Communication control device for a subscriber station for a serial bus system and method for communicating in a serial bus system

Abstract

A communication control device for a subscriber station for a serial bus system and a method for communicating in a serial bus system are provided. The communication control device is designed to control communication of the subscriber station with at least one other subscriber station of the bus system and to generate a transmission signal for transmission onto a bus of the bus system and / or to receive a signal from the bus, wherein the communication control device is designed to generate the transmission signal in accordance with a frame in which a bit having a predetermined time length is provided, wherein the communication control device is designed to generate the transmission signal such that the bit of the transmission signal can be transmitted onto the bus as an explicit state or an implicit state, whereby the implicit state can be overwritten by the explicit state.

Description

Technical Field

[0001] The present invention relates to a communication control device for a user station in a serial bus system and a method for communication in a serial bus system that operates with high data rates and high error robustness. Background Technology

[0002] For example, a bus system in a vehicle used for communication between sensors and control devices should be able to transmit large amounts of data, depending on the number of technical devices or the vehicle's functions. In many applications, it is required to transmit data from the transmitter to the receiver at the highest possible data transmission rate.

[0003] For vehicles, the CAN bus system is currently in the introduction phase. In this system, data is transmitted as messages using CAN FD, conforming to the standard ISO 11898-1:2015 CAN protocol specification. These messages are transmitted between bus users, such as sensors, control devices, and transmitters. To achieve this, a message is sent to the bus within a single frame, switching between two communication phases. In the first communication phase (arbitration), it is agreed which user station in the bus system is permitted to send its frame to the bus in the subsequent second communication phase (data phase or transmission of valid data). Most manufacturers use CAN FD in vehicles at an arbitration bit rate of 500 kbit / s and a data bit rate of 2 Mbit / s in the first step. Therefore, transmission on the bus requires switching between slow and fast operating modes.

[0004] To achieve even higher data rates in the second communication phase, a follow-up bus system for CAN FD has been developed, known as CAN XL and currently standardized as Automation (CiA) within the CAN organization. In addition to pure data transmission via the CAN bus, CAN XL should support other functions such as functional safety, data security, and Quality of Service (QoS). These are fundamental characteristics required in autonomous vehicles.

[0005] Errors may occur when transmitting data in frames via the channel (CAN bus). For example, bits may be distorted or side edges between bits may be shifted due to external influences, especially incident or reflected light at the bus ends. Furthermore, stage errors may occur in user stations that are not transmitters of messages in the current communication on the bus, but merely receivers (receiving nodes), due to a suboptimal clock source.

[0006] These framework conditions help reduce the amount of data that can be effectively transmitted per unit of time, i.e., the net data rate. Summary of the Invention

[0007] Therefore, the objective of this invention is to provide a communication control device for a user station in a serial bus system and a method for communication in a serial bus system, which solves the problems mentioned above. In particular, it is intended to provide a communication control device for a user station in a serial bus system and a method for communication in a serial bus system, wherein high error robustness of communication can be achieved even at high data rates and, where necessary, by increasing the effective data amount per frame.

[0008] This task is solved by a communication control device for a user station in a serial bus system having the features of claim 1. The communication control device is designed to control communication between the user station and at least one other user station in the bus system and to generate a transmit signal for transmission onto the bus of the bus system and / or to receive a signal from the bus. The communication control device is designed to generate the transmit signal according to a frame, wherein bits of a predetermined time length are set in the transmit signal. The communication control device is designed to generate the transmit signal such that bits of the transmit signal can be transmitted onto the bus as either dominant or recessive, such that a recessive state can be overwritten by a dominant state. The communication control device is also designed to shorten at least one bit that should be transmitted onto the bus as dominant by a predetermined value in the transmit signal compared to the bit that should be transmitted as recessive.

[0009] The design of this communication control device enables the transmission of more data per unit of time through the bus than ever before, without compromising the error robustness of the communication in the bus system.

[0010] Therefore, this communication control device enables robust communication in serial bus systems, especially in CAN, CAN FD, or CAN XL, even with further increases in data rates.

[0011] Here, using the communication control device in the bus system, it is possible to maintain the arbitration known by CAN in the first communication phase and still significantly improve the transmission rate again compared to CAN or CAN FD or CAN XL.

[0012] If at least one CAN user station and / or at least one CAN FD user station also exist in the bus system, then the method implemented by the communication control device can also be used, in which the CAN user station and / or the CAN FD user station transmits messages according to the CAN protocol and / or the CAN FD protocol.

[0013] Other advantageous designs of the communication control device are described in the dependent claims.

[0014] It is possible that each bit is divided into four segments without shortening the time range, with a first sampling point provided between the first and second segments for sampling the signal after transmission via the bus, and a second sampling point provided between the third and fourth segments for sampling the signal after transmission via the bus.

[0015] Two segments can be arranged between the first sampling point and the second sampling point without any bit shortening.

[0016] According to one particular design, the communication control device can be designed to: shorten a bit that should be sent as a dominant state to the bus during the transmission signal by a predetermined value in a stage in which the user station obtains at least temporarily dedicated, conflict-free access to the bus. Here, according to another particular design, the communication control device can also be designed to: shorten a bit that should be sent as a dominant state to the bus by a predetermined value smaller than the predetermined value in another stage during the transmission signal in which the user station does not have dedicated, conflict-free access to the bus.

[0017] According to one embodiment, the communication control device is designed to insert at least one predetermined bit into a transmitted signal, which indicates to a receiving node in the bus system that the signal currently received from the bus has at least segmented dominant states, the duration of which is shorter than the duration of recessive states. Here, the communication control device can also be designed to insert at least one predetermined bit into a control segment of a frame and / or into a data segment of a frame.

[0018] It is possible to consider that the communication control device has an evaluation box and a bit length shortening box, wherein the evaluation box is used to evaluate whether, in the transmission signal created by the communication control device, at least one bit that should be sent to the bus as a dominant state should be shortened compared to the bit that should be sent to the bus as a recessive state, and the bit length shortening box is used to shorten at least one bit that should be sent to the bus as a dominant state based on the evaluation result of the evaluation box.

[0019] The communication control device can have a bit length extension frame for extending at least one bit in the bit sequence that is included as a shortened bit in a signal received from the bus.

[0020] It is conceivable that the communication control device has an error frame counting frame for counting error frames received from the bus, wherein the communication control device is designed to: when the count value of the error frame counting frame exceeds a predetermined number, send in the transmission signal a bit that should be sent to the bus as a dominant state with the same value as the bit that should be sent to the bus as a recessive state.

[0021] The communication control device can be designed to generate transmission signals such that the bit time of a signal sent to the bus in the first communication phase can differ from the bit time of a signal sent in the second communication phase for messages exchanged between user stations in the bus system, and wherein it is agreed in the first communication phase which user station in the bus system will obtain at least temporarily dedicated, conflict-free access to the bus in the subsequent second communication phase, and wherein the communication control device is designed to shorten at least one bit that should be sent to the bus as a dominant state in the first and / or second communication phase.

[0022] The frames formed for this message can be constructed in a way that is compatible with CAN FD and / or CAN XL.

[0023] The previously described communication control device can be part of a user station for a serial bus system, which in turn has a transmitting / receiving device for transmitting signals to the bus of the bus system, wherein the transmitting / receiving device is designed to transmit the entire frame to the bus in an operating mode for transmitting and receiving frames during the first communication phase.

[0024] The user station described above can be part of a bus system that further includes a bus and at least two user stations interconnected via the bus, enabling the user stations to communicate serially with each other. Here, at least one of the at least two user stations is the user station described above.

[0025] Furthermore, the aforementioned task is solved by a method for communication in a serial bus system according to claim 15. This method is performed using a communication control device for a user station in a bus system, wherein the method comprises the steps of: using the communication control device to control communication between the user station and at least one other user station in the bus system and to generate a transmit signal for transmission onto the bus of the bus system and / or to receive a signal from the bus, wherein the communication control device generates the transmit signal according to a frame, wherein bits with a predetermined time length are set in the transmit signal, wherein the communication control device generates the transmit signal such that bits of the transmit signal can be transmitted onto the bus as either dominant or recessive, such that a recessive state can be overwritten by a dominant state, and wherein the communication control device shortens at least one bit that should be transmitted onto the bus as a dominant state by a predetermined value in the transmit signal compared to the bit that should be transmitted as a recessive state.

[0026] This method offers the same advantages as those mentioned earlier regarding user stations.

[0027] Other possible implementations of the invention include combinations of features or implementations not explicitly mentioned in the preceding or following descriptions of the embodiments. Furthermore, those skilled in the art will also consider individual aspects as improvements or supplements to the corresponding basic forms of the invention. Attached Figure Description

[0028] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] Figure 1 A simplified block diagram of a bus system according to a first embodiment is shown;

[0030] Figure 2 A diagram is shown illustrating the architecture for messages that can be sent by a user station of a bus system according to the first embodiment;

[0031] Figure 3 A simplified schematic block diagram of a user station of a bus system according to a first embodiment is shown;

[0032] Figure 4 The time-varying curves of the bus signals CAN-XL_H and CAN-XL_L in the user station according to the first embodiment are shown;

[0033] Figure 5 The time-varying curves of the voltage difference VDIFF between bus signals CAN-XL_H and CAN-XL_L in a user station according to the first embodiment are shown.

[0034] Figure 6 The diagram shows a time-varying curve of a portion of the signal appearing at the connector of the user station according to the first embodiment during frame transmission when the bit length adjustment module is inactive; and

[0035] Figure 7 The diagram shows a time-varying curve of a portion of the signal appearing at the connector of the user station according to the first embodiment when the bit length adjustment module is active during frame transmission;

[0036] Figure 8 A diagram illustrating the architecture for messages that can be sent by a user station in a bus system according to the second embodiment is shown; and

[0037] Figure 9 A diagram is shown illustrating the architecture for messages that can be sent by a user station of a bus system according to a third embodiment.

[0038] In the accompanying drawings, unless otherwise specified, the same or functionally equivalent elements are given the same reference numerals. Detailed Implementation

[0039] Figure 1 Bus system 1 is shown as an example, which is specifically designed for use with CAN bus systems, CAN FD bus systems, CAN XL bus systems and / or modifications thereof, as described below. Bus system 1 can be used in vehicles, especially motor vehicles, aircraft, etc., or in hospitals, etc.

[0040] exist Figure 1 In the bus system 100, multiple user stations 10, 20, and 30 are connected to a bus 40 having a first bus core line 41 and a second bus core line 42, respectively. Bus core lines 41 and 42 can also be referred to as CAN_H and CAN_L or CAN-XL_H and CAN-XL_L and are used for transmitting electrical signals after a dominant input level or for generating a recessive or other level for signals in a transmitting state. Messages 45 and 46 in signal form can be serially transmitted between the various user stations 10, 20, and 30 via the bus 40. If an error occurs in the communication on the bus 40, such as... Figure 1 As indicated by the jagged black arrow, error frame 47 (error flag) can be sent. User stations 10, 20, and 30 are, for example, control equipment, sensors, and display devices for motor vehicles.

[0041] like Figure 1As shown, user station 10 has a communication control device 11, a transmitting / receiving device 12, and a bit length adjustment module 15. User station 20 has a communication control device 21, a transmitting / receiving device 22, and optionally a bit length adjustment module 25. User station 30 has a communication control device 31, a transmitting / receiving device 32, and a bit length adjustment module 35. The transmitting / receiving devices 12, 22, and 32 of user stations 10, 20, and 30 are directly connected to bus 40, even if this is... Figure 1 The details are not explained.

[0042] Communication control devices 11, 21, and 31 are respectively used to control the communication between each user station 10, 20, and 30 and at least one other user station among user stations 10, 20, and 30 via bus 40, wherein at least one other user station is connected to bus 40.

[0043] Communication control devices 11 and 31 create and read a first message 45, which may be a modified CAN message 45. Here, the modified CAN message 45 is constructed based on the CAN XL format, which is referenced from... Figure 2 The following is described in more detail, and corresponding bit length adjustment modules 15 and 35 are used for the CAN XL format. Furthermore, communication control devices 11 and 31 can be implemented to provide or receive CAN XL messages 45 or CAN FD messages 46 from transmitting / receiving devices 12 and 32 as needed. Corresponding bit length adjustment modules 15 and 35 are also used here. Communication control devices 11 and 31 thus create and read the first message 45 or the second message 46, wherein the first and second messages 45 and 46 are distinguished by their data transmission standard, i.e., in this case, by CAN XL or CAN FD.

[0044] The communication control device 21 can be implemented like a conventional CAN controller according to ISO 11898-1:2015, especially like a conventional CAN controller or CAN FD controller compatible with CAN FD. Optionally, a bit length adjustment module 25 is additionally present, which has the same function as bit length adjustment modules 15 and 35. The communication control device 21 creates and reads a second message 46, such as a CAN FD message 46. The CAN FD message 46 can include a number of 0 to 64 data bytes, which are transmitted at a significantly faster data rate than in conventional CAN message transmission. In particular, the communication control device 21 is implemented like a conventional CAN FD controller.

[0045] Transmitting / receiving device 22 can be implemented as a conventional CAN transceiver or CAN FD transceiver according to ISO 11898-1:2015. Transmitting / receiving devices 12 and 32 can be implemented to provide or receive messages 45 in CAN XL format or messages 46 in the current CAN FD format as needed from their respective communication control devices 11 and 31.

[0046] Using two user stations 10 and 30, it is possible to form and then transmit messages 45 in CAN XL format, as well as receive such messages 45.

[0047] Figure 2 Message 45 shows frame 450, which is specifically a CAN XL frame, as provided by the communication control unit 11 for the transmitting / receiving device 12, for transmission onto bus 40. Here, in this embodiment, the communication control unit 11 creates frame 450 as a CAN FD-compatible frame. This is similarly applicable to the communication control unit 31 and the transmitting / receiving device 32 of the user station 30.

[0048] according to Figure 2 The frame 450 used for CAN communication on bus 40 is divided into different communication phases 451 and 452, namely the arbitration phase 451 and the data phase 452. After the start bit SOF, the frame 450 has an arbitration segment 453, a control segment 454, a data segment 455, a checksum segment 456, and a frame termination segment 457.

[0049] In arbitration phase 451, user stations 10, 20, and 30 agree, bit by bit, on which identifier (ID) with bits ID28 to ID18 in arbitration phase 453 will send messages 45 and 46 with the highest priority, and thus gain dedicated access to bus 40 of bus system 1 in the subsequent data phase 452 for the next time to be sent. Arbitration phase 451 uses a physical layer similar to that in CAN and CAN-FD. This physical layer corresponds to the physical layer or layer 1 of the known OSI model (Open Systems Interconnection model).

[0050] An important point during phase 451 is the use of the known CSMA / CR method, which allows user stations 10, 20, and 30 to access bus 40 simultaneously without disrupting messages 45 and 46 that have higher priority. This makes it relatively easy to add other bus user stations 10, 20, and 30 to bus system 1, which is highly advantageous.

[0051] The CSMA / CR method results in a requirement for a so-called recessive state to exist on bus 40, which can be overwritten by other user stations 10, 20, and 30 that have a dominant state on bus 40. This recessive state results in high ohmic relationships on each user station 10, 20, and 30, which, combined with parasitic effects on the bus circuitry, leads to a longer time constant. This limits the maximum bit rate of the current CAN-FD physical layer to approximately 2 megabits per second in practical vehicle use.

[0052] In data phase 452, in addition to a portion of control phase 454, valid data from CAN-XL frames or messages 45 from data phase 455, as well as checksum phase 456, are transmitted. Checksum phase 456 can contain a checksum of the data from data phase 452, including stuff bits, which are inserted as inverted bits by the transmitter of message 45 after a predetermined number of identical bits, specifically 10 identical bits. At the end of data phase 452, the system switches back to arbitration phase 451.

[0053] The end segment in the frame termination phase 457 can contain at least one acknowledgment bit. Furthermore, a sequence of 11 identical bits indicating the end of the CAN XL frame 450 can be present. At least one acknowledgment bit can indicate whether the receiver has detected an error in the received CAN XL frame 450 or message 45.

[0054] The transmitter of message 45 only begins to send the bits of data stage 452 onto bus 40 when the user station 10, as the transmitter, has won arbitration and therefore has dedicated access to bus 40 of bus system 1 for transmission.

[0055] In a bus system with CAN XL, proven characteristics are received that ensure the robustness and user-friendliness of CAN and CAN FD, particularly the frame structure with identifiers and arbitration according to the CSMA / CR method. Therefore, the user station 10 partially uses the format known from CAN / CAN-FD according to ISO 11898-1:2015, especially up to the FDF bit (inclusive), in the arbitration phase 451, which is the first communication phase. However, compared to CAN or CAN FD in the data phase 452, which is the second communication phase, the net data transfer rate can be increased to approximately 10 megabits per second. Furthermore, the size of each frame of valid data can be increased to approximately 2 kilobytes or any other value.

[0056] Figure 3The basic architecture of the user station 10 is shown. This user station includes a communication control unit 11, a transmitting / receiving unit 12, and a bit length adjustment module 15, which is part of the communication control unit 11. Apart from the differences mentioned above, the user station 20 starts with a basic architecture similar to... Figure 3 The user station 30 is constructed in the same manner as shown. Figure 3 Constructed in a similar manner as shown, however according to Figure 1 The bit length adjustment module 35 is arranged separately from the communication control device 31 and the transmitting / receiving device 32. Therefore, the user station 30 is not described separately.

[0057] according to Figure 3 In addition to the communication control unit 11 and the transmitting / receiving unit 12, the user station 10 also includes a microcontroller 13 and a system ASIC 16 (ASIC = Application-Specific Integrated Circuit). The communication control unit 11 is assigned to the microcontroller, and the system ASIC can alternatively be a system base chip (SBC) that integrates several functions necessary for the electronic assembly of the user station 10. Besides the transmitting / receiving unit 12, the system ASIC 16 also houses a power supply unit 17 that supplies power to the transmitting / receiving unit 12. The power supply unit 17 typically provides a 5V CAN_Supply voltage. However, it can provide different voltages as needed. As a supplement or alternative, the power supply unit 17 can be designed as a power source.

[0058] The bit length adjustment module 15 has an evaluation box 151, a bit length shortening box 152, and optionally a bit length extending box 153. The evaluation box evaluates the transmitted signal TxD and the received signal RxD using a bit sequence with bits having the same logic value. Additionally, an optional error frame counting box 154 is included. Boxes 151, 152, 153, and 154 will be described in more detail below.

[0059] Furthermore, the transmitting / receiving device 12 has a transmitting module 121 and a receiving module 122. Although the transmitting / receiving device 12 is always referred to below, the receiving module 122 can also be disposed in a separate device outside the transmitting module 121 as an alternative. The transmitting module 121 and the receiving module 122 can be constructed as in a conventional transmitting / receiving device 22. The transmitting module 121 can in particular have at least one operational amplifier and / or transistor. The receiving module 122 can in particular have at least one operational amplifier and / or transistor.

[0060] The transmitting / receiving device 12 is connected to bus 40, more specifically to its first bus line 41 for CAN_H or CAN-XL_H and its second bus line 42 for CAN_L or CAN-XL_L. Voltage supply for the power supply device 17 is provided through at least one connector 43 to supply electrical energy, particularly the voltage CAN-Supply, to the first and second bus lines 41, 42. Connection to ground or CAN_GND is achieved through connector 44. The first and second bus lines 41, 42 are terminated with terminating resistors 49.

[0061] The first and second bus cores 41 and 42 are connected in the transmitting / receiving device 12 not only to the transmitting module 121, also referred to as the transmitter, but also to the receiving module 122, referred to as the receiver, although for the sake of simplicity... Figure 3 The connection is not shown in the image.

[0062] During the operation of the bus system 1, the transmitting module 121 converts the transmitting signal TXD or TxD from the communication control device 11 into corresponding signals CAN-XL_H and CAN-XL_L for the bus cores 41 and 42, and transmits these signals CAN-XL_H and CAN-XL_L to the bus 40 via the connectors for CAN_H and CAN_L, as shown in... Figure 4 As shown in the image.

[0063] The receiving module 122 according to Figure 4 The signals CAN-XL_H and CAN-XL_L received from bus 40 form a received signal RXD or RxD and forward it to the communication control device 11, as shown in... Figure 3 As shown in the diagram. Except in an idle or ready state (idle or standby), the transmitting / receiving device 12 with receiving module 122 always listens for the transmission of data or messages 45, 46 on bus 40 during normal operation, and more precisely, this is regardless of whether the transmitting / receiving device 12 is the transmitter of message 45.

[0064] according to Figure 4 In this example, the signals CAN-XL_H and CAN-XL_L have dominant and recessive bus levels 401 and 402, respectively, at least during arbitration phase 451, as is known from CAN. A differential signal VDIFF = CAN-XL_H - CAN-XL_L is constructed on this bus 40, which... Figure 5The image shows the arbitration phase 451. Each bit of the signal VDIFF, with a bit time t_bt1, can be identified in arbitration phase 451 using a reception threshold T_a, for example, 0.7 V. In the data phase 452, the bits of the signals CAN-XL_H and CAN-XL_L are transmitted faster, that is, with a shorter bit time t_bt2 than in arbitration phase 451. Therefore, the signals CAN-XL_H and CAN-XL_L differ from the conventional signals CAN_H and CAN_L in data phase 452, at least in terms of their faster bit rate.

[0065] Figure 4 The sequences used for states 401 and 402 of signals CAN-XL_H and CAN-XL_L and Figure 5 The resulting change curve of the voltage VDIFF is only used to illustrate the function of user station 10. The sequence of data states for bus states 401 and 402 can be selected as needed.

[0066] In other words, when the transmitting module 121 is switched to the first operating mode B_451 (SLOW), such as Figure 4 As shown, the transmitting module 121 generates a first data state as a bus state 402 having different bus levels for the two bus cores 41 and 42 for the bus line, and generates a second data state as a bus state 401 having the same bus level for the two bus cores 41 and 42 for the bus line of the bus 40.

[0067] Furthermore, regarding the time-varying curves of the signals CAN-XL_H and CAN-XL_L, the transmitting module 121 transmits bits with a higher bit rate to the bus 40 in the second operating mode B_452_TX (FAST_TX), which includes the data phase 452. Moreover, the CAN-XL_H and CAN-XL_L signals can be generated in the data phase 452 using a different physical layer than in CAN FD. Therefore, the bit rate in the data phase 452 can be further increased compared to CAN FD. The user station—which is not the transmitter of frame 450 in the data phase 452—sets a third operating mode B_452_RX (FAST_RX) in its transmitting / receiving device.

[0068] When user station 10 acts as a transmitter and / or receiver for frame 450, Figure 3The bit length adjustment module 15 is active. This bit length adjustment module 15, and particularly its evaluation block 151, evaluates the bit sequence in the frame 450 before the communication control device 11 forwards the TxD signal as the TXD_TC signal at the connector TXD to the transmitting / receiving device 12 for transmission onto the bus 40. Furthermore, if a bit sequence of at least three bits with the same logic value appears in the TxD signal, the bit length adjustment module 15, and particularly its bit length shortening block 152, can shorten the bits of the TxD signal used for the TxD_TC signal, as will be described in more detail below.

[0069] The method performed by the bit length adjustment module 15 is particularly suitable for data phase 452, in which one of the user stations 10, 20, and 30 has dedicated access to bus 40 in order to send one of messages 45 and 46, specifically as frame 450. However, as an alternative or supplementary method, the bit length adjustment module 15 can also use the method in arbitration phase 451.

[0070] Figure 6 An example of a differential signal VDIFF is shown with respect to time t, which is constructed on bus 40 by means of a digital transmit signal TxD. This transmit signal TxD can be generated either according to frame 450 or according to a protocol used for CAN FD.

[0071] The bit sequence shown has two bits, namely bits B1 and B2. These bits B1 and B2 have, for example, a bit length t_bt2, which is the bit length of this data phase 452. However, this bit sequence can appear in any part of frame 450. Therefore, this bit sequence can appear in the first and / or second communication phases 451, 452 of frame 450. The transmit signal TxD is generated by the communication control device 11, which is the transmitter of frame 450, modified in the bit length adjustment module 152 as described in more detail below, and then serially transmitted to the transmit / receive device 12 as the transmit signal TxD_TC.

[0072] Each bit in B1 and B2 has the same architecture. Each bit of the signal VDIFF, and therefore each bit B1 and B2, is divided into four segments SY, P1, PP, and P2 over time t. The sampling point TP is set between the first and second segments SY and PP. Furthermore, each bit of the signal VDIFF is divided into multiple time quanta TQ of equal length over time t. The number of time quanta TQs is the same in all bits. The time quanta TQs are assigned to the segments SY, PP, P1, and P2, where the segments SY, PP, P1, and P2 are not of different lengths over time t, in other words, they have different numbers of time quanta TQs. Figure 6In the example, segments P1 and P2 are of equal length over the time interval t. In other words, segments P1 and P2 have the same number of time quanta TQ.

[0073] A synchronization segment SY, with a length of one time quantum TQ, is set at the beginning of bits B1 and B2. This is followed by a propagation segment PP, with multiple time quantum TQs. A first sampling point TP for sampling the bit is set between segment SY and segment PP. After segment PP, a first stage P1 appears before a second sampling point TP for sampling the bit. A second stage P2 follows the second sampling point TP. If a transition occurs between two different logic values ​​in the transmitted signal TxD, i.e., between 1 and 0 or between 0 and 1, the receiving node or receiver of frame 450 can check whether the transition occurred at the expected time. If no transition occurs at the expected time at the beginning of the bit, the receiver of frame 450 can calculate the time difference and adjust the time length of stage P1 or stage P2 accordingly. Thus, the receiver can continuously synchronize with the time clock of the transmitting node or transmitter of frame 450. This reduces errors (physical layer effects) caused by radiation on bus 40.

[0074] The communication control device 11 is designed to sample bits B1 and B2 at a first sampling point TP and a second sampling point TP in the signal RxD received from the bus 40. The first sampling point and the second sampling point should be arranged between two segments in segments SY, PP, P1, and P2, respectively.

[0075] exist Figure 6 In this example, the differential signal VDIFF changes its voltage level U between approximately +2V and -2V. This change is determined by a digital transmit signal TxD or TxD_TC, which is coupled into bus 40 and changes between logic bit values ​​0 and 1. Overshoot occurs in the differential signal VDIFF during the changes between bit values ​​0 and 1 or 1 and 0. The corresponding values ​​of bits B1 and B2 of the differential signal VDIFF are determined in the transmit / receive device 12 by comparing them with the threshold voltage U_TH of the receive threshold T_a. Here, the transmit / receive device 12 forms the receive signal RxD. If the voltage level U of the differential signal VDIFF is below the threshold voltage U_TH, then the differential signal VDIFF corresponds to the logic value 0 of the digital transmit signal TxD. If the voltage level U of the differential signal VDIFF exceeds the threshold voltage U_TH, then the differential signal VDIFF corresponds to the logic value 1 of the digital transmit signal TxD. Ideally, the logic value of the received signal RxD corresponds to the logic value of the transmitted signal TxD. Otherwise, an error exists.

[0076] If the user site is created in 10 Figure 6 If the transmitted signal TxD is received, then the bit length adjustment module 15, especially its evaluation box 151, will identify bit B1 as a dominant bit and bit B2 as a recessive bit. The bit length shortening box 152 can shorten the dominant bit B1, such as... Figure 7 As shown in the figure. Here, the processing of the bit length adjustment module 15 is as follows.

[0077] The evaluation block 151 checks which bit in the transmitted signal TxD undergoes a logic value transition from 1 to 0 at the beginning or end of that bit. For this purpose, the evaluation block 151 checks, for example, when a falling edge occurs between two bits. If the evaluation block 151 identifies such a falling edge, the subsequent bit is the dominant bit, such as... Figure 6 The bit length shortening box 152 is the same as bit B1 in the evaluation box 151. The bit length shortening box 152 receives the corresponding evaluation result from the evaluation box 151. The predetermined dominant bit-shortening criterion 1521 is stored in the bit length shortening box 152. The bit length shortening box 152 thus... Figure 6 The bit B1 is shortened to Figure 7 Bit B1. In other words, the bit length shortening box 152 shortens all dominant bits of the transmitted signal TxD based on the evaluation results of the evaluation box 151.

[0078] Therefore, in Figure 7 In this case, bit length shortening box 152 has already shortened bit B1. Here, bit length shortening box 152 has shortened the segment PP at bit B1. The duration of segment PP represents the duration of voltage fluctuation decay, which is caused by the change in voltage level on bus 40 during the transition between the dominant and recessive states of the bus signal. When the bus signal transitions from a dominant state to a recessive state, the voltage fluctuation on bus 40 remains longer than when transitioning from a recessive state to a dominant state. Correspondingly, bit length shortening box 152 shortens the segment PP of the bit when a dominant bit should be transmitted through bus 40. In particular, bit length shortening box 152 omits the segment PP of bit B1. Bit length shortening box 152 takes measures for all other dominant bits of the transmitted signal TxD in the same manner. Of course, bit B1 can be shortened for different time lengths, in particular by shortening the time length of a segment P1 or by any other length between the lengths of segments PP and P1. As an alternative, bit B1 can be shortened to a time length less than that of segment P1.

[0079] Here, the bit length shortening block 152 can shorten the dominant bit in the data phase 452 of the transmitted signal TxD according to a dominant bit shortening criterion 1521 that is different from the dominant bit in the arbitration phase 451 of the transmitted signal TxD. Here, the bit length shortening block 152 can use the shortening criterion 1521, according to which the dominant bit in the arbitration phase 451 of the transmitted signal TxD is shortened less than the dominant bit with bit duration t_bt2 in the data phase 452 of the transmitted signal TxD. Specifically, the length or bit duration t_bt1 of the dominant bit in the arbitration phase 451 of the transmitted signal TxD is shortened less with respect to the length or bit duration t_bt1 of the recessive bit in the arbitration phase 451 than the length or bit duration t_bt2 of the dominant bit in the data phase 452 of the transmitted signal TxD is shortened less with respect to the length or bit duration t_bt1 of the recessive bit in the data phase 452. In other words, the percentage reduction of the bit duration t_bt1 of the dominant bit B1 in the arbitration phase 451 is less than the percentage reduction of the bit duration t_bt2 of the dominant bit B1 in the data phase 452 of the transmitted signal TxD.

[0080] However, the length or duration t_bt2 of the recessive bit B2 remains unchanged. Therefore, the bit length shortening box 152 does not modify the length of the recessive bit B2. The same applies to all other recessive bits of the transmitted signal TxD.

[0081] The shortening Figure 6 and Figure 7 In this example, it is particularly advantageous for the dominant bit B1 because the physical layer effect can be better compensated for by the state transition or side edge on bus 40 towards the dominant level or state between the two bits. This shortens the time during which errors may occur in the signal VDIFF on bus 40 due to physical layer effects. Since the segment PP is the dominant part of bits B1 and B2 in terms of length or time, the bit length adjustment module 15 can significantly improve the bit rate. In particular, it can save more than half of the bit time t_bt1 and t_bt2. This can mean even doubling the bit rate.

[0082] Conversely, if user station 10 is the receiving user station of bus system 1, and this user station is not currently the transmitter of frame 450 but only receives frame 450 (receiving node), then user station 10 uses its evaluation frame 151 to identify the shortened bit length of the dominant bit B1 by sampling at the sampling point TP of the received signal RxD. Specifically, the communication control device samples the received signal RxD after each time quantum TQ. Therefore, the receiving node can correctly... Figure 7The signal VDIFF is sampled so that the receiving node receives CAN_H and CAN_L from bus 40 at its connector. Optionally, the bit length extension box 153 can extend the bit B1 of the received signal RxD, which was identified as shortened, back to its normal length. However, as an alternative, the communication control device 11 uses bits of different lengths to evaluate the received signal RxD.

[0083] With this design of user stations 10, 20, and 30 in bus system 1, more bits can be transmitted through bus 40 at the same time. Therefore, the data rate in bus system 1 is increased.

[0084] If user stations 10, 20, and 30 on bus 40 are not expected to understand bit-length shortening, then when one of the bit-length adjustment modules 15, 25, and 35 is active for the transmit signal TxD, user stations 10, 20, and 30 will interfere with communication in bus system 1 via error frames 47. In this case, the error frame counting frame 154 counts the error frames 47 received from bus 40. From a certain number of error frames 47 onwards, the evaluation frame 151 evaluates that the method for shortening the dominant bit is no longer used. Instead, the communication control device 11 then simply uses the conventional protocol, in which the shortening of the dominant bit B1 is not used. Therefore, the bit-length adjustment modules 15, 25, and 35 belonging to user stations 10, 20, and 30 are deactivated.

[0085] This enables robust emergency operation of communication within the bus system 1. This is particularly advantageous when the bus system 1 is used in a vehicle. Thus, emergency operation is ensured, for example, during vehicle operation.

[0086] The communication control device 11, especially its evaluation frame 151, can reduce the count value of the error frame counter frame 154 when a message 45 with a shortened dominant bit B1 is successfully transmitted. Therefore, accidental errors not caused by incompatibility of the communication protocols of user stations 10, 20, and 30 on the bus 40 will not lead to a reduction in the possible transmittable baud rate in the bus system 1.

[0087] In contrast, when updating vehicle software at a service center, it may be desirable to operate at the highest possible data rate. This is possible when the data from the new software is only meaningful to a single user station on bus 40. In such cases, it is possible that the service center tester selectively uses the previously described method for shortening the dominant bit B1 while sending messages 45, 46 on bus 40 until the incompatible user station interrupts the transmission of error frame 47 and enters error-clearing mode. From this moment on, the communication control device 11 can, according to... Figure 7 When sending messages 45 and 46, the method for shortening the dominant bit B1 described above is used without interference. Therefore, compared to regular messages 45 and 46 with a standard-length dominant bit B1, software updates can be transmitted in a shorter time, such as in... Figure 6 As shown in the image.

[0088] According to a modification of this embodiment, the bit length shortening box 152 shortens only the dominant bit B1 in the data phase 452 of the transmitted signal TxD.

[0089] According to another modification of this embodiment, the bit length shortening box 152 only shortens the dominant bit in the arbitration phase 451 of the transmitted signal TxD.

[0090] However, each of the two mentioned modifications produces a slight increase in net data rate in bus system 1 compared to the embodiment described in the former.

[0091] Figure 8 A frame 450A according to the second embodiment is shown. As previously described, this frame 450A can be used by the communication control device 11 to create the transmitted signal TxD and / or to evaluate the received signal RxD.

[0092] In frame 450A, at least one bit B_V is included in control segment 454. The fewer bits B_V included, the less the net data rate that can be transmitted in bus system 1 decreases.

[0093] At least one bit B_V indicates whether the dominant bit B1 in the received signal RxD currently received by the bus 40 is transmitted in the shortened case.

[0094] Therefore, the transmitting node can notify the receiving node on the bus 40 of at least one bit B_V, indicating how the currently received received signal RxD should be evaluated. Thus, the receiving node can appropriately consider the predetermined dominant bit-shortening criterion 1521 when evaluating the currently received received signal RxD.

[0095] In other words, the reserved bits in the header of message 45 can be used to foreshadow the previously described procedure. Figure 7 The use of methods to shorten the dominant position B1.

[0096] This ensures backward compatibility with known communication protocols, especially CAN-based protocols.

[0097] As an alternative, at least one bit B_V is included in data segment 455.

[0098] Figure 9 A frame 450B according to a third embodiment is shown. As previously described, this frame 450B can be used by the communication control device 11 to create the transmitted signal TxD and / or to evaluate the received signal RxD.

[0099] In frame 450B, at least one bit B_V is included in data segment 455. At least one bit B_V indicates that the dominant bit B1 will be transmitted in a shortened form in message 45, which will soon be sent via bus 40. Therefore, the receiving node knows that the dominant bit B1 has been shortened in the subsequent received signal RxD, as in... Figure 7 As shown in the image.

[0100] If more than one bit B_V is included, it is possible to notify which of the following messages 45, 46 on the bus 40 have been modified such that the dominant bit B1 is shortened. For example, a specific identifier for this message 45, 46 can then be encoded in a bit sequence of at least two bits B_V.

[0101] Therefore, the transmitting node can notify the receiving node with bit B_V how the received signal RxD of the next message 45, 46 received by bus 40 should be evaluated. Thus, the receiving node can appropriately take into account the predetermined dominant bit-shortening criterion 1521 when evaluating this received signal RxD.

[0102] In other words, for the current received signal RxD, it is possible to predict in the previous message, such as... Figure 7 The method for shortening the dominant bit B1 as previously described is shown in the illustration.

[0103] It is possible that the dominant bit B1, which is at least segmented and shortened, is also used in messages constructed based on frame 450B.

[0104] This also ensures backward compatibility with known communication protocols, especially CAN-based protocols.

[0105] All previously described design options for user stations 10, 20, 30, bus system 1, and the methods performed therein can be used individually or in all possible combinations. In particular, all features of the previously described embodiments and / or their modifications can be combined arbitrarily. As supplementary or alternative solutions, the following modifications are particularly conceivable.

[0106] Although the invention has been described above using a CAN bus system as an example, the invention can be used in every communication network system and / or communication method, wherein two different communication phases are used, and the bus states generated for the different communication phases are different from each other.

[0107] The bus system 1 according to this embodiment can in particular be a communication network system in which data can be transmitted serially at two different bit rates. An advantageous, but not mandatory, prerequisite is that, at least for a defined time interval, dedicated, conflict-free access to a common channel is guaranteed for user stations 10, 20, and 30 in the bus system 1.

[0108] The number and arrangement of user stations 10, 20, and 30 in the bus system 1 of this embodiment are arbitrary. In particular, user station 20 can be eliminated in the bus system 1. It is possible that one or more user stations of user station 10 or 30 exist in the bus system 1. It is conceivable that all user stations in the bus system 1 are designed identically, that is, only user station 10 or only user station 30 exists.

Claims

1. Communication control device (11; 21; 31) for user station (10; 20; 30) of serial bus system (1). The communication control device (11, 21, 31) is designed to control the communication between the user station (10; 20; 30) and at least one other user station (10; 20; 30) of the bus system (1) and to generate a transmit signal (TxD) for transmission to the bus (40) of the bus system (1) and / or to receive a signal (VDIFF) from the bus (40). The communication control device (11; 21; 31) is designed to generate the transmission signal (TxD) according to the frame (450; 450A; 450B), wherein bits (B1, B2) with predetermined time lengths (t_bt1; t_b2) are set in the transmission signal. The communication control device (11; 21; 31) is designed to generate the transmit signal (TxD) such that its bits (B1, B2) can be transmitted onto the bus (40) as either a dominant state (401) or a recessive state (402), such that the recessive state (402) can be overwritten by the dominant state (401), and The communication control device (11; 21; 31) is designed to shorten at least one bit (B1) that should be sent to the bus (40) as a dominant state (401) by a predetermined value in the transmitted signal (TxD) compared to the bit that should be sent to the bus (40) as a recessive state (402).

2. The communication control device (11; 21; 31) according to claim 1. Each bit (B1, B2) is divided into four segments (SY, PP, P1, P2) without shortening within the time (t) range. A first sampling point (TP) is set between the first and second segments (SY, PP) to sample the signal after transmission via the bus (40), and A second sampling point (TP) is provided between the third and fourth segments (P1, P2) for sampling the signal after transmission via the bus (40).

3. The communication control device (11; 21; 31) according to claim 2, wherein two segments (PP, P1) are arranged between the first sampling point (TP) and the second sampling point (TP) without shortening the bit.

4. The communication control device (11; 21; 31) according to any one of the preceding claims, wherein the communication control device (11; 21; 31) is designed to shorten a bit (B1) that should be sent as a dominant state (401) on the bus (40) in the transmission signal (TxD) by a predetermined value (PP) during the phase in which the user station (10; 20; 30) obtains at least temporarily dedicated, conflict-free access to the bus (40).

5. The communication control device (11; 21; 31) according to claim 4, wherein the communication control device (11; 21; 31) is designed to shorten a bit (B1) that should be sent as a dominant state (401) on the bus (40) in the transmit signal (TxD) by another predetermined value (P1) in other stages when the user station (10; 20; 30) does not have dedicated, conflict-free access to the bus (40), wherein the shortening caused by the other predetermined value is less than the shortening caused by the predetermined value (PP), in which the user station (10; 20; 30) has dedicated, conflict-free access to the bus (40) during the shortening caused by the predetermined value.

6. The communication control device (11; 21; 31) according to any one of claims 1 to 3, wherein the communication control device (11; 21; 31) is designed to insert at least one predetermined bit (B_V) into the transmitted signal (TxD), the predetermined bit indicating to the receiving node in the bus system (1) that the signal (VDIFF) currently received by the bus (40) has at least segmented dominant state (401), the duration of which is shorter than the duration of the recessive state (402).

7. The user station (10; 20; 30) according to claim 6, wherein the communication control device (11; 21; 31) is designed to insert the at least one predetermined bit (B_V) into the control segment (454) of the frame (450A; 450B) and / or into the data segment (455) of the frame (450A; 450B).

8. The communication control device (11; 21; 31) according to any one of claims 1 to 3, wherein the communication control device (11; 21; 31) comprises, A test box (151) is used to evaluate whether at least one bit (B1) in the transmit signal (TxD) created by the communication control device (11; 21; 31) that should be sent as a dominant state (401) to the bus (40) is shorter than a bit (B2) that should be sent as a recessive state (402) to the bus (40). Bit length shortening box (152), the bit length shortening box is used to shorten the at least one bit (B1) that should be sent as a dominant state (401) on the bus (40) based on the evaluation result of the evaluation box (151).

9. The communication control device (11; 21; 31) according to any one of claims 1 to 3, wherein the communication control device (11; 21; 31) has a bit length extension frame (153) for extending at least one bit (B1), the at least one bit being contained in a signal (VDIFF) received from the bus (40) as a shortened bit.

10. The communication control device (11; 21; 31) according to any one of claims 1 to 3. The communication control device (11; 21; 31) has an error frame counting frame (154) for counting error frames (47) received from the bus (40), and The communication control device (11; 21; 31) is designed to: if the count value of the error frame counting block (154) exceeds a predetermined number, send in the transmission signal (TxD) a bit (B1) that should be sent to the bus (40) as a dominant state (401) with the same value as the bit that should be sent to the bus (40) as a recessive state (402).

11. The communication control device (11; 21; 31) according to any one of claims 1 to 3. The communication control device (11; 21; 31) is designed to generate the transmit signal (TXD) such that the bit time (t_bt1) of the signal transmitted on the bus (40) in the first communication phase (451) for the message (45) exchanged between user stations (10; 20; 30) of the bus system (1) can be different from the bit time (t_bt2) of the signal transmitted in the second communication phase (452), and In the first communication phase (451), it is agreed which user stations (10; 20; 30) of the bus system (1) will obtain at least temporary, dedicated, conflict-free access to the bus (40) in the subsequent second communication phase (452), and The communication control device (11; 21; 31) is designed to shorten at least one of the states (401, 452) that should be sent as a dominant state (B1) to the bus (40) in the first and / or second communication phases (451, 452).

12. The communication control device (11; 21; 31) according to claim 11, wherein the frame (450) formed for the message (45) is constructed in a manner compatible with CAN FD and / or CAN XL.

13. Serial bus system (1) User stations (10; 20; 30) have The communication control device (11; 21; 31) according to any one of the preceding claims, and A transmitting / receiving device (22) for transmitting a transmitting signal (TXD) to the bus (40) of the bus system (1). The transmitting / receiving device (22) is designed to transmit the entire frame (450) to the bus (40) in an operating mode (B_452_TX) for transmitting and receiving the frame (450) during the first communication phase (451).

14. Bus system (1), with Bus (40), and At least two user stations (10; 20; 30) are interconnected via the bus (40) in such a way that they can communicate serially with each other and at least one of the user stations (10; 20; 30) is the user station (10; 20; 30) according to claim 13.

15. A method for communication in a serial bus system (1), wherein the method is performed using a communication control device (11; 21; 31) for a user station (10; 20; 30) of the bus system (1), wherein the method comprises the following steps: The communication control device (11; 21; 31) is used to control the communication between the user station (10; 20; 30) and at least one other user station (10; 20; 30) of the bus system (1) and to generate a transmit signal (TxD) for transmission to the bus (40) of the bus system (1) and / or to receive a signal (VDIFF) from the bus (40). The communication control device (11; 21; 31) generates the transmission signal (TxD) according to the frame (450; 450A; 450B), and sets bits (B1, B2) with a predetermined time length (t_bt1; t_b2) in the transmission signal. The communication control device (11; 21; 31) generates the transmit signal (TxD) such that bits (B1, B2) of the transmit signal can be sent to the bus (40) as either a dominant state (401) or a recessive state (402), thereby allowing the recessive state (402) to be overwritten by the dominant state (401). The communication control device (11; 21; 31) shortens at least one bit (B1) that should be sent to the bus (40) as a dominant state (401) by a predetermined value (PP) in the transmit signal (TxD) compared to the bit that should be sent to the bus (40) as a recessive state (402).

Images