JPH05122078A - A/d converting method by use of microcomputer - Google Patents

Abstract

PURPOSE:To unnecessitate an expensive A/D converter and to enable A/D converting even with a microcomputer without a dedicated terminal such as a serial input, etc., by using a general purpose input port and an easy V-F converting circuit. CONSTITUTION:A system consists of a V-F converter 1 converting an analog signal Vin into a pulse having a frequency corresponding to an input voltage and the microcomputer 2 which measures pulse width outputted from the V-F converter 1 and also converts it into digital data so as to execute an processing. The V-F converter 1 is provided with a integrator 3, a comparator 4, resistors R1-R5, a capacitor C and a transistor TR. The integrator 3 outputs the triangle wave of the frequency being proportional to the Vin voltage and the comparator 4 reshapes it to be a square wave. The output of the comparator 4 inverts a polarity by the transistor TR so as to feed it back to the integrator 3. The microcomputer 2 can obtain the input voltage of Vin by measuring pulse width outputted from the V-F converter 1.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an A / D conversion method,
In particular, it relates to an A / D conversion method by a microcomputer.

[0002]

2. Description of the Related Art A / by a conventional microcomputer
The D conversion method is a voltage / frequency conversion (hereinafter referred to as VF converter) type or non-feedback comparison type external or built-in A /
The D converter converts the analog signal into digital data and converts the serial or parallel data into internal data before processing.

FIG. 3 is a block diagram of an A / D converter and a microcomputer for explaining a conventional A / D conversion method. As shown in FIG. 3, the conventional A / D conversion method is an A / D that converts an analog signal into serial data.
It has a converter 5 and a microcomputer 2a for converting the serial data from the A / D converter 5 into digital data for processing. Moreover, the A / D converter 5
Is an integrator 3 for inputting an analog signal Vin and outputting a triangular wave having a frequency corresponding to the voltage of Vin, and a resistor R.
1 and R2 and a capacitor C, a comparator 4 that outputs a square wave from the triangular wave output from the integrator 3, a square wave from the comparator 4, and a signal output from the clock generation circuit 11. A timing control circuit 7 for opening and closing a switch in synchronization with a pulse measurement circuit 9 for measuring a pulse output from the timing control circuit 7, and a data transfer circuit for outputting a result measured by the pulse measurement circuit 9 as serial data. 10 and 10.

[0004]

The above-described conventional A / D conversion method by the microcomputer uses the A / D converter or the microcomputer with the built-in A / D converter, which makes the system expensive. Become. Also,
If the A / D converter is not built-in, a dedicated terminal for serial input or the like for receiving data from the A / D converter is required, so that it cannot be used in a microcomputer without a dedicated terminal.

An object of the present invention is to provide an A / D conversion method by a microcomputer which does not require an expensive A / D converter and can be used by a microcomputer having no dedicated terminal.

[0006]

An A / D conversion method by a microcomputer of the present invention is a voltage / frequency converter for inputting an analog signal and outputting a square wave having a frequency corresponding to the voltage, and the voltage / frequency converter. A square wave output of a frequency converter is input, a frequency is measured, the frequency is converted into digital data, and a microcomputer is provided for processing.

[0007]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram of a VF converter and a microcomputer for explaining an embodiment of the present invention. As shown in FIG. 1, this embodiment uses the analog signal Vin.
A V-F converter 1 for converting the pulse into a pulse having a frequency corresponding to an input voltage, and a microcomputer 2 for measuring the pulse width output from the V-F converter 1 and converting the pulse width into digital data for processing. Have. The VF converter 1 has an integrator 3, a comparator 4, resistors R1 to R5, a capacitor C, and a transistor TR. From integrator 3 to Vin
A triangular wave having a frequency proportional to the voltage is output, and the comparator 4 shapes the square wave. Further, the output of the comparator 4 inverts the polarity of the transistor TR and feeds it back to the integrator 3. Similarly, the output of the comparator 4 is transmitted through the resistor R5 to the comparator 4
Is input to the + side of. The microcomputer 2 can obtain the Vin input voltage by measuring the pulse width output from the FV converter 1.

FIG. 2 is a waveform diagram of the input / output voltage in FIG. As shown in FIG. 2, the analog input voltage Vin is V
It is converted by the −F converter 1 like the pulse output Vout.

[0010]

As described above, the microcomputer A / D conversion method of the present invention uses an expensive A / D conversion circuit by using a general-purpose input port and a simple VF conversion circuit.
There is an effect that A / D conversion can be performed even in a microcomputer that does not require a D converter and does not have a dedicated terminal for serial input or the like.

[Brief description of drawings]

FIG. 1 is a book diagram of a VF converter and a microcomputer for explaining an embodiment of the present invention.

FIG. 2 is a waveform diagram of input / output voltages in FIG.

FIG. 3 is a block diagram of an A / D converter and a microcomputer for explaining a conventional example.

[Explanation of symbols]

 1 VF Converter 2 Microcomputer 3 Integrator 4 Comparator R1 to R4 Resistor C Capacitor Vin Input Voltage Vout Output Voltage TR Transistor

Claims (1)

[Claims] 1. A voltage / frequency converter for inputting an analog signal and outputting a square wave having a frequency corresponding to the voltage, and a square wave output of the voltage / frequency converter for measuring the frequency to obtain digital data. And an A / D conversion method using a microcomputer.