WO2011017997A1 - Procédé et dispositif de commande de bus de communication - Google Patents

Procédé et dispositif de commande de bus de communication Download PDF

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Publication number
WO2011017997A1
WO2011017997A1 PCT/CN2010/075492 CN2010075492W WO2011017997A1 WO 2011017997 A1 WO2011017997 A1 WO 2011017997A1 CN 2010075492 W CN2010075492 W CN 2010075492W WO 2011017997 A1 WO2011017997 A1 WO 2011017997A1
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WO
WIPO (PCT)
Prior art keywords
line card
bus
communication bus
data
idle
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Application number
PCT/CN2010/075492
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English (en)
Chinese (zh)
Inventor
罗伟
石鸿斌
苏红峰
Original Assignee
中兴通讯股份有限公司
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Publication of WO2011017997A1 publication Critical patent/WO2011017997A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/40—Bus networks
    • H04L12/407—Bus networks with decentralised control
    • H04L12/413—Bus networks with decentralised control with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]

Definitions

  • the present invention relates to the field of communications, and more particularly to a communication bus control method and apparatus.
  • BACKGROUND OF THE INVENTION HDLC bus control protocol is taken as an example, advanced data link control (High-Level Data Link)
  • HDLC bit-oriented data link layer protocol for transmitting data over synchronous networks. It is developed by the International Organization for Standardization (ISO) according to IBM's SDLC (Synchronous Data Link Control) protocol extension.
  • the Link Control Protocol focuses on the transmission of data that is segmented into physical blocks or packets that are directed by the start flag and terminated by a termination flag, also known as a frame.
  • Each start (frame header) and termination (end of frame) has a flag code 01111110, which is used as the start and end indication of the frame and the synchronization of the frame. Its frame format structure is shown in Figure 1: The logo code is not allowed to appear inside the frame to avoid ambiguity.
  • the "0-bit insertion method” is used to solve the problem.
  • the method monitors all fields except the flag code on the transmitting end. When it is found that five consecutive "1”s appear, a "0" is inserted after it, and then the subsequent bit stream is continued. At the receiving end, all fields except the flag code are also monitored. When it is found that five consecutive " ⁇ appear, if the next bit is "0", it is automatically deleted to restore the original bit stream; if six consecutive "1"s are found, the termination flag of the frame may be received.
  • the HDLC protocol stipulates that data intervals are not allowed within one frame.
  • the transmitter can continuously output a sequence of flag characters or a continuous high level, which is called an idle (Idle) signal.
  • an idle (Idle) signal is composed of a plurality of line cards with different functions.
  • the master-slave mode is generally used in the device for management.
  • a main control board and All other subordinate route cards are connected and communicated.
  • Each branch route card sends or reports various information to the main control board, and collects the information through the main control board for processing and sends various control information to each line card. It is popular to use the SCC port provided by the Micro Controller Unit (MCU) to encapsulate the information between the various line cards in HDLC, or to replace the MCU by FPGA.
  • MCU Micro Controller Unit
  • FIG communication connection between the plate of FIG. 2, the connection in order to save resources and save the backsheet and the control board The connection port between each line card, the connection between the main control board and each other line card is connected by a bus, as shown in FIG. 2, the bus full-duplex connection and the half-duplex connection.
  • the main control board communicates with other line cards through the full-duplex bus
  • the TX signal of the main control board is connected to the receiving RX of each line card
  • the TX of each line card is connected to the bus through a bus (HDLC bus).
  • the main control board receives RX.
  • the main control board communicates with other line cards through the half-duplex bus, the communication data between the main control board and other line cards is controlled by a bus.
  • the line card needs to control the bus when sending data to the bus: As shown in Figure 2, when the line card 1 sends data to the bus, other line cards Data cannot be sent to the bus. After the line card 1 sends the data, other line cards can send data. When the bus has no data transmission, it maintains tri-state, and the bus data received by each line card passes through the pull-up resistor, so that when there is no data transmission on the bus, the bus data is detected as "1", that is, HDLC. Idle signal.
  • each line card hanging on the transmission bus receives data on the bus, and currently uses the following methods for control, when the line card needs to be sent to the bus.
  • the line card needs to be sent to the bus.
  • a fixed value for example, when it is equal to 7
  • Send data to the bus when two or more line cards detect that the bus is idle and send data to the bus, the bus conflicts and the bus data becomes unstable. In this case, the data is sent.
  • the driver becomes weaker due to the increase of the distance of the connection.
  • different line cards receive different data, which may cause misjudgment to the line card to correctly judge the bus status.
  • Other line cards can detect seven consecutive "" cases from the bus. As shown in Figure 3, line card 1 sends "1" and line card n sends. "0" data, while other line cards receive different data. Therefore, when multiple line cards are sent to the bus at the same time, due to bus conflict, the actual bus data received between the two line cards may be caused.
  • the conflict is a key factor to ensure that each line card can correctly transfer data on the bus.
  • two priorities are set for the bus conflict. In the case of high priority, the bus is checked for 7 consecutive times. 1" that is, the bus is idle, and when the priority is low, it is necessary to continuously detect that the bus data is 15 "1", and the bus is considered to be idle.
  • the line card has the lowest transmission priority. When the line conflict is found during the line card transmission, the priority is increased, and the priority is lowered after the final transmission of a complete frame.
  • the present invention provides a communication bus control method and apparatus for solving the problem of large probability of collision caused by conventional technical means.
  • a communication bus control method including the following steps: setting different delay times for different line cards; when the line card detects that the communication bus is idle, according to the delay set thereto The time delay is performed; the line card that completes the delay preempts the idle communication bus to send data to the communication bus.
  • the present invention also provides a communication bus control device, including: a delay time generating unit, which is set on the line card, is used to set different delay times for different line cards; a delay unit is used for the line card After detecting that the communication bus is idle, the enable line card is delayed according to the delay time set by the delay time generating unit; and the enabling sending unit is configured to enable the line card that completes the delay to preempt the idle communication bus.
  • FIG. 1 is a HDLC frame structure diagram in the related art
  • FIG. 2 is an inter-board HDLC bus communication connection diagram in a communication device in the related art
  • 3 is a schematic diagram of a board bus conflict in the related art
  • FIG. 4 is a schematic diagram of a communication bus control apparatus according to an embodiment of the present invention
  • FIG. 5 is a line card structure diagram of a bus transmitting and receiving data
  • FIG. 7 is a block diagram of a line card for bus communication in accordance with an embodiment of the present invention
  • FIG. 8 is a schematic diagram of a FCS calculation data range.
  • the #1 line card including: a delay time generating unit, which is set on the line card for setting different delay times for different line cards; a delay unit (not shown) for online card detection After the communication bus is idle, the enable line card delays according to the delay time set by the delay time generation module; and enables the sending unit (not shown) for preempting the idle communication on the line card that completes the delay.
  • the line card is enabled to send data to the communication bus.
  • the embodiment further includes: an updating unit (not shown), The online card updates the delay time each time it grabs the communication bus.
  • the method further includes: a conflict determination unit (not shown), configured to determine whether a data conflict occurs when different line cards send data to the communication bus, where the line card sent by the conflict determination unit is sent When the number of times data is inconsistent with the data received by the line card is greater than a predetermined value, the enabling unit prevents the line card from transmitting data to the bus, and the delay time generating unit updates the delay time on the line card.
  • a conflict determination unit (not shown), configured to determine whether a data conflict occurs when different line cards send data to the communication bus, where the line card sent by the conflict determination unit is sent When the number of times data is inconsistent with the data received by the line card is greater than a predetermined value, the enabling unit prevents the line card from transmitting data to the bus, and the delay time generating unit updates the delay time on the line card.
  • the line card must update the delay time each time the bus is preempted, specifically but not limited to each preemption action.
  • the “communication modules” of each board communicate through the shared “communication bus”; the “delay time generation module” of each board generates their own random delay values in real time and sends them to their respective “communication modules”.
  • the “communication module” of the board detects the “communication bus” idle, delays according to its current random delay value, and then preempts the current idle communication bus; the "communication module” of the board detects "communication” After the bus "collision, voluntarily quit.
  • an embodiment of the present invention is a line card communication system in which a half-duplex HDLC bus is connected in an SDH system device. It consists of a main communication board NCP (network processing unit), and multiple blocks (illustrated by 20 route cards in this example). The NCP board is connected to the other branch cards by a half-duplex bus. The communication between the line cards is sent in an HDLC frame, and the destination address of the HDLC frame corresponds to the board address of the line card.
  • NCP network processing unit
  • the NCP line card sends data to other tributary boards and receives data sent by each main route card.
  • Each branch card receives the data sent by the NCP board and sends data to the NCP line card. All line cards are hung on a bus.
  • Each line card can receive data from the bus. When the address of the received data is found to be the address of the line card, it indicates that the received data is sent to itself. The data is received and processed, and if not, it is discarded. Each line card is hung on the bus. To ensure the normal operation of the bus, each line card can send data to the bus if there is data transmission and the bus is not occupied by another line card. And after the data is sent, the right to use the bus is released immediately. As shown in FIG.
  • each line card needs a three-state control logic.
  • the three-state control transmission enable end the line card is turned on. Send data to the bus.
  • the transmission enable of the tri-state control terminal is turned off.
  • the control of each line card to the bus is realized, so as to ensure that each line card transmits data to the bus, the bus conflict can be reduced, the communication between the line cards is normal, and the system is robust.
  • the method includes the following steps: Step 4: S602, setting different delay times for different line cards; For example, each line card generates a random number within a certain range of values according to the principle of random number generation.
  • Step S604 when the line card is first run, it can generate an initial value of a random number based on its address at the device system. Thereafter, a new random value is obtained according to a random number generation principle.
  • Step S604 after detecting that the communication bus is idle, the line card delays according to the delay time set by the line card; for example, each line card receives a number of consecutive "1"s according to the data received on the bus according to the detection equal to the random number. It is time to judge that the bus is idle.
  • the line card can send data to the bus. Since the value generated by each line card random number is different, it can avoid two or more line cards that think that the bus is idle and simultaneously send data to the bus to cause bus collision.
  • Step S606 the line card completing the delay preempts the idle communication bus to send data to the communication bus. For example, after determining that the bus is idle, the line card updates the value of the random number every time a data frame is sent. Further, the line card with a small random value preempts the bus with a high priority, and after each frame of data is transmitted, a random value is regenerated, and the priority level of the line card preempting the bus is changed. After the line card sends a frame of data, it needs to judge whether the bus is idle according to its priority. When it is judged that the bus is idle, the next frame data can be sent. Otherwise, the bus control right is obtained by other line cards, and it is necessary to wait for other line cards to be sent.
  • the next frame of data After one frame of data, it is determined whether or not the next frame of data can be transmitted based on the detection of the bus. In addition, when it is detected that the bus collision of the transmitted data frame causes the data to be retransmitted, the number of consecutive collisions is recorded. If the number of consecutive collisions during the transmission of a certain frame is greater than a set threshold, the frame is discarded. Avoid resending, discard this frame, and regenerate the value of the random number at the same time. The next frame of data is sent at the next transmission. Further, when the line card detects that the transmitted data and the received data are inconsistent, indicating that the bus conflicts, the line card must stop transmitting the frame and wait until the bus is idle.
  • the line card When the line card sends a certain frame, if the bus continues to accumulate to a specified value in the number of collisions, it indicates that the random value of the bus decision at this time appears to be the same for two or two line cards, in order to jump out of this conflict cycle. , then this frame must abandon the retransmission of this frame and change the size of the random value.
  • the delay time mentioned above is a random number generated by the line card, according to the principle of HDLC frame transmission, the value of the set random number must be a value greater than 7, so the minimum value of the generated random number should be 7.
  • the maximum value of a random number is also set, and the maximum value is determined by the number of line cards hanged by the bus, so that the value range of the random value is slightly larger than the number of line cards. Further, the generation of random numbers should try to make the random values generated by each line card different.
  • Each line card can obtain the random value by the FCS school-risk result value of the HDLC frame for which data is transmitted. According to the total number of line cards in the example, determine the value range of the random number of the line card to determine that the bus is idle. According to the HDLC frame definition, the value range is greater than or equal to 7, and according to the actual number of line cards, the value range is 21.
  • the value range of this example is positioned [8, 31].
  • the upper limit of the value range can be further increased (theoretically It can be infinitely large.
  • the expansion of the value range can further reduce the probability of waiting for the idle period value between the two line cards to be equal, and reduce the possibility of bus data collision.
  • the larger the range of random number values The longer the line card waits for idle time, the longer the line card will transmit data once.
  • the upper limit of the random number range is determined by the communication frequency and the idle ratio tolerance.
  • the communication frequency is the frequency of each line card preempting the bus for data transmission
  • the idle ratio tolerance refers to the maximum tolerance of the user to the ratio of the idle time of each line card to the data transmission time.
  • the random number within the selected range is generated according to the random number generation principle.
  • the line card When the line card has data to be sent, it is first necessary to detect the bus status. When the bus is idle, the right to use the bus can be obtained. For the data of the first HDLC frame initially sent by the line card, the bus consecutive "1" is detected. When the number of consecutive "1" is detected is equal to the bus idle initial judgment value of the line card, the line card regards the bus as idle, and the line card transmission enable is turned on to send data to the bus.
  • the delay time generating unit may be a random number generator for generating a delay time on the online card, especially after the online card sends the data; the bus state determining unit is respectively connected with the delay time generating unit and the bus for online The card detects that the number of consecutive "1"s in the data from the bus is greater than the delay time to determine that the bus is idle; the enabling transmitting unit can be a strobe multiplexer for when the bus is idle The line card is enabled to send data to the bus; and the conflict determination unit is configured to determine whether the line card has a data conflict when transmitting data to the bus, and there are more than four methods for determining data conflict, for example, when the line detected by the conflicting unit When the number of times the data sent by the card does not coincide with the data received by the line card is greater than a predetermined value, it is determined that a data collision occurs
  • the HDLC uses a 16-bit Cyclic Redundancy Code (CRC), and its generator polynomial is CCITT polynomial ⁇ ⁇ 16+ ⁇ ⁇ 12+ ⁇ ⁇ 5+1 , and the CRC calculated according to the actual data transmission frame.
  • CRC Cyclic Redundancy Code
  • the value of -16 is FCS, and the corresponding fixed bit is intercepted as the determination value of bus idle. Because of the randomness of data transmitted by each frame and each frame, the calculated value of CRC-16 is different according to the actual transmitted data. The decision value of the bus idle obtained from this CRC value is also random.
  • the initial value of the random value is determined by the board address, but when it transmits a frame of data, its random value is taken from the data of the HDLC frame for CRC calibration.
  • the calculation of the crc value can select an arbitrary CRC calculation formula. In this example, the calculation formula of X 16+X 12+X 5+1 is selected, and the data calculated by the CRC is selected in addition to the frame header and the end of the frame. , that is, the value of the FCS part.
  • the data portion of its calculation is shown in Figure 8. As shown in the figure, the lower 5 bits of the CRC calculation value are intercepted, and the [4:0] bits of the FCS value are set.
  • the final bus decision value bit FCS value is in accordance with the bit.
  • each line The card when the bus conflicts, when the line card detects that the received and transmitted data is inconsistent, that is, the transmitted data is "1", and the received data is "0", in order to accurately determine the bus condition, each line The card must send data to the bus according to the same clock phase. If the same system clock is sent, the data is sent to the bus with the rising edge of the clock. In order to judge the bus data in time, at the falling edge of the clock, the bus is collected. The actual data on it determines whether the data is received and sent consistently. As shown in the rising edge of the clock, the data TXD is transmitted. The TXD data is used as the input RXD through the bus. There is a certain delay on the bus. RXD has a certain delay between TXD.
  • the high-level ⁇ portion of the clock is longer than the PL portion, so that the falling edge can be sampled to the RXD after the delay Delay.
  • the line card that finds the bus conflict needs to immediately turn off the transmission enable, stop sending the frame data to the bus.
  • the bus is detected to be idle, the frame data can be resent to the bus.
  • Bus idle judgment value, and the same as other multi-line cards to seize the bus opportunity equal, in order to eliminate the multi-block line card in the conflict -> fallback -> wait for bus idle -> conflict -> fallback, resulting in a smooth bus
  • the line card continuously detects the number of bus collisions up to 5 times, the frame data to be transmitted is discarded, and the bus is guaranteed.
  • the bus control method of the present invention is not limited to the HDLC communication protocol, and may be other communication such as I2C.
  • the above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Within the principles, any modifications, equivalent substitutions, improvements, etc., are intended to be included within the scope of the present invention.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Small-Scale Networks (AREA)

Abstract

L'invention porte sur un procédé et un dispositif de commande d'un bus de communication. Le procédé comprend les opérations suivantes : un temps de retard est réglé différemment pour différentes cartes de lignes ; la carte de lignes applique un retard conformément au temps de retard réglé pour la carte de lignes lorsqu'elle détecte que le bus de communication est inactif ; la carte de lignes dont le temps de retard a expiré préempte le bus de communication inactif pour envoyer des données au bus de communication. L'invention résout le problème de forte probabilité d'occurrence de conflit dû aux procédés technologiques classiques, réduit le taux de perte de paquet de données dû à un conflit, améliore la stabilité de fonctionnement du bus et permet à un équipement correspondant de fonctionner avec une meilleure fiabilité et une meilleure stabilité.
PCT/CN2010/075492 2009-08-10 2010-07-27 Procédé et dispositif de commande de bus de communication WO2011017997A1 (fr)

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CN101626334B (zh) * 2009-08-10 2013-06-12 中兴通讯股份有限公司 通讯总线控制方法和装置
CN103116563B (zh) * 2012-11-09 2015-08-05 瑞斯康达科技发展股份有限公司 一种主机通信方法、一种主机及通信系统
CN103036754B (zh) * 2012-11-22 2015-11-04 青岛海尔空调电子有限公司 一种多联机空调通信系统及通信方法
CN103560904A (zh) * 2013-10-17 2014-02-05 烽火通信科技股份有限公司 Ipran设备中盘间告警信息的传递方法及系统
CN105591857B (zh) * 2015-03-02 2018-09-25 海信（山东）空调有限公司 一种485多主通信的方法和装置
CN105404599B (zh) * 2015-10-29 2018-05-29 南车株洲电力机车研究所有限公司 一种总线访问出错保护方法
CN105656810B (zh) * 2015-12-25 2020-02-07 北京奇虎科技有限公司 一种更新应用程序的方法及装置
CN107483304B (zh) * 2016-06-07 2020-10-30 中芯国际集成电路制造(上海)有限公司 一种总线结构
CN107634914B (zh) * 2016-07-18 2021-01-22 深圳市中兴微电子技术有限公司 一种帧流控制方法和装置
CN108365944A (zh) * 2018-03-06 2018-08-03 山东比特智能科技股份有限公司 一种半双工总线的通信方法、系统及房控系统
CN112231260B (zh) * 2020-10-21 2022-08-02 中煤科工集团重庆研究院有限公司 一种基于动态优先级的抢占式多主rs485总线通讯方法
CN113067880B (zh) * 2021-03-29 2022-11-18 中车青岛四方车辆研究所有限公司 分布式控制系统链式分时通信方法和存储介质

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