Signal eye pattern detection method applied to high-speed transmission system

Abstract

The invention discloses a signal eye pattern detection method applied to a high-speed transmission system, and belongs to the field of communication. In the chip, according to a state value which is returned by a signal level monitoring circuit and meets the expectation or not, a scanning algorithm is superposed, and finally, the longitudinal high-low position of an eye pattern is output; and transverse eye width boundary data can be obtained in the same way. In the invention, a counter can be selected as a data form for describing the high-low position of the eye height and the left-right boundary of the eye width. Compared with a traditional mode that an oscilloscope is used for observing the quality of the eye diagram, the method provided by the invention does not need an additional oscilloscope, and the eye diagram quality data can be observed in real time in the ASIC; the scanning algorithm provided by the invention is simple to implement, eye pattern quality data is easy to obtain, real-time data reference can be better provided for the system, and execution of system-level behaviors is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a method for detecting a signal eye diagram applied to a high-speed transmission system. Background Art

[0002] The eye diagram is a waveform obtained by superimposing multiple bits of data according to a certain reference point. It is usually observed by inserting a probe into the transmission line of a high-speed link with the help of an external oscilloscope. The signal eye diagram reflects the quality of the signal in the analog circuit and channel transmission process, and provides an intuitive means for observing signal quality. Through the signal eye diagram, basic level parameters such as the rise and fall time of the signal and the threshold level can be observed.

[0003] Generally, we call the vertical axis direction in the blank area of ​​the signal eye diagram the eye height, and the horizontal axis direction the eye width. Due to the differences in the high and low level values, rise time and fall time of different signals, the signal line of the eye diagram tends to become thicker as the number of signal superposition increases. In the system, the eye height can well reflect the noise tolerance of the signal on the transmission line, and the eye width can well reflect the jitter parameters of the signal in the time domain.

[0004] In the current advanced high-speed signal transmission systems, such as MIPI A-PHY, the traditional signal eye diagram detection method has the disadvantages of poor portability, complex operation, and the need for additional equipment and tools, and cannot meet the requirements of fast and accurate data detection in various protocols. Therefore, it is necessary to develop a new signal eye diagram detection method to solve this technical problem. Summary of the invention

[0005] The object of the present invention is to provide a method for detecting a signal eye diagram applied to a high-speed transmission system, so as to solve the problems in the background technology.

[0006] In order to solve the above technical problems, the present invention provides a method for detecting a signal eye diagram applied to a high-speed transmission system, comprising: At a preset reference point inside the chip, the signal level monitoring circuit returns the expected state value, and through the scanning algorithm, the vertical / horizontal high and low positions of the signal eye diagram are finally output; The preset reference point is determined by the clock recovery circuit, and the determination method includes moving the clock one in a stepping manner, obtaining the center point of two data change edges and fixing the position of the clock one, and the center point is the reference point; Within a certain period of time, at a certain reference point, the signal level monitoring circuit counts the number of signals in each level step interval one by one, records it and returns it to the signal eye diagram detection circuit.

[0007] In one embodiment, the scanning method includes: dividing a preset vertical coordinate or horizontal coordinate into a plurality of unit intervals according to the level amplitude of the signal, and recording the number of unit intervals as N; In a certain period of time, the signals whose signal level amplitude is within a predetermined interval are counted, which is recorded as sat_cnt; the signal eye diagram detection scanning circuit is responsible for receiving the expected number of signals in each interval; In the signal eye diagram detection circuit, it is determined whether sat_cnt is within the threshold threshold_B range. If sat_cnt is greater than threshold_B, the counter eye_cnt recording the eye height or eye width position is accumulated, otherwise eye_cnt maintains the original value. After the above process is completed for N intervals, exit the scanning algorithm process.

[0008] In one implementation, the value of the threshold threshold_B is 0.

[0009] In one embodiment, the state machine of the scanning method includes: In the initial state, the initialization configuration before the signal eye diagram scanning is performed. When it is detected for the first time that sat_cnt is greater than the set threshold threshold_B, the initial state is jumped out and the process of scanning the upper boundary of the eye height or the left boundary of the eye width is entered; In this state, eye_cnt that records the boundary position will begin to accumulate. Each time the scanning algorithm cycles, the counter eye_y0 will accumulate 1 until the condition that sat_cnt is greater than the preset threshold threshold_B is no longer met, and the state machine enters the next state; In the state of determining the signal eye width range, the counter eye_y1 will be accumulated; each time the scanning algorithm cycles, eye_y1 will be accumulated by 1 until the condition that sat_cnt is less than the preset threshold threshold_B is no longer met, eye_y1 stops accumulating and enters the next state; In the state of determining the lower boundary of the signal eye diagram, the execution process is consistent with the above. When the scan row and column counter values ​​meet the preset threshold threshold_A, the scanning algorithm ends and returns to the initial state; then the clock two is moved in a step-by-step manner to depict the rise time and fall time parameters of the signal eye diagram.

[0010] In one implementation, to prevent interference from causing the state machine to enter the next state prematurely, the state machine is controlled to enter the next state only when the condition that M sat_cnt values ​​are continuously detected to be less than a preset threshold threshold_B is met, where M≥4.

[0011] The present invention provides a method for detecting a signal eye diagram applied to a high-speed transmission system, which has the following beneficial effects: (1) Compared with the traditional method of using an oscilloscope to observe the eye diagram quality, the method provided by the present invention does not require an additional oscilloscope and can observe the signal quality data in real time inside the ASIC; (2) The scanning algorithm provided by the present invention is simple to implement and the signal quality data is easy to obtain. It can provide a good real-time data reference for the system and is conducive to the execution of system-level behavior. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of the signal eye diagram detection module provided by the present invention in the A-PHY system.

[0013] Figure 2 It is a schematic diagram of a state machine of a control scanning algorithm provided by the present invention.

[0014] Figure 3 It is a schematic diagram of the execution flow of a scanning algorithm provided by the present invention.

[0015] Figure 4 It is a schematic diagram of the corresponding positions of the output data of a scanning algorithm and a signal eye diagram provided by the present invention.

[0016] Figure 5 It is a schematic diagram of obtaining signal changes along the center point provided by the present invention.

[0017] Figure 6 It is a schematic diagram of a signal level interval and a clock stepping interval provided by the present invention. DETAILED DESCRIPTION

[0018] The following is a further detailed description of a signal eye diagram detection method for a high-speed transmission system proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0019] The present invention proposes an eye diagram detection algorithm applied in a high-speed transmission system, which can detect the quality of the eye diagram in real time inside the high-speed transmission system and make some system-level decisions based on the quality of the eye diagram. The present invention is described in detail below using the A-PHY system as an example. It is worth noting that the application scenarios of the present invention include but are not limited to the A-PHY system.

[0020] like Figure 1As shown, the high-speed data is recovered by the clock recovery circuit (CDR, Clock Data Recovery) to recover the clock embedded in the data, and the high-speed data is collected using this clock. The clock and data are transmitted together to the signal level monitoring circuit, and the detectable level amplitude is divided into several unit intervals, namely step intervals, and the number of unit intervals is recorded as N. Also refer to Figure 1 and Figure 5 In the signal level monitoring circuit, the clock recovered by CDR is used to find the center point of two signal change edges in a step-by-step manner as the reference point for signal eye height detection and fix the position of clock 1. At this reference point phase, within a certain period of time, the signal level amplitude is counted within a predetermined interval, recorded as sat_cnt. The eye diagram detection scanning circuit is responsible for receiving the expected number of signals in each interval transmitted from the A-PHY signal level monitoring circuit, which is the expected state value.

[0021] exist Figure 2 In the process, after the signal eye diagram detection circuit receives the expected number of signals in each interval transmitted by the A-PHY PMA, it determines whether sat_cnt is within the threshold threshold_B. If sat_cnt is greater than threshold_B, the counter eye_cnt recording the eye height or eye width position is accumulated, otherwise eye_cnt keeps the original value. After the above process is completed for N intervals, the scanning algorithm process can be exited. Among them, the threshold refers to threshold_B, and the value of threshold_B is 0.

[0022] Figure 3 The state machine that controls the scanning algorithm is shown in the figure. In the initial state, some initialization configurations are performed on the A-PHY clock recovery analog circuit before the signal eye diagram is scanned. When it is detected for the first time that sat_cnt is greater than the set threshold threshold_B, the initial state is jumped out and the process of scanning the upper boundary of the eye height or the left boundary of the eye width is entered.

[0023] Taking the process of scanning the upper boundary of the eye height as an example, in this state, the eye_cnt that records the boundary position will begin to accumulate. Figure 2 Each time the scanning algorithm in the loop is cycled, the counter eye_y0 will accumulate 1 until the condition that sat_cnt is greater than the preset threshold threshold_B is no longer met, and the state machine enters the next state. Among them, eye_cnt is understood as the general term for the counters that record the signal eye height and eye width, that is, eye_cnt includes eye_y0 / 1 / 2, eye_x0 / 1 / 2. Figure 4In the eye diagram shown, eye_y0, eye_y1 and eye_y2 are counters that record the relative positions of the signal eye heights. In the range of 0 to eye_y0, sat_cnt is greater than a preset threshold value threshold_B. Optionally, the value of threshold_B is 0. In the range of eye_y0 to eye_y1, the value of sat_cnt is less than or equal to the preset threshold value threshold_B. In the range of eye_y1 to eye_y2, the value of sat_cnt is greater than the preset threshold value threshold_B. Figure 3 The calculation is performed in the three state processes of determining the upper boundary of the signal eye diagram, determining the range of the signal eye diagram, and determining the lower boundary of the signal eye diagram in the state machine shown. Figure 4 The same can be said for eye_x0, eye_x1 and eye_x2.

[0024] After scanning the number of signals falling within the previously divided unit level intervals one by one and recording them through the counter, Figure 3 Under the control of the state machine shown, the signal quantity in each interval is compared to see if it meets the quality requirements, and the Figure 4 The eye height position diagram of eye_y0, eye_y1 and eye_y2 is shown. eye_y0 and eye_y2 represent the fluctuation of the signal voltage value swept at a fixed clock phase over a period of time, which indicates the noise tolerance of the signal on the transmission line. eye_y1 represents the opening size of the signal in the vertical direction. The ratio of eye_y0, eye_y2 and eye_y1 reflects the signal-to-noise ratio. eye_x0 and eye_x2 represent the jitter of the signal phase swept at a fixed level over a period of time, that is, the short-term deviation of the signal from its ideal position at a specific moment. eye_x1 represents the opening size of the signal in the horizontal direction, which reflects the bit period of the signal, that is, UI (Unit Interval). Then, by moving clock 2 in a step-by-step manner, the rise time and fall time parameters of the signal eye diagram are depicted, that is, Figure 4 The rising and falling sections of the sine wave of the signal are shown.

[0025] Figure 5 A method for determining the center point of the signal change edge is shown, that is, by moving clock 1 until the left and right boundaries of the signal change are obtained, the center point position of the signal change can be obtained; Figure 6 The relationship between clock 1, clock 2 and the signal bit period is shown. The rising and falling segments of the signal eye diagram can be obtained by moving clock 2 in a stepwise manner.

[0026] The present invention adopts double loop discrimination, that is, Figure 3 Under the control of the state machine shown, within a certain period of time, the signal swept in each unit level interval in the phase step interval of clock 2 is counted and compared with the signal quality threshold parameter, thereby obtaining Figure 4 The signal eye diagram shown includes eye height, eye width, signal noise tolerance, and signal time domain jitter parameters.

[0027] In particular, additional protection needs to be set here. To prevent interference from causing the state machine to enter the next state prematurely, the state machine will be controlled to enter the next state only when the condition that M sat_cnt values ​​are continuously detected to be less than the preset threshold threshold_B is met. In this embodiment, the value of M is 4.

[0028] In the state of determining the eye range, the counter eye_y1 is accumulated. Figure 2 Each time the scanning algorithm is cycled, eye_y1 will accumulate 1 until the condition that sat_cnt is less than the preset threshold threshold_B is no longer met, and eye_y1 stops accumulating. Figure 3 The state machine in enters the next state.

[0029] In the state of determining the lower boundary of the eye diagram, the execution process is the same as above. Figure 2 When the scan row and column counter values ​​in meet the preset threshold threshold_A, the scanning algorithm ends. Figure 3 The state machine shown returns to the initial state.

[0030] The present invention provides an eye diagram detection method for a high-speed transmission system. In the chip, the signal level monitoring circuit returns a state value that meets the expected state value at a preset reference point, and the scanning algorithm of the present invention is superimposed to finally output the vertical high and low positions of the eye diagram; and the horizontal eye width boundary data can be obtained in the same way. In the present invention, a counter can be selected as the data form to describe the high and low positions of the eye height and the left and right boundaries of the eye width. Without the help of an external oscilloscope, the performance parameters reflecting the signal quality are calculated in a simple and convenient manner, and the parameters are easy to obtain.

[0031] The detection method provided by the present invention can divide the voltage amplitude into N unit intervals from high to low in a preset vertical coordinate (eye height scan) or horizontal coordinate (eye width scan), taking the eye height scan as an example, and for the N unit intervals, the signal state value of this interval returned by the eye diagram detection circuit is judged one by one whether it meets expectations. If it does not meet expectations, counter 0 accumulates; otherwise, counter 0 stops counting and counter 1 starts counting until a unit interval that does not meet expectations appears again, counter 1 stops working, and counter 2 starts working until the number of intervals reaches N. The scanning process of the eye width is the same. The signal state value of this interval returned by the eye diagram detection circuit includes but is not limited to the number of signals whose level assignment is within this interval within a certain period of time.

[0032] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A method for detecting a signal eye diagram in a high-speed transmission system, characterized in that: include: At a preset reference point inside the chip, according to the expected state value returned by the signal level monitoring circuit, the vertical / horizontal high and low positions of the signal eye diagram are finally output through a scanning method; The preset reference point is determined by the clock recovery circuit, and the determination method includes moving the clock one in a stepping manner, obtaining the center point of two data change edges and fixing the position of the clock one, and the center point is the reference point; Within a certain period of time, at a certain reference point, the signal level monitoring circuit counts the number of signals in each level step interval one by one, records it and returns it to the signal eye diagram detection circuit.

2. The signal eye diagram detection method for a high-speed transmission system according to claim 1, characterized in that: The scanning method comprises: dividing a preset ordinate or abscissa into a plurality of unit intervals according to the level amplitude of the signal, and recording the number of the unit intervals as N; In a certain period of time, the signals whose signal level amplitude is within a predetermined interval are counted, which is recorded as sat_cnt; the signal eye diagram detection scanning circuit is responsible for receiving the expected number of signals in each interval; The signal eye quality is judged inside the signal eye diagram detection circuit, that is, whether sat_cnt is within the threshold threshold_B range. If sat_cnt is greater than threshold_B, the counter eye_cnt that records the eye height or eye width position is accumulated, otherwise eye_cnt keeps the original value. After the above process is completed for N intervals, exit the scanning algorithm process.

3. The signal eye diagram detection method applied to a high-speed transmission system as claimed in claim 2, characterized in that: The value of the threshold threshold_B is 0.

4. The signal eye diagram detection method for a high-speed transmission system as claimed in claim 2, characterized in that: The state machine of the scanning method comprises: In the initial state, the initialization configuration before the signal eye diagram scanning is performed. When the sat_cnt is detected to be greater than the set threshold threshold_B for the first time, the initial state is jumped out and the process of scanning the upper boundary of the signal eye height or the left boundary of the signal eye width is entered; In this state, eye_cnt that records the boundary position will begin to accumulate. Each time the scanning algorithm cycles, the counter eye_y0 will accumulate 1 until the condition that sat_cnt is greater than the preset threshold threshold_B is no longer met, and the state machine enters the next state; In the state of determining the signal eye width range, the counter eye_y1 will be accumulated; each time the scanning algorithm cycles, eye_y1 will be accumulated by 1 until the condition that sat_cnt is less than the preset threshold threshold_B is no longer met, eye_y1 stops accumulating and enters the next state; In the state of determining the lower boundary of the signal eye diagram, the execution process is consistent with the above. When the scan row and column counter values ​​meet the preset threshold threshold_A, the scanning algorithm ends and returns to the initial state; then the clock two is moved in a step-by-step manner to depict the rise time and fall time parameters of the signal eye diagram.

5. The signal eye diagram detection method for a high-speed transmission system as claimed in claim 4, characterized in that: To prevent interference from causing the state machine to enter the next state prematurely, the state machine will be controlled to enter the next state only when the condition that M sat_cnt values ​​are continuously detected to be less than the preset threshold threshold_B is met, M≥4.

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