The present disclosure claims the benefit of priority of co-pending European Patent Application No. 19183693.1, filed on Jul. 1, 2019, and entitled “METHOD OF CONTROLLING COMMUNICATION OVER A LOCAL INTERCONNECT NETWORK BUS,” the contents of which are incorporated in full by reference herein.
The present disclosure relates to a method of controlling communication over a Local Interconnect Network (LIN) bus, and a device performing the method.
The automotive industry is using a serial network protocol known as Local Interconnect Network (LIN) for communication between components in a motor vehicle.
Typically, a master node in the form of an electronic control unit (ECU) embedded in a motor vehicle communicates over a LIN bus with up to 16 slave nodes providing various functionality in the motor vehicle relating to for instance locks, brakes, lighting, battery, etc.
However, if the ECU master node fails, it is not possible to provide the functionality of the slave nodes, since all communication over the LIN bus is initiated by the master node.
An objective is to solve, or at least mitigate, this problem and to provide an improved method of controlling communication over a LIN bus.
In an embodiment, a redundancy master node is connected to a LIN bus, which monitors communication on the LIN bus. If a first “regular” master node does not respond to data being transmitted over the LIN bus, the first ECU master node is assumed to not function correctly, in which case the redundancy ECU master node will act as master node on the LIN bus. In contrast, if the first ECU master node responds to data being transferred over the LIN bus, the redundancy ECU master node will remain silent, as the first ECU master node 201b indeed appears to function correctly.
Advantageously, with this embodiment, in case the regular master node fails, the redundancy ECU master node will assume the role of master node on the LIN bus. Thereby, redundancy is provided for, and the LIN network will function seamlessly even if one master node suffers from a failure.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the element, apparatus, component, means, step, etc.” are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
Aspects and embodiments are now described, by way of example, with reference to the accompanying drawings, in which:
The aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown.
These aspects may, however, be embodied in many different forms and should not be construed as limiting; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and to fully convey the scope of all aspects of invention to those skilled in the art. Like numbers refer to like elements throughout the description.
The ECU 101 is interconnected with various components via a LIN bus, such as components providing functionality relating to locks 102, brakes 103, lighting 104, battery 105, etc. Each component may have its own ECU (or similar device) controlling the associated component and communicating over the LIN bus with the “master” ECU 101. For instance, the lock module 102 is typically a mechanical device for physically locking/unlocking one or more doors of the car, which mechanical lock module is connected to an ECU-type device, i.e. a lock control module, from which it receives signals for a door to lock/unlock, while e.g. brake functionality generally is controlled by the BCS and battery functionality it controlled by the BMS.
The ECU 101 may further by equipped with an interface for wireless transmission of data, for instance for wireless communication of various parameters and data and/or measured properties of the vehicle 100 to a remote location.
Individual components may also be equipped with an interface for wireless transmission of data. For instance, the lock module 102 (or a node in communication with the lock module) may be equipped with a Bluetooth or Near-Field Communication (NFC) interface for wireless communication with a car key, a smart phone or an NFC card to allow a user to lock/unlock the vehicle 100.
Now, in a prior art LIN network no as that shown in
The LIN protocol specifies a sleep-mode and an active mode bus state, where all LIN nodes are requested to be in active state if data is on the bus. After a specified timeout, the nodes enter sleep mode and will be released back to active state by a wakeup frame. This frame may be sent by any node requesting activity on the bus, either the LIN Master following its internal schedule, or one of the attached LIN Slaves being activated by its internal software application. After all nodes are awakened, the master node continues to schedule data on the bus.
However, if the ECU master node 101 fails, it is not possible to provide the functionality of the slave nodes 102-105, since all communication over the LIN bus 106 is initiated by the master node 101.
This is problematic since, for instance, assuming that a user wants to unlock the vehicle by sweeping her NFC-capable car key over the lock module 102. The lock module 102 will thus, after having received a message from the ECU 101 addressing the lock module 102 thereby allowing the lock module 102 to use the bus 106, transmit a message to the ECU 101 over the LIN bus 106 asking the ECU 101 to authenticate credentials transmitted over the NFC interface by the car key.
If the ECU 101 can verify the correctness of the credentials, a message is transmitted over the LIN bus 106 to the lock module 102 which accordingly will unlock the doors of the vehicle 100.
However, if the ECU 101 for some reason does not function correctly, a lock control module controlling the lock module 102 will not receive the message that the credentials are authenticated. This will have as a consequence that the user cannot unlock the vehicle 100.
This is solved in an embodiment illustrated with reference to
Now, to comply with LIN network requirements, a collision avoidance mechanism is required if a redundancy ECU master node 201b is to be connected to the LIN bus 206 for possibly taking over the role as master node from the first ECU master node 201a.
It is to be noted that the two nodes 201a, 201b never will act as master nodes simultaneously but are used for redundancy purposes; either the one or the other will assume the role of a master node.
Now, in a first step S101, the redundancy ECU master node 201b, will monitor communication on the LIN bus 206. If the first ECU master node 201a does not respond to data being transmitted over the LIN bus 206, the first ECU master node 201a is assumed to not function correctly, in which case the redundancy ECU master node 201b will act as a single master node on the LIN bus 206. In contrast, if the first ECU master node 201a responds to data being transferred over the LIN bus 206, the redundancy ECU master node 201b will remain silent, as the first ECU master node 201b indeed appears to function correctly. As an alternative to remaining silent, the redundancy ECU master node 201b may act as a slave node on the LIN bus 206.
Advantageously, with this embodiment, in case the “regular” master node fails—i.e. the first ECU master node 201a—the redundancy ECU master node 201b will assume the role of single master node on the LIN bus 206. Thereby, redundancy is provided for, and the LIN network 210 will function seamlessly even if one master node suffers from a failure.
The LIN protocol is well-known and will thus not be described in any detail herein. However, the master node transmits a header consisting of a break signal followed by synchronization and identifier fields uniquely addressing each slave node on the LIN bus 206. The slave nodes respond with a data frame that consists of between 2, 4 and 8 data bytes plus 3 bytes of control information.
In the LIN protocol, all nodes should wakeup within 100 ms from the end of the wakeup frame. The first master node Zola must transmit data over the LIN bus 206 within 150 ms from the end of the wakeup frame. Hence, regardless of whether any of the slave nodes 202-205 issues the wakeup frame or the first ECU master node Zola itself issues the wakeup frame, the first ECU master node Zola must respond to the issued wakeup frame by transmitting data over the LIN bus within 150 ms.
The redundancy ECU master node 201b then detects in step S101b whether the first ECU master node Zola responds to the wakeup frame within a set time period T, preferably being 150 ms to comply with the LIN protocol even though other timings may be envisaged.
In case no response is detected from the first ECU master node Zola on the LIN bus 206 within the exemplified set time period T=150 ms, the redundancy ECU master node 201b will act as a single master node on the LIN bus. In case a reply indeed is received within the set time period T, the redundancy ECU master node 201b will not act as the master node on the LIN bus 206 and accordingly remain silent and not transmit data over the LIN bus 206 since the first ECU master node 201a will continue to assume the role as the single master node on the LIN bus 206.
In an embodiment, the redundancy ECU master node 201b assumes the role as the master node on the LIN bus 206 during a current, ongoing LIN bus communication cycle. After the nodes again go into sleep state and subsequently wake up, the redundancy ECU master node 201b will again perform steps S101a and S101b for detecting whether the first ECU master node 201a functions as expected or not.
Hence, the redundancy ECU master node 201b acts as the master node for a current LIN bus communication cycle and again detects whether or not the first ECU master node 201a responds to a next issued wakeup frame within the set time period T. As long as the first ECU master node 201a does not signal that it is capable of acting as master node on the LIN bus 206, the redundancy ECU master node 201b will assume the responsibility as master node.
As previously, in step S101a, the redundancy ECU master node 201b detects if a wakeup frame is being transferred over the LIN bus 206. The redundancy ECU master node 201b then detects in step S101b whether the first ECU master node 201a responds to the wakeup frame within the time period T=150 ms.
In case no response is detected from the first ECU master node 201a on the LIN bus 206 within the set time period T=150 ms, the redundancy ECU master node 201b detects in step S101c whether or not this is the third (N=3) wakeup frame to which the first ECU mater node fails to respond within T=150 ms.
If so, the redundancy ECU master node 201b will act as master node on the LIN bus 206. In case N=3 has not yet been reached, the redundancy ECU master node 201b will detect a further wakeup frame to which the first ECU master node 201a fails to respond within T=150 ms. Should the first ECU master node 101a respond adequately before N=3 is reached, the redundancy ECU master node 201b will remain silent on the LIN bus 206.
As in
In this embodiment, the CAN bus 207 is used by the first ECU master node Zola to signal, after the redundancy ECU master node 201b has assumed responsibility as master node on the LIN bus 206, that the first ECU master node Zola is ready to resume the role as master node on the LIN bus 206. After the redundancy ECU master node 201b has received a message over the CAN bus 207 that the first ECU master node Zola is ready to again act as the master node on the LIN bus 206, the redundancy ECU master node 201b will revert to remaining silent on the LIN bus 206.
The aspects of the present disclosure have mainly been described above with reference to a few embodiments and examples thereof. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.
Thus, while various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
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