JP5158424B2 - Waveform measuring device - Google Patents

Description

The present invention relates to a waveform measuring apparatus, and more particularly to a waveform measuring apparatus capable of stably displaying a bus value even when jitter is present when displaying a measurement result of a digital signal on a bus.

Waveform measuring devices are, for example, digital oscilloscopes, etc. In recent years, products that have not only analog input terminals but also logic input terminals to observe multiple signals of mixed analog / logic circuits with a single measuring instrument. It has become.

In such a device, an analog signal is A / D converted and stored in a memory, and binary (“0” (L
Level) or “1” (H level)) is sampled by the sampler and stored in the memory. Then, data is read from the memory and a logic signal or an analog signal is displayed in a waveform on the display screen of the display unit.

  In addition, a plurality of samplers are provided so that logic signals passing through a bus (a plurality of parallel buses) of an object to be measured (for example, an electronic circuit) can be measured simultaneously. Of course, a plurality of AD converters are also provided.

When measuring the logic signals flowing on the parallel bus, it is necessary to analyze not only the logic values of the logic signals of one bus but also the logic values of the logic signals of a plurality of buses.

Displaying the analysis results of such a plurality of logic signals is possible by displaying the bus display, bundle (
called bundle) display. The bus display includes display of bus values and change points.

Here, the bus value is the logic value of a plurality of logic signals measured at the same time measured in synchronization, expressed in hexadecimal, octal, binary, etc. The change point is bundled This indicates the position (time) at which the level of any one of the logic signals (combined) has changed.

Here, an example of displaying a logic waveform as a bus will be described. FIG. 3A is an example of a logic waveform, and FIG. 3B is an example in which the signal of FIG. Further, the upper logic waveform of (A) takes a numerical value of “2” at a high level, and the lower logic waveform takes a numerical value of “1” at a high level.

Therefore, in the bus display of (B), when the bus values are viewed in order from the left, the bus value indicates “0” when the upper logic waveform and the lower logic waveform are low, and the upper logic waveform is high. When the lower logic waveform is low, the bus value indicates “2”, and when both are high, the bus value indicates “3”. Prior art documents of such waveform measuring devices include the following.

JP-A-7-181204

By the way, in the conventional waveform display device, when the logic waveform is displayed on the bus, as shown in FIG. 4, frames are provided at equal intervals in the horizontal direction, and characters are drawn based on these frames. In this way, even if the waveform moves in the time axis direction within the frame due to jitter, the character drawing position basically does not move, so that the character appears to move even during waveform acquisition.

However, since the frame is always fixed in the method of FIG. 4, the character does not move with a slight waveform fluctuation, but when the waveform changes across the frame due to the input waveform, trigger timing, etc., the character as shown in FIG. 5. May appear to move.

The present invention has been made in view of these problems, and an object of the present invention is to provide a waveform measuring apparatus capable of stably displaying a bus value even when jitter is present when displaying a measurement result of a digital signal on a bus. And

In order to achieve such a problem, the invention according to claim 1
In the waveform measurement device that captures the waveform data of the signal under measurement in the memory and displays the waveform of the signal under measurement and the bus value on the display unit.
Change point detection means for detecting a change point which is a reference value for obtaining a bus value;
Change point determination area setting means for setting a change point determination area from the degree of change of the change point obtained by the change point detection means,
Change point determination area display means for displaying the change point determination area set by the change point determination area setting means on the display unit;
Bus value display means for displaying a bus value on the display unit based on the change point determination area;
Bei to give a,
Before SL change point determination area setting means sets an arbitrary change point determination area, widen stepwise change point determination area when it exceeds the change point determination region size is set arbitrarily shaking.

The invention according to claim 2 is the waveform measuring apparatus according to claim 1 ,
The bus value display means displays the bus value at the approximate center between adjacent change point determination areas.

The present invention has the following effects. Since the change point judgment area is enlarged or reduced depending on the waveform fluctuation condition, it improves the character fluctuation during waveform acquisition, which is not always sufficient with the conventional adjustment, automatically detects the waveform fluctuation, and the bus value is It will be possible to check in a stopped state.

Hereinafter, a conventional waveform display apparatus will be described with reference to FIG. The A / D converter 1 converts an input waveform into a digital signal. The ACQ memory (acquisition memory) 5 is a storage unit and stores waveform data output from the A / D converter 1.

The bus processing unit 6 includes a change point detection means 61, a bus value calculation means 62, and a change point determination area setting means 63, and reads waveform data (logic signal waveform data) for a desired acquisition from the acquisition memory 5. A level change point and a bus value are obtained from the waveform of the logic signal, and these values are output.

The change point detection means 61 detects data (time) of a change point (position serving as a reference for obtaining a bus value) at which the level has changed from the waveform data for one acquisition of each of the combined logic signals.

  The bus value calculation means 62 obtains the bus value (analyzed value of the input signal) of the combined logic signal based on the change point of the change point detection means 61.

The change point determination area setting means 63 receives the signal output from the change point detection means 61 and expands or reduces the change point determination area depending on the waveform fluctuation (jitter) that can be understood from this signal. That is, when the shaking is large, the change point determination area is enlarged, and when there is almost no shaking, the change point determination area is reduced.

  The display processing unit 7 includes waveform display means 71, change point display means 72, bus value display means 73, area calculation means 74, and change point determination area display means 75. From the acquisition memory 5, the waveform data of each channel, each bit The waveform data is read out, and the change point and bus value are input from the bus processing unit 6.

The display processing unit 7 is mutually connected to the display memory 8, creates image data from the waveform data, bus values, and change points, writes the image data to the display memory 8, and follows a predetermined update rate of the display screen of the display unit 9. The image data in the memory 8 is read and displayed on the display screen of the display unit 9.

  The waveform display means 71 generates waveform image data from the waveform data. The change point display means 72 calculates the display position on the display screen such as a symbol indicating the change point and a frame surrounding the bus value from the change point of the change point detection means 61, and generates image data. The changing point display means always takes a fixed frame regardless of the magnitude of jitter.

The bus value display means 73 is an analysis value display means, and displays the bus value from the calculation result of the bus value calculation means 62, the display position of the change point of the change point display means 72, and the area of the area calculation means 74. To generate image data. The area calculation unit 74 calculates an area for displaying the bus value on the display screen of the display unit 9. The change point determination area display means 75 displays the change point determination area set by the change point determination area setting means 63.

The display memory 8 stores image data. The display unit 9 has a display screen and displays image data in the display memory 8.

Next, the operation of FIG. 1 will be described with reference to FIG. First, reference numerals 11 to 16 in FIG. 2 are change point determination areas, (A) is an example of a change point determination area when there is almost no waveform fluctuation, and (B) is an intermediate waveform fluctuation. (C) is an example of the change point determination area when the waveform fluctuation is large.

The A / D converter 1 converts the input signal into a digital signal and outputs it to the ACQ memory 5. The waveform data stored in the ACQ memory 5 is output to the change point detection means 61, the bus value calculation means 62, and the waveform display means 71. The change point detection means 61 detects a change point, and the bus value calculation means 62 calculates a bus value.

In actual measurement, change point determination areas having a plurality of sizes are set, but here, for convenience of explanation, three large, medium, and small are set. Next, the change point determination area setting means 63 selects the area “small” in anticipation of almost no shaking. Then, of the regions cut out at equal intervals, the change point detection means 61 detects a region such as reference numeral 11 or reference numeral 12 including the change point, and sets this region as a change point determination region.

Next, a numerical value is drawn so that the center of the character string is the center of the detected area (reference numeral 21) in the frame. That is, the bus value display means 73 acquires the change point determination area from the change point determination area setting means 63 via the change point determination area display means 75 and draws based on this information. Note that the change point determination area may be acquired by directly drawing the pattern from the change point determination area setting means to the bus value display means 73.

In this way, the bus value is written by the bus value display means 73. Here, “0” is drawn in the BUS value 20 of FIG. At this time, the writing position of the character string is drawn with reference to the frame, so that the character string can be confirmed without shaking while the waveform is fluctuating within the area of reference numeral 11 or reference numeral 12. It becomes like this.

On the other hand, when the fluctuation width of the waveform is larger than that of the “small” region, the change point determination region setting unit 63 selects the region “medium” as shown in FIG. Then, similarly to the operation when the area is “small”, an area including a change point such as reference numerals 13 and 14 is detected, and a numerical value is displayed so that the center of the character string comes to the middle of reference numerals 13 and 14. .

Also, when the fluctuation width of the waveform is larger than the area of reference numerals 13 and 14, “large” is selected. Even in this case, as in the case of “medium” and “small”, the area of the code 15 and the code 16 including the change point is detected, and the numerical value is displayed so that the center of the character string is in the middle of the codes 15 and 16 .

It should be noted that although there is no problem if the change point determination area is enlarged step by step, such as “small”, “medium”, etc., if the change point determination area becomes too large suddenly, both overlap as indicated by reference numeral 17. Thus, there may be a case where the area for displaying the character string disappears. In that case, the area of the portion is reduced step by step until an area where characters can be written appears, and when an area where a character string can be displayed appears.

Next, the operation in the display processing unit 7 will be described. The waveform display means 71 takes in the waveform data from the ACQ memory 5 and displays it on the display unit 9. The change point display means 72 displays the change point. The bus value display means 73 acquires the change point determination area via the change point determination area display means 75 or directly from the change point determination area setting means, and displays the bus value based on this information.

The change point determination area display means 75 displays the change point determination area from large, medium, and small based on the information output from the change point determination area calculation means 63.

In this way, the change point determination area setting means 63 expands or reduces the change point determination area depending on the waveform fluctuation condition, so that it is possible to improve the fluctuation of characters during waveform capture, which is not necessarily sufficient with the conventional adjustment, Waveform fluctuations are automatically detected and can be checked when the bus value is stopped.

Note that the present invention is not limited to displaying BUS values as in the example of FIG. 2, but for displaying character strings following the movement of waveforms, such as symbol display and decode display such as a serial bus. Is also effective, and visibility is improved.

It is a block diagram of the waveform measuring apparatus of this invention. (A) is an example of the change point determination area when there is almost no waveform fluctuation, (B) is an example of the change point determination area when the waveform fluctuation is medium, and (C) is an example of the waveform fluctuation. It is an example of the change point determination area | region when is large. It is an example of a bus display of a logic waveform. This is a conventional example in which frames are equally spaced in the horizontal direction and characters are drawn based on these frames. This is an example in which characters overlap due to waveform fluctuations.

Explanation of symbols

1 A / D converter 5 ACQ memory 6 Bus processing unit 7 Display processing unit 8 Display memory 9 Display unit 61 Change point detection means 62 Bus value calculation means 63 Change point determination area calculation means 71 Waveform display means 72 Change point display means 73 Bus value display means 74 Area calculation means 75 Change point determination area display means

Claims (2)

In the waveform measurement device that captures the waveform data of the signal under measurement in the memory and displays the waveform of the signal under measurement and the bus value on the display unit.
Change point detection means for detecting a change point which is a reference value for obtaining a bus value;
Change point determination area setting means for setting a change point determination area from the degree of change of the change point obtained by the change point detection means,
Change point determination area display means for displaying the change point determination area set by the change point determination area setting means on the display unit;
Bus value display means for displaying a bus value on the display unit based on the change point determination area;
Bei to give a,
Before SL change point determination area setting means, characterized in that widening the stepwise change point determination region when setting an arbitrary change point determination area, beyond the change point determination region size is set arbitrarily shaking a wave-shaped measuring device you. The waveform measuring apparatus according to claim 1 , wherein the bus value display means displays a bus value at an approximate center between adjacent change point determination areas.