CN1710429A - A Conditional Trigger Method for Oscilloscope Based on Finite State Machine - Google Patents

Abstract

A condition triggering method of oscilloscope based on finite state computer includes making state computer series be n which is integer being greater than or equal to one ; providing four selectable conditions by system to client as automatic condition referring that sub-condition is always being set up , edge condition referring that condition is being set up when specific edge polarity of specific electric level is satisfied , overtime condition referring that condition is being set up after specific delay time is satisfied and forbidden condition referring that this condition is never being set up.

Description

A Conditional Trigger Method for Oscilloscope Based on Finite State Machine

Technical field:

The invention relates to a trigger method of an electronic measuring instrument, in particular to the technical field of an oscilloscope used for waveform display.

Background technique:

"Triggering" is an essential part of an oscilloscope. Without the function of triggering, it is difficult to stabilize the waveform display. For the capture and observation of some special waveforms, complex trigger mechanisms are unavoidable. A typical trigger machine has an input terminal and an output terminal, the input terminal is generally connected to the signal to be tested and the output terminal is connected to the waveform sampling controller. Its main working process is: the trigger machine continuously monitors the signal to be tested, and once the trigger condition is found to be met, the trigger machine outputs a trigger enable signal. Therefore, the core of the trigger machine is the continuous monitoring of whether the signal to be tested meets the conditions, and different trigger methods and functions correspond to the above "conditions".

Most of the existing oscilloscopes adopt the edge trigger mode, and the detection ability is limited. At present, some high-end oscilloscopes support some more complex trigger methods, such as TV trigger, pulse width trigger, glitch trigger, event trigger, delay trigger, jump trigger, etc., which are of great benefit to signal analysis. However, the waveforms that modern oscilloscopes need to probe are varied. In some special occasions, the signal to be tested is mixed with spurious signals, and sometimes the signal to be tested appears only for a moment. How to find the desired waveform segment among various spurious waveforms is a headache for engineers. Most of the more complex trigger functions provided by high-end oscilloscopes are triggered for a specific situation, but for some special signals, especially waveforms with special shapes, they often seem powerless. For example, find a specific phase jump in a PSK signal, find a slope-specific triangle wave in a series of sine-like wave trains, and so on.

Contents of the invention

Technical problem: the purpose of the present invention is to provide a conditional triggering method for an oscilloscope based on a finite state machine, which has strong versatility and specificity. Versatility lies in: users can arbitrarily set very complex trigger conditions for waveform triggering, and as long as they are set correctly, edge triggering, pulse width triggering, glitch triggering, timeout triggering, delay triggering, runt triggering, jump triggering, etc. Various complex trigger methods in modern oscilloscopes such as variable trigger; the specificity lies in that users can use this trigger method to filter out highly specific waveforms, such as specific amplitude, specific slope and specific time.

Technical solutions:

The conditional triggering method is based on a complex finite state machine with N+1 states. N in the above formula can be any integer greater than or equal to 1, indicating the programmable trigger waiting state of the programmable trigger machine; and "1" in the above formula is the "trigger enable" state, which is common to all trigger machines.

In this state machine, except the trigger enabling state, each state (that is, each programmable trigger waiting state) can jump to any other state. For the convenience of the device, "Con m:n" can be used to represent the programmable transfer condition from the m state to the n state. The total number of transition conditions is M, generally, $m={\mathrm{<figure-callout\; id="2"\; label="P\; N"\; filenames="A20051004073600101.png"\; state="\{\{state\}\}">P</figure-callout>}}_N^{}+1.$ Each condition can be selected from 4 preset conditions. The preset conditions include "automatic condition", "prohibited condition", "timeout condition" and "edge condition". Among them, the automatic condition means that this condition is always established, the edge condition means the condition that is established when a specific edge polarity of a specific level is met (the level and edge polarity are set by the user), and the timeout condition means that the condition is established after a specific time delay is met. Condition (the time is set by the user), the prohibition condition means that this condition will never be established.

The condition trigger method is: the user sets the number of stages of the state machine to n according to the complexity of the waveform, and n is an integer greater than or equal to 1; the system provides the user with four optional conditions, namely: ① automatic condition, ② edge condition, ③Timeout condition, ④Prohibition condition; Among them, the automatic condition means that the secondary condition is always true, the edge condition means the condition that is established when a specific edge polarity of a specific level is met, and the timeout condition refers to the condition that is established after a specific time delay is satisfied. Condition means that this condition will never be established; in order to achieve the correct trigger, the user needs to select each transition condition according to the shape of the waveform. The selection method of the condition is as follows:

a) If you want to make the condition always true, you can choose "automatic condition", which is generally used for the unconditional transfer of the judgment step;

b) If you want the condition to be true when the waveform reaches a specific level and meets a specific edge polarity, you can select "Edge Condition";

c) If you want the condition to be established after a specific time delay, you can choose "timeout condition";

d) If you want to make this condition never true, you can choose "prohibited condition";

The user uses one of the four conditions to be selected provided by the system by the waveform to be measured and the above-mentioned selection method as the condition i: j (i, j are natural numbers less than or equal to n and i≠j); conditional trigger Methods as below:

1) The system judges whether the conditions 1:2～1:n are true in turn, and once it finds that 1:i is true (2≤i≤n), it will jump to step i, otherwise, if all of them are not true, it will continue to stay in this step for judgment;

2) The system judges whether the conditions 2:1～2:n are true in turn, and once it finds that 2:i is true (1≤i≤n and i≠2), it will jump to step i, otherwise, if all of them are not true, it will continue to stay in this step make judgments;

3) The system judges whether the conditions 3:1～3:n are true in turn, and once it finds that 3:i is true (1≤i≤n and i≠3), it will jump to step i, otherwise, if all of them are not true, it will continue to stay in this step make judgments;

...

n-1) The system judges whether the conditions n-1:1～n-1:n are true in turn, and once it finds that n-1:i is true (1≤i≤n and i≠n-1), it will jump to step i , otherwise, if all are not established, continue to stay at this step for judgment;

n) The system sequentially judges whether the conditions n:1～n:n-1 are true, and once it finds that n:i is true (1≤i≤n-1), it will jump to step j, otherwise, if all of them are not true, it will jump to step n+1; n+1) The system judges whether the condition n:t is true, if it is true, it will jump to step n+2, otherwise if it is not true, it will jump to step n;

n+2) The system outputs a trigger enable signal;

n+3) end.

The automatic condition provided by the system means that this condition is always true; when the system runs to judge the condition, it should immediately jump to the step according to the jump method that the condition is true.

The edge condition provided by the system means that when the input waveform reaches a specific level and meets a specific edge polarity, this condition is established; the level should be set arbitrarily by the user between the maximum signal level and the minimum signal level, and the edge polarity The behavior should be selected by the user among "rising edge", "falling edge" and "both edge".

The timeout condition provided by the system means: start timing from the step of judging the condition until the end of a specific time; the condition is not established during the timing period, and the condition is established immediately after the timing stops after reaching a specific time; this time should be set by the user arbitrarily Certainly.

After the selection is completed, the trigger machine starts to work. The state of the state machine jumps as the input waveform changes. Once the state of the state machine jumps to the "trigger enable" state, it means that the input waveform fully meets the user's requirements. At this time, the trigger machine outputs a trigger enable signal to complete the conditional trigger.

Beneficial effects: as long as N is large enough, the trigger method can trigger almost any complex waveform. Engineering practice shows that when N=3 and P=7, it can already meet the application of most occasions.

With appropriate condition settings, this trigger method can also be equivalent to other trigger methods. For example, when Con1 and Con2 in attached drawing 2 are both "automatic", Con4 is edge trigger, and other conditions are prohibited, this trigger mode is equivalent to the edge trigger of an ordinary oscilloscope; when Con2 in attached drawing 2 is Timeout, Con1 and Con4 are edge triggers, and other conditions are prohibited, this trigger mode is equivalent to delayed trigger. Similarly, through the correct and ingenious condition setting of the trigger machine by the user, this trigger method can be equivalent to edge trigger, pulse width trigger, glitch trigger, timeout trigger, delay trigger, runt trigger, jump trigger, etc. in modern oscilloscopes. Various trigger methods.

Description of drawings

Fig. 1 is a schematic diagram of the principle of triggering a finite state machine in the present invention.

FIG. 2 is a schematic diagram of the principle of triggering a finite state machine when N=3.

Fig. 3 is a schematic diagram of the workflow of the present invention.

Fig. 4 is a specific implementation method of the present invention.

Detailed ways

The implementation of the present invention can be divided into two parts: the finite state machine and the condition generator. Wherein, the finite state machine can be realized by logic devices, including programmable logic array (Field Programmable GateArray, FPGA) or application-specific integrated circuit (ASIC), etc. very conveniently. The condition generator can be implemented by an analog-to-digital converter (ADC)+logic device or a level comparator+logic device.

In the oscilloscope conditional trigger method based on the finite state machine of the present invention, the conditional trigger method is:

The user sets the number of stages of the state machine to n according to the complexity of the waveform, and n is an integer greater than or equal to 1; the system provides the user with four optional conditions, namely: ① automatic condition, ② edge condition, ③ timeout condition, ④ Prohibition conditions; Among them, the automatic condition means that the secondary condition is always true, the edge condition means the condition that is true when a specific edge polarity of a specific level is met, the timeout condition means the condition that is true after a specific time delay is satisfied, and the prohibition condition means that this condition is always true. Not true; the selection method of the condition is as follows:

e) If you want to make the condition always true, you can choose "automatic condition", which is generally used for unconditional transfer of the judgment step;

f) If you want the condition to be true when the waveform reaches a specific level and meets a specific edge polarity, you can select "Edge Condition";

g) If you want to delay the condition for a specific time, you can choose "timeout condition";

h) If you want to make this condition never true, you can choose "prohibited condition";

The user uses one of the four conditions to be selected provided by the system by the waveform to be measured and the above-mentioned selection method as the condition i: j (i, j are natural numbers less than or equal to n and i≠j); conditional trigger Methods as below:

1) Systematically determine whether the conditions 1:2～1:n are established in turn, and once it is found that 1:i is established (2≤i≤n), then jump to step i, otherwise, if all of them are not established, continue to stay in this step for judgment;

2) The system judges whether the conditions 2:1～2:n are true in turn, and once it finds that 2:i is true (1≤i≤n and i≠2), it will jump to step i, otherwise, if all of them are not true, it will continue to stay in this step make judgments;

3) Determine whether the conditions 3: 1 ~ 3: n are true in turn. Once 3: i is found to be true (1 ≤ i ≤ n and i ≠ 3), then jump to step i, otherwise, if all are not true, continue to stay in this step judge;

...

n-1) The system judges whether the conditions n-1:1～n-1:n are true in turn, and once it finds that n-1:i is true (1≤i≤n and i≠n-1), it will jump to step i , otherwise, if all are not established, continue to stay at this step for judgment;

n) The system sequentially judges whether the conditions n:1～n:n-1 are true, and once it finds that n:i is true (1≤i≤n-1), it will jump to step i, otherwise, if all of them are not true, it will jump to step n+1; n+1) The system judges whether the condition n:t is true, if it is true, it will jump to step n+2, otherwise if it is not true, it will jump to step n;

n+2) The system outputs a trigger enable signal;

n+3) end.

The automatic condition provided by the system means that this condition is always true; when the system runs to judge the condition, it should immediately jump to the step according to the jump method that the condition is true.

The edge condition provided by the system means that when the input waveform reaches a specific level and meets a specific edge polarity, this condition is established; the level should be set arbitrarily by the user between the maximum signal level and the minimum signal level, and the edge polarity The behavior should be selected by the user among "rising edge", "falling edge" and "both edge".

The timeout condition provided by the system means: start timing from the step of judging the condition until the end of a specific time; the condition is not established during the timing period, and the condition is established immediately after the timing stops after reaching a specific time; this time should be set by the user arbitrarily Certainly.

Accompanying drawing 6 is an embodiment of this method when P=7. In the figure, DA is a digital-to-analog converter. Level comparator + digital-to-analog converter constitutes a complete edge comparator used to generate the required edge trigger conditions. This condition and the overtime, automatic, prohibition and other conditions generated by the FPGA internal algorithm are selected and sent to the finite state machine in the FPGA. The finite state machine completes the final trigger task. The advantage of this method is that it has a relatively fast real-time edge comparison capability and a high overall operating speed.

Claims (4)

1, a kind of oscilloscope condition triggering method based on finite state machine is characterized in that condition triggering method is: the user is n according to the progression that the complexity of waveform is provided with state machine, n be one more than or equal to 1 integer; System provides four kinds of optional conditioies to the user, is respectively: 1. automatically condition, 2. edge condition, 3. overtime condition, 4. disable condition; Wherein, automatically condition refers to that time condition sets up forever, and the edge condition refers to satisfy the condition that the certain edges thereof of particular level is set up along polarity chron, and overtime condition refers to satisfy the condition of setting up after the specific time of time-delay, and disable condition refers to that this condition never sets up; The system of selection of condition is as follows:

I) if want to make this condition to set up forever, can select " condition automatically ", this condition generally is used for the unconditional transfer of determining step;

J) if want that condition is set up when waveform reaches specific level and meets specific edge polarity, can select " edge condition ";

K) if the special time postcondition of wanting to delay time is set up, can select " overtime condition ";

L) if want to make this condition never to set up, can select " disable condition ";

(i, j are the natural number that is less than or equal to n and i ≠ j) to the user as condition i: j by one in four conditions to be selected that system provided by waveform to be measured and above-described system of selection;

Condition triggering method is as follows:

1) Rule of judgment 1: 2～1 successively of uniting: whether n sets up, in case find 1: i set up (2≤i≤n), then jump to step I, this step that then stays on of all being false is else if judged;

2) system's Rule of judgment 2: 1～2 successively: whether n sets up, in case find 2: i sets up (1≤i≤ni ≠ 2), then jumps to step I, and this step that then stays on of all being false is else if judged;

3) system's Rule of judgment 3: 1～3 successively: whether n sets up, in case find 3: i sets up (1≤i≤n and i ≠ 3), then jumps to step I, and this step that then stays on of all being false is else if judged;

……

N-1) system successively Rule of judgment n-1: 1～n-1: n whether set up, in case find n-1: i set up (1≤i≤n and i ≠ n-1), then jump to step I, this step that then stays on of all being false is else if judged;

N) system successively Rule of judgment n: 1～n: n-1 whether set up, in case find n: i set up (1≤i≤n-1), then jump to step I, all being false else if then jumps to step n+1; N+1) whether system's Rule of judgment n: t sets up, if set up then jump to step n+2, all being false else if then jumps to step n;

N+2) system's output triggers enable signal;

N+3) finish.

2. the oscilloscope condition triggering method based on finite state machine according to claim 1 is characterized in that: the automatic condition that system provides refers to that this condition is set up forever; System runs to the jump method that should set up according to condition immediately when judging this condition and carries out the redirect of step.

3. the oscilloscope condition triggering method based on finite state machine according to claim 1 is characterized in that: the edge condition that system provides refers to, reaches particular level and satisfies specific edge polarity chron when importing waveform, and this condition is set up; Its level should be set arbitrarily in maximum signal level and minimum signal level by the user, and edge polarity should be selected in " rising edge ", " negative edge " and " two edge " by the user.

4. the oscilloscope condition triggering method based on finite state machine according to claim 1 is characterized in that: the overtime condition that system provides refers to: pick up counting from entering the step of judging this condition, finish timing up to the specific time; This condition is false during the timing, and this condition is set up immediately after reaching the special time timing and stopping; This time should be set arbitrarily by the user.

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