JP2671622B2 - Control device having A / D converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention converts analog signals into analog signals.
The present invention relates to a control device which is converted and taken as digital data into a microcomputer (hereinafter abbreviated as a microcomputer).

[0002]

2. Description of the Related Art Conventionally, a control device of this type has an A / D converter 2 as shown in FIG. 3 inside or outside a microcomputer. In the example of FIG. 3, the A / D converter 2 is provided outside.

In FIG. 3, a signal selection circuit (multiplexer)
In 5, the data on the channel bus 12 output from the conversion control circuit 4 selects the input 9 to be A / D converted from the plurality of analog inputs 8. The selected input 9 is A / D converted by the A / D conversion circuit 6 by using the start signal 10 from the conversion control circuit 4 as a trigger. When this conversion is completed, the conversion result is output to the conversion data bus 13 and the end signal 11 is output to the conversion control circuit 4 and the data register 7. The data register 7 receives the end signal 11 and stores the data on the converted data bus 13 in the data register 7 designated by the data on the channel bus 12. Thus, the conversion control circuit 4 controls a series of A / D conversion procedures through the start signal 10, the end signal 11 and the channel bus 12. The conversion control circuit 4 is internally provided with a channel register 15 and an end flag 16 as shown in FIG. 4, and by writing the channel number in the channel register 15, the data corresponding to the channel number is written on the channel bus 12. Is output, and the start signal 10 is output. The end flag 16 is set according to the state of the end signal 11. Further, the conversion control circuit 4 and the data register 7 can exchange data with the microcomputer 3 through the system bus 14.

On the other hand, in the microcomputer 3, according to the software processing flow as shown in FIG.
When D conversion becomes necessary, at that timing, the channel number corresponding to the analog input 8 is written to the channel register 15 (SA3), and the end flag 16 is set (SA4). By reading the conversion result from the corresponding data register 7 (SA5), necessary digital data can be taken in internally.

[0005]

However, in the conventional control device configured as described above, when the A / D conversion is attempted at the software processing timing of the microcomputer as shown in FIG. 5, the interrupt processing routine 18c. Since the A / D1 conversion performed by the main processing routine 17c is stopped by the A / D2 conversion performed by the interrupt processing routine 18c at the interrupt timing of No. 1, it cannot be determined by the main processing routine 17c that it has been stopped. The wrong conversion data is read in, which results in malfunction of the control device.

As a countermeasure against this, first of all, A /
Although it was considered to increase the number of D conversion circuits, the cost increase remains a problem. Next, changing the A / D conversion timing (for example, performing A / D conversion only with the main processing routine or interrupt processing routine) was a problem with the control specifications, and the software processing of the microcomputer was complicated. become. Therefore, it has been considered that the simplest method is to simply prohibit other interrupts when executing A / D conversion. However, due to an increase in analog input, etc.
As the number of / D conversions increases, the proportion of time during which other interrupts are prohibited increases, and the control contents become complicated and multiple interrupt processes are executed. A / D conversion is performed in the interrupt processing routine. When the above is executed, there arises a problem that the deviation of the interrupt timing has a great influence on the control.

The present invention is intended to solve the above-mentioned problem, and it is necessary to perform A / A in the interrupt processing which occurs due to the complicated control.
An object of the present invention is to provide a control device in which the microcomputer does not read erroneous data and the control device does not enter an abnormal state even when the D conversion is started in multiplex.

[0008]

In order to achieve the above object, in the present invention, as a first means, means for judging whether or not A / D conversion is being executed in an A / D converter, D
A means for reading / writing the conversion result of the converter between the data registers is provided in the software processing of the microcomputer, and the means for judging the A / D conversion is executed by the means for judging the execution at the head of the interrupt processing requiring the A / D conversion of the microcomputer. Waiting for completion, the previous A / D conversion result is saved in the microcomputer by means of reading and writing, and at the end of the interrupt processing, the A / D conversion result saved in the microcomputer by means of reading and writing again is returned to the original data register. Configure software processing to revert.

As a second means, a means for judging whether or not the A / D conversion is being executed in the A / D converter,
A means for reading the channel number previously A / D converted by the D converter is provided in the software processing of the microcomputer, and the A / D conversion is performed last time by the reading means at the beginning of the interrupt processing requiring the A / D conversion of the microcomputer. The channel number stored in the microcomputer is stored in the microcomputer, the A / D conversion of the channel number stored again is started at the end of the interrupt processing, and the completion of the A / D conversion is waited by the means for judging the execution. Configure software processing.

[0010]

According to the first means, the data in the data register, which is the result of the A / D conversion that has started the conversion immediately before the interrupt, is saved to the microcomputer at the beginning of the interrupt processing, and the original data is restored again at the end of the interrupt processing. The result of the A / D conversion can be prevented from being lost by another A / D conversion which can be returned to the register and executed in the interrupt processing.

According to the second means, the channel number of the A / D conversion that started conversion immediately before the interrupt is stored in the microcomputer at the beginning of the interrupt processing and the A / D corresponding to the channel number at the end of the interrupt processing. The D conversion can be executed again, and another A / D conversion executed in the interrupt process prevents the microcomputer from malfunctioning without the A / D conversion being canceled or the conversion result being lost. it can.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. However, since the configurations of the control device and the conversion control circuit are the same as those of the conventional example shown in FIGS. 3 and 4, description thereof will be omitted here. Note that (SA1) to (SA6) and (SB1) to (S in the drawings used in the following description.
B12) indicates a processing step.

First, FIG. 1 shows a flowchart of software processing in a microcomputer according to a first embodiment of the present invention. In the main processing routine 17a, first, the initial processing (SA
1) is performed to initialize the control device 1. After that, the process 1 (SA2) and the process 2 (SA6), which are specific control processes, are repeated. In the middle of this, A /
D1 conversion processing (SA3 to SA5) is performed. In the interrupt processing routine 18a, normal interrupt processing (SB3) including conversion processing of A / D2 is performed on the way,
In the present invention, before this processing (SB3) (at the beginning of the interrupt processing routine 18a), first, the end flag 16 determines whether or not the A / D conversion is being executed in the A / D converter 2 (S
B1), and if it is being executed, the conversion data is read from the data register 7 of the A / D converter 2 to the microcomputer 3 and stored (SB2) after waiting for the end of the A / D conversion. And
After the processing (SB3) (the end of the interrupt processing routine 18a), the read conversion data is written in the original data register 7 (SB4). By adding such processing before and after the interrupt processing routine 18a, it is possible to solve the above-mentioned problems caused by the timing of the interrupt processing routine 18a interrupting the main processing routine 17a.

Specifically, in the case of this embodiment, four kinds of timings shown in the figure can be considered as the interrupt timings. Timing 1 (T1) is before A / D1 conversion is started, timing 2 (T2) is after A / D1 conversion is started and before conversion is completed, and timing 3 (T3) is A / D1.
After the conversion is completed and before the conversion data is read to the microcomputer 3, timing 4 (T4) is after the conversion data is read to the microcomputer 3. In the case of timing 1 (T1) and timing 4 (T4), the problem mentioned in the above problem does not occur even in the conventional example, but the above problem that can occur in the case of timing 2 (T2) and timing 3 (T3) The above problem is solved by waiting for the completion of the conversion of A / D1 even after the interrupt processing is started and temporarily saving the conversion result in the microcomputer 3 (during normal interrupt processing).

Next, FIG. 2 shows a flow chart of software processing in the microcomputer of the second embodiment of the present invention. In the main processing routine 17b, first, the initial processing (SA
1) is performed to initialize the control device 1. After that, processing 1 (SA2) and processing 2 (SA6), which are specific control processing,
Repeat. Along the way, A
/ D1 conversion processing (SA3 to SA5) is performed.
In the interrupt processing routine 18b, normal interrupt processing (SB3) including conversion processing of A / D2 is performed on the way, but in the present invention, before this processing (SB3) (beginning of the interrupt processing routine 18b), first. Previously the latest A / D
The channel number corresponding to the converted analog input 8 is A
The channel register 15 of the / D converter 2 is read (SB5) and stored in the microcomputer 3. Then, the processing (SB
After 3) (the end of the interrupt processing routine 18b), the A of the analog input 8 corresponding to the stored channel number is input.
The A / D conversion is started again (SB6), and the interrupt processing routine 18b is ended after the completion of the A / D conversion is judged by the judgment of the end flag 16 (SB7). By adding such processing before and after the interrupt processing routine 18b,
Main processing routine 17b of interrupt processing routine 18b
It is possible to solve the above-mentioned problem caused by the interrupt timing to the.

The specific problem of the interrupt timing is the same as that of the first embodiment of the present invention. However, in the case of the present invention, the interrupt processing by the time waiting for the completion of the conversion of A / D1 at the head of the interrupt processing is performed. To reduce the deviation as much as possible, only the channel number of the A / D conversion performed last time is stored at the beginning of the interrupt process, and the A / D of this channel number is stored at the end of the interrupt process.
I am trying to perform the conversion again.

In this embodiment, A is set for one interrupt process.
Although the number of D / D conversions is 2, even if the number increases and the control becomes complicated, the same effect can be obtained by performing the same processing as that of this embodiment.

[0018]

As described above, according to the present invention, if the first means or the second means is used, the number of A / D inputs has increased in recent years and the contents of control have become complicated. A / D
The problem that the microcomputer reads erroneous data due to the start of conversion multiplex and the control device becomes abnormal is solved by the addition of simple software processing of the microcomputer, and the reliability is prevented from decreasing due to the complicated software processing. /
This has the effect of realizing a control device that can execute D conversion.

Further, by using the second means, there is an effect that the deterioration of the control characteristic due to the time delay (waiting for A / D conversion) can be improved in addition to the above.

[Brief description of the drawings]

FIG. 1 is a software processing flowchart of a microcomputer according to a first embodiment of the present invention.

FIG. 2 is a software processing flow chart of the microcomputer in the second embodiment of the present invention.

FIG. 3 is a block diagram of a control device using a microcomputer and an A / D converter.

FIG. 4 is a configuration diagram of a conversion control circuit in the A / D converter.

FIG. 5: Software processing flow chart of a conventional microcomputer in which a problem occurs

FIG. 6 is a software processing flowchart of a conventional general microcomputer

[Explanation of symbols]

 1 Control device 2 A / D converter 3 Microcomputer 4 Data register

Claims (2)

(57) [Claims] 1. An interrupt processing requiring A / D conversion of a microcomputer in a control device for A / D converting an analog signal using an A / D converter and a microcomputer and taking the analog signal into the microcomputer as digital data. Each time, at the beginning of the interrupt processing, it is determined whether or not A / D conversion is being executed, and if it is being executed , wait until the execution is completed, and the A / D conversion result that has been completed is A / D converted.
Save from the converter register and do not perform A / D conversion.
If it is not, the microcomputer software processing has a function of saving the A / D conversion result immediately before the interruption from the register of the A / D converter and returning the conversion result saved at the end of the interrupt processing to the register. A control device having an A / D converter characterized in that. 2. A control device for A / D converting an analog signal by using an A / D converter and a microcomputer and taking the analog signal into the microcomputer as digital data, interrupt processing requiring A / D conversion of the microcomputer. Each time, the channel that started the latest A / D conversion at the beginning of the interrupt processing is stored and the software processing of the microcomputer that executes the A / D conversion of the stored channel is stored at the end of the interrupt processing. A controller having an A / D converter characterized by: