JP3509757B2 - High-speed serial transmission method and method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed serial transmission method and system, and more particularly to a high-speed serial transmission method and system for feeding back the state of a transmission path from a receiving side to a transmitting side to eliminate transmission errors as much as possible.

[0002]

2. Description of the Related Art In a conventional serial transmission system between a transmitting side device and a receiving side device, for example, Japanese Patent Laid-Open No.
In the "Serial transmission method" of Japanese Patent No. 57647, the receiving side monitors the data transmitted from the transmitting side through the transmission line, notifies the transmitting side of information on whether the received data is normal or abnormal, and the transmitting side is normal. When the information notification is received, the next data is sent as it is, but when the abnormality information notification is received, the sending of the next data is stopped and the error processing is performed.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the "serial transmission method" of Japanese Patent Application Laid-Open No. 157647-, the information on whether the received data from the receiving side is normal or abnormal can be notified to the transmitting side, but if the transmitting side receives the notification of abnormal information, It is not possible to set the transmission side corresponding to the transmission line by measuring the amplitude of the reception waveform or measuring the bit error rate on the reception side simply by stopping the data transmission and performing error processing. It was not possible to reduce the transmission error due to the operation of correcting the characteristics of.

Therefore, in the present invention, in high-speed serial transmission, the waveform may be distorted on the receiving side depending on the state of the transmission line (for example, when the transmission line is very long or when the impedance matching of the transmission line is poor). As a result, the eye pattern may be crushed and cause a transmission error. By measuring the state of the transmission line on the receiving side and feeding it back to the transmitting side, data can be transmitted using the transmission conditions that match the transmission line. The purpose is to eliminate transmission errors as much as possible.

[0005]

A high-speed serial transmission method according to the present invention is a high-speed serial transmission method for serially transmitting data from a transmission side to a reception side through a transmission line,
The pseudo random pattern is transmitted from the transmitting side through the transmission line, and the pseudo random pattern of the pseudo random pattern is transmitted at the receiving side .
The amplitude of the received waveform and the bit error rate are measured, and the amplitude is low.
Or if there are many bit errors, increase the current.
The current increase control signal for controlling
If the width is large or there are no bit errors, the current
Current reduction control signal for controlling the
The transmitter side returns the current increase control signal or the power
The pseudo random pattern is transmitted in accordance with the current reduction control signal.
The output current is increased / decreased and sent out.
The amplitude and bit error rate of the received waveform of the random pattern
If the amplitude or bit error is not improved by measuring
Is a clock frequency that controls to reduce the transmission speed.
The reduction control signal is returned to the transmission side, and the transmission side and the
The receiving side simultaneously responds to the clock frequency reduction control signal.
And reduce its own clock frequency.
To do.

The high-speed serial transmission system according to the present invention
Serial transmission of data from the transmitting side to the receiving side through the transmission path
In the high-speed serial transmission method,
LVTTL level parallel signal with similar random pattern
And a pseudo random pattern
LVTTL level transmission input for parallel or parallel signals
The data is synchronized with the transmission clock, and the LVDS level
Converted to serial data and transmitted as output data
Output to the road and serial of the LVDS level
Control the current of the data to adjust the level of the transmission output data
Alternatively, the transmission clock frequency can be controlled to control the transmission rate.
Changing transmission means and feedback system from the receiving side
Control signal or transmission clock control signal or current control signal
And a transmission control means for outputting
Of the LVDS level of the transmitting means by the flow control signal.
Current control means for controlling the current driving the aldata,
It is controlled by the transmission clock control signal from the transmission control means.
The transmission clock frequency of the serial data of the transmission means
Transmission clock variable means for varying the number,
The receiving side is sent from the transmitting unit through the transmission line.
The transmission output data is input as the reception input data and the LV
It is converted back to parallel data of TTL level and received
The received output data is output in synchronization with the
The receiving means for extracting random patterns and the receiving means
Measure the bit error rate of the extracted pseudo random pattern
And a bit error rate measuring means for
Reception level that detects the reception level of the pseudo random pattern
Bell detection means and pseudo-lander extracted by the reception means
The transmit clock is detected from the
Bit error rate measured by the bit error rate measuring means and
Based on the reception level detected by the reception level detection means,
The characteristic information of the transmission line is output and the transmission control of the transmission unit is performed.
To the means such as clock control signal or current control signal
Feedback control that feeds back a feedback control signal
And the transmission clock detected by the reception control means.
Reception clock generation means for generating reception clock in anticipation
And are provided.

[0007]

[0008]

[0009]

[0010]

[0011]

[0012]

[0013]

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to the drawings.

According to the block diagram of FIG. 1 showing an embodiment of the present invention, in the high-speed serial transmission system, a pattern generation unit 10 for generating a pseudo random pattern with a parallel signal of LVTTL level and an LVTTL level of parallel signal. Input data and the pseudo random pattern from the pattern generation unit 10 are synchronized with the transmission clock to obtain the LVD.
The data is converted into S level serial data and output as transmission output data to the transmission line 3, and the current of the LVDS level serial data is controlled to adjust the level of the transmission output data or control the transmission clock frequency to vary the transmission rate. Transmission circuit section 11, a transmission control section 14 that outputs a transmission clock control signal and a current control signal according to a feedback control signal from the receiving side, and a transmission control section 14
The current control circuit 12 controls the current for driving the serial data of the LVDS level of the transmission circuit unit 11 by the current control signal from the transmission circuit unit 11, and the serial data of the transmission circuit unit 11 controlled by the transmission clock control signal from the transmission control unit 14. And a transmission clock circuit 13 for varying the transmission clock frequency of the transmission signal; transmission output data transmitted from the transmission unit 1 through the transmission line 3 is input as reception input data and inversely converted into parallel data of LVTTL level. A receiving circuit unit 20 that outputs received output data in synchronization with a receiving clock and extracts a pseudo random pattern, and a bit error rate measuring unit 22 that measures a bit error rate of the pseudo random pattern extracted by the receiving circuit unit 20. , A reception level for detecting the reception level of the pseudo random pattern extracted by the reception circuit section 20. The transmission clock is detected from the pseudo random pattern extracted by the receiver detection unit 21 and the reception circuit unit 20, and transmission is performed based on the bit error rate measured by the bit error rate measurement unit 22 and the reception level detected by the reception level detection unit 21. A reception control unit 23 that outputs characteristic information of the path 3 and feeds it back to the transmission control circuit unit 14 of the transmission unit 1.
And a reception clock circuit 24 that generates a reception clock in synchronization with the transmission clock detected by the reception control unit 23.

More specifically, the transmission input data is LVTTL.
(Low Voltage Transistor T
It is input to the transmission circuit unit 11 as a parallel signal of the transfer level. Similarly, the pseudo random pattern data generated by the pattern generation unit 10 is also input to the transmission circuit unit 11 as an LVTTL level parallel signal. Here, when the pseudo random pattern is input to the transmission circuit unit 11, the transmission input data is not input to the transmission circuit unit 11. On the contrary, when the transmission input data is input, the pseudo random pattern is not input. That is, input data is switched on the input side of the transmission circuit unit 11.

Then, the transmission circuit section 11 performs parallel / serial conversion on these parallel signals to obtain LVDS (Low).
Voltage Differential Sig
The transmission output data is sent to the receiving unit 2 by a serial signal of (nal) level.

In order to correct the characteristic state of the transmission line 3 by adjusting the transmission level, the transmission circuit section 11 controls the current control circuit 12 to output a serial signal of the LVTTL level as the change point drive current of the data. Control.

Further, the transmission circuit section 11 controls the characteristic state of the transmission line 3 by the control of the transmission clock circuit 13.
This is done by changing the transmission rate of the serial signal.

The transmission output data of the serial signal transmitted from the transmission unit 1 is input to the reception circuit unit 20 of the reception unit 2 as reception input data. The receiving circuit unit 20 converts the input LVDS level serial signal into an LVTTL level parallel signal. When the reception input data corresponds to the transmission input data, the reception circuit section 20 outputs the parallel-converted data as the reception output data,
It is not output to the reception level detection unit 21 and the bit error measurement unit 22.

At the time of initial operation when the system is started up
When the received input data needs to be corrected (such as when the power is turned on) or when the transmission line is changed, the transmitter 1 sends a pseudo random pattern, and the receiver circuit 20 extracts the pseudo random pattern. Reception level detector 21
Then, the reception level is detected and the bit error measuring section 22 measures the bit error rate. In this case, the receiving circuit unit 20
Do not output the pseudo random pattern to the output side of the received output data.

The reception control unit 23 determines how to control the transmission unit 1 based on the measurement result of the bit error rate and the detection result of the reception level, and feeds back the information to the transmission control unit 14. To do.

The transmission line 3 connecting the transmission unit 1 and the reception unit 2 is a printed circuit board backboard using a wiring pattern with impedance matching, a shielded twisted pair cable, or a coaxial cable. Intended.

Next, the operation will be described.

In the receiving section 2, the initial operation and the transmission line 3 are performed first.
When the state of is changed, the reception error rate is measured to measure the state of the transmission line 3. In this, a pseudo random pattern such as a PN (Pseudo Noise) pattern is generated by the pattern generation unit 4 of the transmission unit 1 and is input to the transmission circuit unit 11 instead of the transmission input data. At this time,
Normal transmission input data should not be input to the transmission circuit 11. The pseudo random pattern input to the transmission circuit unit 11 is converted into an LVDS-level serial signal and sent to the reception unit 2. In the reception circuit unit 20, the LVDS-level serial signal is serial-to-parallel converted to receive output data. The output is not output as, but is output to the reception level detection unit 21 and the bit error measurement unit 22. The reception level detection unit 21 measures the amplitude of the reception waveform and controls the reception control unit 23 so that the amplitude falls within a specified value. The control method is as follows.

That is, when the system starts up, the reception level is measured by setting a predetermined initial value. As a result, when the amplitude of the reception waveform is small, the current control circuit 12 of the transmitter 1 controls the current. Conduct the current flowing in the LVDS level serial signal only at the data change points.
Control to increase only at the time of rising and falling. This is because the waveform is blunted by the resistance component of the transmission line to compensate for it. On the contrary, when the amplitude is large, the current is controlled to be reduced, but the minimum is set to the default value. On the other hand, in the bit error measuring unit 22, when there are many bit errors in the initial value state, the current control circuit 12 controls the current by the same method as described above to increase the current flowing through the LVDS. On the contrary, if there is no bit error,
Control to reduce the current, but set the minimum to the default value.

Here, the transmission control unit 14 of the transmission unit 1 and the reception control unit 23 of the reception unit 2 are connected by a control line, and the feedback control information on this control line is "whether the current is increased or decreased. It is information such as "whether the clock frequency is increased or decreased" or "whether it is in the initial state".

When the above control exceeds the variable range, an alarm may be given to inform that the control is impossible.

Further, even if the above-mentioned control is carried out, if the transmission error continues to occur on the receiving side (if control is impossible), the transmission speed of the transmitting side serial data may be reduced depending on the use condition. I do.

That is, the transmission clock circuit 13 of the transmission unit 1
Also, control is performed to simultaneously decrease the clock frequency of the output of the reception clock circuit 24 of the reception unit 2. That is, when the clock frequency is lowered, there is a margin in operation timing, so that the lower the clock frequency is, the less likely the reception error is to occur. However, also in this case, it is possible to determine the variable range of the clock frequency in advance and, when exceeding the variable range, generate an alarm to inform that the control is impossible.

[0031]

The first effect is that the transmission side transmission parameters such as the transmission output level and the transmission rate can be varied according to the state of the transmission line, so that the transmission error can be reduced even if the state of the transmission line is bad. The received data can be automatically maintained in the optimum state.

The second effect is that when there is an abnormality in the transmission line, the control becomes uncontrollable and an alarm can be output, so that the abnormality in the transmission line can be notified.

The third effect is that the transmission side transmission parameters such as the transmission output level and the transmission rate are simply changed according to the state of the transmission line, so that a special circuit for error correction or the like is not required and the system can be simplified. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a high-speed serial transmission system according to an embodiment of the present invention.

[Explanation of symbols]

1 transmitter 2 Receiver 3 transmission lines 11 Transmitting circuit section 10 pattern generator 12 Current control circuit 13 Transmit clock circuit 14 Transmission control unit 20 Receiver circuit 21 Reception level detector 22-bit error measurement unit 23 Reception control unit 24 Receive clock circuit

Claims (2)

(57) [Claims] 1. A high-speed serial transmission method for serially transmitting data from a transmission side to a reception side through a transmission line,
The pseudo random pattern is transmitted from the transmitting side through the transmission line, and the pseudo random pattern of the pseudo random pattern is transmitted at the receiving side .
The amplitude of the received waveform and the bit error rate are measured, and the amplitude is low.
Or if there are many bit errors, increase the current.
The current increase control signal for controlling
If the width is large or there are no bit errors, the current
Current reduction control signal for controlling the
The transmitter side returns the current increase control signal or the power
The pseudo random pattern is transmitted in accordance with the current reduction control signal.
The output current is increased / decreased and sent out.
The amplitude and bit error rate of the received waveform of the random pattern
If the amplitude or bit error is not improved by measuring
Is a clock frequency that controls to reduce the transmission speed.
The reduction control signal is returned to the transmission side, and the transmission side and the
The receiving side simultaneously responds to the clock frequency reduction control signal.
And reduce its own clock frequency, a high-speed serial transmission method. 2. Data is transmitted from a transmitting side to a receiving side through a transmission line.
In a high-speed serial transmission system that serially transmits data
The transmitting side sends a pseudo random pattern to the LVTTL level.
Pattern generating means for generating parallel signals of
LVTTL of pseudo-random pattern or parallel signal
Level transmit input data in sync with the transmit clock
Converted to LVDS level serial data and transmitted output data
Output to the transmission line as a data
Controls the level serial data current to transmit output data.
Adjust the level of the transmitter or control the transmit clock frequency.
Transmission means for varying the transmission rate by
Transmit clock control signal or feedback control signal
Or a transmission control means for outputting a current control signal, and the transmission
LV of the transmission means according to a current control signal from the control means
Controls the current driving the DS level serial data
Current control means and transmission clock from the transmission control means
Of the serial data of the transmitting means controlled by the control signal
Transmission clock variable means for varying the transmission clock frequency
And the receiving side is configured to connect the transmission line from the transmission unit to the transmission line.
The transmission output data sent through
Input and then converted back to LVTTL level parallel data
Converts and outputs the receive output data in synchronization with the receive clock
And receiving means for extracting a pseudo-random pattern
Of the pseudo-random pattern extracted by the receiving means
A bit error rate measuring means for measuring a bit error rate;
The reception level of the pseudo-random pattern extracted by the receiving means
Receiver level detection means for detecting
Detect the transmission clock from the issued pseudo-random pattern
The bit measured by the bit error rate measuring means.
Error rate and reception detected by the reception level detection means
Based on the level, the characteristic information of the transmission line is output and transmitted.
A transmission clock control signal to the transmission control means of the receiver or
Feed back feedback control signal such as current control signal
And the reception control means that is detected by the reception control means.
Receive clock that generates a receive clock in synchronization with the transmitted clock
High-speed characterized by comprising a clock generation means
Serial transmission method.