Means of transport, work machine and bus participant for a PSI-5 bus

Abstract

Bus subscriber (1) for a PSI-5 bus (2), wherein the bus subscriber (1) comprises: • a microcontroller (3) and • a sensor (4), wherein software is installed on the microcontroller (3), by means of which software it is set up to operate the bus participant (1) as a slave in the PSI-5 bus (2), wherein the microcontroller (3) is set up to receive new software via an over-the-air update by means of a means of transport.

Description

[0001] The present invention relates to a means of transportation, a work machine, and a bus device for a PSI-5 bus. In particular, the present invention relates to flexible and cost-effective hardware for implementing PSI-5 bus slaves.

[0002] Modern means of transport are increasingly being equipped with environmental sensors and actuators to support the driver in controlling the vehicle in conjunction with evaluation electronics. The same applies to work machines and their users. The peripheral sensor interface 5 (PSI-5) is a bus system whose design guarantees a high level of interference immunity. It is current and voltage controlled and uses Manchester coding and CRC (cyclic redundancy check). Because it is an open standard, implementation is possible without licensing costs, which is why the PSI-5 standard has spread quickly. Further spread is foreseeable. The PSI-5 is a master-slave system, i.e. there is always a higher-level control unit (master) that queries and controls the lower-level control units (slaves), and synchronizes communication.The digital transmission of information offers significant advantages over currently used analog transmission systems, such as interference immunity and diagnostic capability. PSI-5 is currently used in the automotive sector primarily for sensors (e.g., airbag control units), but is increasingly being used in new sensor developments.

[0003] PSI-5 slave interfaces are not available on the market. Therefore, it is not possible to adapt a PSI-5 for sensors without significant (hardware) development effort. Rather, a major manufacturer must always be involved to develop and implement the required software. DE 10 2013 220 707 D1, US 2014 / 0081526 A1, US 2014 / 0304511 A1, US 2018 / 0154845 A1, US 2015 / 0151694 A1, EP 2 056 178 A1, and DE 10 2011 007 851 A1 show bus architectures, so their study may be helpful in understanding the present invention.

[0004] Based on the aforementioned prior art, it is an object of the present invention to be able to implement PSI-5 bus systems more flexibly and cost-effectively.

[0005] The aforementioned object is achieved according to the invention by a bus participant for a PSI-5 bus, which comprises a microcontroller and a sensor. The microcontroller can be understood as a conventional microcontroller on which software can be installed without the need for permanent and / or complex programming, as with an FPGA or an ASIC. In particular, the microcontroller can be loaded with the software via a simple control unit (e.g., a PC, a tablet, or another automotive control unit). Software is understood to mean, for example, the operating system of the microcontroller. In other words, the software is used to operate the bus participant according to the invention as such on the PSI-5 bus. The sensor can be, for example, an environmental sensor, an electromechanical sensor, an optical sensor, or similar. Its information is also distributed, in particular, via a / the PSI-5 bus.According to the invention, the software is configured to operate the sensor as a slave in the PSI-5. The role of the slave specifically precludes the bus device from querying and / or controlling the other slaves and / or synchronizing communication with them. The use of the microcontroller and the software installed on it allows for flexible adaptation of the functionality of the bus devices according to the invention. Furthermore, component costs can be significantly reduced.

[0006] Functionality enhancements can be achieved through simple software updates without replacing hardware. According to the invention, the software can be updated or provided with new software over the air (e.g., using an additional bus device and / or without an additional processor). Even after delivery to a customer, a means of transport or a corresponding work machine equipped with a bus device according to the invention can have its functionality flexibly modified, in particular expanded.

[0007] The subclaims show preferred developments of the invention.

[0008] The microcontroller is preferably configured to respond to requests received from a master of the PSI-5 bus. In other words, the microcontroller is configured to handle communication from the PSI-5 master. In particular, the microcontroller is configured to respond exclusively to requests received from the master of the PSI-5 bus. These processes can be initiated, for example, by a predefined voltage signal from the PSI-5 bus sent by the master. The microcontroller can, for example, activate the sensor, query data, or adjust the sensor's operating parameters. In particular, the microcontroller can also assume other functions of the bus participant according to the invention, such as evaluating the data supplied by the sensor and / or initiating suitable measures.In this way, the microcontroller can be used for a variety of tasks, making the hardware expenditure for the microcontroller economical by providing a variety of functions.

[0009] The bus subscriber according to the invention can be installed in production vehicles, which are located in the field, particularly after delivery to the respective customer, and are operated there as intended. In other words, the bus subscriber design according to the invention is not considered a prototype.

[0010] The sensor may, for example, include a height sensor, an acceleration sensor (e.g., for the airbag and / or the chassis of a vehicle), an electromagnetic sensor, a magnetostrictive sensor, an optical sensor, a pressure sensor, a vacuum sensor, a yaw rate sensor, and / or a position sensor (e.g., rotary, linear). The above examples are not exhaustive and are for illustrative purposes only.

[0011] The bus participant according to the invention can, for example, also have a servomotor. In other words, the bus participant can have an actuator, wherein the microcontroller is further configured, in particular, to operate the servomotor as a slave in the PSI-5 bus. The above statements therefore also apply accordingly to the actuator / servomotor and its relationship to the microcontroller / bus participant.

[0012] The software for the microcontroller can, for example, be (originally) written in the "C" programming language. In other words, the functionality is based on source code written in the "C" programming language. The widespread use of the "C" programming language ensures worldwide use and updating of the functionality of the bus device according to the invention.

[0013] A core idea of ​​the present invention is to implement the PSI-5 protocol in software on smaller microcontrollers. This provides a separate protocol implementation that is initially independent of an IP or a manufacturer who implements it in an ASIC or FPGA. Such an implementation allows very high degrees of freedom with regard to hardware selection when implementing sensor systems and, compared to ASICs or FPGAs, enables cost-effective implementation even in small quantities. A further advantage of implementation on a microcontroller is the fact that, in addition to protocol processing, the controller can also perform other specific tasks, such as calculating and converting values, converting analog inputs, diagnostics, and the like.

[0014] A further advantage is the simultaneous use of other bus systems, such as CAN, on the same controller.

[0015] Another advantage of using the C programming language is that it allows for maximum independence from the microcontroller model used, allowing for easy porting to other derivatives and systems. The hardware-specific differences between the available controller derivatives regarding the required controller peripherals, such as timers, interrupts, etc., can be handled either via compiler switches or via different libraries. The free availability of compilers such as GNU C allows the open source or open hardware concept to be pursued further if necessary, since GNU C is available for a wide variety of microcontrollers on the market.

[0016] The microcontroller must meet certain requirements regarding timer and interrupt functions in order to resolve the protocol's temporal dependencies. These functions detect the protocol's sync and information pulses. An interrupt function is used to detect the PSI-5 sync pulse, which marks the start of data transmission. The subsequent pulses, which contain the data to be transmitted, are evaluated using one or more timers. These requirements are met by the majority of microcontrollers available today.

[0017] According to a second aspect of the present invention, a means of transport is proposed which has a PSI-5 bus, a PSI bus master, and a bus subscriber according to the first aspect of the invention. The sensor is, in particular, a sensor provided for the operation of the means of transport. In particular, the sensor can be permanently installed and operated in the means of transport. The sensor can, for example, be a vehicle dynamics sensor, an environmental sensor, etc. The software running on the bus subscriber according to the invention can be updated, for example, via an over-the-air interface of the means of transport to enable bug fixing and / or functional enhancements.

[0018] According to a third aspect of the present invention, a work machine is proposed that has a PSI-5 bus, a PSI-5 bus master, and a bus subscriber according to the first aspect of the invention. The sensor can, for example, be a sensor intended for the operation of the work machine. In particular, the sensor is intended to remain permanently in and operate within the work machine. It can be configured, for example, as an optical sensor, force sensor, distance sensor, environmental sensor, or similar.

[0019] In this way, the means of transport according to the invention and the work machine according to the invention realize the features, combinations of features and the advantages resulting from these of the bus participant according to the invention in such a way that, in order to avoid repetition, reference is made to the above statements.

[0020] Further details, features, and advantages of the invention will become apparent from the following description and the figures. They show: Fig. 1 a schematic diagram of the structure of a PSI-5 system according to the invention, and Fig. 2 a schematic representation of an embodiment of a bus connection of a bus participant according to the invention.

[0021] Fig. 1 shows a bus system designed according to the invention, in which a master control unit 6 designed according to the prior art with a microcontroller 3 and a transceiver ASIC 8 connected to the microcontroller 3 via an interface 7 is configured to coordinate the bus communication of a PSI-5 bus 2. The PSI-5 bus 2 is designed as a two-wire system in which individual bus participants 1 comprising individual sensors 4a, 4b or series-connected bus participants 1 comprising sensors 4c, 4d, 4e, 4f, 4g are operated and linked in terms of information technology. While the sensor 4a is designed as a conventional sensor, the sensor 4b is integrated into the bus system as a slave via a microcontroller 3, according to the invention. The sensors 4c and 4d are also integrated into the PSI-5 bus 2 as slaves via microcontroller 3, according to the invention.The sensors 4e, 4f are designed in a conventional manner, while the bus participant 1 comprising the sensor 4g is integrated into the PSI-5 bus 2 via a microcontroller 3 in accordance with the invention.

[0022] Fig.Figure 2 shows a schematic diagram of the electrical network for integrating a sensor 4 configured according to the invention with a microcontroller 3. Since PSI-5 is current-carrying in one transmission direction and microcontrollers generally do not have current interfaces, these must be implemented externally. Commercially available circuits for constant current sources can be used for this purpose. Adaptation to higher voltage levels than those used by microcontrollers, e.g., the 12 V vehicle power supply systems commonly used in motor vehicles, must also be implemented externally using appropriate voltage dividers. Simple resistive voltage dividers are generally sufficient for this purpose. PSI-5 transceivers, which are increasingly available on the market, can also achieve this. The microcontroller 3 is configured to actuate a switch 9, by means of which a constant current source is used to drive a predefined current I sinkbetween the wires of the PSI-5 bus 2. The constant current source is a capacitor C S connected in parallel, across which the bus voltage V SS (control signal from the master bus device, not shown). The resistors R CS refer to the contact resistance of the sensor connector. This results in a flexible, cost-effective, and largely manufacturer-independent bus topology. Furthermore, sensors and actuators, in particular, can be easily and cost-effectively integrated into PSI-5 bus systems. List of reference symbols: 1 bus participant 2 PSI-5 buses 3 microcontrollers 4, 4a-4g sensors 6 Control unit 7 Interface 8 Transceiver ASIC 9 switches C S capacitor I sink predefined current R CS Contact resistance of the sensor connector VSS Bus voltage

Claims

[1] Bus subscriber (1) for a PSI-5 bus (2), wherein the bus subscriber (1) comprises: • a microcontroller (3) and • a sensor (4), wherein software is installed on the microcontroller (3), by means of which software it is set up to operate the bus participant (1) as a slave in the PSI-5 bus (2), wherein the microcontroller (3) is set up to receive new software via an over-the-air update by means of a means of transport. [2] Bus subscriber according to claim 1, wherein the microcontroller (3) is arranged to answer requests received from a master of the PSI-5 bus (2). [3] Bus subscriber according to one of the preceding claims, wherein the sensor (4) - a height sensor and / or - an acceleration sensor and / or - an electromagnetic sensor and / or - a magnetostrictive sensor and / or - an optical sensor and / or - a pressure sensor and / or - a vacuum sensor and / or - a yaw rate sensor and / or - includes a position sensor. [4] Bus subscriber according to one of the preceding claims further comprising a servo motor, wherein the microcontroller (3) is further configured to operate the servo motor as a slave in the PSI-5 bus (2). [5] Bus subscriber according to one of the preceding claims, wherein the software is written in the programming language C. [6] Means of transport including - a PSI-5 bus (2), - a PSI-5 bus master (6) and - a bus subscriber (1) according to one of the preceding claims, wherein the sensor (4) of the bus subscriber (1) is a sensor (4) for the operation of the means of transport, wherein the means of transport is configured to receive new software for the microcontroller (3) via an over-the-air update. [7] Working machine comprehensive - a PSI-5 bus (2), - a PSI-5 bus master (6) and - a bus subscriber (2) according to one of the preceding claims 1 to 5, wherein the sensor (4) of the bus subscriber (1) is a sensor (4) for the operation of the work machine.

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