JPH03191872A - Measuring method for serial digital output voltage - Google Patents

Abstract

PURPOSE:To obtain a comparison level which follows up an output level and automatically measure a serial digital output by comparing the output level with the comparison level and changing the comparison level by an amount corresponding to a step level according to the result of comparison. CONSTITUTION:A comparison level Vt is generated at a comparison step and compared with a serial digital output level V0. Then, a new step level Vs is made by dividing the previous step level Vs by a factor of (n) and a new comparison level Vt is added to or subtracted from the comparison level Vt according to the result of comparison at the comparison step to make a new comparison level Vt. Then, at a judgment step, whether the new step level Vs is below a limit level is judged. When the new step level Vs is not below the limit level, an operation is returned to the comparison step. When the new step level Vs is below the limit level, the comparison level Vt is made a measured voltage. Thus, since the step level Vs is divided by a factor of (n) every change, the comparison level Vt follows up the output level V0 with a high accuracy and the automatic measurement of a serial digital output can be realized.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figure 5) Means for solving the problem to be solved by the invention (Figure 1) Working example (a) 1 Description of Examples (Figures 2 to 4) (b)
Description of other embodiments Effects of the invention [Summary] Regarding a method for measuring serial digital output voltage output from a circuit such as an encoder, the present invention aims to automatically measure voltage in a short time without human intervention, In a method for measuring serial digital output voltage in which the serial digital output voltage is measured by a measurement unit, a comparison step is used to compare the serial digital output level and a comparison level, and a new step level is created by dividing the previous step level by 1/n. A step level creation step that adds or subtracts the new step level to the comparison level based on the comparison result of the comparison step to create a new comparison level, and a comparison level creation step that creates a new comparison level. and a determination step of determining whether the new step level is below the limit level, and if not, returning to the comparison step, and if it is determined in the determination step that the new step level is below the limit level, the comparison level is taken as the measurement voltage.

[Industrial application field]

The present invention relates to a method for measuring a serial digital output voltage output from a circuit such as an encoder.

Measuring the voltage of serial data output from a circuit such as an encoder is important in understanding circuit characteristics and output characteristics.

Serial data is a signal that changes high and low for each bit, and cannot be measured with a DC voltmeter.

Therefore, a technique is required to measure the voltage of serial data that changes at a predetermined period.

[Conventional technology]

FIG. 5 is an explanatory diagram of the prior art.

As shown in FIG. 5(A), a circuit, for example, C0DECr
c is an encoder C0DER, a decoder DECODER,
This is an IC composed of a filter circuit 11L.

On the C0DER side, the analog human input signal is input to the bandpass filter FIL, sampled by the encoder C0DER, and the amplitude component is converted into an 8-bit digital code.

On the other hand, the reverse conversion is performed on the DECODER side, and an 8-bit digital code is output as an analog signal.

The digital signal output on the C0DER side is 8 bits, but
It is not an 8-bit parallel output, but is output as a serial signal on two signal lines by parallel-to-serial conversion.

Such a CODECIC has a built-in band-pass filter, and cannot output a digital code corresponding to the voltage by inputting a constant DC voltage to analog human power in a stopped state.

That is, the filter is a voice band bandpass filter (60
~40QOHz), and it is necessary to always input a (sine wave) as an analog signal.

Therefore, the digital code is not fixed (but is constantly changing, as shown in FIG. 5(B)).

For measuring the voltage of such a changing digital output,
Conventionally, as shown in Figure 5 (C), a sine wave is input to the analog signal input, the serial digital signal output that changes from high to low is observed with an oscilloscope O5C, and the low side voltage of the digital signal is measured. That's what I was doing.

[Problem to be solved by the invention]

However, voltage measurement using the oscilloscope O8C requires manual observation and is time consuming, resulting in a large number of measurement steps and a problem in that measurement errors are likely to occur.

Therefore, an object of the present invention is to provide a method for measuring a serial digital output voltage that can automatically measure the voltage in a short time without human intervention.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention.

As shown in FIG. 1, the present invention provides a method for measuring a serial digital output voltage in which the serial digital output voltage is measured by a measuring section, including a comparing step of comparing the serial digital output level 0 with a comparison level Vt; A new step level V that is 1/n of the previous step level Vs
s, a comparison level creation step of adding or subtracting the new step level Vs from the comparison level Vt to create a new comparison level Vt according to the comparison result of the comparison step; and a determination step of determining whether the new step level Vs is below the limit level, and if not, returning to the comparison step, and if it is determined in the determination step that the new step level Vs is below the limit level, then The comparison level VL is used as the measurement voltage.

[Effect]

In the present invention, a comparison level Vt is generated and an output level Vo
The comparison level VL is changed by the step level Vs based on the comparison result, and the comparison level Vt is changed to the output level ■0.
I am trying to follow.

Since this step level Vs is increased by 17n every time it changes, the comparison level ■[ follows the output level Vo with high precision, and when the step level Vs falls within the IIJIIIt level, the comparison level Vt becomes the output level Vo. Since they are approximately equal, voltage measurement can be realized with this.

Therefore, it is possible to measure the voltage of the serial digital output in a short time without human intervention.

〔Example〕

(a) Description of one embodiment FIG. 2 is a block diagram for one embodiment of the present invention.

In the figure, l is the measurement unit, and C0DECIC (Fig. 5 (A
)) It receives the digital serial data Dout and the sampling pulse SAMP and measures the low-side voltage of the digital serial data, and has the following configuration.

IO is a control unit, which is composed of a processor (MPU) and has registers loa and 10b with a comparison level vth and a step level ■5tep, which receives the comparison result and controls the change of the comparison level vth. It is a comparator, and the level Vof of the digital serial data Dout and
A comparison level (hereinafter referred to as threshold level) vth set by the control unit (hereinafter referred to as MPU) 10 is compared and VLh>Voj! If so, high level, vth≦Vo
12 is a gate circuit that outputs the output of the comparator 11 to MPU10 at the timing of the sampling pulse SAMP;
3 is a timer circuit, which is set by MPUl0 and issues a time limit output to MPUl0 after counting a certain period of time (for example, 100m5); 14 is a digital/analog (D/A) converter, which outputs a digital threshold level from MPUl0. It converts vth into an analog quantity and outputs it to the comparator 11.

Here, input the frequency of the bandpass filter band to the analog input of C0DECIC, for example, a sine wave with a 2KH21 peak-to-peak amplitude of 1 volt, and input the synchronization signal 5Y.
Manually output 1 OKHz as NC.

Furthermore, digital serial data DouL is output every 10 KHz as the C0DER side output.

Further, it is assumed that the sampling pulse SAMP uses the clock signal of CODEC.

FIG. 3 is a processing flow diagram of an embodiment of the present invention, and FIG. 4 is a detailed explanatory diagram of the present invention.

■ MPUl0 has a large threshold level Vthmax (e.g., t, 1°2 volts) in register loa.
is set, and the timer circuit 13 is activated. And M
PU10 outputs the threshold level V L hmax of the register 10 a to the D/A converter 14 and inputs it to the comparator 11 .

The comparator 11 outputs the serial data Dout and the threshold level V L hma from the D/A converter 14.
x is compared, and the comparison result is input to MPUl0 via the gate circuit 12 at the timing of the sampling pulse SAMP.

Therefore, as shown in FIG. 4(A), since the sampling pulse SAMP is generated during the low level period of the serial data DouL, the comparison result input to MPU10 is
A comparison between the first level Vol of the serial data DouL and the threshold level Vth is shown.

■ MPU10 takes in the comparison result for each sampling pulse SAMP, and when the comparison result is high level (Vth>V
off), and if not, timer circuit 1
3 checks whether the timer limit has been issued, and if it has not, returns to the judgment of the comparison result, and if the timer limit has been issued, the threshold maximum value vthmax is smaller than the low level output ■ol, so it is determined that measurement is impossible. , outputs this.

■ On the other hand, if the comparison result is high level, MPU10 sets the threshold level Vth to the register 10a.
in (for example, O volts), and set the step level Vsteρ in the register 10b (VLhmax-Vt
hmin) and starts the timer circuit 13.

Then, the MPU 10 outputs the threshold level Vthmin of the register 10a to the D/A converter I4, inputs it to the comparator 11, and outputs the sampling pulse SAM.
Import the comparison results for each P.

■ For MPU10, the comparison result is high level (Vth>V
of), and if it is high level, it is checked whether or not the timer circuit 13 has issued a time limit, and if it has not, it returns to the judgment of the comparison result, and if it has issued a time limit, it outputs a low level ■oI! Since the threshold maximum value VLhmin is larger, it is output as unmeasurable.

■ If the comparison result is not at a high level, vth≧Vol
It is.

Therefore, MPU10 halves the step level Vstep (N-1) of the register 10b, creates a new step level Vstep (N), and updates the register Job.

Then, MPU10 updates the threshold level vth of register 10a to (VLh+VSLep).

■ MPU10 is the step level V of register 10b.
sLep is the limit level (for example, 0°05 volts)
It is checked whether the value is below, and if it is below, the threshold level vth at that time is output to the display or printer as a measurement result and the process ends.

■ On the other hand, if the step level Vstep is equal to or higher than the limit level, MPU10 continues the measurement, outputs the threshold level vth of the register 10a to the D/A converter 14, inputs it to the comparator 11, and sends it to the comparator 11 for each sampling pulse SAMP. Import the comparison results.

As a result of the comparison, if it is determined that MPU10 does not have Vth>Voil, the threshold level vth is set to the output level Voj! Since the threshold level vth is lower, the process returns to step (2) to raise the threshold level vth.

■ On the other hand, MPU10Gj, Vth>Voj! ? If it is determined that there is, the thread 7 hold level VLh becomes the output level Voj! Therefore, the threshold level vth is lowered.

That is, MPU10 halves the step level VsLep (N-1) of the register 10b, creates a new step level Vsteρ(N), and updates the register IOb.

Then, the MPU10 updates the threshold level vth of the register loa to (vth-VsLep), and returns to step (2).

In this way, as shown in FIG. 4(B), first, the low level output Vo1 of the serial data Dout changes between the maximum value VLhmax and the minimum value VLhmax of the threshold level.
It is checked whether it is within the range of thmin, and if it is not, it is excluded as unmeasurable.

This is because such items are non-standard and there is no point in measuring them.

Low level output Voj! is between the maximum value Vthmax and the minimum [Vthmin, the measurement is performed as follows.

That is, the threshold level vth is compared with the low level output Vol, and the threshold level vth is raised or lowered based on the comparison result.

At this time, the step level VsLep' for raising or lowering the threshold level vth is set to Mlcl/2.
and low level output ■O1! , and when the step level Vstep becomes less than the limit level,
The threshold level vth at that time is taken as the measurement voltage.

This automatically measures the serial data output voltage.

(b) Description of other embodiments In the embodiments described above, the low level output voltage of serial data is measured, but the high level output voltage may also be measured. The limit level is not limited to the example.

Although the present invention has been described above using examples, the present invention can be modified in various ways according to the gist of the present invention, and these are not excluded from the present invention.

〔Effect of the invention〕

As explained above, according to the present invention, the serial digital output voltage can be automatically measured, which not only has the effect of reducing the number of manual measurement steps, but also eliminates measurement errors such as misreading, making it possible to accurately measure the serial digital output voltage. It also has the effect of being measurable.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of the present invention, Fig. 2 is a configuration diagram for an embodiment of the present invention, Fig. 3 is a processing flow diagram of an embodiment of the present invention, and Fig. 4 is a detailed explanation of the present invention. FIG. 5 is an explanatory diagram of the prior art. In the figure, 1-measuring section, 1-control section, 11-comparator, 12-gate circuit, 14-D/A converter.

Claims (1)

[Claims] A method for measuring a serial digital output voltage in which the serial digital output voltage is measured by a measuring unit (1), comprising: a serial digital output level (Vo) and a comparison level (Vo);
Vt) and a new step level (Vs) which is 1/n of the previous step level (Vs).
) and the comparison result of the comparison step, the comparison level (Vt
) to create a new comparison level (Vt) by adding or subtracting the new step level (Vs) to If not, a determination step of returning to the comparison step, and if the new step level (Vs) is determined to be less than or equal to the limit level in the determination step, the comparison level (Vt) is set as the measurement voltage. How to measure serial digital output voltage.