JPH04128981A - Microcomputer - Google Patents

Abstract

PURPOSE:To contrive highly accurate timing of A/D conversion input of a microcomputer by providing the microcomputer with a means of transmitting a signal bilaterally or unilaterally between an A/D conversion block and a timer block without intervention of internal bus. CONSTITUTION:A microcomputer has a mixing circuit 6 that carries out logical operation on a conversion start demand signal from timer 4 and a setting signal from mode register 3 and that outputs a result of the logic operation to an A/D conversion circuit 1, sets a timing of A/D conversion input in a compare register 5 by means of program, and makes a timer 4 start counting. When a value on timer 4 coincides with a value in compare register 5, the microcomputer generates a start demand signal 9, inputs it in the mixing circuit 6, carries out logic operation on a setting signal from mode register 3 and the start demand signal 9, and demands the A/D conversion circuit 1 to start conversion operation. Further, the microcomputer inputs analog data in the A/D conversion circuit 1 from an external input terminal 7, and when the conversion ends, the microcomputer loads a result register with a digital value of a result of the conversion. For this season, highly accurate timing of A/D conversion can be done eliminating troublesome treatment of program.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a microcomputer, and an internal A/D of a microcomputer.
This invention relates to a conversion device.

[Conventional technology]

In particular, the conventional A/D converter for a microcomputer will be explained with reference to FIG. In Figure 2, this A/
The D converter operates by inputting analog data such as voltage values from the external input terminal 7.

This analog data is converted into digital data by the A/D conversion circuit 1, and the result is stored in the result register 2.

The time required to store the voltage value of the external input terminal 7 in the result register 2 will be referred to as conversion time. (This time is generally several tens of microseconds.) In addition to result register 2, internal bus 10 also includes mode registers 3. The comparison register 5 is also contacted.

The input of A/D conversion values is generally performed at time intervals (several ms) longer than the conversion time. Therefore, the order in which A/D conversion is performed by controlling the above-mentioned A/D conversion device by a program is as follows.
This will be explained using FIG.

In FIGS. 2 and 4, a timer 4 is generally used to generate a timing of several ms, and is started at timer start 11. When the timer 4 counts for a certain period of time, a timer interrupt signal is generated at the next time point 12.

When an interrupt signal is generated, a transition is made to the interrupt operation indicated by line 13, and the interrupt processing is reached at A/D conversion start 14, where A/D conversion start processing is performed.
When the A/D conversion is completed and a conversion end signal is generated, it is used as an A/D conversion end interrupt signal shown at the next time point 16, and the conversion result is stored in a predetermined memory in the process of the conversion result manual 17.

[Problem to be solved by the invention]

The above-described processing procedure uses two interrupts, the timer interrupt at time 12 and the A/D conversion end interrupt at time 16, and therefore has the disadvantage that the program control burden is large and cumbersome.

Also, immediately after timer 4 counts for a certain period of time, the A/D
Before starting the conversion operation, delays and variations occur in the line 13 due to transition to interrupt processing by the microcomputer. Therefore, the timing of reception of analog data from the outside is delayed and variations occur. Therefore, in systems that require precision in reception timing, this A/D converter has the disadvantage that it cannot fully satisfy the specifications.

It is an object of the present invention to solve the above-mentioned drawbacks, perform A/D conversion at regular intervals, reduce the burden on software programs when inputting values, and improve the accuracy of the timing of A/D conversion input. Our goal is to provide a microcomputer with improved functionality.

[Means to solve the problem]

The configuration of the microcomputer of the present invention includes an A/D conversion circuit, a result register for storing the conversion result, and the A/D conversion circuit.
A having a mode register that controls the operation of the conversion circuit.
An A/D conversion device is provided between the /D conversion block and the timer block having a timer and a comparison register, which is provided with means for mutually transmitting signals or transmitting signals in the - direction without going through an internal bus. It is characterized by

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 shows A of a microcomputer according to an embodiment of the present invention.
FIG. 2 is a block diagram of a /D conversion device.

In FIG. 1, the A/D converter of this embodiment performs a logical operation on the conversion start request signal from the timer 4 and the setting signal of the mode register 3, in addition to the conventional A/D converter.
A mixing circuit 6 is provided at the conversion circuit FIIr1 to output the result. The timing of A/D conversion input is set in the comparison register 5 by a program, and the timer 4 is caused to count.

When the values in the timer 4 and comparison register 5 match, a start request signal 9 is generated and input to the mixing circuit 6. Mixing circuit 6
Then, the A/D conversion circuit 1 performs a logical operation on the setting signal of the mode register 3 and the start request signal 9, and requests the A/D conversion circuit 1 to start a conversion operation. When analog data is input and conversion is completed, the digital value of the conversion result is stored in result register 2.
In this embodiment, each operation other than setting the A/D conversion input timing is executed by hardware.

An example of control by a program using the A/D conversion device of this embodiment will be explained with reference to FIG.

As before, timer start 1 is used to generate timing.
A value is set in timer 4 in part 1.

When timer 4 counts for a certain period of time, timer attack 1
2' is generated, which causes the A/D conversion block to
Since it is directly connected as the start request signal 9 in the figure, the timer interrupt 12 simultaneously performs the A/D conversion start processing 14.
The process from ' to A/D conversion start processing 14 is processed by hardware, as shown in section 15, and no processing is given to the program.

When the A/D conversion is completed, an A/D conversion end interrupt 16 is generated, and the conversion result input process is performed by the conversion result manual section 17.

In this embodiment, the match signal of the comparison register 5 and timer 4 is used as the signal connected to the A/D conversion block.
Any method that uses a signal generated by the operation of a timer, such as the timing when an arbitrary bit of the timer changes or the timing when the timer overflows, can be applied as an embodiment of the present invention.

Further, the logical operation of the mixing circuit 6 in FIG. 1 may be of any type as long as it uses the signal from the timer block.

〔Effect of the invention〕

As explained above, in the present invention, the start timing of the conversion operation is determined by the signal output from the timer, so the A/D input is performed after the signal output from the timer is detected by the program. Eliminate misalignment,
This eliminates the complexity of programs such as using both timer interrupts and A/D conversion end interrupts, resulting in improved accuracy and
This has the effect of allowing conversion.

[Brief explanation of drawings]

FIG. 1 shows A of a microcomputer according to an embodiment of the present invention.
2 is a block diagram of an A/D converter for a conventional microcomputer. FIG. 3 is a flow diagram showing an example of how the A/D converter shown in FIG. 1 is used by a program. FIG. 4 is a flow diagram showing an example of how the A/D converter shown in FIG. 2 is used by a program. 1...A/D conversion circuit, 2...Result register, 3...
- - Mode register, 4 - Timer, 5 - Comparison register, 6 - Mixing circuit, 7 - External input terminal, 8
... Conversion end signal, 9... Lock start request signal, 10...
・Internal bus, 11...Timer start, 12...Time point, 12'...Timer interrupt, 13...Interrupt transition, 14...A/D conversion start, 15...Hardware processing part , 16...-A/D conversion end interrupt, 1
7...Input conversion result.

Claims (1)

[Claims] between an A/D conversion block that includes an A/D conversion circuit, a result register that stores the conversion result, and a mode register that controls the operation of the A/D conversion circuit; and a timer block that includes a timer and a comparison register; A microcomputer characterized by comprising an A/D conversion device provided with means for mutually or unidirectionally transmitting signals without going through an internal bus.