WO2021058432A1 - Détecteur de conflit pour une station d'abonné d'un système de bus série et procédé de communication dans un système de bus série - Google Patents

Détecteur de conflit pour une station d'abonné d'un système de bus série et procédé de communication dans un système de bus série Download PDF

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Publication number
WO2021058432A1
WO2021058432A1 PCT/EP2020/076297 EP2020076297W WO2021058432A1 WO 2021058432 A1 WO2021058432 A1 WO 2021058432A1 EP 2020076297 W EP2020076297 W EP 2020076297W WO 2021058432 A1 WO2021058432 A1 WO 2021058432A1
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WIPO (PCT)
Prior art keywords
bus
subscriber station
signal
conflict
block
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PCT/EP2020/076297
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German (de)
English (en)
Inventor
Florian Hartwich
Steffen Walker
Arthur Mutter
Original Assignee
Robert Bosch Gmbh
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Application filed by Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Priority to CN202080081858.9A priority Critical patent/CN114747183B/zh
Publication of WO2021058432A1 publication Critical patent/WO2021058432A1/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 a conflict detector for a subscriber station of a serial bus system and a method for detecting a bus conflict in a serial bus system that operates at a high data rate and with great error resistance.
  • a bus system is often used for communication between sensors and control units, for example in vehicles, in which data is transmitted as messages in the ISO11898-1: 2015 standard as a CAN protocol specification with CAN FD.
  • the messages are transmitted serially between the bus subscribers of the bus system, such as sensor, control unit, encoder, etc.
  • CAN FD successor system In order to solve these problems, a CAN FD successor system is currently being developed, which will be called CAN XL in the following.
  • CAN XL In the data phase of a CAN-XL frame, both bus states (0, 1) should be driven in order to achieve higher data rates.
  • a conflict detector for a subscriber station of a serial bus system and a method for detecting a bus conflict in a serial bus system which solve the problems mentioned above.
  • a conflict detector for a subscriber station of a serial bus system and a method for detecting a bus conflict in a serial bus system are to be provided, in which a high data rate and a flexible reaction to current operating states as well as a high level of error resistance of the communication can be realized.
  • the object is achieved by a conflict detector for a subscriber station of a serial bus system with the features of claim 1.
  • the conflict detector has a first filter block for filtering a signal received serially from a bus of the bus system, a second filter block for filtering a digital transmission signal that was sent serially to the bus by a communication control device of the subscriber station for a frame, and wherein the subscriber station is designed, in a first communication phase to generate bus states for the frame with a first operating mode and in a second communication phase to generate bus states for the frame with a second operating mode that differs from the first operating mode, and a detection block having a capacitor on one of them Connection, an output of the first filter block and an output of the second filter block is connected, wherein the detection block is designed to detect from a voltage on the capacitor whether the subscriber station in the second communication phase an exclusive, collision-free Has access to the bus or not.
  • a transmission conflict in the data phase can be detected from the bus signal in a very uncomplicated, yet very reliable and thus very safe manner, even if both bus states are actively driven in a frame in the data phase. This also applies if there is a superposition of driven signals on the bus, whereby "analog" levels are set on the bus, so that the resulting received signal RXD can no longer be precisely predicted.
  • the detection or detection of the bus conflict by using the bus signal can be implemented very inexpensively, since only a few additional, but inexpensive components are required for conflict detection by using existing components of the transmitting / receiving device of a subscriber station of the bus system.
  • bus conflict can be detected very precisely by using the bus signal and the transmission signal.
  • the transmitting / receiving device (transceiver) for CAN XL can guarantee a very safe operation of the bus system at an affordable price, which favors the use of CAN XL.
  • the conflict detector can be provided separately from the transmitting / receiving device (transceiver). It is possible that the bus conflict detection can also be used with currently available CAN transceivers.
  • each subscriber station of the bus system is able to disrupt or interrupt the transmission of any other subscriber station with an error frame.
  • the error frames used implement simple error handling, which in turn increases the robustness of the CAN XL protocol.
  • time can be saved in the event of an error by aborting a message currently being sent and then transferring other information on the bus. This is particularly useful for frames that are longer than a CAN FD frame with 64 bytes in the data phase, especially for frames that should contain 2-4 KB or more.
  • the conflict detector can be used to ensure that the frames are received with great flexibility with regard to current events in the operation of the bus system and with a low error rate, even if the amount of user data per frame increases.
  • communication in the serial bus system can also take place with a high level of error resistance if there is a high data rate and an increase in the amount of useful data per frame. Therefore, with the conflict detector in the bus system, it is possible in particular to maintain an arbitration known from CAN in a first communication phase and nevertheless to increase the transmission rate again considerably compared to Classical CAN or CAN FD.
  • the size of the user data can be up to 4096 bytes per frame. Of course, any other values for the number of bytes per frame are possible, in particular 2048 bytes or some other value.
  • the method carried out by the conflict detector can also be used if the bus system also has at least one CAN FD-tolerant CAN subscriber station, which is designed in accordance with the ISO 11898-1: 2015 standard, and / or at least one CAN FD subscriber station that send messages according to the Classical CAN protocol and / or CAN FD protocol.
  • the conflict detector can also be used with CAN FD to replace or supplement the transmitter delay compensation function used there. With such a function, the TLD runtime is compensated for by the TxD signal via the transceiver to the RxD signal.
  • the TLD runtime can also be referred to as Transmitter Loop Delay (TLD).
  • the detection block is designed to indicate with a conflict display signal for the communication control device when the detection block detects that the subscriber station does not have exclusive, collision-free access to the bus in the second communication phase.
  • the detection block is designed to increase the voltage on the capacitor with a predetermined voltage threshold Compare to determine whether the subscriber station does not have exclusive, collision-free access to the bus in the second communication phase.
  • the first filter block has a first low-pass filter and a first voltage-current converter, the first voltage-current converter being connected downstream of the first low-pass filter, the second filter block having an inverter, a second low-pass filter and a second voltage Having current converter, wherein the second voltage-current converter is connected downstream of the second low-pass filter, and wherein the capacitor is connected to the output of the first voltage-current converter and the output of the second voltage-current converter.
  • the second low-pass filter can be configured to filter the transmission signal more strongly in the event that the number of 1 states in the transmission signal increases than in the event that the number of 0 states in the transmission signal increases.
  • the first low-pass filter may have a filter time constant that is less than the number of bit times that an error frame lasts.
  • the second low-pass filter can have a filter time constant that is smaller than the number of bit times that an error frame lasts.
  • the capacitor can be connected in parallel to a resistor, the second connection of the resistor being connected to ground.
  • the conflict detector also optionally has a plausibility check block, the plausibility check block being designed to check at least twice in the duration of an error frame whether the subscriber station does not have exclusive, collision-free access to the bus in the second communication phase.
  • the conflict detector described above can be part of a subscriber station for a serial bus system, which also has a communication control device for Controlling a communication of the subscriber station with at least one other subscriber station of the bus system, and a transmitting / receiving device for transmitting one of the
  • Communication control device for a frame generated signal on a bus of the bus system and for receiving a signal from the bus, wherein the transmitting / receiving device generates bus states for the frame with a first operating mode in a first communication phase and bus states for the frame with in a second communication phase a second operating mode, which differ from the first operating mode.
  • the conflict detector is connected in a receiving block of the transmitting / receiving device after a voltage divider in order to tap the signal received serially from the bus as a divided signal.
  • the bus states of the signal received from the bus in the first communication phase can be longer, in particular have a longer bit time, than the bus states of the signal received in the second communication phase. Additionally or alternatively, the bus states of the signal received from the bus in the first communication phase were generated with a different physical layer than the bus states of the signal received in the second communication phase.
  • the communication control device is configured to output a switch-on signal to the conflict detector in order to switch on the conflict detector only for the second communication phase and to switch it off for the first communication phase, or to switch the conflict detector from one communication phase to another.
  • the subscriber station described above can be part of a bus system which also comprises a bus and at least two subscriber stations which are connected to one another via the bus in such a way that they can communicate with one another serially. In this case, at least one of the at least two subscriber stations is a previously described subscriber station.
  • the aforementioned object is also achieved by a method for communication in a serial bus system according to claim 15.
  • the method is carried out with a conflict detector for a subscriber station of the serial bus system, the conflict detector executing the steps of filtering, with a first filter block, a signal received serially from a bus of the bus system, filtering, with a second filter block, a digital transmission signal that was sent serially to the bus by a communication control device of the subscriber station for a frame, and wherein the subscriber station generates bus states for the frame with a first operating mode in a first communication phase and generates bus states for the frame with a second operating mode in a second communication phase, which differs from the first operating mode is different, and
  • Detecting with a detection block, a voltage on a capacitor of the detection block, an output of the first filter block and an output of the second filter block being connected to a connection of the capacitor, and wherein in the step of detecting it is detected whether the subscriber station is in the second Communication phase has exclusive, collision-free access to the bus or not.
  • the method offers the same advantages as mentioned above with regard to the conflict detector and / or the subscriber station.
  • FIG. 1 shows a simplified block diagram of a bus system according to a first exemplary embodiment
  • FIG. 2 shows a diagram to illustrate the structure of messages that can be sent by a transmitting / receiving device for a subscriber station of the bus system according to the first exemplary embodiment
  • FIG. 3 shows a simplified schematic block diagram of a subscriber station of the bus system according to the first exemplary embodiment
  • FIG. 8 shows a simplified schematic block diagram of a conflict detector for a subscriber station of the bus system according to the first exemplary embodiment
  • FIG. 9 shows a time profile of a transmission signal TxD1 in a data phase of a message which is sent by a first subscriber station of the bus system according to the first exemplary embodiment
  • FIG. 10 shows a time profile of a transmission signal TxD2 which is sent by another subscriber station in order to abort the transmission signal TxD1 from FIG. 8;
  • 11 to 13 show a time profile of signals which arise on the basis of the transmit signals TxD1, TxD2 from FIGS. 9 and 10 in the bus system according to the first exemplary embodiment;
  • FIG. 14 shows a simplified schematic block diagram of an interconnection of the conflict detector with the reception block of a transceiver for a subscriber station of the bus system according to a second exemplary embodiment
  • 16 shows a simplified schematic block diagram of a conflict detector according to a third exemplary embodiment.
  • FIG. 1 shows a bus system 1 which, in particular, is fundamentally designed for a Classical CAN bus system, a CAN FD bus system, a CAN XL bus system, and / or modifications thereof, as described below.
  • the bus system 1 can be used in a vehicle, in particular a motor vehicle, an airplane, etc., or in a hospital, etc. use.
  • the bus system 1 has a multiplicity of subscriber stations 10, 20, 30, each of which is connected to a bus 40 with a first bus wire 41 and a second bus wire 42.
  • the bus wires 41, 42 can also be called CAN_H and CAN_L or CAN-XL_H and CAN-XL_L and are used for electrical signal transmission after coupling in the differential level or dominant level or generating recessive levels for a signal in the transmission state.
  • Messages 45, 46 in the form of signals between the individual subscriber stations 10, 20, 30 can be transmitted serially via bus 40.
  • the subscriber stations 10, 20, 30 are, for example, control devices, sensors, display devices, etc. of a motor vehicle.
  • an error frame 47 (Error Flag) are sent.
  • the error frame 47 consists, for example, of six dominant bits.
  • An error-free message 45, 46 is confirmed by the recipients by an acknowledge bit, which is a dominant bit that is driven in an acknowledge time slot sent recessively by the sender. Except for the acknowledge time slot, the sender of a message 45, 46 expects that he always sees the level on bus 40 that he himself is sending. Otherwise, the sender of the message 45, 46 recognizes a bit error and considers the message 45, 46 to be invalid. Unsuccessful messages 45, 46 are repeated.
  • the subscriber station 10 has a
  • the subscriber station 20 has a communication control device 21, a transmitting / receiving device 22 and optionally a conflict detector 25.
  • the subscriber station 30 has a communication control device 31, a transmitting / receiving device 32 and a conflict detector 35.
  • the transmitting / receiving devices 12, 22, 32 of the subscriber stations 10, 20, 30 are each connected directly to the bus 40, even if this is not illustrated in FIG.
  • the communication control devices 11, 21, 31 each serve to control communication between the respective subscriber station 10, 20, 30 via the bus 40 with at least one other subscriber station of the subscriber stations 10, 20, 30 that are connected to the bus 40.
  • the communication control device 11 creates and reads first messages 45, which are modified CAN messages 45, for example.
  • the modified CAN messages 45 are structured on the basis of a CAN XL format, which is described in more detail with reference to FIG. 2.
  • the communication control device 21 can be designed like a conventional CAN controller according to ISO 11898-1: 2015, with the exception of the differences described in more detail below.
  • the communication control device 21 creates and reads second messages 46, for example Classical CAN Messages 46.
  • the Classical CAN messages 46 are structured according to the Classical basic format, in which the message 46 can contain a number of up to 8 data bytes.
  • the CAN message 46 is structured as a CAN FD message, in which a number of up to 64 data bytes can be included, which are also transmitted at a significantly faster data rate than in the case of the classical CAN message 46.
  • the communication control device 21 is designed like a conventional CAN FD controller.
  • the communication control device 31 can be designed to provide a CAN XL message 45 or a Classical CAN message 46 for the transmitting / receiving device 32 or to receive it from it, as required.
  • the communication control device 31 thus creates and reads a first message 45 or second message 46, the first and second messages 45, 46 differing in their data transmission standard, namely in this case CAN XL or CAN.
  • the Classical CAN message 46 is structured as a CAN FD message. In the latter case it is
  • Communication control device 31 designed like a conventional CAN FD controller.
  • the transmitting / receiving device 12 can be designed as a CAN XL transceiver, with the exception of the differences described in more detail below.
  • the transmitting / receiving device 22 can be designed like a conventional CAN transceiver or CAN FD transceiver.
  • the transmitting / receiving device 32 can be designed to provide messages 45 in accordance with the CAN XL format or messages 46 in accordance with the current CAN basic format for the communication control device 31 or to receive them from it, as required.
  • the transmitting / receiving devices 12, 32 can additionally or alternatively be designed like a conventional CAN FD transceiver.
  • FIG. 2 shows a CAN XL frame 450 for the message 45, as it is sent by the transmitting / receiving device 12 or the transmitting / receiving device 32.
  • the CAN XL frame 450 is divided into different communication phases 451 to 453 for the CAN communication on the bus 40, namely an arbitration phase 451, a data phase 452 and a frame end phase 453.
  • an identifier is used to negotiate bit by bit between the subscriber stations 10, 20, 30 which subscriber station 10, 20, 30 would like to send the message 45, 46 with the highest priority and therefore for the next time to send in the subsequent data phase 452 gets exclusive access to bus 40 of bus system 1.
  • the user data of the CAN-XL frame or the message 45 are sent.
  • the useful data can have, for example, up to 4096 bytes or a larger value in accordance with the value range of a data length code.
  • a checksum field can contain a checksum over the data of data phase 452 including the stuff bits that are received from the send block of message 45 after a predetermined number of identical bits, in particular 10 or a different number of identical bits, as the inverse Bit can be inserted.
  • a reintegration pattern can be included which enables the receiving subscriber stations to find the beginning of the frame end phase 453 after an error.
  • at least one acknowledge bit can be contained in an end field in the frame end phase 453. The at least one acknowledge bit can be used to indicate whether or not a recipient has discovered an error in the received CAN XL frame 450 or message 45.
  • a physical layer is used as in the case of Classical CAN and CAN FD.
  • the physical layer corresponds to the bit transmission layer or layer 1 of the well-known OSI model (Open Systems Interconnection Model).
  • the known CSMA / CR method is used, which allows the subscriber stations 10, 20, 30 to access the bus 40 at the same time without the higher-priority message 45, 46 being destroyed. As a result, further bus subscriber stations 10, 20, 30 can be added to bus system 1 relatively easily, which is very advantageous.
  • a send block 121 according to FIG. 3 for sending the message 45 begins sending bits of the data phase 452 on the bus 40 only when the subscriber station 10 of the send block 121 has won the arbitration and the subscriber station 10 of the send block 121 thus has exclusive access to send on bus 40 of bus system 1.
  • bus system 1 with CAN XL compared to Classical CAN or CAN FD: a) Adoption and, if necessary, adaptation of proven properties that are responsible for the robustness and user-friendliness of Classical CAN and CAN FD, in particular Frame structure with identifier and arbitration according to the CSMA / CR method, b) increase the net data transmission rate to about 10 megabits per second, c) increase the size of the user data per frame to any length, for example up to about 4 kbytes.
  • Fig. 3 shows the basic structure of the subscriber station 10 with the communication control device 11, the transmitting / receiving device 12 and the conflict detector 15.
  • the conflict detector 15 has a first filter block 151, a second filter block 152 and a detection block 153.
  • the subscriber station 30 is constructed in a manner similar to that shown in FIG. 3, except that the conflict detector 35 is not integrated in the transceiver 32, but is provided separately from the communication control device 31 and the transceiver 32. If the detector 25 is present, the transmitter / receiver device 22 is constructed identically to the transmitter / receiver device 12 with respect to the detector 15. The subscriber stations 20, 30 and the conflict detectors 25, 35 are therefore not described separately. The functions of the conflict detector 15 described below are identical in the conflict detectors 25, 35.
  • ASIC application-specific integrated circuit
  • SBC system base chip
  • an energy supply device 17 is installed in the system ASIC 16, which supplies the transmitting / receiving device 12 with electrical energy.
  • the energy supply device 17 usually supplies a voltage CAN_Supply of 5 V from a connection 43. However, depending on requirements, the energy supply device 17 can supply a different voltage with a different value. Additionally or alternatively, the energy supply device 17 can be configured as a power source.
  • the transmitting / receiving device 12 also has a transmitting block 121 and a receiving block 122. Even if the transmitting / receiving device 12 is always referred to below, it is alternatively possible to provide the receiving block 122 in a separate device external to the transmitting block 121.
  • the transmission block 121 and the reception block 122 can be constructed in the same way as in a conventional transmission / reception device 22.
  • the Transmission block 121 can in particular have at least one operational amplifier and / or one transistor.
  • the receiving block 122 can in particular have at least one operational amplifier and / or one transistor.
  • the transmitting / receiving device 12 is connected to the bus 40, more precisely its first bus core 41 for CAN_H or CAN-XL_H and its second bus core 42 for CAN_L or CAN-XL_L.
  • the voltage supply for the energy supply device 17 for supplying the first and second bus wires 41, 42 with electrical energy, in particular with the CAN supply voltage, takes place via at least the connection 43.
  • the connection to ground or CAN_GND is implemented via a connection 44.
  • the first and second bus wires 41, 42 are terminated with a terminating resistor 49.
  • the first and second bus wires 41, 42 are connected in the transmitting / receiving device 12 not only to the transmitting block 121, which is also referred to as a transmitter, and to the receiving block 122, which is also referred to as the receiver, even if the connection in FIG 3 is not shown for the sake of simplicity.
  • the signals CAN_H, CAN_L of the first and second bus wires 41, 42 in the transmitting / receiving device 12 are also available for the conflict detector 15.
  • the first and second bus wires 41, 42 in the transmitting / receiving device 12 can also be connected to the conflict detector 15. This is described in more detail below with reference to FIG. 8.
  • the transmission block 121 in the transmission operation of the transmission / reception device 12, a transmission signal TXD or TxD of the communication control device 11 with digital states 0 (state L) and 1 (state H) in corresponding signals Data_0 and Data_l for the bus wires 41, 42 implement.
  • the transmission signal TXD or TxD is illustrated schematically in FIG. 3 and more precisely in FIG. 4.
  • the transmission block 121 can then send these signals Data_0 and Data_l according to FIG. 4 to the connections for CAN_H and CAN_L or CAN-XL_H and CAN-XL_L on the bus 40, as shown in FIG. 5.
  • the reception block 122 of FIG. 3 forms bus signals received from the bus 40 at the connections CAN_H, CAN_L on CAN-XL_H and CAN-XL_L 5, a differential voltage VDIFF according to FIG. 6 and converts this into a received signal RXD or RxD with digital states 0 (state L) and 1 (state H), as schematically illustrated in FIG. 3 and as in FIG. 7 in more detail shown.
  • the reception block 122 of FIG. 3 forwards the reception signal RXD or RxD to the communication control device 11, as shown in FIG. 3. With the exception of an idle or standby state (idle or standby), the transmitting / receiving device 12 with the receiving block 122 always listens to a transmission of data or messages 45 in normal operation,
  • the transmission / reception device 12 sets a transmission signal TXD or TxD of the communication control device 11 according to FIG. 4 into corresponding signals CAN-XL_H and CAN-XL_L for the bus wires 41, 42 and sends these signals CAN-XL_H and CAN-XL_L to the connections for CAN_H and CAN_L on the bus 40, as shown in FIG. 5.
  • a differential voltage VDIFF CAN-XL_H - CAN-XL_L is formed on bus 40 over time t, the course of which is shown in FIG. 6.
  • the sequence of the data states H, L from FIG. 4 and thus the resulting bus states U_D0, U_D1 for the signals CAN-XL_H, CAN-XL_L in FIG. 5 and the resulting curve of the voltage VDIFF from FIG. 6 and the received signal RxD 7 only serves to illustrate the function of the transmitting / receiving device 12.
  • the sequence of the data states H, L from FIG. 4 and thus the resulting bus states U_D0, U_D1 in FIG. 5 and the signals from FIG. 6 and FIG 7 can be selected as required.
  • the transmitting / receiving device 12 forms the received signal RXD or RxD from the signals CAN-XL_H and CAN-XL_L received from the bus 40 with receiving thresholds T_u, T_d according to FIG. 6, as shown in FIG. 7 over time t.
  • At least one reception threshold T_u is used for phases 451, 453, which is in the hatched area in the left Part of Fig. 6 is located.
  • the transmitting / receiving device 12 uses the first reception threshold T_u, known from Classical CAN / CAN FD, with the typical position of 0.7 V according to ISO11898-2: 2016, around the To be able to reliably recognize bus states 401, 402 in the first operating mode.
  • T_u known from Classical CAN / CAN FD
  • a switch is made to at least one reception threshold T_d, which lies in the hatched area in the right-hand part of FIG.
  • the transmitting / receiving device 12 forwards the received signal RXD or RxD to the communication control device 11, as shown in FIG. 3.
  • the signals CAN-XL_H and CAN-XL_L have the dominant ones in the aforementioned communication phases 451, 453 corresponding to the states H (high), L (low) of the transmission signal TxD from FIG. 4 Bus level 401 and recessive bus level 402, as known from CAN.
  • the signals CAN-XL_H and CAN-XL_L according to FIG. 5 differ in the data phase 452 from the conventional signals CAN_H and CAN_L.
  • the bus levels U_D1, U_D0 are now actively driven in accordance with the data states H, L of the transmission signal TXD.
  • the difference signal VDIFF CAN-XL_H - CAN-XL_L is formed on bus 40, as shown in FIG. 6.
  • a switch is made from a first bit time T_btl in phases 451, 453 to a second bit time T_bt2 in phase 452.
  • the first bit time T_btl can be greater than the second bit time T_bt2, even if this is not shown in FIGS. 4 to 7 for the sake of simplicity.
  • the bits of the signals in phases 451, 453 are transmitted more slowly than in data phase 452.
  • the second bit time T_bt2 has the value 100 ns.
  • the bit duration T_bt2 in the data phase 452 in the example of FIGS. 4 to 7 described above is significantly shorter than the bit duration T_btl that is used in the arbitration phase 451 and the frame end phase 453.
  • the transmitting / receiving device 12 is thus switched from the state which corresponds to the left part of FIG. 5 for the data phase 452 to the state which corresponds to the right part of FIG. 5.
  • the transmitting / receiving device 12 is thus switched from a first operating mode to a second operating mode.
  • FIG. 8 shows a structure of the conflict detector 15, which can be used for an operating case in the data phase 452, which is illustrated with reference to FIGS. 9 to 13 and is described below.
  • the conflict detector 15 of Fig. 8 has a low-pass filter 1511 and a voltage-to-current converter 1512 in the first filter block 151.
  • the second filter block 151 has a low-pass filter 1521 and a voltage-to-current converter 1522.
  • the detection block 153 has a resistor 1531 and a capacitor 1532 connected in parallel.
  • the detection block 153 has a detector 1533, the input of which is connected to the output of the first filter block 151 and to the output of the second filter block 152.
  • the input of the detector 1533 is connected to the end of the parallel circuit comprising resistor 1531 and capacitor 1532, which is connected to the output of the first filter block 151 and to the output of the second filter block 152.
  • the other end of the parallel circuit made up of resistor 1531 and capacitor 1532 is connected to a connection 43 for system ground CAN_GND.
  • a voltage U_C is applied to the capacitor 1532 and thus to the detector 1533.
  • the detector 1533 If the detector 1533 detects or detects by evaluating the voltage U_C that a collision with an error frame 47 occurs on the bus 40, the detector 1533 generates a corresponding state in a conflict display signal S_K.
  • the collision detector 15 can thus indicate the collision and thus the conflict on the bus 40 with the conflict indication signal S_K, as described below.
  • the conflict indication signal S_K can in particular be sent to the communication control device 11 via the connection RxD or via an additional connection.
  • the conflict detector 15 receives the differential voltage VDIFF with the first filter block 151 and forms it with the low-pass filter 1511 is a filtered differential voltage VDIFF_F shown in FIG.
  • the voltage-to-current converter 1512 converts the filtered differential voltage VDIFF_F into an electrical current II, which charges the capacitor 1532.
  • the conflict detector 15 receives the transmission signal TxD with the second filter block 152 and uses it to form an inverted transmission signal with an inverter 1520 and a filtered inverted transmission signal TxD_F with the low-pass filter 1521, more precisely a filtered inverted transmission signal voltage TxD_F, which is shown in FIG. 9.
  • the voltage-to-current converter 1522 converts the filtered inverted transmission signal TxD_F into an electrical current I2, which discharges the capacitor 1532.
  • the differential voltage VDIFF charges the capacitor 1532, the inverted signal TxD discharges the capacitor 1532. If both signals have the same signal profile, the voltage U_C on the capacitor remains at 0V.
  • VDIFF has more logical O levels (VDIFF> 0) than are sent via the transmit signal TxD, the capacitor 1532 is charged and U_C rises until the conflict is recognized on the bus 40.
  • the total current 13 at the capacitor 1532 is calculated according to equation (1) as
  • Slight deviations between currents II and 12 can be dissipated with resistor 1531.
  • a mismatch between the two voltage / current converters 1512, 1522 of FIG. 8 can thereby be compensated for.
  • the predetermined voltage threshold T_K can be configured by a user.
  • the predetermined voltage threshold T_K is preferably determined taking into account the signal profiles from FIGS. 9 to 13.
  • the transmitting / receiving device 12 sends the transmission signal TxDl as a transmission signal TxD for a frame 450, whereby, for example, the subscriber station 30, which in the data phase 452 is actually only the recipient of the frame 450 would like to achieve an abortion of the frame 450 and therefore sends the transmit signal TxD2.
  • a transmission conflict thus occurs on bus 40 in which subscriber station 10 no longer has exclusive, collision-free access to bus 40 in data phase 452.
  • the subscriber station 30 as an RX subscriber station has to send a message 45, 46 with a higher priority, and / or
  • CAN-XL subscriber stations for example the subscriber stations 10, 30 inadvertently use the same identifier and thus both send in the data phase 452. If, for example, the subscriber station 30 would like to abort the frame 450 which the transceiver 12 sends with the signal TxDl of FIG. 9, the subscriber station 30 sends the transmit signal TxD2 according to FIG. 10 to the bus 40 Sending the error frame 47, which begins with the falling edge of the transmission signal TxD2 at a point in time t2, therefore results in voltage states for CAN_XL_H, CAN_XL_L on bus 40 according to FIG. 11 and FIG. 12, which depend on the voltage states on bus 40 in normal operation the data phase 452 according to FIG.
  • the sending subscriber station that sends the send signal TxD1 switches to a send operating mode in the data phase 452 for driving the bus wires 41, 42.
  • the at least one reception threshold Td shown in FIG. 11 is switched on for all receiving subscriber stations, such as subscriber stations 10, 30.
  • the bus driver of the only receiving subscriber station 30 remains in the passive receiving state (CAN recessive state) until the receiving subscriber station 30 possibly sends the error frame 47, as shown in FIG. 10 for the transmit signal TxD2 and mentioned above.
  • the error frame 47 according to the right-hand part of FIG. 10 will then be actively sent as "dominant".
  • an error frame 47 is represented by the stringing together of 6 or more (depending on the bit stuffing method) bits with positive VDIFF, as was the case with CAN / CAN FD.
  • the transient course of the differential voltage VDIFF changes very sharply in the sequence shown in FIG. 11.
  • a bit with a positive differential voltage VDIFF that is to say the bus state U_D1
  • the positive differential voltage VDIFF is increased.
  • the resulting voltage value for the bus state U_D0 depends heavily on the parameters of the driving transmitting / receiving devices 12, 22, 32 or of the transmitter 121, as well as the arrangement of the terminating resistors 49.
  • the conflict detector 15 of FIG. 8 therefore compares the voltage U_C with the voltage threshold T_K of FIG. 12 with the detector block 1533.
  • the capacitor 1532 is no longer charged. As a result, the voltage U_C remains at around 0V.
  • the voltage U_C is also checked and / or compared by the detector block 1533 with the voltage threshold T_K from FIG. 12. If the voltage threshold T_K of FIG. 12 is not exceeded by the voltage U_C, then this is interpreted in such a way that there is no collision with an error frame 47.
  • the signal VDIFF im is detected by the conflict detector 15, 25, 35 and low-pass filtered.
  • the output of the low pass filter 1511 is observed. If the output signal of the low-pass filter 1511 increases, this can have the following causes: 1.) An error frame 47 was sent to the bus 40 by another subscriber station 10, 20, 30.
  • the data sent by the subscriber station 10 contain more 0 states (L states) than in the last measurement or detection, which would also lead to an increase in the filtered differential voltage VDIFF_F.
  • the inverted TxD signal is also low-pass filtered.
  • the output of the low pass filter 1521 is observed. If the voltage VDIFF_F rises while the signal TxD_F remains the same, this must be due to 1.), that is, an error frame 47 is present.
  • the filter time constant tau_TP for each of the low-pass filters 1512, 1522 is designed according to the following rule:
  • the filter time constant tau_TP for each of the low-pass filters 1512, 1522 should therefore be greater than the transit time TLD but less than 6 bit times T_btl for bits in the phases 451, 453.
  • the conflict detector 15 is configured in such a way that the low-pass filtering of the transmission signal TxD is configured asymmetrically.
  • the transmission signal TxD is filtered more intensely with the low-pass filter 1521 when the 1 or H states in the transmission signal TxD increase than the transmission signal TxD is filtered when the 0 or L states in the transmission signal TxD increase.
  • the filter time constant tau_TP of the second low-pass filter 1522 is thus variable in the operation of the bus system 1. This will balance the following two cases.
  • the current I2 formed from the filtered inverted transmission signal TxD_F would increase earlier than the current II formed from the filtered signal VDIFF_F avoids that an error frame 47 is erroneously recognized when the filtered voltage VDIFF_F increases.
  • TLD Propagation Delay
  • the communication control device 11 reacts in the data phase 452 to the send conflict or bus conflict signaled with the signal S_K with the termination of the data phase 452 and possibly also with the sending of a bit pattern, for example an error frame 47, which tells the other subscriber stations 20, 30 the end of the data phase 452 signals.
  • the communication control device 11 switches back to the arbitration phase 451.
  • the conflict can be signaled in the data phase 452 by the conflict display signal S_K from the respective transceiver 22, 32 to the associated
  • the signal can be the received signal RXD, which the corresponding transceiver 22 or the conflict detector 35 predetermine Modified bit pattern to signal conflict.
  • the corresponding transmitting / receiving device 22, 32 or the conflict detector 25, 35 can generate a separate signal that is sent via a separate signal line to the associated communication control device 21, 31 and in particular at least one switching pulse or a predetermined bit pattern for signaling the Has conflict.
  • the conventional CAN bit error check can be replaced by comparing the send signal TXD with the receive signal RXD by checking the conflict indication signal S_K.
  • the conflict display signal S_K has, in particular, a predetermined bit pattern which signals or displays the transmission conflict or bus conflict.
  • the conflict indication signal S_K can send a T as an "OK signal” and an 'O' as a "conflict message".
  • the design of the transmitting / receiving device 12 is used both for homogeneous CAN-XL bus systems in which only CAN XL messages 45 and no CAN FD messages 46 are sent, and for mixed bus systems can be used in which either CAN XL messages 45 or CAN FD messages 46 are sent.
  • the transmitting / receiving device 12 can therefore be used universally.
  • conflict detector 15 does not require any information about the number of bits in a phase, in particular the data phase 452.
  • the conflict detector 15 is implicitly able to detect additional edge changes that are only expected in the event of a bus conflict. This is because additional edges in the RxD signal generated by the bus conflict would lead to the evaluation logic of the communication control device III getting mixed up.
  • 14 shows a configuration of a reception block 122 which is interconnected with a conflict detector 15A according to a second exemplary embodiment.
  • the receiving block 122 has a voltage divider 1221 provided on the input side on the bus wires 41, 42, a bias module 1222, a receiving comparator 1223 and a comparator 1224 for a wake-up circuit 126.
  • the wake-up circuit 126 can implement an energy-saving mode in which the receiving block 122 is only supplied with electrical power when communication takes place on bus 40.
  • a node in the receive comparator 1223 of the receive block 122 can be selected for tapping the signal VDIFF_D.
  • the circuit for the conflict detector 15A of Fig. 8 can be implemented in the low voltage range (5V range). This reduces the semiconductor area requirement of the transmitting / receiving device 12. This reduces the space requirement and the costs for the transmitting / receiving device 12, which is very advantageous.
  • the communication control device 11 and / or the transmitting / receiving device 12 sends an enable signal or switch-on signal S_E to the conflict detector 15A if the conflict detector 15A is only to work during a valid transmission process.
  • the conflict detector 15A is only to work during a valid transmission process.
  • Communication control device 11 can be configured to output a switch-on signal S_E to conflict detector 15A in order to switch on conflict detector 15A only for data phase 452 and to switch it off for the other phases 451, 453.
  • the conflict detector 15A is switched from one communication phase to another communication phase with the signal S_E.
  • 15 shows a configuration of a reception block 1220 which is interconnected with the conflict detector 15A according to the second exemplary embodiment. In this case, the signal VDIFF_D divided down by the voltage divider 1221 for the conflict detector 15 is not tapped in the receiving comparator 1223, but rather directly after the voltage divider 1221.
  • the circuit for the conflict detector 15A of FIG. 8 can be implemented in the low-voltage range (5V range), so that the same advantages with regard to the semiconductor area requirement of the transceiver 12 can be achieved.
  • FIG. 16 shows a configuration of a conflict detector 15B according to a third embodiment.
  • the query of the detector result is repeated several times, but at least twice, within the time of a possible error frame 47.
  • the time of a possible error frame 47 lasts, for example, 6 time periods T_btl of a bit of the arbitration phase 451.
  • the conflict detector 15B of the present exemplary embodiment also has a plausibility check block 1534 in its detection block 153B at the output of the conflict detector 15B.
  • the plausibility check block 1534 has at least one flip-flop 341, 342 which is connected as a shift register. Only when a predetermined number of U_C levels has been recognized, which indicate a conflict on bus 40, is a conflict with an error frame 47 recognized. As a result, the conflict detector 15B can signal the conflict with the conflict indication signal S_K, as described in the previous exemplary embodiments.
  • the conflict detector 15B can, in comparison with the conflict detector 15 from FIG. 8, additionally increase the security against incorrect triggering of the conflict detector 15A.
  • the conflict detector 15A generated conflict display signal S_K even more precisely and detects the conflict on bus 40 even more reliably than in the previous exemplary embodiments.
  • the invention can be used in any communication network and / or communication method in which two different communication phases are used in which the bus states that are generated for the different communication phases differ.
  • the invention can be used in the development of other serial communication networks, such as in particular Ethernet, field bus systems, etc.
  • the bus system 1 can be a communication network in which data can be transmitted serially at two different bit rates. It is advantageous, but not a mandatory requirement, that in the bus system 1 an exclusive, collision-free access of a subscriber station 10, 20, 30 to a common channel is guaranteed at least for certain periods of time.
  • the number and arrangement of the subscriber stations 10, 20, 30 in the bus system 1 of the exemplary embodiments is arbitrary.
  • the subscriber station 20 in the bus system 1 can be omitted.
  • one or more of the subscriber stations 10 or 30 can be present in the bus system 1.
  • all subscriber stations in the bus system 1 are configured identically, that is to say only subscriber station 10 or only subscriber station 30 are present. All variants described above for the detection of the bus conflict can be subject to time filtering in order to increase the robustness with regard to electromagnetic compatibility (EMC) and against electrostatic charge (ESD), pulses and other disturbances.
  • EMC electromagnetic compatibility
  • ESD electrostatic charge

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Abstract

L'invention porte sur un détecteur de conflit (15 ; 15A ; 15B ; 25 ; 35) pour un système de bus série (1), et sur un procédé de détection d'un conflit de bus dans un système de bus série (1). Le détecteur de conflit (15 ; 15A ; 15B ; 25 ; 35) comporte un premier bloc de filtrage (151) pour filtrer un signal (VDIFF) reçu en série en provenance d'un bus (40) du système de bus (1), un second bloc de filtrage (152) pour filtrer un signal émis numérique (TxD ; TxD1) qui a été envoyé en série au bus (40) par un dispositif de commande de communication (11) de la station d'abonné (10 ; 20 ; 30) pour une trame (450), la station d'abonné (10 ; 20 ; 30) étant conçue pour produire des états de bus (401 ; 402) pour la trame (450) en utilisant un premier mode dans une première phase de communication (451 ; 453, 451) et pour produire des états de bus (401 ; 402 ; U_D0 ; U_D1) pour la trame (450) en utilisant un second mode, qui diffère du premier mode, dans une seconde phase de communication (452), et un bloc de détection (153 ; 153A) qui comporte un condensateur (1532), dont une borne est connectée à une sortie du premier bloc de filtre (151) et à une sortie du second bloc de filtre (152), le bloc de détection (153 ; 153A) étant conçu pour détecter, d'après une tension (U_C) aux bornes du condensateur (1532), si la station d'abonné (10 ; 20 ; 30) a un accès exclusif sans conflit au bus (40) dans la seconde phase de communication (452).
PCT/EP2020/076297 2019-09-26 2020-09-21 Détecteur de conflit pour une station d'abonné d'un système de bus série et procédé de communication dans un système de bus série WO2021058432A1 (fr)

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DE102021207186A1 (de) 2021-07-08 2023-01-12 Robert Bosch Gesellschaft mit beschränkter Haftung Empfangsmodul und Verfahren zum Empfangen von differentiellen Signalen in einem seriellen Bussystem
DE102021207196A1 (de) * 2021-07-08 2023-01-12 Robert Bosch Gesellschaft mit beschränkter Haftung Empfangsmodul und Verfahren zum Empfangen von differentiellen Signalen in einem seriellen Bussystem

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