Commander subscriber station for serial bus system, responder subscriber station for serial bus system and method of communicating in serial bus system
By designing commander and responder user stations that support multi-frame format switching in a CAN bus system, the robustness problem of high bit rate communication was solved, achieving a data transmission rate of up to 8 Mbit/s and cost-effectiveness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-25
- Publication Date
- 2026-04-10
AI Technical Summary
In the existing technology, the commander user station of the CAN bus system cannot achieve a bit rate communication higher than 2 Mbit/s, and FDL communication lacks robustness and high net data transmission rate at high bit rates.
A commander user station and a responder user station were designed. The station employs a communication control device and a synchronization module, which can distinguish the bit time of different communication stages. Communication can be achieved at a high bit rate by disabling the synchronization function, and it supports multi-frame format switching, including CAN FD and FDL frame formats.
Robust communication at bit rates up to 8 Mbit/s was achieved in the CAN bus system, improving data transmission rate while reducing system cost.
Smart Images
Figure CN121844544A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a commander user station for a serial bus system, a responder user station for a serial bus system, and a method for communication in a serial bus system. Background Technology
[0002] Bus systems are used in many technological fields for communication between technical devices, such as sensors and control devices.
[0003] It is known that classic CAN and / or CAN FD are used for communication between devices in vehicles and / or in the case of other technical devices, both of which are standardized in the international standard ISO 11898-1:2015.
[0004] User stations in such bus systems are also called nodes. These user stations have microcontrollers that support all the functions of the aforementioned standards for classic CAN and / or CAN FD.
[0005] In such a bus system, at least one user station can exist, which only needs to perform one or more very simple functions, such as turning on or off indicator lights, especially light-emitting diodes (LEDs), under the control of a microcontroller at another user station, and / or changing their color as needed. Furthermore, sensors can exist and be manipulated, which should periodically provide their detection data to the microcontroller at another user station. Such a user station performing simple functions can also be called a responder. A user station with a microcontroller controlling the responder is also called a commander.
[0006] To connect responders to CAN bus systems at a lower cost, the specification for the CAN protocol variant "CAN FDLight" is currently being harmonized. "CAN FDLight," also abbreviated as FDL, specifies communication between the commander and at least one responder. In FDL communication, frames should be used without bit rate switching. FDL is currently specified in document CiA604-1 and should also be adopted in the next version of ISO 11898-1.
[0007] FDL is specific to CAN bus systems, where a commander CAN user station controls the functions of one or more responder CAN user stations. FDL does not support arbitration. Therefore, to communicate with the responders, the commander uses the principle of "polling," also known as "polling." The commander is a control device with a microcontroller on which application software runs. This microcontroller includes a CAN controller capable of sending and receiving CAN FD frames according to ISO 11898-1:2015. Polling is also performed by sending CAN FD frames.
[0008] The responder is an application-specific integrated circuit (ASIC) that has an FDL controller. The responder has limited or no local computing power and, as described above, can implement simple functions such as controlling the on / off state of light-emitting diodes (LEDs) and their color. The responder sends a CAN FD frame only when requested for this purpose by the commander via polling. Therefore, the responder CAN user station (responder) sends its functional information, such as sensor values, to the commander CAN user station (commander) via a CAN FD message after being polled by the commander.
[0009] To enable cost-effective integration of responders onto a single ASIC in hybrid semiconductor processes, such as one or more bipolar transistors and one or more CMOS transistors and one or more DMOS transistors (BCD technology), an FDL controller is integrated into the responder. The FDL controller is significantly simpler compared to the CAN FD controller.
[0010] In other words, the FDL specification omits some features of the CAN FD protocol, as specified in ISO 11898-1:2015. For example, error containment (fault containment) is omitted, for which an error counter is set and error frames can be created and sent when needed. Furthermore, the responder is not designed to participate in CAN arbitration. The commander thus controls communication to avoid access conflicts to the CAN bus.
[0011] In FDL communication, only frames in FBFF format are used, employing an 11-bit identifier and without bit rate switching. This saves additional ASCII area and facilitates timing recovery from the CAN bit stream, eliminating the need for a quartz oscillator in the responder.
[0012] The downside is that, currently, for commanders using CAN controllers according to ISO 11898-1:2015, it is not possible to achieve a bit rate higher than 2 Mbit / s for communication with responders on the bus.
[0013] To enable higher bit rates at some future time, document CiA604-3 describes some features for the Commander that differ from those in ISO 11898-1:2015. These features include disabling bus monitoring, disabling the need to send Commander acknowledgment responses (ACK responses) to responders, and disabling the transmission of error frames and overload frames.
[0014] However, the problem is that these functions are insufficient to actually enable communication on the bus at bit rates higher than 2 Mbit / s, for example, up to 8 Mbit / s. Summary of the Invention
[0015] Therefore, the object of the present invention is to provide a commander user station for a serial bus system, a responder user station for a serial bus system, and a method for communication in a serial bus system, which solve the above-mentioned problems. In particular, it is intended to provide a commander user station for a serial bus system, a responder user station for a serial bus system, and a method for communication in a serial bus system, wherein communication in the serial bus system is enabled not only with high fault robustness but also with a higher bit rate and higher net data transfer rate than has been achieved to date.
[0016] This task is solved by a commander user station for a serial bus system having the features of claim 1. The commander user station comprises: a communication control unit for controlling communication between the user station and responder user stations of the bus system, and for evaluating at least one signal received from the bus of the bus system according to a frame, wherein bit times in a first communication phase of the frame are distinguishable from bit times in a second communication phase; and a synchronization module for synchronizing the communication control unit with the signals received from the bus, wherein the synchronization module is designed to disable its synchronization function when the bit times of the first communication phase of a predetermined frame have a predetermined value corresponding to a bit rate greater than a predetermined bit rate, and when the communication control unit is to act as the sender of a predetermined frame such that the commander user station is the sender of signals received from the bus.
[0017] The described commander user station is capable of FDL communication with responder user stations at bit rates higher than currently feasible. Specifically, bit rates greater than 2 Mbit / s, and particularly up to 8 Mbit / s. For bit rates up to 2 Mbit / s, CAN controllers and CAN transceivers already present in vehicles and / or other technical devices can be used, specified for CAN FD according to international standard ISO 11898-1:2015. In particular, CANSIC transceivers can be used, which can achieve bit rates up to 8 Mbit / s.
[0018] The described commander user station therefore supports more than one frame format. Thus, the commander user station can be designed to select a frame format from at least two different frame formats, in which the next frame is sent onto the bus. The described commander user station can therefore selectively disable or enable its synchronization function for predetermined frames, or frames using predetermined frame formats, as needed.
[0019] Thus, the commander user station can also be used very advantageously in applications where data should be exchanged between the commander user station and at least one responder user station connected via a bus in a shorter time than has been the case so far.
[0020] In summary, the described user station helps to design bus systems more cost-effectively; however, it still enables robust or reliable CAN communication.
[0021] An advantageous alternative design for the user station is proposed in the dependent claims.
[0022] The synchronization module may have a synchronization block designed to synchronize the communication control device with signals received from the bus, and a configuration block storing values for at least one synchronization configuration bit, the values indicating whether the bit rate is greater than a predetermined bit rate.
[0023] The synchronization module may also have an evaluation block for evaluating the value of at least one configuration bit, and a switch block for turning the synchronization block on or off based on the evaluation of the evaluation block.
[0024] The commander user station can be a CAN FD user station, where the predetermined frames are CAN FD frames in FBFF format.
[0025] The predetermined bit rate can be 2 Mbit / s.
[0026] The previously mentioned task is further solved by a responder user station for a serial bus system having the features of claim 6. The responder user station comprises: a communication control unit for controlling communication between the user station and the commander user station of the bus system, and for evaluating at least one signal received from the bus of the bus system according to a predetermined frame, wherein bit times in a first communication phase are distinguishable from bit times in a second communication phase; and a synchronization module for synchronizing the communication control unit with the signals received from the bus, wherein the synchronization module is designed to disable its synchronization function when the communication control unit should act as the sender of a frame, such that the responder user station is the sender of signals received from the bus.
[0027] In the responder user station, the synchronization module can be designed to disable its synchronization function when the bit time of the first communication phase of a predetermined frame has a predetermined value corresponding to a bit rate greater than a predetermined bit rate, and when the communication control device should act as the sender of the frame, such that the responder user station is the sender of the signal received from the bus.
[0028] It is conceivable that the synchronization module has a synchronization block designed to synchronize the communication control device with signals received from the bus, and a configuration block storing values for at least one synchronization configuration bit, the values indicating whether the bit rate is greater than a predetermined bit rate.
[0029] The synchronization module may also have an evaluation block for evaluating the value of at least one configuration bit, and a switch block for turning the synchronization block on or off based on the evaluation of the evaluation block.
[0030] The responder user station can be a user station designed for communication according to CAN FD, wherein the predetermined frame is a CAN FD frame in FBFF format.
[0031] For responder user sites, the predetermined bit rate can also be 2 Mbit / s.
[0032] The previously described commander user station and at least one previously described responder user station can be part of a bus system having a bus and at least two user stations connected to each other via the bus such that the at least two user stations can communicate with each other serially, wherein each of the at least two user stations further has a transmitting / receiving device for transmitting signals to the bus of the bus system and / or for receiving signals from the bus of the bus system.
[0033] The bus system may also have at least one third user station designed to send and / or receive signals according to frames, wherein the at least one third user station has a communication control device designed to negotiate with the commander user station in the first communication phase of a frame whether the third user station or the commander user station will have exclusive, conflict-free access to the bus at least temporarily in the subsequent second communication phase.
[0034] The previously mentioned task is further solved by the method for communication in a serial bus system according to claim 14. This method utilizes the previously described commander user station and the previously described responder user station.
[0035] This method offers the same advantages as previously mentioned regarding user sites.
[0036] Other possible implementations of the invention include combinations of features or embodiments not explicitly mentioned previously or described below with reference to the examples. Those skilled in the art will also add various aspects as improvements or supplements to the corresponding basic forms of the invention. Attached Figure Description
[0037] The invention will now be described in more detail with reference to the accompanying drawings and embodiments.
[0038] Figure 1 A simplified block diagram of a bus system according to a first embodiment is shown; Figure 2 The message indicates the format of a CAN FD frame according to the previously mentioned standard ISO 11898-1:2015, and the message can be sent by the transmitting / receiving device of the user station of the bus system according to the first embodiment. Figure 3 The message indicates a CAN FD frame in FDL format, particularly FBFF format, without bit rate switching. The message replaces... Figure 2 The CAN FD frames can be transmitted by the transmitting / receiving device of the user station of the bus system according to the first embodiment; Figure 4 A simplified schematic block diagram of a first user station (commander) of a bus system according to a first embodiment is shown; Figure 5 The diagram illustrates the time variation of digital transmission signals during the operation of the bus system in the case of a first user station, which is connected to the same bus of the bus system as at least one second user station. Figure 6 This illustrates the time variation process of bus signals CAN_H and CAN_L in the case of a first user station according to the first embodiment; Figure 7 The time variation process of the differential voltage VDIFF of bus signals CAN_H and CAN_L in the case of the first user station according to the first embodiment is shown; Figure 8 The diagram illustrates the time variation of a digital received signal generated by a first or second user station from a signal received from a bus, the signal received from the bus being based on a transmitted signal from the first user station; and Figure 9 A simplified schematic block diagram of a second user station (responder) in a bus system according to the first embodiment is shown.
[0039] In the figures, unless otherwise specified, identical or functionally equivalent elements are given the same reference numerals. Detailed Implementation
[0040] Figure 1 Bus system 1 is shown as an example, which is specifically designed for use with CAN bus systems, CAN FD 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.
[0041] exist Figure 1 In the bus system 1, there is a bus 40, to which a commander user station 100 and multiple responder user stations 101, 102, 103…10N are respectively connected. N is a natural number greater than or equal to 1. One to N responder user stations 101, 102, 103…10N can be connected to the bus 40. The bus 40 is capable of having… Figure 1 The first bus core line 41 (not shown in the text) Figure 4 ) and the second bus core wire 42 ( Figure 4 The bus core wires can also be called CAN_H and CAN_L, and are used to transmit electrical signals in transmit mode after the signal has been coupled to a dominant level, a recessive level, or other levels.
[0042] Commander user station 100 is, for example, a controller for a motor vehicle or other technical equipment, as described in more detail below. Responder user stations 101, 102, 103…10N are, for example, capable of having at least one sensor, at least one display device, at least one actuator, at least one transmitter, etc., of a motor vehicle or other technical equipment, as described in more detail below.
[0043] As in Figure 1As shown, the commander user station 100 has a communication control unit 11, a transmitting / receiving unit 12, and a synchronization module 15. Each of the responder user stations 101, 102, 103…10N has a communication control unit 21, a transmitting / receiving unit 22, and a synchronization module 25. The transmitting / receiving units 12, 22 of user stations 101…10N are directly connected to bus 40, although this… Figure 1 It is not shown in the document.
[0044] Commander user station 100 is designed to create messages 45 and 46 in the form of signals. However, commander user station 100 is designed to send message 46 in the form of signals only to one of the user stations 101…10N via bus 40. Message 46 is constructed in largely the same way as message 45, as per the description of… Figure 2 and Figure 3 It also needs to be described in detail.
[0045] Figure 1 User stations 101…10N are designed to create messages 46 in the form of signals and transmit them to the commander user station 100 via bus 40. Message 46 can be transmitted serially between user station 100 and one of user stations 101 to 10N.
[0046] Communication control devices 11 and 21 are respectively used to control communication between user station 100 and one of user stations 101...10N via bus 40. Communication control devices 11 and 21 create a transmission signal TxD when needed. The following section discusses... Figure 5 The transmitted signal will be described in more detail below. Furthermore, communication control devices 11, 21, and 31 read or decode the received signal RxD, and the following will discuss... Figure 8 The received signal will be described in more detail.
[0047] The communication control device 11 can be implemented at least partially as a conventional CAN controller according to ISO 11898-1:2015, that is, as a CANFD controller or a classic CAN controller compatible with CAN FD. The CAN FD message 45 can include 0 to 64 data bytes, which are transmitted at a significantly faster data rate than in classic CAN messages.
[0048] The communication control device 11 is implemented to provide CAN FD messages 45, 46 or receive FDL messages 46 from user stations 101…101N as needed. Corresponding synchronization modules 15, 25 are used for sending and receiving FDL messages 46. The FDL messages 46 are constructed based on the FDL format, which is related to… Figure 3 To describe in more detail.
[0049] The communication control device 11 creates and thus reads either a first message 45 or a second message 46, wherein the first and second messages 45 and 46 differ in their data transmission standards, namely CAN FD and FDL in this case. As previously mentioned regarding the prior art, only frames without bit rate switching are used in FDL communication. Furthermore, no arbitration is implemented in FDL communication, in which the arbitration phase of message 45 negotiates which user has exclusive access to bus 40 in the subsequent data phase.
[0050] The communication control device 21 is implemented as an FDL controller. Additionally, a synchronization module 25 exists, which has functions compatible with those of the synchronization module 15. The communication control device 21 creates a second message 46, such as an FDL message 46, and is designed to read messages 45 and 46.
[0051] In order to communicate with one of the user stations 101…100N, user station 100 sends a polling request to the desired user station 101…100N via bus 40. Polling is achieved by sending a polling request based on… Figure 3 The message 46 of the FDL frame shown in the figure will be used. Only when user station 100 has requested user stations 101…100N to send a message via polling will the responding user stations 101…100N send a message based on the information provided. Figure 3 The FDL-frame message 46 is sent to the commander user station 100 via bus 40.
[0052] Therefore, user station 100 functions as an instruction giver / querier, and user stations 101…101N function as responders. Thus, user station 100 is also referred to as the FDL commander, and user stations 101…101N are referred to as FDL responders.
[0053] Figure 2 A frame 450, capable of being created by user station 100, is shown for a message 45 having up to 64 data bytes in CAN FD FEFF format. The CAN FD frame 450 can be provided by communication control device 11, i.e., encoded in digital transmit signals TxD, to an associated transmit / receive device 12 for transmission via bus 40 to another CAN FD user station (not shown).
[0054] Frame 450 is divided into two communication phases, referred to as Arbitration Phase 451 (first communication phase) and Data Phase 452 (second communication phase). Frame 450 begins and ends in Arbitration Phase 451. Frame 450 begins with the SOF bit and includes an Arbitration field 453, a Control field 454, a Data field 455, a Checksum field 456 (CRC field), an Acknowledge field 457 (ACK = Acknowledge), and an End of Frame field EOF (EOF = End of Frame).
[0055] The bits in the arbitration phase 451 of frame 450 may have a longer bit duration than the bits in the data phase 452, such as... Figure 2 As illustrated in the example, the switching from a bit with arbitration phase 451 to a bit with data phase 452 is performed in the BRS bit, as shown in... Figure 2 SP is used to represent it.
[0056] exist Figure 2 The bit indicated by a thick line at its bottom edge is transmitted as dominant or "0" in frame 450. Figure 2 The bit shown in bold at the top of the frame is transmitted as a recessive "1" in frame 450. Figure 2 The bit shown in bold in frame 450 has a predetermined, fixed, or specified value.
[0057] Arbitration field 453 includes the identifier of frame 450 in the basic ID field and ID-ext field. This identifier has 29 bits. The SRR bit and IDE bit are set between the basic ID field and the ID-ext field. The RRS bit is placed at the end of arbitration field 453. Figure 2 This shows the FEFF format with a 29-bit "extended identifier".
[0058] Control field 454 begins with the FDF bit, followed by the res bit. Next are the BRS bit and the ESI bit. The ESI bit is therefore the first bit in frame 450 with the data phase 452.
[0059] Control field 454 ends with the DLC field, which encodes the length of the subsequent data field 455. For frame 450, the res bit must be sent explicitly with a logical value of 0, or in other words, as (logical) 0.
[0060] If the DLC field of control field 453 has a value of 0, then data field 455 does not exist. Data field 455 has a length corresponding to the value encoded in the DLC field. As previously mentioned, this value can be up to 64 bytes.
[0061] The checksum field 456 contains the number of padding bits modulo 8 that are inserted into frame 450 according to the bit padding rules, i.e., the opposite bits can be inserted after each of the five identical bits. In addition, the checksum field 456 contains the CRC checksum in the CRC field, which can also be called CRC-Checksumme, and ends with the CRC delimiter CRC-Del.
[0062] The switching from the bit with data phase 452 to the bit with arbitration phase 451 is performed in the bit CRC-Del, as shown in... Figure 2 SP is used to represent it.
[0063] The acknowledgment field 457 contains the ACK bit slot, where a user station that is currently only the receiver of frame 450 and not the sender of the frame can acknowledge or not acknowledge the correct reception of frame 450 from bus 40. The acknowledgment field 457 ends with the ACK-Del bit, which is also known as the ACK delimiter.
[0064] The End of Frame (EOF) field contains a bit sequence that marks the end of frame 450. Therefore, the bit sequence of the EOF field is used to characterize the end of frame 450. The EOF field, together with the ACK delimiter, is sent at the end of frame 450 as a recessive sequence of 8 bits. This is a bit sequence that cannot appear within frame 450. Thus, the end of frame 450 can be reliably identified by user stations 100, 101…10N.
[0065] Following the 7-bit End of Frame (EOF) field, frame 450 is followed by the Inter Frame Space (IFS), which... Figure 2 Not shown in the diagram. In the case of CANFD, the inter-frame space (IFS) is designed according to ISO 11898-1:2015. The inter-frame space (IFS) has at least 3 bits.
[0066] Furthermore, the fields and bits mentioned are known from ISO 11898-1:2015, and therefore will not be described in more detail here.
[0067] In the arbitration phase 451 of CAN FD, user station 100 or other CAN FD user stations negotiate bit-by-bit on bus 40 using identifiers (IDs) such as bits ID28 to ID18 in the arbitration field 453: which user station 100 wants to send message 45 with the highest priority and thus obtain exclusive access to bus 40 of bus system 1 for transmission in the subsequent data phase 452. In the arbitration phase 451, the physical layer is used as in the cases of CAN and CAN FD. The physical layer corresponds to the bit transport layer or layer 1 of the known OSI model (Open Systems Interconnection model). User stations 101…10N, as FDL responders, do not support arbitration, as previously mentioned and described in more detail below.
[0068] For the sake of CAN arbitration-free operation, where the known CSMA / CR method resolves conflicts when two CAN nodes (user stations) simultaneously initiate messages, the commander must pre-determine which responder can send a message and when. That is, if the commander has already polled a specific responder for transmission, the commander waits until the responder has responded before sending any other messages. If a responder that has been polled but has not yet started responding sees another message start on CAN bus 40, that responder considers its polling complete and does not start its message 46. Document CiA604-1 specifies the earliest possible time when a responder can respond to a poll with a message. If a responder needs more time to prepare data for transmission, the start of that transmission can be delayed. The response times of each responder in the CAN system are known to the commander.
[0069] Conflicts between FDL responders (user stations 101…10N) and commanders (user station 100), or other CAN FD nodes with arbitration capabilities (e.g., user station 100), can also be avoided by assigning a higher arbitration priority identifier to the responder for transmission. Thus, if other nodes simultaneously initiate messages as responders, those other nodes will lose arbitration and become the receiver.
[0070] User station 100, as the sender of messages 45 and 46, only begins sending bits of data stage 452 onto bus 40 when user station 100, as the sender, wins the arbitration and thus has exclusive access to bus 40 of bus system 1 for transmission. The same applies to each CAN FD user station 10 connected to bus 40 and wishing to send messages 45 and 46 onto bus 40.
[0071] Figure 3Message 46 indicates that the user station (responder) 101…10N or its communication control device 21 provides an FDL frame 460 for transmission onto the bus 40, encoded in the digital transmission signal TxD, to its respective transmitting / receiving device 22. In this case, the communication control device 21 creates frame 460 as CAN FD compatible, as also... Figure 3 As explained in the text.
[0072] according to Figure 3 For CAN communication on bus 40, FDL frame 460 is also divided into different communication phases 451 and 452: arbitration phase 451 and data phase 452. Frame 460 has an arbitration field 463, a control field 464, a data field 465, a checksum field 466, and an acknowledgment field 467 after the start bit (SOF). This is followed by the end-of-frame field EOF, as per... Figure 2 That's the case with frame 450.
[0073] The FDL format corresponds to the FBFF format from ISO 11898-1:2015. In this format, the sender can decide whether to set the BRS bit to 1 or 0, where BRS = BitRate Switch. If the BRS bit is set to 1, the bit rate is increased or the bit time is decreased in data phase 452. If the BRS bit is set to 0, the bit rate or bit time is the same in both communication phases 451 and 452. Currently, it is specified in FDL that the bit rate is not switched within frame 460. Therefore, BRS=0 is sent. In this case, the commander (user station 100) must set the BRS bit to 0 in message 46 to the responder (one of user stations 101…10N) so that the responder understands the commander's intent.
[0074] However, in arbitration phase 451, during the FDL communication with frame 460, the responder does not implement the previous agreement regarding... Figure 2 The arbitration described. In other words, the communication control unit 21, as an FDL responder, is designed to write the identifier (ID) already assigned to the responder into frame 460. For example, if user station 101 (responder) receives a poll from user station 100 (commander), then user station 101 will... Figure 3FDL frame 460, or message 46, is transmitted to user station 100 via bus 40. In CAN communication and in FDL, the identifier (ID) is the sender's address or content description, but not the receiver's address. Each identifier is only allowed to be sent by a predetermined number of user stations 100 to 10N, thus the commander identifies multiple or one corresponding sender. If user stations 100 to 10N are capable of sending different data packets, then that user station, and only that user station, also uses a different identifier (ID) to send said data. However, for simplicity, the commander can query (polle) the responder with a different identifier (ID). Alternatively, the commander can query (polle) the responder with frame 460, which typically has a query identifier (ID), and then encode in the data field 465 of that frame 460 which responder is being referred to. The referred responder then responds, each of them using its own identifier (ID).
[0075] When transitioning to the data phase 452, no bit rate switching occurs in frame 460. That is, the bit time of the bits in the arbitration phase 451 and the data phase 452 is the same. However, it is possible that the bit time in the first communication phase (arbitration phase) 451 may differ from the bit time in the second communication phase (data phase) 452.
[0076] In data phase 452, in addition to a portion of the control field 464 of frame 460, message 46 from data field 465 or valid data from FDL frame 460, along with checksum field 466, are transmitted. At the end of checksum field 466 or before acknowledgment field 467, according to... Figure 3 The data phase 452 was then transferred to the arbitration phase 451.
[0077] As in Figure 3 As shown, the corresponding user stations 101…10N, in the arbitration phase 451 as the first communication phase, partially, and especially up to the FDF bit (inclusive), use a format known from CAN / CANFD according to ISO 11898-1:2015, such as… Figure 2 As shown in the diagram. The corresponding user station 101 uses the FDL format described below in the first communication phase, starting from the FDF bit, and in the data phase 452, which is the second communication phase. As in the case of CAN FD, recessive and dominant levels are used for transmission on the bus 40 in the FDL data phase 452.
[0078] Generally, two different padding rules are applied when generating frame 460. The CAN FD is either used until the FDF bit in the arbitration field 463, or... Figure 2The dynamic bit padding rule applies to frame 450, allowing a reverse padding bit to be inserted after five identical bits. In data phase 452, up to the SBC field, a fixed padding rule applies, allowing a fixed number of padding bits to be inserted after a fixed number of bits. Alternatively, instead of just one padding bit, two or more bits can be inserted as fixed padding bits.
[0079] DLC fields and data field 465 are as previously stated. Figure 2 Design it as described. In particular, when the DLC field of control field 463 has a value of 0, data field 465 has a length of 0 bytes.
[0080] Following data field 465, frame 460 is followed by checksum field 466, which is constructed as in the case of CAN FD, as follows: Figure 2 As shown in the image.
[0081] Next is confirmation field 467, which is constructed as in the case of CAN FD, and also... Figure 2 As shown in the diagram. The acknowledgment field 467 contains the ACK bit slot, where a user station that is currently only the receiver of frame 460 and not the sender of the frame can acknowledge or not acknowledge the correct reception of frame 460 from bus 40. The acknowledgment field 467 ends with the ACK-Del bit, which is also known as the ACK delimiter.
[0082] Following confirmation field 467, frame 460 is followed by the end field (EOF = End of Frame), as shown in the following... Figure 2 That's the case with CANFD.
[0083] The End-of-Flight (EOF) field is 7 hidden bits long.
[0084] Following the End of Frame (EOF) field, in frame 460, comes the Inter Frame Space (IFS), as previously discussed. Figure 2 As explained in frame 450.
[0085] Figure 4 The basic structure of user station 100 is shown, which includes a communication control device 11, a transmitting / receiving device 12, and a synchronization module 15, which is part of the communication control device 11.
[0086] according to Figure 4In addition to the communication control device 11 and the transmitting / receiving device 12, the user station 100 has a microcontroller 13 with the communication control device 11 and a system ASIC 16 (ASIC = AnwendungsspezifischeIntegrierte Schaltung), which can alternatively be a system base chip (SBC) on which the functions required for the electronic components of the user station 100 can be integrated. The system ASIC 16 particularly has an application 161, which can be designed as a computer program (App) or software. Such an application is a technical application 161. Application 161 is, for example, any application in a vehicle. In particular, this application is a windshield washer system and / or a driver assistance system, etc. For example, the windshield washer system controls the movement of at least one windshield wiper (actuator) and / or can turn on or off warning lights (actuators) using data from a rain sensor and / or a wind sensor and / or a speed sensor and / or a light sensor. However, this application is not limited to windshield washer systems or parts thereof.
[0087] In addition to the transmitting / receiving device 12, a power supply device 17 is installed in the system ASIC 16 to supply power to the transmitting / receiving device 12. The power supply device 17 typically provides a 5V voltage (CAN_Supply). However, depending on requirements, the power supply device 17 can provide other voltages with different values. Additionally or alternatively, the power supply device 17 can be designed as a power source.
[0088] If the communication control unit 11 is functioning as the FDL commander, then the communication control unit 11 may create a frame 460 in which no bit rate switching / bit rate transformation is performed, and / or evaluate such a frame 460.
[0089] The synchronization module 15 includes a synchronization block 151, a configuration block 152, an evaluation block 153, and a switch block 154. The configuration block 152 can store values for at least one synchronization configuration bit 1521. The synchronization block 151 can be a bit-timing-control unit (BTL) of the communication control device 11.
[0090] Synchronization module 15, especially evaluation block 153 and switch block 154, can be implemented at least partially as software.
[0091] Synchronization block 151 has the synchronization functions described in ISO 11898-1:2015 and the FDL specification according to CiA document CiA604-3. However, this synchronization function can be switched on and off as needed, as will be described in more detail below.
[0092] In addition to the synchronization module 16, the transmitting / receiving device 12 also has a transmitting module 121 and a receiving module 122. Although the transmitting / receiving device 12 is always referred to below, it is alternatively possible to house the receiving module 122 in a separate device outside the transmitting module 121. The transmitting module 121 and the receiving module 122 can be constructed as in the case of the 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.
[0093] The transmitting / receiving device 12 is connected to bus 40, more specifically to its first bus line 41 for CAN_H and its second bus line 42 for CAN_L. The power supply device 17 provides voltage via at least one terminal 43 to supply electrical energy, specifically the CAN-Supply voltage, to the first and second bus lines 41, 42. Connection to ground or CAN_GND is achieved via terminal 44. The first and second bus lines 41, 42 are terminated with terminating resistor 49.
[0094] Even if connected Figure 4 For simplicity, the first and second bus cores 41 and 42 are connected not only to the transmitting module 121 (also called the transmitter) but also to the receiving module 122 (also called the receiver) in the transmitting / receiving device 12.
[0095] During the operation of bus system 1, Figure 4 The transmitting module 121 can serially convert the transmitting signal TxD of the communication control device 11 into corresponding signals CAN_H and CAN_L for the CAN or CAN FD of the bus core lines 41 and 42, and transmit these signals at the terminals of CAN_H and CAN_L to the bus 40. The communication control device 11 serially transmits the signals at time t. Figure 5 The transmission signal TxD is sent to the transmission module 121 via the terminal TXD, such as Figure 4 As shown in the example. Figure 5 As shown, the transmitted signal TxD has voltage states H (High) and L (Low) with corresponding voltage U.
[0096] according to Figure 6 For example, signals CAN_H and CAN_L have dominant and recessive bus levels 401 and 402 in arbitration phase 451, as known from CAN. A difference signal VDIFF = CAN_H - CAN_L is formed on bus 40, which... Figure 7The diagram shows the arbitration phase 451. In both the arbitration phase 451 and the data phase 452, individual bits of the signal VDIFF with a bit time t_bt1 can be identified using, for example, a receive threshold T_a of 0.7 V. In the data phase 452 of frame 450, the bits of signals CAN_H and CAN_L can be transmitted faster than in the arbitration phase 451, i.e., with a shorter bit time t_bt2, as previously mentioned. Therefore, in the case of CANFD for frame 450, signals CAN_H and CAN_L in the data phase 452 differ from conventional signals CAN_H and CAN_L, at least in terms of their faster bit rate.
[0097] Figure 5 The sequence of states H and L of the transmitted signal TxD and Figure 6 The states 401 and 402 obtained from the signals CAN_H and CAN_L are as follows: Figure 7 The change process of the voltage VDIFF obtained therefrom is only used to illustrate the function of user station 100. The sequence of data states for bus states 401 and 402 can be selected as needed.
[0098] Receiver module 122 from such Figure 6 The signals CAN_H and CAN_L received from bus 40 shown are either Figure 7 The differential voltage VDIFF forms the received signal RxD. To generate... Figure 8 The digital received signal RxD, the receiving module 122 according to Figure 6 or Figure 7 At sampling point AP, at least one of the signals VDIFF or CAN_H and CAN_L received from bus 40 is sampled, as is known. Figure 8 The received signal RxD is shown in the case of no propagation time delay. For example... Figure 4 As shown, the receiving module 122 transfers the received signal RxD to the corresponding communication control device 11.
[0099] For message 46 based on frame 460 Figures 5 to 8 The corresponding signals are applicable.
[0100] During the operation of bus system 1, user station 100 (commander), or more precisely, communication control unit 11, performs bus monitoring. According to ISO 11898-1:2015, user station 100, and especially communication control unit 11, at sampling point AP (sample point), classifies the data according to frames 450, 460 and the transmitted signal TxD (…). Figure 5 The bits transmitted by the signal itself and the received signal RxD ( Figure 8The bits observed on bus 40 are compared. Distinctions are considered errors, except for the arbitration and ACK bits.
[0101] However, according to document CiA604-3, user station 100 (commander), more precisely communication control device 11, shuts down bus monitoring for shorter bit times t_bt1, t_bt2. Specifically, bit times t_bt1, t_bt2 are equal, as previously described. Such shorter bit times exist at higher bit rates exceeding 2 Mbit / s, where the so-called loop-delay of user station 100 (CAN node) reaches bit times t_bt1, t_bt2, or a larger range. The so-called loop-delay refers to the time elapsed until user station 100 can internally recognize a bit transmitted via terminal TXD of transmit signal TxD as a bit transmitted via terminal RXD of receive signal RxD.
[0102] Furthermore, during the operation of bus system 1, user station 100 (commander), or more precisely, communication control device 11, uses synchronization block 151 to perform synchronization functions for all the following frames 450, 460, which have bits with bit times t_bt1, t_bt2 for bit rates up to 2 Mbit / s.
[0103] Synchronization block 151 observes the edges from recessive to dominant or vice versa, i.e. Figure 6 Or rather Figure 7 The transitions between states 401, 402, or 402, 401 occur within the bit time intervals t_bt1, t_bt2. Synchronization block 151 synchronizes the position of the sampling point AP (sample point) within the bit time intervals t_bt1, t_bt2 based on the observed edges. The receiver is thus synchronized with the sender of frames 450, 460. If the edge ideally occurs at the beginning of the bit time intervals t_bt1, t_bt2, then no synchronization is needed. If the edge occurs between the beginning of the bit time intervals t_bt1, t_bt2 and the sampling point (sample point), then a so-called "late edge" exists. This causes synchronization, in which the current bit time intervals t_bt1, t_bt2 are extended. If the edge occurs between the sampling point AP (sample point) and the end of the bit time intervals t_bt1, t_bt2, then an so-called "early edge" exists. This causes synchronization, in which the current bit time intervals t_bt1, t_bt2 are shortened.
[0104] According to ISO 11898-1:2015 and the FDL specification of CiA604-3 cited in that ISO, the transmitters of frames 450 and 460 also synchronize. However, there is a limitation: user station 100 transmitting dominant bits does not synchronize with lagging edges (“Late Edges”). This is because, due to “loop delay”, the transmitter sees all the bits it has transmitted late. Therefore, synchronization with these lagging edges would prolong these bits and cause bit rate distortion. Permissible synchronization with “early edges” ensures stable CAN arbitration at the beginning of frames 450 and 460. Synchronization with ACK edges (in which the transmitter transmits recessive bits) ensures that all user stations in bus system 1 synchronize with the same edges.
[0105] The synchronization function is described in more detail in ISO 11898-1:2015 and the FDL specification according to CiA document CiA604-3.
[0106] However, the synchronization function of synchronization block 151 can be switched on and off as needed using synchronization module 15, as described below.
[0107] Evaluation block 153 is designed to evaluate the synchronization configuration bit 1521 in configuration block 152. Synchronization configuration bit 1521 is set when user station 100 (commander), or more precisely, communication control unit 11, is to send frame 450 or 460 at a bit time t_bt1 of the first communication phase 451, the bit time corresponding to a bit rate greater than a predetermined bit rate. The predetermined bit rate is in particular greater than 2 Mbit / s.
[0108] If the evaluation of evaluation block 153 results in the synchronization configuration bit 1521 being set, then evaluation block 153 verifies whether user station 100 (commander), or more precisely, communication control unit 11, should (currently) act as a sender, i.e., whether it should send frame 460 to the responder on bus 40. Synchronization configuration bit 1521 is set, for example, along with bit rate configuration, either via software or via fixed wiring. During the operation of bus system 1, this bit remains constant.
[0109] If the evaluation of evaluation block 153 determines that user station 100 (commander), or more precisely, communication control device 11, should act as the sender and should send frame 460 to the responder on bus 40, then evaluation block 151 instructs switch block 154 to turn off synchronization block 151. Therefore, for all bits of frame 460 that user station 100, as commander, should send to bus 40, up to the last bit of the end-of-flight (EOF) field, switch block 154 turns off or shuts down synchronization block 151 and thus disables or shuts down its previously described synchronization function.
[0110] By disabling synchronization block 151, the transmitter is prevented from synchronizing with its own transmitted edges, which are seen not within the transmitted bit time but in one of the following bit times. As a result, synchronization will not cause reception errors in other user stations 101…10N of the bus system.
[0111] After the last bit of the End of Frame (EOF) field of the transmitted frame, Figure 4 Switch block 154 then switches on synchronization block 151 and thus activates its previously described synchronization function.
[0112] according to Figure 9 In addition to the communication control unit 21 and the transmitting / receiving unit 22, the responder user station 101 has a simple control unit (FSM) or optionally a microcontroller 23 with the communication control unit 21, and a system ASIC 26 (ASIC = AnwendungsspezifischeIntegrierte Schaltung), which can alternatively be a system base chip (SBC) on which multiple functions necessary for the electronic components of the user station 101 are integrated. The system ASIC 26, in particular, has an application 261, which can be designed as a computer program (App). Such an application is a technical application 261. Application 261 is, for example, application 161 used by the commander user station 100 (… Figure 4 A control device that controls or should provide data to an application 161, such as a sensor, transmitter, or actuator.
[0113] In addition to the transmitting / receiving device 22, a power supply device 27 is also installed in the system ASIC 26 to supply power to the transmitting / receiving device 22. The power supply device 27 typically provides a 5V voltage (CAN_Supply). However, depending on requirements, the power supply device 27 can provide other voltages with different values. Additionally or alternatively, the power supply device 27 can be designed as a power source.
[0114] Communication control unit 21 creates a frame 460 in which no bit rate switching or bit rate transformation is performed and / or evaluates such a frame 460 based on a frame 460 received from commander user station 100. Communication control unit 21 can also be referred to as an FDL responder. Units 21 and 22 can only send such a frame 460 onto bus 40 upon request (polling) from commander user station 100.
[0115] also, Figure 9 The sending module 222 is used in conjunction with the previously targeted Figure 4 It is constructed in the same manner as described in the sending module 122.
[0116] Figure 9 The synchronization module 25 has a synchronization block 251, a configuration block 252, an evaluation block 253, and a switch block 253. The configuration block 252 stores at least one configuration bit 2521, 2522.
[0117] Synchronization module 25 can also disable synchronization for frames 460 or messages 46 sent by user station 101, as previously mentioned. Figure 4 The synchronization module 25 is described for frames 450 and 460. Therefore, the synchronization module 25 always disables synchronization for frame 460, or message 46, sent by user station 101 at high bit rates. High bit rates are, for example, greater than 2 Mbit / s.
[0118] Unlike Figure 4 Synchronization module 15, Figure 9 The synchronization module 25 is optionally designed to disable synchronization in the assigned responders, even at low bit rates, for frames 460 or messages 46 sent by user station 101, as needed. For this purpose, additional configuration bits 2522 can be set, for example. Low bit rates are, for example, less than or equal to 2 Mbit / s. This shutdown has little impact on communication between the commander user station 100 and the corresponding responder user stations 101…10N.
[0119] This allows for selection. Figure 9 The synchronization module 25 is optionally designed to disable its synchronization function for frames 460 or messages 46 sent by user station 101, both at low and high bit rates, i.e., regardless of the bit rate. In other words, this allows for selection... Figure 9 The synchronization module 25 is designed to disable its synchronization function independently of the bit rate for frames 460 or messages 46 sent by user station 101.
[0120] User stations 101…10N can abandon this synchronization because no arbitration is performed in the FDL, and no ACK bit is sent even at higher bit rates.
[0121] Furthermore, synchronization module 25 is constructed in the same manner as previously described for synchronization module 15.
[0122] Synchronization modules 15 and 25 are thus able to communicate with the CAN FD Light or FDL even when the bit rate is greater than or equal to 2 Mbit / s.
[0123] All previously described design schemes for user stations 100, 101…10N, 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 modifications thereof can be arbitrarily combined. Additional or alternative modifications, especially the following, are conceivable.
[0124] Although the invention has been described previously using a CAN bus system as an example, it can be used in cases where each communication network and / or communication method employs two different communication phases, in which the bus states generated for the different communication phases can be different.
[0125] In particular, the bus system 1 according to the embodiment can be a communication network in which data can be transmitted serially at two different bit rates. Advantageously, but not mandatory, is that in the case of bus system 1, exclusive and conflict-free access to the common channel by user stations 100, 101...10N is guaranteed at least for a specific time interval.
[0126] The number and arrangement of user stations 100, 101…10N in the bus system 1 of the embodiment are arbitrary. It is possible that one or more user stations 100 exist in the bus system 1. It is also possible that more than one user station 100 exists in the bus system 1, with at least one user station 101…10N assigned to that user station 100, as previously described. To avoid interfering with arbitration between user stations 100 on the bus 40, the message 46 of user station 101…10N (responder) therefore has an identifier (ID) that has a higher priority than the identifiers (IDs) of user station 100 or other CAN FD user stations.
[0127] In particular, there is only one user station 100 (commander) and at least one user station 101…10N (responder), such as Figure 1 As shown in the image.
[0128] It is conceivable that in user station 100, module 15 is arranged separately from communication control device 11. It is conceivable that in at least one of user stations 100, 101...10N, module 25 is arranged separately from communication control device 21.
Claims
1. A commander user station (100) for a serial bus system (1), the commander user station having: A communication control device (11) is configured to control communication between the user station (100) and responder user stations (101; 102; ... 101N) of the bus system (1), and to evaluate, based on frames (450; 460), at least one signal (VDIFF; RxD) received from the bus (40) of the bus system (1) in which the bit time (t_bt1) in the first communication phase (451) of the frame is distinguishable from the bit time (t_bt2) in the second communication phase (452), and Synchronization module (15), which is used to synchronize the communication control device (11) with the signal (VDIFF; RxD) received from the bus (40), in, The synchronization module (15) is designed to disable the synchronization function of the synchronization module when the bit time (t_bt1) of the first communication phase (451) of the predetermined frame (460) has a predetermined value corresponding to a bit rate greater than the predetermined bit rate, and when the communication control device (11) is to act as the sender of the predetermined frame (460), so that the commander user station (100) is the sender of the signal (VDIFF; RxD) received from the bus (40).
2. The commander user station (100) according to claim 1, wherein, The synchronization module (15) has: Synchronization block (151), the synchronization block being designed to synchronize the communication control device (11) with the signals (VDIFF; RxD) received from the bus (40), and A configuration block (152) stores a value for at least one synchronization configuration bit (1521) indicating whether the bit rate is greater than a predetermined bit rate.
3. The commander user station (100) according to claim 2, wherein, The synchronization module (15) further includes: Evaluation block (153), which is used to evaluate the value of the at least one configuration bit (1521), and A switch block (154) is used to turn the synchronization of the synchronization block (151) on or off based on the evaluation of the evaluation block (153).
4. The commander user station (100) according to any one of the preceding claims. in, The commander user station (100) is a CAN FD user station. The predetermined frame (460) is a CAN FD frame in FBFF format.
5. The commander user station (100) according to any one of the preceding claims, wherein, The predetermined bit rate is 2 Mbit / s.
6. A responder user station (101; 102; ... 101N) for a serial bus system (1), said responder user station having: A communication control device (21) is configured to control communication between the user stations (101; 102; ... 101N) and the commander user station (100) of the bus system (1), and to evaluate at least one signal (VDIFF; RxD) received from the bus (40) of the bus system (1) according to a predetermined frame (460), in which the bit time (t_bt1) in the first communication phase (451) is distinguishable from the bit time (t_bt2) in the second communication phase (452), and Synchronization module (25), which is used to synchronize the communication control device (21) with the signal (VDIFF; RxD) received from the bus (40), in, The synchronization module (25) is designed to disable the synchronization function of the synchronization module when the communication control device (21) is to act as the sender of the frame (460) such that the responder user station (101; 102; ... 101N) is the sender of the signal (VDIFF; RxD) received from the bus (40).
7. The responder user station (101; 102; ... 101N) according to claim 6, wherein, The synchronization module (25) is designed to disable the synchronization function of the synchronization module when the bit time (t_bt1) of the first communication phase (451) of the predetermined frame (460) has a predetermined value corresponding to a bit rate greater than the predetermined bit rate, and when the communication control device (21) is to act as the sender of the frame (460) such that the responder user station (101; 102; ... 101N) is the sender of the signal (VDIFF; RxD) received from the bus (40).
8. The responder user station (101; 102; ... 101N) according to claim 7, wherein, The synchronization module (25) has: Synchronization block (251), the synchronization block being designed to synchronize the communication control device (21) with the signals (VDIFF; RxD) received from the bus (40), and A configuration block (252) stores a value for at least one synchronization configuration bit (2521) that indicates whether the bit rate is greater than a predetermined bit rate.
9. The responder user station (101; 102; ... 101N) according to claim 7 or 8, wherein, The synchronization module (25) further includes: Evaluation block (253), which is used to evaluate the value of the at least one configuration bit (2521), and A switch block (254) is used to turn the synchronization of the synchronization block (251) on or off based on the evaluation of the evaluation block (253).
10. The responder user station (101; 102; ... 101N) according to any one of claims 7 to 9. in, The responder user stations (101; 102; ... 101N) are user stations designed for communication according to CAN FD. The predetermined frame (460) is a CAN FD frame in FBFF format.
11. The responder user station (101; 102; ... 101N) according to any one of claims 7 to 10, wherein, The predetermined bit rate is 2 Mbit / s.
12. A bus system (1) having: Bus (40), and At least two user stations (100; 101…10N) are connected to each other via the bus (40) such that the at least two user stations are able to communicate with each other serially, and one of the user stations is a commander user station (100) according to any one of claims 1 to 5, and at least one of the user stations is a responder user station (101…101N) according to any one of claims 6 to 11. in, Each of the at least two user stations (100; 101…10N) further has a transmitting / receiving device (12; 22) for transmitting a transmitting signal (TxD) to the bus (40) of the bus system (1) and / or for receiving a signal (VDIFF) from the bus (40) of the bus system (1).
13. The bus system (1) according to claim 12. It also has at least one third user station (100), which is designed to transmit and / or receive signals according to frames (450; 460). in, The at least one third user station (100) has a communication control device (11) designed to negotiate with the commander user station (100) in the first communication phase (451) of the frame (450; 460) whether the third user station (100) or the commander user station (100) will have exclusive, conflict-free access to the bus (40) at least temporarily in the following second communication phase (452).
14. A method for communication in a serial bus system (1), wherein, The method is implemented using a commander user station (100) according to any one of claims 1 to 5 and a responder user station (101…101N) according to any one of claims 6 to 11.