JP2019165433A - Bidirectional transmission system, serializer circuit, deserializer circuit, and automobile - Google Patents

Abstract

To provide a bidirectional transmission system which can automatically optimize the operation parameter of a circuit.SOLUTION: A first receiver 204 receives second serial data D2S transmitted from a second circuit 300. A second receiver 302 receives first serial data D1S transmitted from a first circuit 200. An automatic adjustment circuit 304 generates a control signal CTRL1 so that an error rate of the first serial data D1S received by the second receiver 302 is reduced. A second driver 306 drives a differential transmission line 102 according to the second serial data D2S which includes the control signal CTRL1. The operation parameter of the first driver 202 is set on the basis of the control signal CTRL1 included in the second serial data D2S.SELECTED DRAWING: Figure 1

Description

  The present invention relates to bidirectional transmission.

  In order to transmit data at high speed between a plurality of semiconductor devices, a differential serial interface is widely used. In particular, in clockless transmission employing a CDR (Clock Data Recovery) method, data can be transmitted at high speed using a single differential line by embedding a clock in serial data.

  Applications of such a differential serial interface are spreading, and for example, a differential serial interface is also used for data transmission between in-vehicle devices in an automobile. Patent Document 1 discloses an AC-coupled interface capable of bidirectional transmission on a single transmission line.

International Publication No. WO2008 / 099523

  The transmission distance for in-vehicle use may exceed 5 m. In such long-distance transmission, the influence of the low-pass filter formed by the parasitic resistance and parasitic capacitance of the transmission path cannot be ignored, and the high-frequency component of the transmitted serial signal is attenuated. Therefore, the waveform distortion observed on the receiving side becomes significant. In order to solve the problem of waveform distortion in the transmission path, a pre-emphasis circuit is introduced on the transmission side. The pre-emphasis circuit emphasizes a high-frequency component that attenuates in the transmission path on the transmission side.

  The operating parameters of the pre-emphasis circuit need to be optimized according to the characteristics of the transmission path. It is difficult to apply optimized pre-emphasis settings in one transmission line to other transmission lines, and the designer of a set (platform) equipped with a differential serial interface depends on the characteristics of the board and cable for each set. Therefore, it was necessary to adjust the setting of the pre-emphasis circuit. This adjustment is not easy, and increases the set design time and increases the cost.

  The present invention has been made in such a situation, and one exemplary object of an embodiment thereof is to provide a bidirectional transmission system capable of automatically optimizing the operation parameters of a circuit.

  One embodiment of the present invention relates to a bidirectional transmission system. The bidirectional transmission system includes a first circuit and a second circuit connected via a differential transmission path. The first circuit is coupled to one end of the differential transmission path, coupled to the first driver for driving the differential transmission path in accordance with the first serial data, and to one end of the differential transmission path, and from the second circuit. A first receiver that receives the transmitted second serial data; and a controller that sets operating parameters of the first driver based on a control signal included in the second serial data. The second circuit is coupled to the other end of the differential transmission line, and receives a first serial data transmitted from the first circuit, and an error rate of the first serial data received by the second receiver. An automatic adjustment circuit for generating a control signal so as to decrease, and a second driver coupled to the other end of the differential transmission path and driving the differential transmission path in accordance with second serial data including the control signal, Prepare.

  Note that any combination of the above-described components, or a conversion of the expression of the present invention between methods, apparatuses, and the like is also effective as an aspect of the present invention.

  According to an aspect of the present invention, the operation parameters of the circuit can be automatically optimized.

1 is a block diagram of a bidirectional transmission system according to an embodiment. It is a flowchart explaining operation | movement of the bidirectional | two-way transmission system of FIG. It is a time chart which shows operation | movement of the bidirectional | two-way transmission system of FIG. It is a figure explaining the operation parameter of the 1st driver. It is a block diagram of a bidirectional transmission system according to Modification 1. It is a block diagram of an image processing system provided with a bidirectional transmission system. It is a figure which shows the motor vehicle provided with the image processing system of FIG. It is a figure explaining another operation parameter of the 1st driver.

(Outline of the embodiment)
One embodiment disclosed herein relates to a bidirectional transmission system. The bidirectional transmission system includes a first circuit and a second circuit connected via a differential transmission path. The first circuit is coupled to one end of the differential transmission path, coupled to the first driver for driving the differential transmission path in accordance with the first serial data, and to one end of the differential transmission path, and from the second circuit. A first receiver that receives the transmitted second serial data; and a controller that sets operating parameters of the first driver based on a control signal included in the second serial data. The second circuit is coupled to the other end of the differential transmission line, and receives a first serial data transmitted from the first circuit, and an error rate of the first serial data received by the second receiver. An automatic adjustment circuit for generating a control signal so as to decrease, and a second driver coupled to the other end of the differential transmission path and driving the differential transmission path in accordance with second serial data including the control signal, Prepare.

  According to this aspect, in the second circuit, the error rate of the received first serial data is monitored, and the control signal is fed back to the first circuit so that the error rate is lowered, so that the operation parameter of the first driver is automatically set. Can be optimized.

  The error rate generally refers to the ratio of the number of erroneous codes (bits or symbols) to the total number of codes (bits or symbols) transmitted during a predetermined time interval. Can be understood in a broader sense, and an index indicating the quality of communication is generally referred to as an error rate. For example, when the total number of codes sent during a predetermined time interval is constant, the number of erroneous codes can be treated as an error rate.

  The first driver may adjust the amplitude of a signal transmitted through the differential transmission path, and the control signal may include data for controlling the amplitude. Thereby, the amplitude of the differential signal is optimized according to the state of the transmission line, and the error rate can be improved.

  The first driver has a pre-emphasis function, at least one of a pre-emphasis amount and a waveform is adjustable, and the control signal may include data for controlling the pre-emphasis function. Thereby, the parameters of the pre-emphasis function are optimized according to the state of the transmission line, and the error rate can be improved.

  The first driver has a de-emphasis function, at least one of a de-emphasis amount and a waveform is adjustable, and the control signal may include data for controlling the de-emphasis function. Thereby, the parameter of the de-emphasis function is optimized according to the state of the transmission line, and the error rate can be improved.

  The second receiver may have an equalizer function. The automatic adjustment circuit may adjust the equalizer function of the second receiver so that the error rate of the first serial data received by the second receiver is reduced. Thereby, the parameter of the equalizer function is optimized according to the state of the transmission line, and the error rate can be improved.

  The automatic adjustment circuit may adjust the operation parameter of the first driver of the first circuit according to the control signal after adjusting the equalizer function.

  The first serial data is encoded by a predetermined method in the first circuit, and the automatic adjustment circuit may determine that the received first serial data is not correct when it is not a correct symbol. As a result, the error rate can be detected regardless of the value of the serial data itself transmitted. The predetermined method may be 8b / 10b.

  One embodiment of the present specification discloses a serializer circuit that is connected to a deserializer circuit via a differential transmission path to form a bidirectional transmission system. The deserializer circuit is coupled to one end of the differential transmission path, and the second receiver that receives the first serial data transmitted from the serializer circuit and the error rate of the first serial data received by the second receiver are reduced. And an automatic adjustment circuit for generating a control signal and a second driver coupled to one end of the differential transmission path and driving the differential transmission path in accordance with the second serial data including the control signal. The serializer circuit is coupled to the other end of the differential transmission path, coupled to the first driver that drives the differential transmission path in accordance with the first serial data, and to the other end of the differential transmission path. A first receiver that receives the transmitted second serial data; and a controller that sets operating parameters of the first driver based on a control signal included in the second serial data.

  One embodiment of the present specification discloses a deserializer circuit that is connected to a serializer circuit via a differential transmission path to form a bidirectional transmission system. The serializer circuit is coupled to one end of the differential transmission path, coupled to the first driver for driving the differential transmission path in accordance with the first serial data, and one end of the differential transmission path, and transmitted from the deserializer circuit. A first receiver that receives the second serial data, and a controller that sets operating parameters of the first driver based on a control signal included in the second serial data. The deserializer circuit is coupled to the other end of the differential transmission path, and the error rate of the second receiver that receives the first serial data transmitted from the serializer circuit and the first serial data received by the second receiver is reduced. Thus, an automatic adjustment circuit for generating a control signal and a second driver coupled to the other end of the differential transmission path and driving the differential transmission path in accordance with second serial data including the control signal are provided.

  The predetermined method may be 8b / 10b.

  An automobile is disclosed in an embodiment of the present specification. The automobile may include a camera, a processor, and the above-described bidirectional transmission system provided between the camera and the processor.

(Embodiment)
The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  In this specification, “the state in which the member A is connected to the member B” means that the member A and the member B are physically directly connected, or the member A and the member B are electrically connected to each other. Including the case of being indirectly connected through other members that do not substantially affect the state of connection, or do not impair the functions and effects achieved by the combination thereof.

  Similarly, “the state in which the member C is provided between the member A and the member B” refers to the case where the member A and the member C or the member B and the member C are directly connected, as well as their electric It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.

<Configuration of Bidirectional Transmission System 100>
FIG. 1 is a block diagram of a bidirectional transmission system 100 according to an embodiment. The bidirectional transmission system 100 includes a first circuit 200 and a second circuit 300 that are connected via a differential transmission path 102. The first circuit 200 is coupled to a corresponding one end of the differential transmission path 102 via a capacitor C1 _P / C1 _N , and the second circuit 300 is coupled to a corresponding one end of the differential transmission path 102 and a capacitor C2 _P / coupled via C2 _N.

  The first circuit 200 and the second circuit 300 are capable of serial transmission in both directions. The transmission rate from the first circuit 200 to the second circuit 300, the transmission rate from the second circuit 300 to the first circuit 200, and , May be different. For example, large-capacity data such as image data is transmitted at several Gbps from the first circuit 200 to the second circuit 300, and the first circuit 200 or the first circuit 200 is connected from the second circuit 300 to the first circuit 200. Data for controlling other circuits to be transmitted is transmitted at several tens of Mbps.

<Configuration of First Circuit 200>
The first circuit 200 includes a first driver 202, a first receiver 204, a controller 206, a parallel / serial converter 210, and a serial / parallel converter 212.

Inside the first circuit 200 (or outside), first parallel data D1P _TX to be transmitted to the second circuit 300 is generated. The content of the first parallel data D1P _TX is not particularly limited, and may include image data, audio data, or other data. The parallel-serial converter 210 converts the first parallel data D1P _TX into the first serial data D1S _TX . The first driver 202 is AC-coupled via one end of the differential transmission path 102 and a capacitor, and drives the differential transmission path 102 according to the first serial data D1S _TX . Thus, the first serial data D1S is transmitted from the first circuit 200 to the second circuit 300.

  The second serial data D2S is transmitted from the second circuit 300 to the first circuit 200. The first receiver 204 is coupled to one end of the differential transmission path 102 and receives the second serial data D2S transmitted from the second circuit 300.

The controller 206 sets the operation parameter PRM of the first driver 202 based on the control signal CTRL1 included in the second serial data D2S. Specifically, the received second serial data D2S _RX may be converted into second parallel data D2P _RX by the serial / parallel converter 212, and the control signal CTRL1 may be extracted from the second parallel data D2P _RX . The above is the configuration of the first circuit 200.

<Configuration of Second Circuit 300>
Next, the configuration of the second circuit 300 will be described. The second circuit 300 includes a second receiver 302, an automatic adjustment circuit 304, a second driver 306, a serial / parallel converter 310, and a parallel / serial converter 312.

The second receiver 302 is coupled to the other end of the differential transmission path 102 and receives the first serial data D1S transmitted from the first circuit 200. The serial / parallel converter 310 converts the first serial data D1S _RX received by the second receiver 302 into first parallel data D1P _RX . The first parallel data D1P _RX is supplied to a circuit block (not shown).

The automatic adjustment circuit 304 monitors the first serial data D1S _RX received by the second receiver 302, and generates the control signal CTRL1 so that the error rate decreases.

The parallel-serial converter 312 receives the control signal CTRL1 and converts it into second serial data D2S _TX including the control signal CTRL1. The second driver 306 is coupled to the other end of the differential transmission path 102 and drives the differential transmission path 102 according to the second serial data D2S _TX including the control signal CTRL1. The above is the configuration of the second circuit 300.

<Operation of Bidirectional Transmission System 100>
FIG. 2 is a flowchart for explaining the operation of the bidirectional transmission system 100 of FIG. When the bidirectional transmission system 100 is activated, the automatic adjustment mode is set (S100), and the parameters of the first circuit 200 and the second circuit 300 are initialized.

The first circuit 200 transmits the first serial data D1S _TX to the second circuit 300 (S104). This transmission occurs over a period of time. The first serial data D1S _TX may be generated by converting the automatic adjustment data sequence for automatic adjustment generated by the controller 206 into serial data by the parallel-serial converter 210.

In the second circuit 300, the automatic adjustment circuit 304 acquires the error rate ER of the first serial data D1S _RX received by the second receiver 302 (S106).

  The automatic adjustment circuit 304 compares the error rate ER with an allowable threshold value TH (S108). If the error rate ER is lower than the threshold value TH (Y in S108), the automatic adjustment mode is terminated (S110). On the contrary, if the error rate ER is higher than the threshold value TH (N in S108), the control signal CTRL1 is generated (S110).

  The second serial data D2S including the control signal CTRL1 is transmitted from the second circuit 300 to the first circuit 200 (S112). The first circuit 200 updates the operation parameter of the first driver 202 based on the control signal CTRL1 included in the received second serial data D2S (S112). Then, the process returns to step S104.

FIG. 3 is a time chart showing the operation of the bidirectional transmission system 100 of FIG. In the first transmission period T ₁ of the first serial data D1S are transmitted, error rate ER ₁ of the section is measured. Error rate ER ₁ at this time is higher than the threshold value TH, a new control signal CTRL1 is fed back from the second circuit 300 to the first circuit 200, the operating parameters of the first driver 202 is changed.

Subsequently, in the second transmission period T ₂ is the first serial data D1S are transmitted, error rate ER ₂ of the section is measured. Higher than the error rate ER ₂ also threshold TH at this time, a new control signal CTRL1 is fed back from the second circuit 300 to the first circuit 200, the operating parameters of the first driver 202 is further changed.

By repeating this operation, the error rate ER gradually decreases. When the error rate ER becomes lower than the threshold value TH in the _Nth transmission section _TN , the automatic adjustment is completed. When the automatic adjustment is completed, the operation parameters at that time are held in the memory, and the normal transmission mode is entered.

The above is the operation of the bidirectional transmission system 100. According to this bidirectional transmission system 100, the second circuit 300 monitors the error rate of the received first serial data D1S _RX , and feeds back the control signal CTRL1 to the first circuit 200 so that the error rate decreases. Thus, the operation parameter of the first driver 2202 can be automatically optimized. This frees the designer of the set from the task of optimizing parameters with trial and error.

<Driver operating parameters>
FIG. 4 is a diagram for explaining the operation parameters of the first driver 202. FIG. 4 shows an output waveform (non-inverted output V _OUTP ) of the first driver 202.

The first driver 202 is configured to be able to adjust the amplitude V _AMP of the differential signal propagating through the differential transmission path 102. One of the operating parameters of the first driver 202 is the amplitude V _AMP , and the control signal CTRL1 includes first data for controlling the amplitude. The first data may be multi-gradation data that defines the amplitude level V _AMP . Alternatively, the first data may be binary data that indicates whether to increase or decrease the current amplitude level V _AMP .

The first driver 202 has a pre-emphasis function. One of the operating parameters of the first driver 202 may be a pre-emphasis amount _{V PE,} the control signal CTRL1 includes a second data for controlling the amount of pre-emphasis _{V PE.} One of the operation parameters of the first driver 202 may be a waveform of the pre-emphasis _PE , and a time constant τ is exemplified as a parameter that defines the waveform. The control signal CTRL1 may include third data for controlling the time constant τ.

In one embodiment, the automatic adjustment circuit 304 may first fix the parameters (V _PE , τ) relating to pre-emphasis to initial values and gradually increase the amplitude V _AMP from the initial values. If the error rate ER is still higher than the threshold value TH even when the amplitude V _AMP reaches a certain value, the amplitude V _AMP is fixed in that state, and one of the parameters related to pre-emphasis (for example, the pre-emphasis amount) V _PE ) may be increased. If the pre-emphasis amount V _PE reaches a certain value and the error rate ER is still higher than the threshold value TH, the pre-emphasis amount V _PE is fixed in that state, and the remaining parameters (time constant τ) May be changed.

  The method of optimizing the operation parameter by the automatic adjustment circuit 304 is not particularly limited, and a known optimal solution search algorithm such as a hill-climbing method can be used.

<Error rate detection>
In the first circuit 200, the first serial data D1S is encoded by a predetermined method. The automatic adjustment circuit 304 may determine an error when the received first serial data D1S _RX is not a correct symbol. For example, 8b10b can be used for encoding. In this case, 8-bit data from 00h to FFh is represented by 32 symbols named D00.0 to D31.7. On the receiving side, when the received data is not any of D00.0 to D31.7, it can be determined as an error. According to this method, error detection can be performed without depending on the transmitted 8-bit data.

<Modification 1>
FIG. 5 is a block diagram of a bidirectional transmission system 100A according to the first modification. In this modification, the second receiver 302A of the second circuit 300A has an equalizer function, and the parameters of the equalizer can be controlled according to the control signal CTRL2. The automatic adjustment circuit 304A optimizes the control signal CTRL2 in addition to the control signal CTRL1 so that the error rate decreases.

  In the first modification, the automatic adjustment circuit 304 may change the equalizer parameter of the second receiver 302A and change the operation parameter of the first driver 202 when the error rate is higher than the threshold value.

<Application>
Next, the application of the bidirectional transmission system 100 will be described. FIG. 6 is a block diagram of an image processing system 400 including the bidirectional transmission system 100.

  The image processing system 400 includes a plurality of cameras 402 and an SOC (System on Chip) 404. The SOC 404 performs predetermined image processing on the image data IMG obtained from the plurality of cameras 402. The SOC 404 supplies a signal (camera control signal) for controlling the cameras 402 to the plurality of cameras 402. For example, the imaging timings of the plurality of cameras 402 are synchronized based on a synchronization signal SYNC which is one of camera control signals. Although two cameras are shown in FIG. 6, more cameras 402 may be provided, or one camera may be provided.

  When the distance between the camera 402 and the SOC 404 is long, it is difficult for the interface circuit built in the camera 402 to accurately transmit the image data IMG to the SOC 404. On the other hand, it is difficult for the interface circuit built in the SOC 404 to accurately transmit the camera control signal to the camera 402. In such an application, the above-described bidirectional transmission system 100 can be suitably used.

  The bidirectional transmission system 406 is provided between the camera 402 and the SOC 404 and is configured using the architecture of the bidirectional transmission system 100 described above. The bidirectional transmission system 406 transmits the image data IMG of the camera 402 to the SOC 404 as the first serial data D1S. In addition, the bidirectional transmission system 100 transmits the second serial data D2S including the synchronization signal SYNC to the camera 402.

  The bidirectional transmission system 406 includes a serializer circuit 410, a deserializer circuit 420, and a differential transmission path 430. The serializer circuit 410 corresponds to the first circuit 200, the deserializer circuit 420 corresponds to the second circuit 300, and the differential transmission path 430 corresponds to the differential transmission path 102.

  In the normal operation mode, the serializer circuit 410 receives the image data IMG from the camera 402, converts it into first serial data D1S, and transmits it to the deserializer circuit 420. The deserializer circuit 420 receives the first serial data D1S and supplies the image data IMG to the SOC 404.

  In the normal operation mode, the deserializer circuit 420 receives the camera control signal (synchronization signal SYNC) from the SOC 404, converts it into second serial data D2S, and transmits it to the serializer circuit 410.

  After the image processing system 400 is activated, it is set to the automatic adjustment mode before shifting to the normal operation mode. The first serial data D1S in the automatic adjustment mode does not need to be the image data IMG. During the automatic adjustment mode, the second serial data D2S includes the control signal CTRL1, and the operating parameters of the first driver 202 built in the serializer circuit 410 (first circuit 200) are optimized.

  FIG. 7 is a diagram illustrating an automobile including the image processing system 400 of FIG. The automobile 500 includes a plurality of cameras 402. Each camera 402 is connected to the SOC 404 via a bidirectional transmission system 406. For example, the SOC 404 controls the plurality of cameras 402 according to the traveling state of the automobile 500 and processes image data from them. For example, the SOC 404 enables the rear camera 402 </ b> B during back travel and displays an image from the rear camera 402 on the in-vehicle display 502. When the around view mode is selected when parking, the SOC 404 enables the plurality of cameras 402, combines the images obtained from them, and displays the combined image on the in-vehicle display 502.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are within the scope of the present invention. is there. Hereinafter, such modifications will be described.

<De-emphasis function>
In the embodiment, the case where the first driver 202 has a pre-emphasis function has been described. However, the present invention is not limited to this, and a de-emphasis function may be provided. In this case, the de-emphasis operation parameter may be changed according to the control signal CTRL1.

<Error detection>
The error detection method is not limited to the method using 8b10b. For example, in the automatic adjustment mode, the first circuit 200 may transmit a predetermined bit sequence as the first serial data D1S. For example, a reproducible pseudo random signal (PRBS) may be used. The first circuit 200 may detect whether an error is detected by determining whether the received bit sequence matches the expected value.

<Operation parameters of the first driver>
In FIG. 4, the time constant τ is exemplified as the parameter that defines the waveform of the first driver, but the present invention is not limited thereto. FIG. 8 is a diagram for explaining another operation parameter of the first driver. The output voltage V _OUTP of the first driver can be adjusted during a period Td during which the peak level V _AMP + V _PE is maintained, and this period Td may be used as an operation parameter. That is, the waveform of the output voltage V _OUTP is variable. As a result, the effective time constant τ ′ required for the output voltage V _OUTP to attenuate to the predetermined voltage level can be adjusted. The control signal CTRL1 may include third data for controlling the peak maintenance time Td. According to this modification, the circuit configuration can be simplified as compared with the case where the time constant τ is changed.

<Optimization of operating parameters>
There may be various modifications to the method for optimizing the operating parameters. For example, the following processing may be performed when optimizing the operation parameters of FIG.

First, the automatic adjustment circuit 304 initializes a plurality of parameters (V _PE , V _AMP , Td) related to pre-emphasis. In this state, BER is measured and compared with a threshold value to determine pass / fail. If it is a pass determination, the process ends.

If it is a fail determination, one of a plurality of parameters (for example, V _AMP ) is changed by one step. If a pass determination is obtained, the process ends there. If the path determination cannot be obtained, another parameter _VPE and Td are alternately changed step by step until the path determination is obtained. If the path determination cannot be obtained even if each of V _PE and Td is changed by a predetermined number of steps, V _AMP is further changed by one step, and parameters V _PE and Td are changed until the path determination is obtained in that state. Change one step at a time alternately. This process is repeated until V _AMP is changed by a predetermined number of steps.

  Although the present invention has been described using specific terms based on the embodiments, the embodiments merely show one aspect of the principle and application of the present invention. Many variations and modifications of the arrangement are allowed without departing from the spirit of the present invention defined in the scope.

DESCRIPTION OF SYMBOLS 100 Bidirectional transmission system 102 Differential transmission path 200 1st circuit 202 1st driver 204 1st receiver 206 Controller 210 Parallel serial converter 212 Serial parallel converter 300 2nd circuit 302 2nd receiver 304 Automatic adjustment circuit 306 2nd driver 310 Serial Parallel Converter 312 Parallel Serial Converter D1P First Parallel Data D1S First Serial Data CTRL Control Signal D2S Second Serial Data 400 Image Processing System 402 Camera 404 SOC
406 Bidirectional transmission system 410 Serializer circuit 420 Deserializer circuit 430 Differential transmission path 500 Automobile 502 In-vehicle display

Claims (18)

Comprising a first circuit and a second circuit connected via a differential transmission line;
The first circuit includes:
A first driver coupled to one end of the differential transmission path and driving the differential transmission path according to first serial data;
A first receiver coupled to the one end of the differential transmission path and receiving second serial data transmitted from the second circuit;
A controller for setting operating parameters of the first driver based on a control signal included in the second serial data;
With
The second circuit includes:
A second receiver coupled to the other end of the differential transmission path and receiving the first serial data transmitted from the first circuit;
An automatic adjustment circuit for generating the control signal so that an error rate of the first serial data received by the second receiver is reduced;
A second driver coupled to the other end of the differential transmission path and driving the differential transmission path in response to the second serial data including the control signal;
A bidirectional transmission system comprising: The first driver is capable of adjusting an amplitude of a signal transmitted through the differential transmission path,
The bidirectional transmission system according to claim 1, wherein the control signal includes data for controlling the amplitude. The first driver has a pre-emphasis function, and at least one of a pre-emphasis amount and a waveform is adjustable,
The bidirectional transmission system according to claim 1, wherein the control signal includes data for controlling the pre-emphasis function. The first driver has a de-emphasis function, and at least one of a de-emphasis amount and a waveform is adjustable,
The bidirectional transmission system according to claim 1, wherein the control signal includes data for controlling the de-emphasis function. The second receiver has an equalizer function;
5. The bidirectional transmission system according to claim 1, wherein the automatic adjustment circuit adjusts an equalizer function of the second receiver so that an error rate of the first serial data is lowered. 6.   6. The bidirectional transmission system according to claim 5, wherein the automatic adjustment circuit adjusts the operation parameter of the first driver of the first circuit according to the control signal after adjusting the equalizer function. The first serial data is encoded in a predetermined manner in the first circuit;
7. The bidirectional transmission system according to claim 1, wherein the automatic adjustment circuit determines that an error occurs when the received first serial data is not a correct symbol.   The bidirectional transmission system according to claim 7, wherein the predetermined method is 8b / 10b. A serializer circuit that is connected to a deserializer circuit via a differential transmission path to form a bidirectional transmission system,
The deserializer circuit is
A second receiver coupled to one end of the differential transmission path and receiving first serial data transmitted from the serializer circuit;
An automatic adjustment circuit for generating a control signal so that an error rate of the first serial data received by the second receiver is reduced;
A second driver coupled to the one end of the differential transmission path and driving the differential transmission path in response to second serial data including the control signal;
With
The serializer circuit is
A first driver coupled to the other end of the differential transmission path and driving the differential transmission path according to the first serial data;
A first receiver coupled to the other end of the differential transmission path and receiving the second serial data transmitted from the deserializer circuit;
A controller for setting operation parameters of the first driver based on the control signal included in the second serial data;
A serializer circuit comprising: The first driver is capable of adjusting an amplitude of a signal transmitted through the differential transmission path,
The serializer circuit according to claim 9, wherein the control signal includes data for controlling the amplitude. The first driver has a pre-emphasis function, and at least one of a pre-emphasis amount and a waveform is adjustable,
The serializer circuit according to claim 9, wherein the control signal includes data for controlling the pre-emphasis function. The first driver has a de-emphasis function, and at least one of a de-emphasis amount and a waveform is adjustable,
11. The serializer circuit according to claim 9, wherein the control signal includes data for controlling the de-emphasis function. A deserializer circuit that is connected to a serializer circuit via a differential transmission path to form a bidirectional transmission system,
The serializer circuit is
A first driver coupled to one end of the differential transmission path and driving the differential transmission path according to first serial data;
A first receiver coupled to the one end of the differential transmission path and receiving second serial data transmitted from the deserializer circuit;
A controller for setting operating parameters of the first driver based on a control signal included in the second serial data;
With
The deserializer circuit is
A second receiver coupled to the other end of the differential transmission path and receiving the first serial data transmitted from the serializer circuit;
An automatic adjustment circuit for generating a control signal so that an error rate of the first serial data received by the second receiver is reduced;
A second driver coupled to the other end of the differential transmission path and driving the differential transmission path in response to the second serial data including the control signal;
A deserializer circuit comprising: The second receiver has an equalizer function;
The deserializer circuit according to claim 13, wherein the automatic adjustment circuit adjusts an equalizer function of the second receiver so that an error rate of the first serial data is lowered.   The deserializer circuit according to claim 14, wherein the automatic adjustment circuit adjusts the operation parameter of the first driver of the serializer circuit by the control signal after adjusting the equalizer function. The first serial data is encoded in a predetermined manner in the serializer circuit,
The deserializer circuit according to any one of claims 13 to 15, wherein the automatic adjustment circuit determines an error when the received first serial data is not a correct symbol.   The deserializer circuit according to claim 16, wherein the predetermined method is 8b / 10b. A camera,
A processor;
The bidirectional transmission system according to any one of claims 1 to 8, provided between the camera and the processor;
An automobile characterized by comprising:

Images