is being counted by counter 4 is executed for the first and second processes as well. The processing program that has the timed element that requested the processing is called process 2, and will be named processes 3, 4, and 5 below...The count value of timer 4 at the current time (denoted as tc') and the process In order to compare the count value (denoted as tW') up to the start time of 3, tw'-tc
If the result is positive (tW'>tc'), the timer 4 continues counting and the contents of the pointer address are not changed.

Then, with the subtraction result as tw and the count value (denoted as tw2) up to the start time of the processing program having the time element stored at the timer address, tW·1tW2 is executed.

If the result is positive (tw, > tw2), timer address +2
The subtraction result of tw, - tw2 is stored at the address, and then the start address of process 3 is stored at the pointer address +4.

If the result is negative (tw.<tw2), the count value (tw2) up to the start time of the program having the time element stored at the timer address is stored at the timer address +2. Similarly, the start address indicated at pointer address +2 is saved, the saved contents are stored at pointer address +4, and the start address of process 3 is stored at pointer address +2.

If tW'-tc' is negative, the timer 4 stops counting, writes the value of tw' to the timer 4, and restarts counting. Accordingly, the start address of process 3 is stored in the pointer address, and the start address of the processing program having the time element, which has been stored in the pointer address until now, is stored in the pointer address 12. The start address of the processing program with the time element stored at the pointer address + 2 address,
Store it in the pointer address +4 and execute the priority shift. Then, the subtraction result of tw'-tc' is inverted and stored in the timer address, and the count value stored in the timer address is moved to the timer address +2. MPU here again
When I detects an interrupt due to the output of timer 4, the interrupt service program sets the start address of the processing program having the time element stored at the pointer address of RAM 3 to the return address, as described above. The start address of the processing program that has a time element at pointer address +2 is moved to the pointer address, and similarly the contents at pointer address +4 are moved to the pointer +2 address.

Regarding the timer address, set the count value up to the start time of the processing program with the time limit element stored in the timer address in timer 4, and similarly set the count value stored in the timer address + 2 address in the timer address. do.

FIG. 3 shows a flowchart showing the basic operation of the present invention. Further, the fourth is a time chart when tW minus tc, and FIG. 5 is a time chart when tc<tw.

Note that tT represents a timer count setting value, and tx represents a requested timer count value. By executing the above processing, it is possible to perform the same operation as using several timers 4 and performing multiple processes with timed elements, and the processes with timed elements are processes 4 and 5. , 6, etc., the problem can be solved by repeating the process in the same way.

By executing such processing, even if the number of request signals for processing with a timed element increases, it is possible to process them within the memory capacity of RAM3 and ROM2, and this method requires only one timer. Only one MPU is required.
By using only one interrupt input terminal, it is possible to use it in conjunction with other interrupt processing.

In addition, in this explanation, for easy understanding, one word consists of 8
Although the example has been shown in which the bit data is one word and the address is two words, it is obvious that the present invention can be applied to other words having a different word structure.

Furthermore, in the above explanation, the microprocessor has an interrupt input terminal as an example, but the microprocessor is not necessarily limited to this, and it can also be used with a microprocessor that does not have an interrupt input terminal. By inputting the timer's output signal to a normal data input terminal and having the main program constantly monitor this input, the same effect as a microprocessor with an interrupt input terminal can be obtained.

As described in detail above, according to the present invention, when executing a process that has a timed element that is to be executed after a certain time, a program that determines the priority of the process and determines a timer count value, and a program that determines the timer count value, and By simply preparing a program that handles branching and priority determination, one timer and one interrupt input terminal can perform time-limited processing within the memory capacity.
Moreover, a control method for a timed circuit with a small number of circuit elements can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a circuit showing a conventional example, Fig. 2 is a block diagram of a circuit showing an embodiment of the present invention, Fig. 3 is a flowchart showing its basic operation, and Fig. 4 is a block diagram of a circuit showing an embodiment of the present invention.
FIG. 5 is a time chart when tc<tW. 1. ...Microprocessor (MPU), 2...Read-only memory (ROM), 3...Random access...
Memory (RAM), 4, 5, 6... timer, 7... input/output circuit, 8, 9, 10... detector, 11, 12, 13...
- Controlled object, 20... bus line. Groove↑Figure 2 Figure 3 Figure 4 Mountain boat

Claims (1)

[Claims] 1. In a control circuit that uses an element with arithmetic, judgment, and processing functions such as a microprocessor, a predetermined time is set in a timer in response to a processing request that has a time limit element, and the timer is operated. If a processing request with other time limit elements comes in, the time set in the timer is compared with the time to be set in the timer for the new processing request, and the priority is determined. The high priority time is set again in the timer, and the low priority time compared above is temporarily stored, and the high priority time is set based on the same judgment each time a processing request with a time limit element or a processing request is canceled. A timed circuit control method characterized by setting a timer.