DE102018214963A1 - Transceiver for a serial bus system and method for sending a message in a serial bus system - Google Patents

Abstract

A transceiver (12; 120; 1200) for a serial bus system (1) and a method for sending a message with different bit rates in a serial bus system (1) are provided. The transmitting / receiving device (12; 120; 1200) comprises a first driver (123, 124, 125) for driving a first signal (CAN_H) for a first bus wire (41) of a bus (40) of the bus system (1) which bus system (1) is guaranteed exclusive, collision-free access of a subscriber station (10, 20, 30) to the bus (40) of the bus system (1) at least temporarily, a second driver (123, 124, 127) for driving a second signal (CAN_L) for the second bus wire (42) of the bus (40), a communication phase detection block (152) for detecting different communication phases on the bus (40), and a vibration reduction unit (15; 150) for reducing vibrations on the bus wires (41, 42), which occur after a change of state of the signal (CAN_H, CAN_L), which is transmitted on at least one of the bus wires (41, 42), from a dominant bus state (402) to a recessive bus state (401), the Vibration reduction unit (15; 150; 1500) is configured, depending on the communication phase on the bus (40), which was detected by the communication phase detection block (152), to influence currents which are generated by the first driver (123, 124, 125) and / or the second driver (123 , 124, 127) for the signals (CAN_H, CAN_L).

Description

Technical field

The present invention relates to a transceiver for a serial bus system and a method for sending a message in a serial bus system that operates with a high data rate and high error resilience.

State of the art

A bus system is frequently used for communication between sensors and control devices, for example in vehicles, in which data is transmitted as messages in the ISO11898-1: 2015 standard as a CAN protocol specification with CAN FD. The messages are transmitted between the bus participants in the bus system, such as sensors, control units, transmitters, etc.

With an increasing number of functions of a technical system or a vehicle, the data traffic in the bus system also increases. In addition, it is often required that the data can be transferred from the sender to the receiver faster than before. The consequence of this is that the required bandwidth of the bus system will continue to increase.

In order to be able to transmit data with a higher bit rate than with CAN, an option for switching to a higher bit rate within a message was created in the CAN FD message format. In such techniques, the maximum possible data rate is increased by using a higher clock rate in the area of the data fields beyond a value of 1 Mbit / s. Such messages are also referred to below as CAN FD frames or CAN FD messages. With CAN FD, the user data length is extended from 8 to up to 64 bytes and the data transfer rates are significantly higher than with CAN.

Even if a CAN or CAN FD-based communication network offers many advantages in terms of its robustness, for example, it has a significantly lower speed compared to data transmission with 100 Base-T1 Ethernet, for example. In addition, the user data length of up to 64 bytes previously achieved with CAN FD is too short for some applications.

Disclosure of the invention

It is therefore an object of the present invention to provide a transceiver for a serial bus system and a method for transmitting a message in a serial bus system, which solve the aforementioned problems. In particular, a transceiver for a serial bus system and a method for sending a message in a serial bus system are to be provided, in which a high data rate and an increase in the amount of user data per frame can be realized with great robustness for errors.

The object is achieved by a transceiver for a serial bus system with the features of claim 1. The transmitting / receiving device comprises a first driver for driving a first signal for a first bus wire of a bus of the bus system, in which bus system an exclusive, collision-free access of a subscriber station to the bus of the bus system is guaranteed at least temporarily, a second driver for driving a second one Signals for the second bus wire of the bus, a communication phase detection block for detecting different communication phases on the bus, and a vibration reduction unit for reducing vibrations on the bus wires, which after a change of state of the signal, which is transmitted to at least one of the bus wires, by one dominant bus state to a recessive bus state occur, wherein the vibration reduction unit is designed, depending on the communication phase on the bus, which was detected by the communication phase detection block, to influence currents by the first driver and / or de in the second driver for the signals.

With the transmitting / receiving device, it is possible, in particular, to maintain an arbitration known from CAN in a first communication phase and yet to significantly increase the transmission rate again compared to CAN or CAN FD. This can be achieved by significantly reducing the tendency to oscillate in the second communication phase, in which the user data is transmitted, at the transition from the dominant to the recessive state. As a result, bits can be scanned earlier in the bit time and more reliably in the data phase. As a result, the bit rate and thus the transmission speed from transmitter to receiver can be significantly increased. However, great robustness against errors is guaranteed at the same time.

Due to the design of the transmitting / receiving device, no error frames (error frames) are required anymore, however, error frames (error frames) can still be used if desired. This helps to realize a net data rate of at least 10 Mbps. In addition, the size of the user data can be up to 4096 bytes per frame.

The method carried out by the transceiver can also be used come when there is at least one CAN subscriber station and / or at least one CAN FD subscriber station in the bus system, which send messages according to the CAN protocol and / or CAN FD protocol.

Advantageous further developments of the subscriber station are specified in the dependent claims.

According to a special embodiment variant, the vibration reduction unit is designed to influence the currents which are driven by the first driver and / or the second driver for the signals on at least one bus wire after completion of an arbitration phase of the communication.

The communication phases on the bus may differ in that in a phase in which it is negotiated which of the subscriber stations of the bus system subsequently gets exclusive, collision-free access to the bus, bits of the signal have a bit time that is at least by a factor 10 is greater than a bit time of bits that are driven in the phase of communication in which the subscriber station has exclusive, collision-free access to the bus.

According to one option, the vibration reduction unit is configured such that the vibration reduction unit is only activated when the first driver and / or the second driver drives a signal on the bus.

The transceiver may also have a first driver replica for driving a signal for the first bus wire to reduce currents supplied by the first driver for the first bus wire and / or a second driver replica for driving a signal for the second bus wire to supply currents in addition to the second driver for the second bus wire, wherein the vibration reduction unit can have a transistor which is connected in such a way that the transistor in the conductive state drives at least one of the driver simulations for driving a signal for the first and / or second bus wire, and wherein the vibration reduction unit is configured to switch the transistor on if a change in state of the received signal from a dominant bus state to a recessive bus state is detected.

Here, the first driver simulation can have a driver, a transistor and a diode, the cathode of which is connected to a drain connection of the transistor, and the anode of which is connected to the first bus wire, the driver being connected for driving the transistor, and wherein Source connection of the transistor is connected to ground. In addition, the second driver simulation can have a driver, a transistor and a diode, the cathode of which is connected to a source connection of the transistor, and the anode of which is connected to a voltage supply for the first and second bus wires, the driver interconnecting to drive the transistor and a drain connection of the transistor is connected to the second bus wire.

It is conceivable that the vibration reduction unit has a detection block, which is designed to detect a change in state of the received signal from the dominant bus state to the recessive bus state, and whose input is connected in parallel to an input of a receive comparator of the transceiver, and an RS -Time control block, which is designed to control the signal on at least one bus wire depending on the detection result of the detection block and the detected communication phase on the bus.

Here, the vibration reduction unit can also have a phase position detection block for detecting the temporal position of the signals on the bus wires of the bus with respect to one another, the RS timing block also being designed for controlling the signal on at least one bus wire as a function of the detection result of the phase position detection block, to adjust the phase of the signal on the bus wire.

The transmitting / receiving device described above can be part of a subscriber station for a bus system, which also has a communication control device for controlling communication of the subscriber station with at least one other subscriber station of the bus system, the transmitting / receiving device for sending messages to a bus of the bus system and configured to receive messages from the bus.

Here, the communication control device or the transmitting / receiving device has a block which is designed to detect a change in state of a signal received from the bus from the dominant bus state to the recessive bus state, the vibration reduction unit being designed to process the transistor as a function of the detection result of the block head for.

The communication control device can optionally be designed to send a signal to the transmitting / receiving device, which the transmitting / receiving device serves as the basis for the Signals used for the bus wires, and to compare the signal with a signal received by the transceiver from the bus to generate a control signal, and wherein the communication control device is configured to output the control signal for controlling the vibration reduction unit to the transceiver.

The subscriber station described above can be part of a bus system which also comprises a bus and at least two subscriber stations which are connected to one another via the bus in such a way that they can communicate with one another in series. Here, at least one of the at least two subscriber stations is a previously described subscriber station.

The aforementioned object is also achieved by a method for sending a message in a serial bus system according to claim 14. The method is carried out with a transceiver for a bus system, in which exclusive, collision-free access of a subscriber station to a bus of the bus system is ensured at least at times, the transceiver having a first driver, a second driver and a vibration reduction unit , the method comprising the steps of driving, with the first driver, a first signal for a first bus wire of the bus and driving, with the second driver, a second signal for the second bus wire of the bus, detection, with a communication phase detection block, of different communication phases on the bus, and reduction, with a vibration reduction unit, of vibrations on the bus wires, which occur after a change of state of the signal, which is transmitted to at least one of the bus wires, from a dominant bus state to a recessive bus state, the vibration reduction Unit depends on the communication phase on the bus, which was detected by the communication phase detection block, influences currents which are driven by the first driver and / or the second driver for the signals.

The method offers the same advantages as previously mentioned with regard to the subscriber station.

Further possible implementations of the invention also include combinations of features or embodiments described above or below with reference to the exemplary embodiments that are not explicitly mentioned. The person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

Figure list

• 1 ein vereinfachtes Blockschaltbild eines Bussystems gemäß einem ersten Ausführungsbeispiel;
• 2 ein Schaubild zur Veranschaulichung des Aufbaus von Nachrichten, die von Teilnehmerstationen des Bussystems gemäß dem ersten Ausführungsbeispiel gesendet werden können;
• 3 ein elektrisches Schaltbild eines Senders einer Sende-/Empfangseinrichtung des Bussystems gemäß dem ersten Ausführungsbeispiel;
• 4A einen zeitlichen Verlauf eines Sendesignals TxD bei der Sende-/Empfangseinrichtung gemäß dem ersten Ausführungsbeispiel sowie 4B einen zeitlichen Verlauf eines Sendesignals TxD bei einer herkömmlichen Sende-/Empfangseinrichtung;
• 5A einen zeitlichen Verlauf von Bussignalen CAN_H und CAN_L bei der Sende-/Empfangseinrichtung gemäß dem ersten Ausführungsbeispiel sowie 5B einen zeitlichen Verlauf der Bussignale CAN_H und CAN_L bei der herkömmlichen Sende-/Empfangseinrichtung;
• 6A einen zeitlichen Verlauf einer Differenzspannung VDIFF der Bussignale CAN_H und CAN_L bei der Sende-/Empfangseinrichtung gemäß dem ersten Ausführungsbeispiel sowie 6B einen zeitlichen Verlauf der Differenzspannung VDIFF der Bussignale CAN_H und CAN_L bei der herkömmlichen Sende-/Empfangseinrichtung;
• 7A einen zeitlichen Verlauf eines Empfangssignals RxD bei der Sende-/Empfangseinrichtung gemäß dem ersten Ausführungsbeispiel sowie 7B einen zeitlichen Verlauf eines Empfangssignals RxD bei einer herkömmlichen Sende-/Empfangseinrichtung;
• 8 ein elektrisches Schaltbild einer Sende-/Empfangseinrichtung des Bussystems gemäß einer Modifikation des ersten Ausführungsbeispiels;
• 9 ein elektrisches Schaltbild einer Sende-/Empfangseinrichtung eines Bussystems gemäß einem zweiten Ausführungsbeispiel; und
• 10 ein elektrisches Schaltbild einer Sende-/Empfangseinrichtung eines Bussystems gemäß einem dritten Ausführungsbeispiel.

The invention is described in more detail below with reference to the accompanying drawing and using exemplary embodiments. Show it:

• 1 a simplified block diagram of a bus system according to a first embodiment;
• 2 a diagram illustrating the structure of messages that can be sent from subscriber stations of the bus system according to the first embodiment;
• 3 an electrical circuit diagram of a transmitter of a transceiver of the bus system according to the first embodiment;
• 4A a time course of a transmission signal TxD in the transmission / reception device according to the first embodiment and 4B a time course of a transmission signal TxD in a conventional transceiver;
• 5A a time course of bus signals CAN_H and CAN_L in the transceiver according to the first embodiment and 5B a time course of the bus signals CAN_H and CAN_L in the conventional transceiver;
• 6A a time profile of a differential voltage VDIFF of the bus signals CAN_H and CAN_L in the transceiver according to the first embodiment and 6B a time course of the differential voltage VDIFF of the bus signals CAN_H and CAN_L in the conventional transceiver;
• 7A a time course of a received signal RxD in the transceiver according to the first embodiment and 7B a time course of a received signal RxD in a conventional transceiver;
• 8th an electrical circuit diagram of a transceiver of the bus system according to a modification of the first embodiment;
• 9 an electrical circuit diagram of a transceiver of a bus system according to a second embodiment; and
• 10 an electrical circuit diagram of a transceiver of a bus system according to a third embodiment.

In the figures, identical or functionally identical elements are provided with the same reference numerals, unless stated otherwise.

Description of the embodiments

1 shows a bus system as an example 1 , which is configured in particular fundamentally for a CAN bus system, a CAN FD bus system, a CAN FE bus system, and / or modifications thereof, as described below. The bus system 1 can be used in a vehicle, in particular a motor vehicle, an aircraft, etc., or in a hospital, etc.

In 1 has the bus system 1 a variety of subscriber stations 10 . 20th . 30th each connected to a bus 40 with a first bus wire 41 and a second bus wire 42 are connected. The bus veins 41 . 42 can also be called CAN_H and CAN_L and are used for electrical signal transmission after coupling in of the dominant levels or generation of recessive levels for a signal in the transmission state. Via the bus 40 are news 45 . 46 in the form of signals between the individual subscriber stations 10 . 20th . 30th serially transferable. The subscriber stations 10 . 20th . 30th are, for example, control devices, sensors, display devices, etc. of a motor vehicle.

As in 1 has shown the subscriber station 10 a communication control device 11 , a transceiver 12 and a vibration reduction unit 15 , The subscriber station 20th on the other hand has a communication control device 21 and a transceiver 22 , The subscriber station 30th has a communication control device 31 , a transceiver 32 and a vibration reduction unit 35 , The sending / receiving devices 12 . 22 . 32 of the subscriber stations 10 . 20th . 30th are each directly on the bus 40 connected even if this is in 1 is not illustrated.

The communication control devices 11 . 21 . 31 each serve to control communication of the respective subscriber station 10 . 20th . 30th over the bus 40 with another subscriber station of the subscriber stations 10 . 20th . 30th that on the bus 40 are connected.

The communication control device 11 creates and reads first messages 45 which, for example, modified CAN messages 45 are. Here are the modified CAN messages 45 built on a CAN FE format that is related to 2 is described in more detail.

The communication control device 21 can be designed like a conventional CAN controller. The communication control device 21 creates and reads second messages 46 , for example Classic CAN messages 46 , The Classic CAN messages 46 are structured according to the classic basic format, in which in the message 46 a number of up to 8 data bytes can be included. Alternatively, there is the Classic CAN message 46 constructed as a CAN FD message, in which a number of up to 64 data bytes can be included, which in addition with a significantly faster data rate than with the Classic CAN message 46 be transmitted. In the latter case, the communication control device 21 designed like a conventional CAN FD controller.

The communication control device 31 can be executed to receive a CAN FE message as required 45 or a Classic CAN message 46 for the transceiver 32 provide or receive from this. The communication control device 31 creates and reads a first message 45 or second message 46 , being the first and second message 44 . 46 distinguish by their data transmission standard, namely in this case CAN FE or CAN. Alternatively, there is the Classic CAN message 46 constructed as a CAN FD message. In the latter case, the communication control device 31 designed like a conventional CAN FD controller.

The transceiver 12 can be designed as a CAN FE transceiver except for the differences described in more detail below. The transceiver 22 can be designed like a conventional CAN transceiver or CAN FD transceiver. The transceiver 32 can be run to messages as needed 45 according to the CAN FE format or messages 46 according to the current CAN basic format for the communication control device 31 provide or receive from this. The sending / receiving devices 12 . 32 can be implemented additionally or alternatively as a conventional CAN FD transceiver.

With the two subscriber stations 10 . 30th is an education and then transmission of messages 45 with the CAN FE format and the receipt of such messages 45 realizable.

2 shows for the message 45 a CAN FE frame 450 as it is from the transceiver 22 or the transmitting / receiving device 32 is sent. The CAN FE frame 450 is for CAN communication on the bus 40 divided into different fields, namely a start field 451 , an arbitration field 452 , a control panel 453 , a data field 454 , a checksum field 455 and an end field 456 ,

The starting field 451 has, for example, a bit that is also called SOF bit and indicates the start of the frame or start of frame. In the arbitration field 452 an identifier with, for example, 32 bits is included to identify the sender of the message. The arbitration field 452 can additionally contain protocol format information consisting of one or more bits, which is suitable for distinguishing CAN FE frames from CAN frames or CAN FD frames.

In the control panel 453 For example, a 13-bit data length code (data length code) is contained, which can then assume values from 1 to 4096 with the step size of 1, for example, or alternatively can assume values from 0 to 4095. The data length code can also comprise fewer or more bits and the value range and the step-by-step can assume different values. The control panel 453 can additionally contain protocol format information consisting of one or more bits, which is suitable for distinguishing CAN FE frames from CAN frames or CAN FD frames.

In the data field 454 are the user data of the CAN-EL frame or the message 45 contain. Depending on the value range of the data length code, the user data can have up to 4096 bytes, for example. In the checksum field 455 is a checksum of the data in the data field 454 including the stuff bits contained by the sender of the message 45 after every 10 identical bits are inserted as an inverse bit. In the end field 456 it contains at least one acknowledge bit and also a sequence of 11 identical bits that represent the end of the CAN FE frame 450 Show. The at least one acknowledge bit can be used to indicate whether a receiver is in the received CAN FE frame 450 or the message 45 discovered an error or not.

In the phases for sending the arbitration field 452 and the end field 456 a physical layer like for CAN and CAN-FD is used. An important point during these phases is that the known CSMA / CR method is used, which simultaneous access by the subscriber stations 10 . 20th . 30th on the bus 40 allowed without the higher priority message 45 . 46 gets destroyed. This allows the bus system 1 relatively easy further bus subscriber stations 10 . 20th . 30th be added, which is very beneficial.

The consequence of the CSMA / CR method is that there are so-called recessive states on the bus 40 must be given by other subscriber stations 10 . 20th . 30th with dominant states on the bus 40 can be overwritten. In a recessive state, the individual subscriber station prevails 10 . 20th . 30th high-impedance conditions, which, in combination with the parasites of the bus circuit, results in longer time constants. This leads to a limitation of the maximum bit rate of today's CAN FD physical layer to currently around 2 megabits per second in real vehicle use.

The control panel 453 and the data field 454 are from a sender of the message 45 first on the bus 40 sent when the subscriber station 20th when the sender won the arbitration and the subscriber station 20th as sender to send the fields 453 to 456 exclusive access to the bus 40 of the bus system 1 Has. Arbitration is carried out with the help of the identifier in the arbitration field 452 bit by bit between the subscriber stations 10 . 20th . 30th negotiated which subscriber station 10 . 20th . 30th the message 45 . 46 want to send with the highest priority and therefore for the next time to send the fields 453 to 455 exclusive access to the bus 40 of the bus system 1 gets.

The arbitration at the beginning of a frame 450 or the message 45 . 46 and the acknowledgment in the end field 456 at the end of the frame 450 or the message 45 . 46 is only possible if the bit time is significantly more than twice as long as the signal transit time between any two subscriber stations 10 . 20th . 30th of the bus system 1 , Therefore, the bit rate in the arbitration phase when the fields are transmitted 451 . 452 . 456 chosen slower than in the other fields of the frame 450 , In particular, the bit rate in the arbitration phase is selected as 500 kbit / s, which results in a bit time of approx. 2µs, whereas the bit rate in the other communication phase (s) is selected as 5 to 8 Mbit / s, resulting in a bit time of approx. 0 , 2µs and shorter follows. Thus, the bit time of the signal in the arbitration phase is at least a factor 10 greater than the bit time of the signal in the other communication phase (s).

1. a) Übernahme und ggf. Anpassung bewährter Eigenschaften, die für die Robustheit und Anwenderfreundlichkeit von CAN und CAN FD verantwortlich sind, insbesondere Rahmenstruktur mit Identifier und Arbitrierung nach dem CSMA/CR-Verfahren,
2. b) Steigerung der Netto-Datenübertragungsrate auf etwa 10 Megabit pro Sekunde,
3. c) Anheben der Größe der Nutzdaten pro Rahmen auf etwa 4kbyte,
4. d) Optional: Vollständiger oder teilweiser Verzicht auf das Versenden von Fehlerrahmen (Error Frames) bei Erkennen von Fehlern. Jedoch ist es mit der zuvor beschriebenen Schwingungsreduktionseinheit 15 möglich, dass Fehlerrahmen (Error Frames) weiter verwendet werden können, da die Schwingungsreduktionseinheit 15 die Buszustands-Übergänge in der Datenphase zeitlich nur sehr kurz beeinflusst. Dadurch sind Fehlerrahmen (Error Frames) in der Lage, über den aktuellen Busverkehr zu dominieren (6x dominant in Folge), wie erforderlich. Das ist aus Anwendersicht ein Vorteil.

In general, the following properties can be implemented in the bus system with CAN FE compared to CAN or CAN FD:

1. a) Adopting and, if necessary, adapting proven properties that are responsible for the robustness and user-friendliness of CAN and CAN FD, in particular frame structure with identifier and arbitration according to the CSMA / CR process,
2. b) increasing the net data transfer rate to approximately 10 megabits per second,
3. c) increasing the size of the user data per frame to approximately 4 kbytes,
4. d) Optional: Complete or partial waiver of sending error frames when errors are detected. However it is with the vibration reduction unit described above 15 possible that error frames can continue to be used because the vibration reduction unit 15 the bus state transitions in the data phase are only influenced for a very short time. As a result, error frames are able to dominate over the current bus traffic (6x dominant in succession), as required. From the user's point of view, this is an advantage.

3 shows the basic structure of the transceiver 12 with the vibration reduction unit 15 , The transceiver 32 is constructed in the same way and is therefore not described separately.

Even if subsequently always from the transmitting / receiving device 12 is spoken, it is alternatively possible to provide a receiver in a separate device externally from the transmitter. The receiver can be like a conventional transceiver 12 be constructed.

The transceiver 12 is on the bus 40 , more precisely its first bus line 41 for CAN_H and its second bus wire 42 connected for CAN_L. The power supply, in particular CAN supply, for the first and second bus wires 41 . 42 takes place via at least one connection 43 , The connection to ground or CAN_GND is via a connection 44 realized. The first and second bus wire 41 . 42 are with a terminating resistor 49 terminated.

The first and second bus wire 41 . 42 are in the transmitting / receiving device 12 with a transmitter 121 , also known as a transmitter, and with a receiver 122 connected, which is also referred to as a receiver. Both with the transmitter 121 as well as the recipient 122 is an interface unit 125 for driving signals over the connections 111 . 112 to the communication control device 11 connected.

For driving the signals of the connections 111 . 112 has the connection unit 125 a transmit signal driver 1251 for a transmit signal TxD, which is also referred to as a TxD signal, and at the connection 111 from the communication control device 11 Will be received. In addition, the interface unit 125 a receive signal driver 1252 for a receive signal RxD, which is also referred to as an RxD signal, from the bus wires 41 . 42 by means of the receiver 122 was received and via the connection 112 to the communication control device 11 is passed on. The drivers 1251 . 1252 are about a digital part 1253 with the transmitter 121 and the recipient 122 connected. The digital part 1253 can monitor the signals TxD, RxD.

According to 3 are components of the vibration reduction unit 15 in the transmitter 121 built-in. Other components of the vibration reduction unit 15 are in the receiver 122 built-in. Here the transmitter has 121 in addition to a driver 1211 with driver circuit and a first output stage consisting of transistor and diode for the first bus wire 41 and a driver 1212 with the driver circuit and a second output stage consisting of transistor and diode for the second bus wire 42 a driver replica 1213 for the first bus wire 41 and a driver replica 1214 for the second bus wire 42 , The driver 1211 can also be referred to as CAN_H driver 1211 of a conventional transmitter in the present exemplary embodiment. The driver 1212 , which also matches the driver 1211 driver circuit shown, can also be referred to in the present embodiment as a CAN_L driver 1212 of a conventional transmitter. The driver simulation 1213 is thus provided for CAN_H in the present exemplary embodiment. The driver simulation 1214 is thus provided for CAN_L in the present exemplary embodiment. The driver simulations 1213 . 1214 are also components of the vibration reduction unit 15 , The driver simulations 1213 . 1214 are also components of the vibration reduction unit 15 ,

The recipient 122 has a receiving comparator 1221 whose input is in a resistive, in particular symmetrical, voltage divider 1222 , more precisely its center tap, is connected, and a bus bias unit 1223 , The bus bias unit 1223 feeds the resistive voltage divider 1222 at one end with a predetermined bus bias or a predetermined bus bias potential. The resistive voltage divider 1222 is at its other end to the first and second bus wires 41 . 42 connected. The input of the receiving comparator 1221 is with the vibration reduction unit 15 interconnected as detailed below.

The vibration reduction unit 15 includes a change of state detection block 151 and a communication phase detection block 152 , The inputs of the blocks 151 . 152 are each parallel to the input of the receiving comparator 1221 switched. The outputs of the blocks 151 . 152 are on an RS timing block 153 connected or with the RS timing block 153 connected. The block 153 is used to control the signal on the first bus wire 41 or CAN_H and / or the signal on the second bus wire 42 or CAN_L, as described in more detail below. The blocks 151 . 152 . 153 are components of the vibration reduction unit 15 and the recipient 122 ,

Regarding the driver replicas 1213 . 1214 includes the vibration reduction unit 15 a first RS driver 155 and a second RS driver 156 , as well as transistors 157 . 159 and diodes 158 . 160 , The first RS driver 155 forms together with the transistor 157 and the diode 158 the driver simulation 1213 for the signal CAN_H. The second RS driver 156 forms together with the transistor 159 and the diode 160 the driver simulation 1214 for CAN_L. The transistors 157 . 159 can be designed as high-voltage switches. Alternatively, the transistors 157 . 159 each be designed as a series connection of low-voltage switching transistor and high-voltage cascode. Cascodes always have a fixed gate potential and do not switch, they only shield the high voltage. The transistor 157 includes, for example, a high-voltage NMOS cascode. The transistor 159 includes, for example, a high-voltage PMOS cascode.

According to 3 is the RS timing block 153 each connected at its output to the CAN_H_RS drivers 155 and CAN_L_RS drivers 156 or connected to them. The first RS driver 155 is at its output with the gate of the transistor 157 connected. The source of the transistor 157 is about the connection 44 connected to ground or CAN_GND. The drain of the transistor 157 is with the cathode of the diode 158 connected. The anode of the diode 158 is with the first bus line 41 , i.e. CAN_H, connected.

In addition, the second RS driver 156 at its output to the gate of the transistor 159 connected. The drain of the transistor 159 is with the second bus wire 42 , so CAN_L connected. The source of the transistor 159 is with the cathode of the diode 160 connected. The anode of the diode 160 is about the connection 43 connected to the power supply or CAN_SUPPLY.

Operation of the transceiver 12 according to 3 is also based on the waveforms of 4A to 7B explained in more detail.

4A to 7A each show a temporal course of signals at the transmitting / receiving device 12 according to the present embodiment. This results in a 4A shown transmission signal TxD the signals according to 5A to 7A on.

With the transmission signal TxD from 4A finds a change of state from a first bus state in the course of time t with three consecutive bits 401 to a second bus state 402 and then back to the first bus state 401 instead of. The first bus state 401 can also be called a recessive state or high level. The second bus state 402 can also be called a dominant state or a low level. As a result of the transmission signal TxD from 4A is the voltage V for the signals CAN_H and CAN_L according to 5A on, the differential voltage VDIFF = CAN_H - CAN_L according to 6A and a receive signal RxD according to 7A on. The voltage V for the signals CAN_H and CAN_L corresponds in the first bus state 401 or recessive state of half of the bus bias potential of the bus bias unit 1223 ,

In comparison, in the 4B to 7B each illustrates the temporal courses of signals in a transceiver according to a conventional transceiver, such as the transceiver 13 the subscriber station 20th ,

From the comparison of the signals from 5A and 5B it emerges very clearly that the transmitting / receiving device 12 According to the present exemplary embodiment, with the same transmit signal TxD, the CAN-H and CAN_L signals, or the differential voltage VDIFF calculated therefrom, change significantly faster after the change in state from the state 401 on the condition 402 or from dominant to recessive. Is the threshold voltage of the receiver 122 set to the usual value of 0.7 V, as in 6A and 6B illustrated, the recipient recognizes 122 even if the state changes 401 on the condition 402 or from dominant to recessive no alleged changes of state from the state 402 on the condition 401 or from recessive to dominant. Thus, sampling the received signal RxD at the currently usual sampling point AP can lead to the desired result, as in FIG 7A shown. This applies even if the length of the bit time tdom of the state 401 or a dominant bit compared to a conventional transceiver or the transceiver 13 the subscriber station 20th somewhat extended, as from the comparison of 7A and 7B seen.

Thus the transceiver has 12 according to the present exemplary embodiment, a lower tendency to oscillate than a conventional transceiver or the transceiver 13 ,

In operation of the transceiver 12 of 3 there will be a change in the bus state 401 after 402 or from dominant to recessive through the change of state detection block 151 detected if the TxD signal is in a recessive bus state or the bus state 401 begins at least for the time of a bit, as in 4A illustrated. Lies according to the output of the communication phase detection block 152 the RS timing block controls a corresponding communication phase 153 of 3 the CAN_H_RS driver 155 and / or the CAN_L_RS driver 156.

The communication phase acquisition block 152 can the arbitration phase 452 , the fields 453 to 455 or specifically the data field 453 as well as the end field 456 , especially the end bit (EOF). This allows the functionality of the vibration reduction unit 15 either for all communication phases or fields as desired 451 to 456 a message 45 apply or only when arbitration is complete, i.e. for the data field 454 and if necessary, previously for the control panel 453 , The latter is useful if there are otherwise too many subscriber stations 10 . 20th . 30th the function of the transmitting / receiving device at the same time during arbitration 12 can activate and thus reduce the effective bus resistance too much.
As a result of the control of the CAN_H_RS driver 155 and / or the CAN_L_RS driver 156 switch the transistors 157 and or 159 , The control of the CAN_H_RS driver 155 causes when the bus state changes 402 to the bus status 401 or from dominant to recessive, a reduction in the currents on the first bus wire 41 or the CAN_H line. The control of the CAN_L_RS driver 156 causes when the bus state changes 402 to the bus status 401 or from dominant to recessive, an increase in the currents or a supply of currents on the second bus wire 42 or the CAN_L line. The driver simulation thus works 1213 for CAN_H as source. In contrast, the driver simulation works 1214 for CAN_L as a sink.

In the example of a bus system 1 of 1 , would after the transition of the bus state 402 to the bus status 401 or from dominant to recessive, the signal CAN_L is pulled to a voltage VDIFF - Vd or voltage values of 5 V - 0.65 V, where 5V is the value of the differential voltage VDIFF = CAN_H - CAN_L and for Vd as the diode forward voltage of the diodes 158 . 160 a voltage value of 0.65 V was assumed. The signal CAN_H would be pulled in this example and a transition of the bus state from dominant to recessive to 0.65 V. It is advantageous here if the CAN_H_RS driver 155 and / or the CAN_L_RS driver 156 can only be activated as long as the signals CAN_H, CAN_L on the bus wires 41 . 42 are still approximately at the target voltage of VDIFF / 2, i.e. 2.5 V. However, if the differential bus voltage VDIFF has a different value, such as that the voltage VDIFF in the recessive state may have a voltage value of, for example, -4 V, then the driver is actuated 155 . 156 not critical to time.

By controlling the driver simulation 1213 enables that when the bus state changes 402 to the bus status 401 or from dominant to recessive on the CAN_H bus wire 41 currents can also be reduced. By controlling the driver simulation 1214 enables that when the bus state changes 402 to the bus status 401 or from dominant to recessive on the CAN_L bus wire 42 streams can also be supplied.

Through the described control of the RS timing blocks 153 . 154 an energy present in the resonant circuit is reduced. The RS timing blocks 153 . 154 are designed in such a way that the time of the control of the sink and / or source can be set in fractions of the bit time, preferably continuously. This is also the time when the drivers are activated 155 . 156 or the switching transistors 157 . 159 adjustable in fractions of the bit time, preferably continuously. The setting can either be based on a detection of a detection device during operation of the transmitting / receiving device 12 be made or fixed or, in particular, configurable by a user.

Thus, with the transceiver 12 carried out a method for reducing a tendency to oscillate in the transition between different bit states. The method can only be used in the second communication phase of the CAN frame as required 450 Depending on the default setting, this will also be carried out in the first communication phase of the CAN frame 450 executed.

In the exemplary embodiment described, only the subscriber stations have 10 . 30th the functionality of the transceiver 12 , The subscriber stations 10 . 30th are preferably subscriber stations or nodes with a high tendency to oscillate. The high tendency of the subscriber stations to vibrate 10 . 30th can differ in particular by their position in the bus system 1 , the position of the termination resistors 49 , the stub length or stub line length to the subscriber stations 10 . 30th , etc. result.

According to a modification of the first exemplary embodiment, it is also possible according to a simplified approach to use only one of the two driver simulations 1213 . 1214 for the signals CAN_H or CAN_L to shorten the oscillation time after the change of state from dominant to recessive. This also brings an improvement over a conventional transceiver or the transceiver 13 the subscriber station 20th , In this case, when switching from 2 only that Driver simulation 1213 . 1214 for the associated signal CAN_H or CAN_L to be operated.

According to a modification of the first exemplary embodiment, the functionality of the transmitting / receiving device described above is 12 only active if the transceiver 12 sends itself or acts as a sender.

According to a further modification of the first exemplary embodiment, the transmitting / receiving device is also 22 the subscriber station 20th like the transceiver 12 executed. In this case, the previously described functionality of the transmitting / receiving device 12 for all subscriber stations 10 . 20th . 30th of the bus system is active, especially as required. In this case, the evaluation of the transmission signal TxD would be advantageous, so that the transmission signal TxD from the connection 111 the RS timing block 153 is fed.

Due to the described design of the transmitting / receiving device (s) 12 . 32 data rates far higher than with CAN or CAN-FD can be achieved in the data phase. In addition, the data length in the data field 454 can be increased up to 4096 bytes. As a result, the advantages of CAN in terms of arbitration can be retained and yet a larger number of data can be effectively transmitted in a shorter time than before, that is to say without the data having to be repeated due to an error, as explained below.

Another advantage is that error frames in the bus system 1 in the transmission of messages 45 are not required, but can optionally be used. Messages are used if no error frames are used 45 no longer destroyed, eliminating a need for duplicate message transmission. This increases the net data rate.

8th shows a transceiver 12A according to a modification of the first embodiment. In contrast to the circuit of 3 has the transceiver 12A of 8th additionally two voltage sources 161 . 162 , The voltage source 161 is in the path between the source of the transistor 157 and the connection 44 switched. The voltage source 162 is in the path between the anode of the diode 160 and the connection 43 switched.

The voltage sources 161 . 162 each have a voltage with a value resulting from a voltage at the connection 43 minus a diode forward voltage Vd results. In the example of a CAN bus system or a CAN FD bus system, V_CAN_SUPPLY / 2 - Vd would apply. According to the current standard, the value would be 2.5 V - 0.65 V if the diodes 158 . 160 have a voltage value of 0.65V for the diode forward voltage Vd. Thus the bus wires 41 . 42 pulled up to 2.5V and you can see the transistors 157 . 159 leave switched on longer. In other words, the drivers 155 . 156 can the transistors 157 . 159 drive longer than before in terms of 3 for the current CAN standard. This is the driver control 155 . 156 less time-critical than before for the current standard of CAN in the example mentioned.

9 shows the basic structure of a transceiver for a second embodiment 120 that have a vibration reduction unit 150 having. The bus system 1 and the transceiver 120 are constructed in the same way, except for the differences described below, as previously according to the preceding exemplary embodiment or its modifications for the bus system 1 and the transceiver 12 described.

The vibration reduction unit 150 also has a phase position detection block 165 , The phase position detection block 165 of 10 records and evaluates the timing of the signals on the two bus wires 41 . 42 to each other. The phase position detection block controls depending on the result 165 the drivers 155 . 156 or the switching transistors 157 . 159 via the RS timing block 153 on. The input of the phase position detection block 165 can also be parallel to the inputs of the receive comparator 1221 be switched. The output of the phase position detection block 165 becomes the RS timing block 153 fed as another input.

Thus, in general, with the RS timing block 153 control separately or independently of each other for the bus wires 41 . 42 , in particular the signals CAN_H and CAN_L, are carried out. Thus, with the RS timing block 153 the control separately for the bus wires 41 . 42 , in particular for the signals CAN_H, CAN_L. This can change the phase of the signals on the two bus wires 41 . 42 to change. Will also be the detection result of the phase position detection block 165 The phase relationship of the signals on the two bus wires can also be used 41 . 42 be changed in a targeted manner. As a result, the damping of the vibration is accelerated even further after the change of state.

10 shows the basic structure of a subscriber station 100 with a communication control device 110 and a transceiver 1200 according to a third Embodiment. The bus system 1 and the subscriber station 100 are constructed in the same way, except for the differences described below, as previously according to the first exemplary embodiment or its modifications for the bus system 1 and the subscriber station 10 described.

The communication control device 110 is structured like the communication control device except for the differences described below 11 of the first embodiment. The transceiver 1200 is structured like the transmitting / receiving device except for the differences described below 12 of the first embodiment.

The communication control device 110 has next to the connections 111 . 112 an additional connection for the signals TxD, RxD 115 for a control signal RS_Control_Out.

The transceiver 1200 has a connection 1221A for receiving the transmission signal TxD from the connector 111 the communication control device 110 , as previously described more generally in relation to the first embodiment. In addition, the transceiver has 1200 a connection 1221B for sending the received signal RxD to the connection 112 the communication control device 110 , as previously described more generally in relation to the first embodiment. In addition, the transceiver points 1200 a connection 1225 on which the control signal RS_Control_Out is received as control signal RS_Control_In.

To generate the control signal RS_Control_Out for the connection 115 has the communication control device 110 a control block 116 , The control block 116 monitors the bus traffic on the bus wires 41 . 42 by the control block 116 that as first information 1161 stored transmission signal TxD and that at the connection 112 received, and if necessary buffered, received signal RxD compared. Occurs in the recessive bus state, i.e. the first bus state 401 If there are deviations between the two signals TxD, RxD, such as, for example, changes in state in the received signal RxD that were not contained in the transmitted signal TxD, conclusions can be drawn about the network or the bus from this 40 and the signal integrity is pulled.

Furthermore lie in the control block 116 the communication control device 110 second information 1162 such as bit rate, propagation delay for both switching operations, that is, a change of state from the first bus state 401 to the second bus state 402 , The information 1162 can alternatively be kept in a further block, not shown, in particular memory.

The RxD output on the connection 1221B Instead of a digital signal, the output signal of an analog-digital converter, which represents the differential voltage of the received signal RxD.

Taking this information into account 1161 . 1162 the control block generates 116 the control signal RS_Control_Out, which from the connection 115 is output on the connector 1225 the transmitting / receiving device 1200 is received and to a vibration reduction unit 1500 is passed on. Accordingly, the vibration reduction unit 1500 the blocks 151 . 152 . 153 of the vibration reduction units 15 . 150 the previous embodiments are omitted.

In this way, the control of the reduction in the tendency to oscillate (ringing suppression) is not carried out here by the transmitting / receiving device 1200 controlled, but by the communication control device 110 , Here, the communication control device 110 , more precisely, her control block 116 who have favourited Vibration Reduction Unit 1500 the special properties of the subscriber station 100 and the network or bus 40 to adjust. In other words, the communication controller 110 , more precisely, her control block 116 , the vibration reduction unit 1500 Set node and network sensitive. The control block 116 thus offers a learning function for the subscriber station 100 ,

This can also significantly reduce the tendency to oscillate when the state changes from the second bus state 402 to the first bus state 401 will be realized. It can also be a significant benefit for the bus system 1 can be achieved as an overall system.

All previously described configurations of the vibration reduction units 15 . 150 . 1500 of the transmitting / receiving devices 12 . 120 . 1200 of the subscriber stations 10 . 20th . 30th . 100 , the bus system 1 and the method carried out therein can be used individually or in all possible combinations. In particular, all features of the previously described exemplary embodiments and / or their modifications can be combined as desired. In addition or as an alternative, the following modifications are particularly conceivable.

The bus system described above 1 According to the exemplary embodiments, a bus system based on the CAN protocol is used. The bus system 1 According to the exemplary embodiments, however, there can also be another type of communication network in which data can be transmitted serially at two different bit rates. It is advantageous, but not an essential requirement, for the bus system 1 Exclusive, collision-free access by a subscriber station at least for certain periods of time 10 . 20th . 30th is guaranteed on a common channel.

The number and arrangement of the subscriber stations 10 . 20th . 30th in the bus system 1 the exemplary embodiments are arbitrary. In particular, the subscriber station 10 in the bus system 1 omitted. It is possible that one or more of the subscriber stations 20th or 30th in the bus system 1 available.

Claims (14)

Transmitting / receiving device (12; 120; 1200) for a serial bus system (1), with a first driver (123, 124, 125) for driving a first signal (CAN_H) for a first bus wire (41) of a bus (40) of the bus system (1), in which bus system (1) at least occasionally exclusive, collision-free access by one Subscriber station (10, 20, 30) on the bus (40) of the bus system (1) is guaranteed, a second driver (123, 124, 127) for driving a second signal (CAN_L) for the second bus wire (42) of the bus (40), a communication phase detection block (152) for detecting different communication phases on the bus (40), and a vibration reduction unit (15; 150) for reducing vibrations on the bus wires (41, 42), which after a change of state of the signal (CAN_H, CAN_L), which is transmitted to at least one of the bus wires (41, 42), from a dominant bus state (402) occur in a recessive bus state (401), wherein the vibration reduction unit (15; 150; 1500) is designed, depending on the communication phase on the bus (40), which was detected by the communication phase detection block (152), to influence currents generated by the first driver (123, 124, 125) and / or the second driver (123, 124, 127) for the signals (CAN_H, CAN_L). Transceiver (12; 120; 1200) after Claim 1 The vibration reduction unit (15; 150) is designed to influence the currents from the first driver (123, 124, 125) and / or on at least one bus wire (41; 42) after completion of an arbitration phase (452) of the communication the second driver (123, 124, 127) for the signals (CAN_H, CAN_L) are driven. Transceiver (12; 120) after Claim 1 or 2 , the communication phases on the bus (40) differ in that in a phase in which negotiations are taking place, which of the subscriber stations (10, 20, 30) of the bus system (1) subsequently at least temporarily has exclusive, collision-free access to the bus (40), bits of the signals have a bit time that is at least a factor of 10 greater than a bit time of bits that are driven in the communication phase in which the subscriber station (10, 20, 30) has exclusive, collision-free access to the bus (40). Transmitting / receiving device (12; 120; 1200) according to one of the preceding claims, wherein the vibration reduction unit (15; 150) is configured such that the vibration reduction unit (15; 150) is only activated when the first driver (123, 124, 125) and / or the second driver (123, 124, 125) drives a signal on the bus (40). Transmitting / receiving device (12; 120; 1200) according to one of the preceding claims, also with a first driver replica (1213) for driving a signal for the first bus wire (41) to reduce currents supplied by the first driver (1211) for the first bus wire (41), and / or a second driver simulation (1214) for driving a signal for the second bus wire (42) in order to supply currents in addition to the second driver (1212) for the second bus wire (41), wherein the vibration reduction unit (15; 150; 1500) has a transistor (151) which is connected such that the transistor (151) in the conductive state has at least one of the driver simulations (1213, 1214) for driving a signal for the first and / or controls the second bus wire (41, 42), and wherein the vibration reduction unit (15; 150; 1500) is designed to switch the transistor (151) conductive if a change in state of the received signal from a dominant bus state (402) to a recessive bus state (401) is detected. Transceiver (12; 120; 1200) after Claim 5 , the first driver simulation (1213) having a driver (155), a transistor (157) and a diode (158), the cathode of which is connected to a drain of the transistor (157), and the anode of which is connected to the first bus wire ( 41) is connected, the driver (155) for driving the transistor (157) being connected, and a source connection of the transistor (157) being connected to ground. Transceiver (12; 120; 1200) after Claim 5 or 6 . the second driver replica (1214) having a driver (156), a transistor (159) and a diode (160), the cathode of which is connected to a source of the transistor (157), and the anode of which is connected to a voltage supply for the first and a second bus wire (41, 42) is connected, the driver (156) for driving the transistor (159) being connected, and a drain connection of the transistor (157) being connected to the second bus wire (42). Transmitting / receiving device (12; 120) according to one of the preceding claims, wherein the vibration reduction unit (15; 150) a detection block (151), which is designed to detect a change in state of the received signal from the dominant bus state (402) to the recessive bus state (401), and its input parallel to an input of a receive comparator of the transceiver (12; 120 ) is switched, and an RS timing block (153), which is designed to control the signal on at least one bus wire (41; 42) depending on the detection result of the detection block (165) and the detected communication phase on the bus (40). Transceiver (12; 120) after Claim 8 , wherein the vibration reduction unit (15; 150) also has a phase position detection block (165) for detecting the temporal position of the signals on the bus wires (41, 42) of the bus (40) relative to one another, the RS timing block (153) also for Control of the signal on at least one bus wire (41; 42) depending on the detection result of the phase position detection block (165) is configured to adjust the phase position of the signal on the bus wire (41; 42). Subscriber station (10; 30; 100) for a bus system (1), with a communication control device (11; 110) for controlling communication of the subscriber station (10; 30; 100) with at least one further subscriber station (10; 20; 30; 100) of the bus system (1), and a transmitting / receiving device (12; 120 ; 1200) according to one of the preceding claims for sending messages (45) on a bus (40) of the bus system (1) and for receiving messages (45) from the bus (40). Participant station (10; 30; 100) after Claim 10 , wherein the communication control device (110) or the transceiver (12; 120) has a block (116; 152) which is configured to change the state of a signal received by the bus (40) from the dominant bus state (402) to the to detect recessive bus state (401), the vibration reduction unit (15; 150; 1500) being designed to control the transistor (151) as a function of the detection result of the block (116; 141). Participant station (100) after Claim 10 or 11 , wherein the communication control device (110) is designed to send a signal (TxD) to the transceiver (1200), which the transceiver (1200) serves as the basis for the signals (CAN_H, CAN_L) for the bus wires ( 41, 42) and to compare the signal (TxD) with a signal (RxD) received by the transceiver (1200) from the bus (40) to generate a control signal, and wherein the communication control device (110) is designed, to output the control signal for controlling the vibration reduction unit (1500) to the transmitting / receiving device (1200). Bus system (1), with a bus (40), and at least two subscriber stations (10; 30; 100), which are connected to one another via the bus (40) in such a way that they can communicate with each other serially and of which at least one subscriber station (10 ; 30; 100) a subscriber station (10; 30; 100) according to one of the Claims 10 to 12 is. Method for sending a message (45) in a serial bus system (1), the method being carried out with a transmitting / receiving device (12; 120; 1200) for a bus system (1), in which exclusive, collision-free access is at least temporarily a subscriber station (10, 20, 30) on a bus (40) of the bus system (1) is ensured, the transceiver (12; 120; 1200) having a first driver (123, 124, 125) and a second driver (1212) and a vibration reduction unit (15; 150; 1500), the method comprising the steps of driving, with the first driver (123, 124, 125), a first signal (CAN_H) for a first bus wire (41) of the Busses (40) and driving, with the second driver (1212), a second signal (CAN_L) for the second bus wire (42) of the bus (40), and detecting, with a communication phase detection block (152), of different communication phases the bus (40), and reduction, with a vibration reduction ion unit (15; 150; 1500), of vibrations on the bus wires (41, 42) which, after a change in state of the signal (CAN_H, CAN_L) which is transmitted to at least one of the bus wires (41, 42), from a dominant bus state (402) to a recessive one Bus state (401) occur, the vibration reduction unit (15; 150; 1500) depending on the communication phase on the bus (40) that of the communication phase detection block (152), influences currents which are driven by the first driver (123, 124, 125) and / or the second driver (123, 124, 127) for the signals (CAN_H, CAN_L).

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