JP3001325B2 - Microcomputer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcomputer, and more particularly to an A / D converter with a built-in microcomputer.

[0002]

2. Description of the Related Art A conventional microcomputer having a built-in A / D converter, as shown in FIG. 2, inputs a selection circuit 3 for selecting a plurality of analog signals 2 by a control signal 20 and a selected analog signal. An input circuit 1, a voltage holding circuit 4 for holding an analog signal passed through the input circuit 1,
A reference voltage generation circuit 5 for generating a reference voltage 6, a comparator 7 for comparing the reference voltage 6 with an analog signal held in a voltage holding circuit 4, and a register for storing a comparison result output from the comparator 7 It has a circuit 8 and a control circuit 21 for controlling each of them.

[0003]

In such a conventional microcomputer, a system in which a signal having a plurality of valid input levels is input (for example, key input)
In the case where the input signal 2 is determined by applying an A / D converter, an A / D conversion time and a time for determining whether the signal is a valid signal or an invalid signal are required for each input signal.

When there are a large number of valid signals (when there are a plurality of key inputs), the determination time is further increased. In addition, since the input signal is analog, there is a brush in which an input error is considered in advance, and there is a case where low input accuracy is a problem. Further, there is a problem that the program becomes complicated because the above-mentioned input accuracy is taken into consideration, and the determination time is further increased.

An object of the present invention is to provide a microcomputer which solves the above-mentioned problem and enables accurate and short-time determination.

[0006]

According to the present invention, an A / D converter is provided.
In a microcomputer with a built-in converter,
The contents of a reference value register for preliminarily setting an A / D conversion value to be validated and an error register for setting an effective range of the variation of the A / D conversion value to be validated are input and converted by the A / D converter. An arithmetic unit that performs a comparison operation with the contents of the register circuit in which the value is stored, and outputs a valid signal when the contents of the register circuit are determined to be a valid A / D conversion value, and outputs the contents of the register circuit by the valid signal. An output signal determining unit having a holding register for holding, a learning circuit for taking an average of the old holding register and the holding register holding the contents of the previous register in synchronization with the valid signal and outputting an average value thereof; And a reference voltage generator having a reference voltage register for storing the output information of the average value, and in particular, an interrupt control circuit for generating an interrupt by the valid signal. Characterized in that it has a.

[0007]

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

In FIG. 1, according to the configuration of the present invention, an input circuit 1 to which an analog signal is input, a selection circuit 3 for selecting an analog signal to be converted, and holding the selected analog signal through the input circuit 1 A voltage holding circuit 4, a reference voltage generation circuit 5 for generating a reference voltage 6, a comparator 7 for comparing the reference voltage 6 with the input analog signal, and comparison result information output from the comparator 7 A reference value register 9 for setting a reference value for determining a valid input signal in a microcomputer having a built-in A / D converter having a register circuit 8 for storing data and a control circuit 21 for controlling each of them. An effective range setting unit including an error register 10 for setting a range value in which the variation of the input-converted A / D conversion value is valid; A computing unit 11 for comparing the A / D conversion value stored in the path 8 with a reference value and a range value set in the effective range setting unit, and storing in the register circuit 8 based on an output signal of the computing unit 11 A valid signal judging unit including a holding register 13 for transferring and holding the obtained comparison result information; an old holding register 14 for holding the information of the previous holding register 13 in synchronization with the output of the valid signal; A learning circuit 15 for calculating the average of the contents held by the register 13 and outputting the average value information and a reference voltage generator including a reference voltage register 17 for storing the output average value information are provided. An interrupt control circuit for generating an interrupt by a signal is provided.

First, the analog signal 2 is input from the input circuit 1 selected by the selection circuit 3 and is held in the voltage holding circuit 4.

On the other hand, the average value 16 of the A / D conversion value of the effective output signal 12 calculated by the learning circuit 15 is stored in a reference voltage register 17 included in the reference voltage generation circuit 5, and converts the analog signal 2 into an analog signal. When performing the / D conversion, the comparator 7
Is generated by the reference voltage generation circuit 5 as the reference voltage 6.

Next, the result of A / D conversion from the reference voltage 6 generated by the reference voltage generation circuit 5 is stored in the register circuit 8.

The A / D converted value stored in the register circuit 8 is based on the range data of a valid signal set in advance in a reference value register and an error register 10 and an arithmetic unit 11
A comparison operation is performed by using the output signal 12 as the operation result.
Is output. In response to the output of the output signal 12, the interrupt control circuit 18 that generates an interrupt outputs an interrupt request signal 19.

Further, in response to the output of the output signal 12, the contents of the register circuit 8 are held in the holding register 13, and the contents of the previous register circuit 8 are moved from the holding register 13 to the old holding register 14, and are held. The contents of the register 13 and the old holding register 14 are operated by the learning circuit 15 to calculate an average value 16. This average value 16 is held in a reference voltage register 17 in the reference voltage generation circuit 5 and is used as a reference voltage at the next A / D conversion.

[0014]

As described above, according to the present invention, the A / D
In a microcomputer with a built-in converter,
A reference value register for presetting an A / D conversion value of an analog signal determined to be valid, an output signal determination unit for comparing the A / D conversion value and determining a valid signal, a previous A / D conversion value and a current A / D conversion value By incorporating a comparator for comparing the D-converted value and a reference voltage generator incorporating a learning circuit for calculating an average value thereof, and an interrupt control circuit for generating an interrupt when the signal is determined to be the valid signal, A This has the effect of reducing the / D conversion time, the valid signal determination time, and the interrupt generation timing.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing an A / D converter of a conventional microcomputer.

[Description of Signs] 1 input circuit 2 analog signal 3 selection circuit 4 voltage holding circuit 5 reference voltage generation circuit 6 reference voltage 7 comparator 8 register circuit 9 reference value register 10 error register 11 arithmetic unit 12 output signal 13 holding register 14 old Holding register 15 Learning circuit 16 Average value 17 Reference voltage register 18 Interrupt control circuit 19 Interrupt request signal 20 Control signal 21 Control circuit

Claims (2)

(57) [Claims] An input circuit for inputting an analog signal, a selection circuit for selecting an analog signal to be converted, a voltage holding circuit for holding the selected analog signal via the input circuit, and generating a reference voltage A reference voltage generation circuit, a comparator for comparing the reference voltage with the input analog signal, a register circuit for storing comparison result information output from the comparator, and controlling the circuits and the comparator. A microcomputer having an A / D converter having a control circuit for converting the A / D converter into a reference value register for presetting a reference value for determining a valid input signal; An effective range setting unit including an error register for setting a range value in which the variation of the conversion value is valid; An arithmetic unit for comparing the converted value with a reference value and a range value set in the effective range setting unit; and a holding register for transferring and holding the comparison result information stored in the register circuit by an output signal of the arithmetic unit. Providing a valid signal determination unit including, and synchronized with the output of the valid signal,
A learning circuit for calculating the average of the contents held in the old holding register holding the information of the previous holding register and the holding register and outputting the average value information is provided, and a reference voltage for storing the output average value information is provided. A microcomputer, wherein the register is included in the reference voltage generation unit. 2. The microcomputer according to claim 1, further comprising: an interrupt control circuit for generating an interrupt according to a valid signal of said valid signal determining unit.