JPH03142582A - Microcomputer - Google Patents

Abstract

PURPOSE:To widely reduce processings by inputting a CPU control signal and afterwards, outputting an A/D conversion start signal after the lapse of set prescribed time. CONSTITUTION:According to a CPU control signal 1, a control circuit 5 generates count start/end signal 2/3 and is returned by a clear signal 4. A counter 8 counts the number of clocks to be generated by a clock generating circuit 6 and a comparator circuit 11 compares the count value with the set value of a moduloregister 9. When the value is coincident, the count clear signal 4 is sent to the control circuit 5 and the counter 8. Based on a coincidence signal 10, an A/D conversion control circuit 13 sends a start signal 12 to an A/D conversion circuit 20. Thus, when the A/D converting value of a certain input signal is measured and standby is required until the converting value is made stable, arbitrary standby set can be executed and it is not necessary to control the standby time by a software. Then, the processing are widely reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microcomputer, and particularly to a microcomputer having an A/D conversion circuit.

[Conventional technology]

Conventional microcomputers perform A/D conversion by executing an A/D conversion start instruction command.

FIG. 3 shows a part of a conventional microcomputer.

The A/D control circuit 13 receives the CPU control signal 1 and performs an A/D control circuit 13.
A D conversion start signal 12 was output to the A/D conversion circuit 20.

[The problem that the invention attempts to solve]

The above-mentioned conventional microcomputers have the disadvantage that when performing an A/D conversion operation, when an A/D conversion value after an arbitrary period of time is required, separate time management is required using a software or hard timer. be.

SUMMARY OF THE INVENTION An object of the present invention is to provide a microcomputer that eliminates the above drawbacks and eliminates the need for time management operations even when A/D conversion values after a predetermined period of time have passed.

[Means to solve the problem]

The structure of the present invention is a microcomputer equipped with means for outputting an A/D conversion start signal to an A/D conversion circuit based on a CPU control signal. After the A/D
The present invention is characterized by providing means for outputting a conversion start signal.

〔Example〕

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

FIG. 1 is a block diagram showing a part of a microcomputer according to an embodiment of the present invention.

In FIG. 1, the microcomputer of this embodiment is
The circuit includes a control circuit 5, a counter circuit 8, a comparison circuit 11, a modulo register 9, an A/D control circuit 13, a clock generation circuit 6, and an A/D conversion circuit 20.

Here, the control circuit 5 is a circuit that outputs a count start signal 2 and a count end signal 3 in response to a CPU control signal 1, and returns to the initial state in response to a count clear signal 4.

The counter circuit 8 starts counting the clock signal 7 output from the clock generation circuit 6 based on the count start signal 2, and stops counting the clock signal 7 when the count end signal 3 is supplied. The circuit stops and returns to the initial state by the count/clear signal 4.

The comparison circuit 11 compares the count value of the counter circuit 8 and the set value of the modulo register 9, outputs a match signal 10 when the two match, and sends the count/clear signal 4 to the control circuit 5. This is a circuit that outputs to the counter circuit 8. This comparison circuit 11 compares the data set in a separately installed storage circuit with the count value of the counter circuit 8, and when the two match, a match signal 10 is generated.
This is a circuit that outputs .

Based on the coincidence signal IO, the A/D control circuit (3)
This circuit outputs the A/D conversion start signal 12 to the A/D conversion circuit. In this embodiment, the A/
When measuring a D-converted value, if a weight is required until the converted value becomes stable, an arbitrary weight can be set.

As described above, the microcomputer of this embodiment can arbitrarily set the time required for stabilizing the A/D conversion value using the built-in hardware.

FIG. 2 is a block diagram showing a microcomputer according to another embodiment of the invention.

In FIG. 2, the difference between this embodiment and FIG. 1 is that the counter circuit 8 and comparison circuit 11 in FIG. 1 are replaced by a counter circuit 16, and other parts are 1st
It is similar to the figure.

The counter circuit 16 uses the set value of the modulo register 9 as
This circuit starts counting by latching the count start signal 2 output from the control circuit 5, and outputs an overflow signal 14 and a borrow signal 15 when the count overflows or underflows.

The A/D control circuit 13 receives the overflow signal 14
Based on the and PO□-signal I5, A/D start signal 1
This is a circuit that outputs 2.

In this embodiment, control based on UP/DOWN counts of a counter is possible. In the microcomputer of this embodiment, it is preferable to incorporate a counter circuit that subtracts or adds the value of the memory circuit itself that stores the setting f value.

〔Effect of the invention〕

As explained above, the present invention allows arbitrary wait time control using a preset count value, so when measuring the A/D conversion value of an external input signal, it is possible to control the wait time until the A/D conversion value stabilizes. Since time [11] can be controlled by microcomputer hardware, there is no need to control the wait time by software, which greatly speeds up processing. It has the effect of being able to reduce the amount of data to i.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a part of a microcomputer according to an embodiment of the present invention, FIG. 2 is a block diagram showing a part of a conventional microcomputer according to another embodiment of the invention, and FIG. FIG. 1...CPU control belief signal...Count/start signal, 3...Count/end signal, 4...Count/clear signal, 5... ...
・Control circuit, 6...Clock generation circuit, 7...
... Clock signal, 8.16 ... Counter circuit, 9 ... Modulo register, 10 ... Match signal, 11 ... Comparison circuit, 12 ... A /D
Conversion start signal, 13...A/D control circuit,
14... Overflow signal, 15...
・Borrow signal.

Claims (1)

[Claims] In a microcomputer equipped with a means for outputting an A/D conversion start signal to an A/D conversion circuit based on a CPU control signal, the A/D A microcomputer characterized by comprising means for outputting a conversion start signal.