JP2007060235A - Data sampling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data sampling device capable of preventing erroneous sampling. <P>SOLUTION: When an amplitude level of an input waveform as a sampling target exceeds a threshold β of data B, L-level data Bhld generated by a twice match filter corresponding to the threshold β are held by a peak hold register and acquired by a sampling register before the elapse of a prescribed period of time teg. By this, the L-level data Bhld corresponding to the threshold β of the data B are held by the peak hold register regardless of the inclination and shape of a rising waveform or a falling waveform of the input waveform as the sampling target, after the amplitude level of the input waveform once exceeds the threshold β of the data B. Consequently, it is possible to surely obtain a data value based on the input waveform as the sampling target by acquiring the held L-level data Bhld by the sampling register. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a data sampling apparatus capable of determining and outputting a data value based on a digital waveform to be sampled based on a predetermined threshold.

  Conventionally, as one form of a data sampling apparatus capable of determining and outputting a data value based on a digital waveform to be sampled based on a predetermined threshold, there is one disclosed in Patent Document 1 below, for example.

  Such a data sampling device is used for receiving serial data flowing through a communication bus of a network such as a LAN, and may be applied to baseband transmission of digital data, for example. Specifically, for example, there is a so-called Safe-by-Wire as a safety sub-network used in a vehicle airbag system, as shown in FIG. A digital waveform is the target of data sampling.

  That is, in safe-by-wire, a power phase Pph intended to supply power to each node and a data phase Dph intended to transmit a data signal are alternately formed. The transmission waveform (digital waveform) sent to the communication bus is configured. For this reason, as shown in FIG. 7A, the node that sends the message (data signal) has a waveform in the negative direction from the maximum value (for example, + Vcc) of the digital waveform corresponding to the power phase Pph during the data phase Dph. A data waveform is formed by falling. On the other hand, at the node that receives the message, for example, two threshold values α and β are provided between 0 V and + Vcc, and the waveform is determined by determining whether or not the amplitude level of the input waveform exceeds these threshold values by a comparator or the like. The data value based on the data is determined and the data is decoded.

  For example, in the example shown in FIG. 7A, since the lower limit of the amplitude level is between the threshold α and the threshold β in the first and second data phases Dph from the left, the data output from the comparator Each Bin is “0” corresponding to “Data A”, and the lower limit of the amplitude level exceeds the threshold value β in the third data phase Dph. Therefore, the output data Bin corresponds to “1” corresponding to “Data B”. (See FIG. 7B). It should be noted that the examples such as the input waveform shown in each diagram of FIG. 7 are expressed more simply than the original safe-by-wire method by reducing the number of threshold values for determining the data value. .

Thus, although an example of safe-by-wire is described here, in general, in baseband transmission of digital data, the amplitude of the input waveform is set by providing a predetermined threshold for the input waveform. The data value is determined by judging whether the level exceeds the threshold. Then, the determination as to whether or not the amplitude level exceeds the threshold, that is, data sampling is performed at a preset timing, or the falling waveform exceeds the threshold α as shown in FIG. In many cases, it is performed in the middle of the period td (approximately the center of the data phase Dph).
JP 2001-60941 A

  However, according to such a conventional data sampling device, the data sampling timing is set to be approximately the center of the preset timing or the data phase Dph. For this reason, there is a possibility that erroneous data is sampled when the slope of the input waveform forming the data phase Dph becomes small (gradual).

  That is, as shown in FIG. 7C, when the rising edge of the input waveform becomes gentle in the data phase Dph, such sampling is performed even if the data is sampled almost at the center of the data phase Dph. May fall in the middle of the rise of the input waveform. Therefore, when the timing around the input waveform exceeds the threshold β and the sampling timing overlap, the amplitude level of the input waveform is determined to be between the threshold α and the threshold β due to a slight difference in the timing. (Data Bin is “0”) and when it is determined that the amplitude level exceeds the threshold β (data Bin is “1”), there is a problem that it may lead to erroneous sampling (FIG. 7). (Dashed ellipse shown in (C)). As will be described later, a similar problem can occur even when the falling edge of the input waveform becomes gentle (see FIG. 4B).

  Note that such problems are not limited to those specified in the communication protocol so that the rise and fall of the input waveform are completed within a specified period, as long as the design specifications of each node comply with the protocol. Since the slope of the input waveform is within the planned range of the protocol, it is generally considered difficult to occur. However, in safe-by-wire, where the communication protocol does not have such specifications, the rise time and fall time of the transmission waveform (digital waveform) sent to the communication bus depends on the design specifications of each node. Such a problem of erroneous sampling may occur.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a data sampling apparatus capable of preventing erroneous sampling.

  In order to achieve the above object, in the data sampling device according to claim 1, the data value based on the digital waveform to be sampled is determined based on a predetermined threshold value [α, β, γ]. A data sampling device capable of outputting the data based on a first threshold value [α] closest to a maximum value or a minimum value of the digital waveform among the predetermined threshold values [α, β, γ]. Of the predetermined threshold values [α, β, γ], second threshold values [β, γ other than the first threshold value [α] among the first determination means [21] capable of determining the amplitude level of the waveform ] Based on the second determination means [22, 22a, 22b] capable of determining the amplitude level of the digital waveform, and the second level of the amplitude level away from the first threshold [α]. That the threshold [β, γ] was exceeded When it is determined by the second determination means [22, 22a, 22b], data information generation means [25, 25a, 25b] capable of generating data information representing a predetermined data value, and the data information generation means [ 25, 25a, 25b] after the data information is generated, the digital waveform amplitude level is the maximum value or minimum value closest to the first threshold [α]. Data information holding means [27, 27a, 27b] that can be held for a predetermined period after the first determination means [21] determines that the first threshold value [α] has been exceeded in the direction. The data information held in the data information holding means [27, 27a, 27b] is transferred to the data information holding means [27, 27a, 27b] before the lapse of the predetermined period. Obtainable sampling means [23,29,29a, 29b] is technically characterized by comprising a, a. The numbers in [] can correspond to the symbols described in the [Best Mode for Carrying Out the Invention] column (the same applies hereinafter).

  In the data sampling device according to claim 2, the data information generation means [25, 25a, 25b] is characterized in that the second determination means [22, 22a] is the data sampling device according to claim 1. , 22b] generates the data information after determining that the amplitude level has exceeded the second threshold value [β, γ] two or more times in a direction away from the first threshold value [α]. It is a technical feature.

  In the data sampling device according to claim 3, the amplitude level of the digital waveform is the highest in the first threshold value [α] during the predetermined period. After the first determination means [21] determines that the first threshold value [α] has been exceeded in the direction of the closest maximum value or minimum value, the digital waveform to be sampled follows It is a technical feature that it is a period until sampling of another digital waveform.

  In the first aspect of the invention, the second determination means [22, 22a, 22b] indicates that the amplitude level has exceeded the second threshold value [β, γ] in the direction away from the first threshold value [α]. If it is determined, data information representing a predetermined data value is generated by the data information generating means [25, 25a, 25b], and the generated data information is converted into a digital waveform after the data information is generated. A predetermined period after the first determining means [21] determines that the amplitude level has exceeded the first threshold value [α] in the direction of the maximum value or the minimum value closest to the first threshold value [α]. Until later, it is held by the data information holding means [27, 27a, 27b]. Then, the held data information is acquired from the data information holding means [27, 27a, 27b] by the sampling means [23, 29, 29a, 29b] before the lapse of a predetermined period.

  Thus, in the first aspect of the present invention, when the amplitude level of the digital waveform to be sampled exceeds the second threshold value [β, γ], it is generated corresponding to the second threshold value [β, γ]. Data information is held by the data information holding means [27, 27a, 27b], and is acquired by the sampling means [23, 29, 29a, 29b] before a predetermined period of time elapses. For this reason, once the amplitude level exceeds the second threshold value [β, γ], the second waveform does not depend on the slope or shape of the rising waveform or falling waveform of the digital waveform to be sampled. Since the data information corresponding to the threshold value [β, γ] is held in the data information holding means [27, 27a, 27b], the held data information is acquired by the sampling means [23, 29, 29a, 29b]. Thus, it is possible to reliably obtain a data value based on the digital waveform to be sampled and output it. Therefore, erroneous sampling can be prevented.

  In the invention of claim 2, the data information generating means [25, 25a, 25b] is such that the second determining means [22, 22a, 22b] is directed toward the direction in which the amplitude level is away from the first threshold [α]. After determining that the second threshold value [β, γ] has been exceeded twice or more, data information is generated. Thus, in the invention of claim 2, data information corresponding to the second threshold value [β, γ] is not generated unless it is determined twice or more that the second threshold value [β, γ] has been exceeded. For example, generation of erroneous data information when the amplitude level of the digital waveform fluctuates due to external noise or the like can be prevented. Therefore, erroneous sampling can be prevented more reliably.

  In the invention of claim 3, it is determined that the amplitude level of the digital waveform exceeds the first threshold value [α] toward the maximum value or the minimum value closest to the first threshold value [α] during the predetermined period. Since it is a period from after determination by one determination means [21] to sampling of another digital waveform subsequent to the digital waveform to be sampled, for example, sampling is performed at substantially the center of the digital waveform. The degree of freedom of sampling processing can be increased as compared with the case where the sampling time is defined as a fixed time.

  Hereinafter, embodiments of a data sampling device of the present invention will be described with reference to the drawings. In the present embodiment, an example in which the data sampling device of the present invention (hereinafter referred to as “sampling device”) is applied to a receiving node connected to safe-by-wire will be described. Since safe-by-wire has already been described in the [Background Art] column, it is omitted here. First, the configuration of the sampling device 20 according to the present embodiment will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the sampling device 20 is connected to a safe-by-wire (not shown) via an input terminal IN, and mainly includes comparators 21 and 22, an edge generation unit 23, and a second coincidence filter 25. , A peak hold register 27 and a sampling register 29. Thereby, in the sampling device 20, the data value based on the input waveform (digital waveform) input from the input terminal IN can be determined on the basis of predetermined threshold values α and β described later and output from the output terminal OUT-B. I have to. A timing clock is supplied to the CLK terminal shown in FIG. 1 from a timing generator (not shown).

  The comparators 21 and 22 are comparators that can determine the amplitude level of the input waveform (digital waveform) input from the input terminal IN. The voltage (amplitude level) input to the comparison input is the reference voltage input to the reference input. It is judged whether it is larger than. For example, in the case of the comparator 21 (first determination means), based on the threshold value α (first threshold value) of the data A closest to the maximum value of the input waveform among the predetermined threshold values (α, β), A reference voltage or the like is configured so that the amplitude level of the input waveform can be determined (H → L of data Ain in (1) shown in FIG. 2A). In the case of the comparator 22 (second determination means), the amplitude level of the input waveform is based on the threshold value β (second threshold value) of the data B other than the threshold value α of the data A among the predetermined threshold values. A reference voltage or the like is configured so as to be able to determine (H → L of data Bin in (2) shown in FIG. 2A).

  The edge generation unit 23 is connected to the output of the comparator 21, and the comparator 21 indicates that the amplitude level of the input waveform has exceeded the threshold value α of the data A toward the maximum value closest to the threshold value α of the data A. This is a one-shot pulse generator that can output one pulse that has continued until a predetermined period after the determination, and is configured to be able to output the pulse in synchronization with the rising timing of the timing clock CLK. Specifically, after the output of the comparator 21 is switched from H to L (L → H of data Ain in (8) shown in FIG. 2A), the timing clock rises (shown in FIG. 2A). (9)) Data Aeg is output for a predetermined period teg.

  The coincidence filter 25 is connected to the output of the comparator 22, and the comparator 22 determines that the amplitude level of the input waveform exceeds the threshold value β of the data B in a direction away from the threshold value α of the data A. In this case, the synchronization register can generate data information representing a predetermined data value, and is configured to be able to output the data information in synchronization with the rising timing of the timing clock CLK. Specifically, when the output of the comparator 22 determines that the amplitude level of the input waveform has exceeded the threshold value β of the data B in the direction of the rising timing of the timing clock CLK two or more times (FIG. 2A ) (3)), and then the output data Bfil (data information representing a predetermined data value) is changed from H to L ((4) shown in FIG. 2A).

  The output of the data Bfil (L level) by the twice coincidence filter 25 is determined at the rising edge of CLK based on the output of the comparator 22 that the amplitude level of the input waveform has exceeded the threshold value β of the data B. Until the amplitude level returns to between the threshold value α of the data A and the threshold value β of the data B (indicating data A) ((6), (7 shown in FIG. 2A)). )). As described above, in the twice coincidence filter 25, the data Bfil is set to the L level when it is determined that the threshold value β has been exceeded twice or more. For example, the amplitude level of the input waveform due to external noise or the like. It is possible to prevent the data Bfil from being erroneously set to the L level when the value fluctuates.

  The peak hold register 27 is connected to the output of the edge generation unit 23 and the output of the twice coincidence filter 25, and the data Bfil (L level) output from the twice coincidence filter 25 is converted into the data Bfil (L level). ) Is output, a predetermined period after the comparator 21 determines that the amplitude level of the input waveform has exceeded the threshold value α of the data A in the direction of the maximum value closest to the threshold value α of the data A Until this time, it is a register that can hold data Bhld (L level), and is configured to be able to output the data information in synchronization with the rising timing of the timing clock CLK. Specifically, from the rising timing of the timing clock CLK after the L-level data Bfil is output from the twice coincidence filter 25 ((5) shown in FIG. 2A), the data Aeg ( Until the rising edge of the timing clock CLK after the one-shot pulse) is output ((10) shown in FIG. 2 (A)), the L-level data Bhld (data information) is held (FIG. 2 (A)). (11)).

  The sampling register 29 is connected to the output of the edge generation unit 23 and the output of the peak hold register 27, respectively. The L level data Bhld held in the peak hold register 27 is peak-held before the predetermined period teg has elapsed. A register that can be acquired from the register 27 and configured to output the data information in synchronization with the rising timing of the timing clock CLK. Specifically, L-level data Bhld held in the peak hold register 27 is acquired, that is, sampled at the rising timing of the timing clock CLK after the data Aeg (one-shot pulse) is output from the edge generator 23 ( It is shown in FIG. 2 (A) (12)).

  By configuring the sampling device 20 in this way, when the amplitude level of the input waveform to be sampled exceeds the threshold value β of the data B ((2) shown in FIG. 2A), 2 corresponding to the threshold value β. The L-level data Bhld generated by the degree coincidence filter 25 is held by the peak hold register 27 ((5) shown in FIG. 2A) and is acquired by the sampling register 29 before the lapse of a predetermined period teg ( It is shown in FIG. 2 (A) (12)). Thereby, once the amplitude level of the input waveform exceeds the threshold value β of the data B, the threshold value β of the data B is set regardless of the inclination or shape of the rising waveform or falling waveform of the input waveform to be sampled. Since the corresponding L level data Bhld is held in the peak hold register 27, the data value based on the input waveform to be sampled can be reliably obtained by acquiring the held L level data Bhld by the sampling register 29. Can get to. Therefore, erroneous sampling can be prevented.

  For example, in the sampling device 20, as shown in FIG. 2B, not only when the input waveform can be normally sampled even if it is sampled in the middle of the period td when the input waveform exceeds the threshold value α, As shown in (B), even when there is a possibility that the input waveform cannot be normally sampled if sampling is performed in the middle of the period td because the rise of the input waveform has become gradual (in FIG. 3 (B) As shown in FIG. 3A, the data value based on the input waveform can be reliably sampled via the data Bhld that is the output of the peak hold register 27.

  Similarly, even when there is a possibility that the input waveform cannot be normally sampled if sampling is performed in the middle of the period td because the falling of the input waveform has become gentle (inside the broken line ellipse shown in FIG. 4B). As shown in FIG. 4A, the data value based on the input waveform can be reliably sampled via the data Bhld that is the output of the peak hold register 27. 3 and 4 are the same as those shown in FIG.

  In the sampling device 20 described above, when the “predetermined threshold value” is two, that is, the threshold value α of the data A and the threshold value β of the data B are described, the safe-by-wire is simplified, and is described. Even when there are three or more “predetermined threshold values”, the sampling apparatus 20 can be basically configured in the same manner.

  Here, as an example in which three types of predetermined threshold values α, β, and γ are set, the configuration of the sampling device 20 ′ will be described with reference to FIGS. 5 and 6. In these drawings, the same components and waveforms as practically the same as those in the case of the sampling apparatus 20 described above are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 5, the sampling device 20 ′ mainly includes comparators 21, 22a and 22b, an edge generation unit 23, double coincidence filters 25a and 25b, peak hold registers 27a and 27b, and sampling registers 29a and 29b. Is done. That is, in the sampling apparatus 20 described above, since there are two types of thresholds to be set, α and β, there is one comparator (comparator 22) corresponding to the second determination means (see FIG. 1). In the sampling apparatus 20 ′, there are three threshold values to be set in addition to α and β, so that there are two comparators corresponding to the second determination means (comparators 22a and 22b). As a result, the double match filter, the peak hold register, and the sampling register are all required twice (double match filters 25a and 25b, peak hold registers 27a and 27b, sampling registers 29a and 29b).

  That is, the input terminal IN to which the input waveform is input is connected to the comparators 22a and 22b in addition to the comparator 21, and the coincidence filter 25a is output twice to the output of the comparator 22a and twice to the output of the comparator 22b. Match filters 25b are connected to each other. A peak hold register 27a is connected to the output of the twice coincidence filter 25a, and a sampling register 29a is connected to the output of the peak hold register 27a. The output of the sampling register 29a is connected to the output terminal OUT-B in the same manner as the output of the sampling register 29 of the sampling device 20 described above. On the other hand, the peak hold register 27b is connected to the output of the twice coincidence filter 25b, the sampling register 29b is connected to the output of the peak hold register 27b, and the output is connected to the output terminal OUT-C.

  In the sampling device 20 ′ configured as described above, when the amplitude level of the input waveform to be sampled exceeds the threshold value γ of the data C ((2) ′ shown in FIG. 6), it matches twice corresponding to the threshold value γ. The L level data Chld generated by the filter 25b ((3) ′, (4) ′ shown in FIG. 6) is held by the peak hold register 27b ((5) ′ shown in FIG. 6). Further, when the amplitude level exceeds the threshold value β of the data B ((2) shown in FIG. 6), it is generated by the twice matching filter 25a corresponding to the threshold value β ((3), (4) shown in FIG. 6). The L-level data Bhld is held by the peak hold register 27a ((5) shown in FIG. 6). Then, they are acquired by the sampling registers 29b and 29a before the lapse of the predetermined period teg ((11) ′, (12) ′, (11), (12) shown in FIG. 6), respectively.

  Thereby, once the amplitude level of the input waveform exceeds the threshold value γ of the data C and the threshold value β of the data B, regardless of the inclination or shape of the rising waveform or falling waveform of the input waveform to be sampled, The L level data Chld corresponding to the threshold value γ of the data C is held in the peak hold register 27b, and the L level data Blld corresponding to the threshold value β of the data B is held in the peak hold register 27a. Therefore, by acquiring the held L level data Chld and Bhld by the sampling registers 29b and 29a, a data value based on the input waveform to be sampled can be reliably obtained. Therefore, the above-described sampling apparatus 20 erroneous sampling can be prevented even when such three types of threshold values α, β, and γ are set.

  Since the sampling device 20 according to the above-described embodiment has been described by exemplifying a device compliant with safe-by-wire, the waveform is decreased in the minus direction from the maximum value (for example, + Vcc) of the digital waveform corresponding to the power phase Pph. However, the present invention is not limited to this, and the data waveform is formed by raising the waveform in the positive direction from the minimum value (for example, GND) of the digital waveform corresponding to the ground level. Can be applied to. In this case, the first determination unit determines the amplitude level of the digital waveform based on the first threshold value closest to the maximum value of the digital waveform, and the second determination unit determines a value other than the first threshold value. The amplitude level of the digital waveform is determined based on the second threshold value. The actions and effects are the same as those in the sampling device 20.

  In the sampling device 20 according to the above-described embodiment, the data Bhld held in the peak hold register 27 is acquired by the sampling register 29 before the lapse of the predetermined period teg. As long as it is up to the sampling of the next input waveform following the waveform, it is not limited to before the predetermined period teg. Therefore, the degree of freedom of the sampling process can be increased as compared with the case where the sampling time, such as sampling at substantially the center of the input waveform, is defined as a fixed time.

It is a block diagram which shows the structural example of the data sampling apparatus which concerns on one Embodiment of this invention. FIGS. 2A and 2B are timing charts showing an example of sampling processing when a digital waveform capable of normal data sampling is input. FIG. 2A shows the sampling apparatus according to this embodiment, and FIG. 2B shows a conventional sampling apparatus. It is due to. FIGS. 3A and 3B are timing charts showing an example of sampling processing when a digital waveform that may cause erroneous sampling is input. FIG. 3A shows the sampling apparatus according to this embodiment, and FIG. 3B shows the conventional sampling. By the device. FIGS. 4A and 4B are timing charts showing an example of sampling processing when a digital waveform that may cause erroneous sampling is input. FIG. 4A shows the sampling apparatus according to this embodiment, and FIG. 4B shows the conventional sampling. By the device. It is a block diagram which shows the other structural example of the data sampling apparatus which concerns on one Embodiment of this invention. It is a timing chart which shows the example of a sampling process in case the digital waveform which may have an erroneous sampling is input, and the thing by the other structural example of the sampling apparatus which concerns on this embodiment is shown. Fig. 7 (A) shows an example of a transmission waveform (input waveform) configuration, and Fig. 7 (B) shows normal data sampling. Examples of possible input waveforms and the like, and FIG. 7C show examples of input waveforms and the like that may cause erroneous sampling.

Explanation of symbols

20, 20 '... Sampling device (data sampling device)
21... Comparator (first determination means)
22, 22 a, 22 b... Comparator (second determination means)
23 ... Edge generation unit (sampling means)
25, 25a, 25b ... twice matching filter (data information generating means)
27, 27a, 27b ... Peak hold register (data information holding means)
29, 29a, 29b ... Sampling registers (sampling means)
CLK: Timing clock IN: Input terminal OUT-B, OUT-C: Output terminal α: Data A threshold (first threshold)
β: threshold value of data B (second threshold value)
γ ... Threshold of data C (second threshold)
teg ... predetermined period

Claims (3)

A data sampling device capable of determining and outputting a data value based on a digital waveform to be sampled based on a predetermined threshold,
First determination means capable of determining an amplitude level of the digital waveform based on a first threshold value closest to the maximum value or the minimum value of the digital waveform among the predetermined threshold values;
A second determination unit capable of determining an amplitude level of the digital waveform based on a second threshold other than the first threshold among the predetermined thresholds;
Data capable of generating data information representing a predetermined data value when the second determination means determines that the amplitude level exceeds the second threshold in a direction away from the first threshold. Information generating means;
After the data information is generated, the data information generated by the data information generating means is directed toward the maximum value or minimum value in which the amplitude level of the digital waveform is closest to the first threshold value. Data information holding means capable of holding until a predetermined period after the first determination means determines that the first threshold is exceeded;
Sampling means capable of acquiring the data information held in the data information holding means from the data information holding means before the lapse of the predetermined period;
A data sampling device comprising: The data information generating means includes
After the second determination means determines that the amplitude level has exceeded the second threshold value in a direction away from the first threshold value two or more times,
The data sampling apparatus according to claim 1, wherein the data information is generated.   During the predetermined period, it is determined by the first determination means that the amplitude level of the digital waveform has exceeded the first threshold value in the direction of the maximum value or the minimum value closest to the first threshold value. 3. The data sampling apparatus according to claim 1, wherein the data sampling apparatus is in a period from after the sampling until sampling of another digital waveform following the digital waveform to be sampled.

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