JP5293860B1 - Serial communication system, image forming system, and transmission apparatus - Google Patents

Abstract

When data is encoded and then a code for detecting an error in data generated during transmission is added and transmitted by serial communication, an error occurs when the data received from the transmitting device is decoded in the receiving device. Prevent it from occurring.
A transmission apparatus encodes a packet P by adding a neutral DC pattern 44, and then adds an error correction code 46 in which DC balance is maintained instead of the neutral DC pattern 44, and transmits the packet by serial communication. To do. The receiving apparatus receives the packet P transmitted from the transmitting apparatus, performs error detection using the error correction code 46, adds a neutral DC pattern 44 instead of the error correction code 46, and decodes the packet P. The neutral DC pattern 44 is deleted.
[Selection] Figure 3

Description

  The present invention relates to a serial communication system, an image forming system, and a transmission apparatus.

  A technique for improving the quality of signal transmission in serial transmission is known. For example, Patent Document 1 describes a technique for performing serial transmission by performing an 8-bit / 10-bit conversion process on 8-bit word string data and then inserting an additional word data group including 10-bit word synchronization data. Has been. Patent Document 2 describes a technique in which a check code is added for each frame, and when an error during transmission is detected, the frame is retransmitted.

JP 2001-197454 A JP 05-260125 A

  The present invention decodes data received from a transmitting device at a receiving device when the transmitting device encodes the data, adds a code for detecting an error in data generated during transmission, and transmits the data by serial communication. The purpose is to prevent errors from occurring.

The serial communication system according to claim 1 of the present invention is composed of a first code and a second code, and the difference between the number of the first code and the number of the second code is N bits kept in a first pattern adding unit that adds a neutral DC pattern data, the said data is neutral DC pattern is added in a first pattern adding unit, DC balance data of the number of more bits than the data is And generating an error correction code for detecting an error in the data generated during transmission based on the data encoded by the encoding unit so as to maintain a DC balance, instead of the neutral DC pattern encoded in the data in the encoding unit, an error detection code addition unit for adding the error correction code, the data to which the error correction code is added A transmission device and a transmission section that transmits in real communication, the a reception section that receives the data transmitted from the transmitting unit, an error of the data using the added to the received data the error correction code An error detection unit that performs detection, a second pattern addition unit that adds a neutral DC pattern instead of the error correction code added to the data after error detection in the error detection unit, and the second pattern addition A receiving unit including a decoding unit that decodes the data to which the neutral DC pattern is added, and a pattern deletion unit that deletes the neutral DC pattern from the decoded data.

The serial communication system according to a second aspect of the present invention is the serial communication system according to the first aspect, wherein the transmitting device is configured to add the data before the neutral DC pattern is added by the first pattern adding unit. And a scramble unit for performing a scramble process on the data after the neutral DC pattern is deleted by the pattern deletion unit. And

An image forming system according to claim 3 of the present invention transmits the data representing an image before the neutral DC pattern is added by the transmission device according to claim 1 and the first pattern adding unit. An image processing device that includes an image processing unit that performs image processing on the data; and the receiving device according to claim 1; and after the neutral DC pattern is deleted by the pattern deletion unit, an image corresponding to the data is displayed. And an image forming apparatus including an image forming unit to be formed.

The transmission device according to claim 4 of the present invention is configured by an N-bit that includes a first code and a second code, and a difference between the number of the first code and the number of the second code is zero. A first pattern adding unit that adds a neutral DC pattern to data and the data to which the neutral DC pattern is added by the first pattern adding unit are DC balanced to data having a larger number of bits than the data. An encoding unit that encodes the data and an error correction code that detects an error in the data that occurs during transmission based on the data encoded by the encoding unit so as to maintain a DC balance, instead of the neutral DC pattern encoded in data unit, an error detection code addition unit for adding the error correction code, a serial communication the data to which the error correction code is added Characterized in that it comprises a transmitter which transmits.

According to the first aspect of the present invention, when data is encoded in the transmission apparatus and then transmitted by serial communication with a code for detecting an error in data generated during transmission, the transmission apparatus It is possible to prevent an error from occurring when the data received from the client is decrypted.
According to the invention which concerns on Claim 2, compared with the case where a scramble part is not provided, EMI (Electro Magnetic Interference) can be reduced.
According to the invention of claim 3, in the transmission device, when the data is encoded and then transmitted by serial communication with a code for detecting an error in data generated during transmission, the transmission device It is possible to prevent an error from occurring when the data received from the client is decrypted.
According to the invention of claim 4, when data is encoded in the transmission apparatus and then transmitted by serial communication with a code for detecting an error in data generated during transmission, the transmission apparatus It is possible to prevent an error from occurring when the data received from the client is decrypted.

The figure which shows an example of the serial communication system which concerns on embodiment The figure which shows the function structure of a transmitter Diagram explaining packet transmission operation The figure explaining an example of conversion of an error correction code The figure which shows the function structure of a receiver The figure explaining the reception operation of the packet The figure which shows an example of the image forming system which concerns on a modification

1. Embodiment FIG. 1 is a diagram illustrating an example of a serial communication system 1 according to the present embodiment. The serial communication system 1 includes a transmission device 10 and a reception device 20. The transmission device 10 and the reception device 20 are connected via the transmission path 2.

  The transmission device 10 includes a control unit 11 and a communication unit 12. The control unit 11 includes a CPU (Central Processing Unit) and a memory. The CPU performs various controls and processes by executing programs stored in the memory. The communication unit 12 includes an application specific integrated circuit (ASIC), a memory, and a serial interface. The ASIC controls the serial interface. The serial interface is connected to the transmission path 2.

  The receiving device 20 includes a control unit 21 and a communication unit 22. The control unit 21 includes a CPU and a memory. The CPU performs various controls and processes by executing programs stored in the memory. The communication unit 22 includes an ASIC, a memory, and a serial interface. The ASIC controls the serial interface. The serial interface is connected to the transmission path 2. The communication unit 12 and the communication unit 22 perform communication in accordance with an interface standard called DisplayPort, for example.

  FIG. 2 is a diagram illustrating a functional configuration of the transmission device 10. The transmitting apparatus 10 includes a buffer 31, a scrambler 32, a pattern adding unit 33 (an example of a first pattern adding unit), an encoding unit 34, an error detection code adding unit 35, a P / S (Parallel to Serial) conversion unit 36 and transmission unit 37. These functions are realized by the communication unit 12.

  FIG. 3 is a diagram for explaining the transmission operation of the packet P. The buffer 31 stores a packet P (an example of data) transmitted from the control unit 11 to the receiving device 20. FIG. 3A is a diagram illustrating an example of the packet P stored in the buffer 31. The packet P has a header part 41 and a data part 42. In the header part 41, for example, control information necessary for transmission of the packet P is stored. The data section 42 stores data # 0 to # 10. This packet P is divided every 16 bits.

  The packet P is extracted from the buffer 31 and input to the scramble unit 32. In order to reduce EMI, the scrambler 32 performs a scramble process on the data part 42 of the input packet P and outputs it, as shown in FIG. In the scramble process, exclusive OR of the data # 0 to # 10 and the random number is taken. The packet P output from the scramble unit 32 is input to the pattern adding unit 33.

  As shown in FIG. 3C, the pattern adding unit 33 adds a start of packet 43, a neutral DC pattern 44, and an idle pattern 45 to the input packet P and outputs the result. The start of packet 43 is inserted at the beginning of the packet P. For this start of packet 43, for example, K28.1 code and K28.6 code are used.

  The neutral DC pattern 44 is a bit pattern of 20 bits (an example of N bits) that is the same as an error correction code 46 described later. The neutral DC pattern 44 is neutral in running disparity, and the DC balance is maintained. This DC balance means that the balance of the numbers 1 and 0 is equal. Keeping DC balance means making the appearance frequency of 1 and 0 uniform. For example, when the data is viewed along the transmission direction, data in which DC balance is maintained is generated by arranging the bits so that 1 and 0 do not continue for a predetermined number or more. The running disparity is a difference between the accumulated number of 1 and the accumulated number of 0 included in the data transmitted so far in the data encoded by the 8B / 10B system. For example, when the cumulative number of 1 is larger than the cumulative number of 0, the running disparity is positive. On the other hand, when the cumulative number of 0 is larger than the cumulative number of 1, the running disparity is negative. When the accumulated number of 1s is equal to the accumulated number of 0s, that is, when the difference between the accumulated number of 1s and the accumulated number of 0s is 0, the running disparity is neutral. For the neutral DC pattern 44, for example, two D21.2 codes (1010100101) are used. This D21.2 code is composed of 0 (an example of a first code) and 1 (an example of a second code). The D21.2 code is arranged so that 1 and 0 do not continue 3 or more, and the appearance frequency of 1 and 0 is not biased, so that the DC balance is maintained. Further, since the number of 1's and the number of 0's are both 5 and the difference between the number of 1's and 0's is 0, the D21.2 code has a neutral running disparity.

  The idle pattern 45 is inserted into an empty section before and after the packet P. For this idle pattern 45, for example, K28.5 code and D0.0 code are used. For example, when the running disparity when the data # 10 of the packet P is transmitted is positive, the K28.5 code having a negative running disparity is arranged at the head of the idle pattern 45 following the neutral DC pattern 44. Is done. On the other hand, when the running disparity when the data # 10 of the packet P is transmitted is negative, the K28.5 code having a positive running disparity is arranged in the head idle pattern 45. This is because the running disparity when the data # 10 is transmitted and the running disparity when the neutral DC pattern 44 is transmitted do not change because the running disparity of the neutral DC pattern 44 is neutral. is there. The packet P output from the pattern adding unit 33 is input to the encoding unit 34.

  The encoding unit 34 encodes the input packet P according to the 8B / 10B encoding method and outputs the result. As a result, as shown in FIG. 3D, the 16-bit packet P is converted into a 20-bit packet P in which DC balance is maintained. That is, the encoding unit 34 encodes the packet P so that the DC balance is maintained. The packet P output from the encoding unit 34 is input to the error detection code adding unit 35.

  Based on the header part 41 and the data part 42 of the input packet P, the error detection code adding part 35 generates an error correction code 46 that detects and corrects an error in data that occurs during transmission. As this error correction code 46, for example, a Hamming code is used. Specifically, the error detection code adding unit 35 calculates an error correction code 46 based on the header part 41 and the data part 42 of the input packet P. The error detection code adding unit 35 converts the calculated error correction code 46 into a 20-bit error correction code 46 in which DC balance is maintained.

  FIG. 4 is a diagram for explaining an example of conversion of the error correction code 46. An arrow A direction in the figure indicates a transmission direction of the packet P. Here, it is assumed that the calculated error correction code 46 is “10010111”. First, the error detection code adding unit 35 generates “01101000” which is the inverted data 46B of the error correction code 46. Next, the error detection code adding unit 35 inserts the upper 4 bits of the normal data 46A of the error correction code 46 and the upper 4 bits of the inverted data 46B, and further inserts “10” into the empty bit 46C. The data is 10 bits. Next, the error detection code adding unit 35 inserts the lower 4 bits of the normal data 46A of the error correction code 46 and the lower 4 bits of the inverted data 46B, and further inserts “10” into the empty bit 46D. The data is 10 bits. As a result, a 20-bit error correction code 46 in which DC balance is maintained is generated.

  Next, as shown in FIG. 3E, the error detection code adding unit 35 deletes the neutral DC pattern 44 added to the packet P, and adds a 20-bit error correction code 46 instead. Output. The packet P output from the error detection code adding unit 35 is input to the P / S conversion unit 36. The P / S converter 36 converts the input packet P into a serial format packet P and outputs it. The packet P output from the P / S conversion unit 36 is input to the transmission unit 37. The transmitting unit 37 transmits the input packet P to the receiving device 20 by serial communication.

  FIG. 5 is a diagram illustrating a functional configuration of the receiving device 20. The receiving device 20 includes a receiving unit 51, an S / P (Serial to Parallel) converting unit 52, an error detecting unit 53, a pattern adding unit 54 (an example of a second pattern adding unit), a decoding unit 55, It functions as a pattern deletion unit 56, a descrambling unit 57, and a buffer 58. These functions are realized by the communication unit 22.

  FIG. 6 is a diagram for explaining the reception operation of the packet P. The reception unit 51 receives the packet P transmitted from the transmission device 10. The packet P received by the receiving unit 51 is input to the S / P conversion unit 52. The S / P converter 52 converts the input packet P into a parallel packet P and outputs it. The packet P output from the S / P conversion unit 52 is input to the error detection unit 53. The error detection unit 53 performs error detection and correction using the error correction code 46 added to the input packet P and outputs the result. For example, when a Hamming code is used as the error correction code 46, the error detection unit 53 calculates the syndrome of the error correction code 46, and performs 1-bit error correction and 2-bit error detection. For example, when the error detection unit 53 detects a 1-bit error 42a, the error detection unit 53 corrects the error 42a. The packet P output from the error detection unit 53 is input to the pattern addition unit 54.

  As shown in FIG. 6B, the pattern addition unit 54 deletes the error correction code 46 from the input packet P, adds the neutral DC pattern 44 described above, and outputs it. The packet P output from the pattern adding unit 54 is input to the decoding unit 55. The decoding unit 55 decodes and outputs the input packet P according to the 8B / 10B encoding method. Thereby, as shown in FIG. 6C, the 20-bit packet P is converted into the original 16-bit packet P. The packet P output from the decoding unit 55 is input to the pattern deletion unit 56.

  The pattern deletion unit 56 deletes the start-of-packet 43 and the neutral DC pattern 44 from the input packet P and outputs the result, as shown in FIG. The packet P output from the pattern deletion unit 56 is input to the descrambling unit 57. As shown in FIG. 6E, the descrambling unit 57 performs descrambling processing for releasing the scramble on the data unit 42 of the input packet P and outputs the result. In this descrambling process, the same random number as in the scramble process is used, and an exclusive OR of the data # 0 to # 10 and this random number is taken. The packet P output from the descrambling unit 57 is stored in the buffer 58.

  In this embodiment, the neutral DC pattern 44 is added to the packet P and encoded, and then an error correction code 46 is added instead of the neutral DC pattern 44. As described above, since the running disparity of the neutral DC pattern 44 is neutral, the running disparity when the data # 10 at the end of the packet P is transmitted and the running when the neutral DC pattern 44 is transmitted. Disparity does not change. Therefore, for example, when the running disparity when data # 10 is transmitted is positive, the running disparity can be provided by placing a code having a negative running disparity at the head of the idle pattern 45 following the neutral DC pattern 44. No parity mismatch occurs.

  However, for example, when encoding is performed by adding the error correction code 46 to the packet P without adding the neutral DC pattern 44, the following problems occur. In the error correction code 46, the DC balance is maintained, but no consideration is given to the running disparity. Therefore, for example, even when the running disparity when the data # 10 is transmitted is positive, the running disparity when the error correction code 46 is transmitted may be positive or negative. . In this case, the running disparity may be inconsistent between the data # 10 and the error correction code 46. If a mismatch occurs in the running disparity, a running disparity error occurs when the receiving device 20 decodes the packet P, and the integrity of the packet P cannot be guaranteed.

  In order to prevent such a problem, in this embodiment, before encoding and decoding the packet P, a neutral DC pattern 44 having a running disparity of neutral is added to the packet P instead of the error correction code 46. It is doing. According to the present embodiment, when the transmission device 10 encodes the packet P and then adds the error correction code 46 and transmits the serial communication, the reception device 20 receives the packet P received from the transmission device 10. Generation of a running disparity error is prevented when decoding.

2. Modified Embodiment The above-described embodiment is an example of the present invention. The present invention is not limited to the above-described embodiment, and may be modified. Moreover, you may implement combining the following modifications.

(1) Modification 1
The codes used for the start-of-packet 43, the neutral DC pattern 44, or the idle pattern 45 described in the above embodiment are merely examples, and the present invention is not limited to this. For example, a D21.5 code (1010101010) may be used for the neutral DC pattern 44. Moreover, the DC balance of the neutral DC pattern 44 is not necessarily maintained. The neutral DC pattern 44 may be any bit pattern as long as the running disparity is neutral and the pattern has the same bit length as the error correction code 46. For the start of packet 43, for example, K28.1 code and D0.7 code, or K28.2 code and D15.0 code may be used. As the idle pattern, for example, an increment pattern of K28.5 code and D code may be used.

The bit length of the data described in the above embodiment is merely an example, and the present invention is not limited to this. For example, an 11-bit error correction code 46 may be converted into a 40-bit error correction code 46 and used. In this case, the bit length of the neutral DC pattern 44 is 40 bits which is the same as that of the error correction code 46. For example, for the neutral DC pattern 44, for example, four D21.2 codes may be used.
The contents of the packet P (packet length, contents of the header part 41 and the data part 42) shown in FIGS. 3 and 6 are merely examples, and the present invention is not limited to this.

(2) Modification 2
The code added to the packet P in order to detect data errors that occur during transmission is not limited to the error correction code 46. For example, instead of the error correction code 46, an error detection code that performs only error detection may be used. As this error detection code, for example, a checksum or parity is used. In this case, the error detection code adding unit 35 generates an error detection code in which DC balance is maintained based on the header part 41 and the data part 42 of the packet P. The error detection unit 53 performs error detection using the error detection code of the packet P.

(3) Modification 3
The serial communication technique described in the embodiment may be applied to the image forming system 3. FIG. 7 is a diagram illustrating an example of the image forming system 3 according to the modification. The image forming system 3 includes an image processing device 4 and an image forming device 5. The image processing apparatus 4 includes an image processing unit 13 in addition to the control unit 11 and the communication unit 12 described above. The image processing device 4 receives image data described in a page description language from a client device (not shown). The image processing unit 13 performs various image processing on the image data and outputs the processed image data. This image processing includes, for example, RIP (Raster Image Processing) processing. The image data output from the image processing unit 13 is packetized and stored in the buffer 31. At this time, for example, the color information of the image data is stored in the header portion 41 of the packet P stored in the buffer 31, and the image data is stored in the data portion 42. The image forming apparatus 5 includes an image forming unit 23 in addition to the control unit 21 and the communication unit 22 described above. The image forming unit 23 forms an image corresponding to the image data of the packet P stored in the buffer 58 by electrophotography. The image forming unit 23 may form an image by an image forming method other than an electrophotographic method such as an ink jet method.

(4) Modification 4
The scramble unit 32 and the descramble unit 57 are not necessarily provided.

(5) Modification 5
In the above-described embodiment, the transmission device 10 and the reception device 20 employ DisplayPort as the interface standard, but standards other than the DisplayPort may be employed. For example, other interface standards such as XAUI and PCI Express may be used.

(6) Modification 6
The communication unit 12 and the communication unit 22 may exchange data by an electric signal (electric communication), or may exchange data by an optical signal (optical communication). In the case of telecommunications, the transmission path 2 is constituted by a coaxial cable, for example. On the other hand, in the case of optical communication, the transmission path 2 is constituted by an optical fiber, for example.

(7) Modification 7
In the above-described embodiment, the apparatuses are connected by the transmission line 2, but the present invention is not limited to this structure. For example, in a configuration in which data is transmitted between IC (Integrated Circuit) chips arranged on a printed circuit board via a substrate pattern, data may be transmitted with the configuration of the communication unit described above.

(8) Modification 8
The function of the communication unit 12 may be realized by the CPU of the control unit 11 executing a program stored in the memory. Similarly, the function of the communication unit 22 may be realized by the CPU of the control unit 21 executing a program stored in the memory. In this case, the program executed by the CPU is provided in a state of being recorded on a recording medium such as a magnetic tape, a magnetic disk, a flexible disk, an optical disk, a magneto-optical disk, or a memory, and is installed in the transmission device 10 or the reception device 20. Also good. Further, this program may be downloaded to the transmission device 10 or the reception device 20 via a communication line such as the Internet.

DESCRIPTION OF SYMBOLS 1 ... Serial communication system, 2 ... Transmission path, 3 ... Image forming system, 4 ... Image processing apparatus, 5 ... Image forming apparatus, 10 ... Transmission apparatus, 20 ... Reception apparatus, 31 ... Buffer, 32 ... Scramble part, 33 ... Pattern adding unit 34 ... Coding unit 35 ... Error detection code adding unit 36 ... P / S conversion unit 37 ... Transmission unit 51 ... Reception unit 52 ... S / P conversion unit 53 ... Error detection unit 54 ... pattern adding unit, 55 ... decoding unit, 56 ... pattern deleting unit, 57 ... descrambling unit, 58 ... buffer

Claims (4)

A first pattern that is composed of a first code and a second code and adds an N-bit neutral DC pattern in which the difference between the number of the first code and the number of the second code is 0 to the data An additional part;
An encoding unit that encodes the data to which a neutral DC pattern is added by the first pattern addition unit so that DC balance is maintained in data having a larger number of bits than the data ;
An error correction code for detecting an error in the data generated during transmission based on the data encoded by the encoding unit is generated so as to maintain a DC balance, and the error correction code in the data encoded by the encoding unit In place of the neutral DC pattern, an error detection code adding unit for adding the error correction code ;
A transmission device comprising: a transmission unit that transmits the data to which the error correction code is added by serial communication;
A receiver for receiving the data transmitted from the transmitter;
An error detection unit that performs error detection of the data using the error correction code added to the received data;
A second pattern addition unit for adding a neutral DC pattern instead of the error correction code added to the data after error detection in the error detection unit;
A decoding unit for decoding the data to which the neutral DC pattern is added by the second pattern addition unit ;
A serial communication system comprising: a receiving device including a pattern deleting unit that deletes the neutral DC pattern from the decoded data. The transmission device includes a scramble unit that scrambles the data before the neutral DC pattern is added by the first pattern addition unit,
2. The serial communication according to claim 1, wherein the receiving device includes a descrambling unit that performs descrambling processing on the data to be descrambled after the neutral DC pattern is deleted by the pattern deletion unit. system. The transmission device according to claim 1, which transmits the data representing an image;
An image processing apparatus comprising: an image processing unit that performs image processing on the data before the neutral DC pattern is added by the first pattern adding unit;
A receiving device according to claim 1;
An image forming system comprising: an image forming unit configured to form an image according to the data after the neutral DC pattern is deleted by the pattern deleting unit. A first pattern that is composed of a first code and a second code and adds an N-bit neutral DC pattern in which the difference between the number of the first code and the number of the second code is 0 to the data An additional part;
An encoding unit that encodes the data to which a neutral DC pattern is added by the first pattern addition unit so that DC balance is maintained in data having a larger number of bits than the data ;
An error correction code for detecting an error in the data generated during transmission based on the data encoded by the encoding unit is generated so as to maintain a DC balance, and the error correction code in the data encoded by the encoding unit In place of the neutral DC pattern, an error detection code adding unit for adding the error correction code ;
A transmission unit that transmits the data to which the error correction code is added by serial communication.

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