Initializing and operating a bus system

Abstract

A system (105) comprises a primary electronic module (110) and at least one secondary electronic module (115), wherein the secondary modules (115) are connected to the primary module (110) by means of a signal line (125) in the manner of a daisy chain. A method (300) for initializing such a system (105) comprises the following steps: a) opening the signal line (125) in all secondary modules (115); b) providing an initialization signal on the signal line (125) by means of the primary module (110); c) initializing a secondary module (115) which receives the initialization signal and has not yet been initialized; d) closing the signal line (125) by means of the secondary module (115) initialized last; and e) repeating steps b) to d) until all secondary modules (115) have been initialized.

Description

[0001] Initializing and operating a bus system

[0002] The present invention relates to a bus system with multiple electronic modules. In particular, the invention relates to the operation of such a bus system.

[0003] A device, such as a household appliance or a motor vehicle, comprises a system with multiple electronic modules connected to each other via a serial bus. The system can control the device or part of it. A predetermined bus protocol governs access to the shared medium and the transmission of data from a transmitter to one or more receivers. For this purpose, each module can be configured with a unique communication address and can fulfill a predetermined purpose within the device or motor vehicle.

[0004] If the system needs to be reconfigured, for example, by removing a module from the system, adding it to the system, or changing its position within the surrounding device, the corresponding information must be distributed to the remaining modules in the system. Various proposals have been made for dynamically configuring the modules within the system, with the system establishing its operational readiness within a configuration phase. A primary module can control the initialization phase and create an overview of the system's topography. Secondary modules can communicate with the primary module and negotiate their respective configurations.

[0005] For rapid and reliable initialization of such a bus system, one or more dedicated lines may be required. These can increase the complexity or susceptibility of the system to errors. Furthermore, such lines may be inoperative after the initialization phase, so the effort required for initialization alone can be significant.

[0006] An object underlying the present invention is to provide an improved technique for initializing a system with a primary and at least one secondary electronic module. The invention solves this problem by means of the subject matter of the independent claims. Subclaims specify preferred embodiments. A system comprises a primary and at least one secondary electronic module, wherein the secondary modules are connected to the primary module via a signal line in the manner of a daisy chain.A method for initializing such a system comprises the following steps: a) opening the signal line in all secondary modules; b) providing an initialization signal on the signal line by the primary module; c) initializing a secondary module that receives the initialization signal and is not yet initialized; d) closing the signal line by the last initialized secondary module; and e) repeating steps b) to d) until all secondary modules are initialized.

[0007] In a daisy chain, the signal line is looped from the primary module through all designated secondary modules one after the other. Each of the secondary modules can open or close the signal line. If the signal line is open on a secondary module, all secondary modules further away from the first module are disconnected. Using the described procedure, the order in which the secondary modules are initialized can be predetermined based on their position on the signal line. The secondary modules initialize one after the other, thus eliminating conflicts, for example, due to data collisions.

[0008] Preferably, initializing a secondary module comprises its communication with the primary module. Preferably, during initialization of the secondary modules, the primary module can collect information about their arrangement on the signal line. Conversely, the primary module can distribute predetermined information or resources to the secondary modules. Information that can be transmitted from a secondary module to the primary module can include, for example, an identification, a function, a position, a version, or a feature. Information that can be transmitted in the reverse direction from the primary module to the initializing secondary module includes, for example, a configuration or a position of the secondary module in the system.

[0009] Optionally, a software component of the secondary module can be updated from the primary module. To do this, the communication can first determine that the secondary module is using a software component for which an update is available from the primary module. The update can then be transmitted from the primary module to the secondary module and activated there. Initialization of the secondary module can then continue.

[0010] If there is no communication between the primary module and a not yet initialized secondary module for a predetermined time after an initialization signal has been provided, the system initialization can be terminated. This state usually occurs when all secondary modules in the system have been initialized. If a secondary module cannot be initialized, it can still close the signal line to allow a secondary module further away from the primary module on the signal line to be initialized. If one or more secondary modules have not initialized, the primary module can detect this. A decision can be made as to whether the system has been reconfigured from a last known state or whether an error condition exists in which part of the system is not functional.The primary module can then initiate an appropriate action to respond to the decision made. This action may, in particular, include providing an error message.

[0011] In addition to the signal line, the secondary modules can be connected to the primary module via a data bus. Communication between the primary module and an initializing secondary module can take place via the data bus. The data bus is preferably serial, so that the number of lines can be kept to a minimum. For example, the data bus can comprise a CAN bus or a similar bus. In another embodiment, the signal line can be implemented as a single-wire bus, and communication takes place via the signal line. Once the system initialization is complete, communication between the modules can take place primarily on the data bus.

[0012] In another embodiment, the communication comprises transmitting a configuration from the secondary module to the primary module. The primary module determines a topology of secondary modules in the system based on the received configurations.

[0013] Once all secondary modules in the system have been initialized, the signal line runs from the primary module through all secondary modules in sequence. In a subsequent phase, the signal line can serve another purpose. In particular, after all modules have been initialized, one of the modules can connect the signal line to a predetermined potential to provide an interrupt request. The interrupt request can be provided, in particular, if the module detects an error condition that it cannot correct itself. Typically, the interrupt request is transmitted from one of the secondary modules to the primary module. The primary module can then execute a higher-level function or send a signal to a secondary or higher-level device.

[0014] According to a further aspect of the present invention, a primary electronic module comprises an output for connection to a signal line in the manner of a daisy chain; and a processing device configured to provide an initialization signal to at least one secondary electronic module via the signal line. Furthermore, the primary electronic module can be configured for connection to a data bus, wherein the data bus is connected to the secondary module. This allows communication between the primary and a secondary electronic module after the primary module has provided the initialization signal to the secondary module. The communication can control the initialization of the secondary module.

[0015] According to yet another aspect of the present invention, a secondary electronic module comprises an input and an output for a daisy-chain signal line; a switch between the input and the output; and a processing device configured to detect an initialization signal at the input when the switch is open, initialize the secondary electronic module, and close the switch. One or more secondary electronic modules may interact with a primary electronic module described herein.

[0016] The secondary electronic module can further comprise a further switch for connecting the signal line to a predetermined potential in order to provide an interrupt request. The further switch is preferably connected to the output, so that the interrupt request can only be forwarded to the primary module when the switch between the output and the input is closed. This allows for improved, undisturbed initialization of the secondary electronic module. In another embodiment, the further switch can also be connected to the input if it is desired that an interrupt request can also be provided during the initialization of the secondary module.A system comprises a primary electronic module described herein, as well as at least one secondary electronic module described herein, and a signal line that connects the secondary modules to the primary module in a daisy chain fashion. Additionally, a data bus may be provided to which the modules are connected. The data bus may, in particular, comprise a serial data bus configured as a single-wire or multi-wire connection. The data bus cannot support or require a physical order of participants on the medium.

[0017] The system or one of its modules can be configured to partially or completely execute a method described herein. For this purpose, the system or one of its modules can comprise a processing device, which is particularly electronically implemented and comprises, for example, a programmable microcomputer or microcontroller. The method can be in the form of a computer program product with program code means. The computer program product can also be stored on a computer-readable data carrier. Features or advantages of the method can be transferred to the system or one of its modules, or vice versa.

[0018] The technique described herein can be used particularly advantageously when multiple similar or identical secondary modules are used in the system. For example, the position of one of the modules on the signal line can be changed, and during a subsequent initialization phase of the system, the secondary modules can be configured to compensate for the change.

[0019] According to a further aspect of the present invention, an electrical device comprises a system described herein. The device may, in particular, comprise a household appliance or a motor vehicle.

[0020] In an illustrative example of a proposed system, secondary modules on board a motor vehicle can each implement a direction indicator (blinker). From the primary module, the signal line can be routed successively to secondary modules for providing a turn signal on the front left, front right, rear right, and rear left of the vehicle. If the first two secondary modules of the system are swapped, they can be adapted to their new functions during a subsequent initialization phase of the system, since the primary module knows the order in which the signal line runs through the secondary modules. The first secondary module to be initialized (last front right) can be initialized for the front left position, and the second secondary module (last front left) can be initialized for the front right position.Remaining secondary modules for the rear right and rear left positions have not changed their positions on the signal line, so their configurations can remain unchanged.

[0021] The invention will now be described in more detail with reference to the accompanying figures, in which:

[0022] Figure 1 a system;

[0023] Figure 2 an electronic module; and

[0024] Figure 3 shows a flow diagram of a process.

[0025] Figure 1 shows a device 100 with an electronic system 105. The system 105 comprises a primary electronic module 110 and several secondary electronic modules 115. The modules 110, 115 are preferably connected to one another via a data bus 120. The data bus 120 is preferably serially organized and, in this case, is embodied purely as an example as a CAN bus. Additionally, a signal line 125 is provided, which runs in a daisy chain fashion from the primary module 110 through all secondary modules 115 in a predetermined sequence. Furthermore, the modules 110, 115 can be connected to a power source via supply lines 130.

[0026] The system 105 may include virtually any number of secondary modules 115. The order in which the secondary modules 115 are connected to the signal line 125 may determine the order in which the secondary modules 115 are initialized. Initialization may occur after a power supply is applied or after a reset of the system 105 or the data bus 120.

[0027] Designations for connected lines or signals are entered on the modules 110, 115. The supply lines 130 are designated VBIIS and GND. Data lines of the data bus 120 are designated D+ and D-. If the signal line 125 is understood as a current emanating from the primary module 110, CIC_OUT designates a connection to a downstream module 115 and CIC_IN a connection to an upstream module 110, 115. Figure 2 shows a secondary module 115 in a preferred embodiment. The secondary module 115 comprises an input 205 and an output 210 for the signal line 125. The input 205 can be connected to a line carrying the CIC_IN signal, and the output 210 can be connected to a line carrying the CIC_OUT signal. In addition, a first switch 215, a second switch 220, a transistor 225 and a processing device 230 are provided.It should be noted that the second switch 220 and / or the transistor 225 may also be omitted in a simple embodiment of a technique described herein.

[0028] Switches 215 and 220 are coupled to each other and can be set to a first or a second position based on a CF_COMPLETE signal. If the secondary module 115 or the processing device 230 has not yet been initialized, switches 215, 220 are preferably controlled to the illustrated first position. Switches 215 and 220 are preferably implemented using semiconductors, for example, transistors or circuits with at least one transistor.

[0029] In the first position, an initialization signal CS received via input 205 from primary module 110 can be forwarded to processing device 230 to cause it to perform an initialization.

[0030] Once initialization is complete, the processing device 230 of the secondary module 115 can move the switches 215, 220 to the second position. By switching the first switch 215, the input 205 is connected to the output 210, effectively extending the signal line 125 to the following secondary module 115. At the same time, the input 205 is disconnected from the processing device 230, so that an initialization signal arriving at the input 205 is not evaluated by the local processing device 230, but is forwarded via the output 210 to the following secondary module 115.

[0031] In the second position, the second switch 220 is closed. The processing device 230 can provide an interrupt request INT to close the transistor 225. The transistor 225 operates like a switch in an open-collector circuit and acts on the signal line 125 running through the secondary module 115. The signal line 125 can be connected to a predetermined electrical potential, in the illustrated embodiment to ground, through the transistor 225. As a result, the level of the signal line 125 can be recognizable as 0 V for all modules 110, 115. A dedicated module 110, 115, typically the primary module 110, can detect this level or a transition (edge) to this level, interrupt normal operation of the system 105, and handle the interrupt request.

[0032] In the illustrated embodiment, transistor 225 acts on output 210. An interrupt request can only be transmitted to primary module 110 when first switch 215 is in the second position. By using the optional second switch 220, which separates transistor 225 from processing device 230 in the first position, a downstream secondary module 115 can be prevented from receiving an interrupt request from processing device 230 while first switch 215 is in the first position. If primary module 110 is intended to handle the interrupt request, second switch 220 can also be omitted. In yet another embodiment, transistor 225 can also act on input 205 instead of output 210, so that an interrupt request can also be issued during initialization of secondary module 115.

[0033] Figure 3 shows a flowchart of a method 300 for controlling a system 105. Method steps shown in a left column are typically executed by the primary module 110. Method steps in a right column are assigned to a secondary module 115. It should be noted that the same steps in the right column can be performed consecutively for multiple secondary modules 115. Steps 305 and 365 shown between the columns can apply to the entire system 105.

[0034] In step 305, the system 105 is uninitialized. This state can occur, for example, immediately after power-on or during a reset. In a step 310, the secondary module 115 can open the signal line 125 by setting its first switch 215 to the first position. At the same time, in a step 315, the primary module 110 can be initialized.

[0035] In a step 320, the primary module 110 can transmit an initialization signal via the signal line 125. Preferably, no addressing of a secondary module 110 occurs. At this time, only the secondary module 115 that immediately follows the primary module 110 along the signal line 125 can evaluate the initialization signal in a step 325. In a step 330, the secondary module 115 can acknowledge the initialization signal to the primary module 110. The primary module 110 can receive the acknowledgment signal in a step 325 and communicate with the secondary module 115. Parameters can be exchanged between the modules 110, 115 in a step 335. The secondary module 115 can be initialized in a step 340.

[0036] Once initialization is complete, the secondary module 115 may close the signal line 125 (in a step 345) by moving its first switch 215 to the second position. It may also signal the completion of its own initialization to the primary module 110 in a step 350.

[0037] If the primary module 110 receives the confirmation in a step 355, it can return to step 320 and send another initialization signal via the signal line 125. The further initialization signal reaches the next downstream secondary module 115, which can then also be initialized in the manner described.

[0038] If no response from one of the secondary modules 115 follows the transmission of the initialization signal by the primary module 110 in step 320 within a predetermined time, a timeout can be determined in step 360. Subsequently, in step 365, it can be determined that the system 105 is fully initialized or that no further secondary module 115 can be initialized. The initialization of the system 105 is thus complete, and normal operation can begin. This determination is preferably performed by the primary module 110. Step 365 can also be executed if a predetermined number of secondary modules 115 have reported their initializations to the primary module 110.

[0039] At this point in time, all first switches 215 of the secondary modules 115 should each be in the second position and connect the respective input 205 of the secondary module 115 to its output 210. The primary module 110 can connect the signal line 125 to a predetermined electrical potential, for example, a predetermined positive voltage, which can be several volts. For this purpose, a voltage source can be provided on the first module 110. In a step 370, the primary module 110 or a secondary module 115 can connect the signal line 125 to another electrical potential, usually a lower potential. The other potential is preferably connected to the signal line 125 with a higher impedance than the first potential. By connecting, the potential effective on the signal line 125 can be changed, and the change can be detected and evaluated by one of the modules 110, 115.In the illustrated embodiment, an evaluation is preferably performed in a step 375 by the primary module 110; in another embodiment, the evaluation can also be performed by a secondary module 115 or by multiple modules 110, 115. The interrupt request can then be handled by the evaluating module 110, 115. For this purpose, a function of a secondary module 115 can be changed or suspended. If the interrupt request indicates a catastrophic event, for example, the modules 110, 115 can restrict or deactivate their functions. In this way, individual parts of a device or motor vehicle 100 can be shut down gracefully. Optionally, the system 100 can be completely reinitialized. For this purpose, a corresponding message can be sent from an evaluating module 110, 115 to all other modules 110, 115.

[0040] Reference symbol

[0041] 100 devices

[0042] 105 System

[0043] 110 primary module

[0044] 115 secondary module

[0045] 120 data bus

[0046] 125 signal line

[0047] 130 supply line

[0048] D+, D- Data lines of the data bus 120 VBUS, GND Supply line 130 CIC_IN Input CIC-OUT Output

[0049] 205 Entrance

[0050] 210 Exit

[0051] 215 first switch

[0052] 220 second switch

[0053] 225 transistors

[0054] 230 processing facility

[0055] INT Signal: Interrupt request

[0056] CF_COMPLETE Signal: Initialization completed

[0057] CS Signal: Initialization

[0058] 300 procedures

[0059] 305 Reset

[0060] 310 Open Daisy Chain

[0061] 315 Initialize

[0062] 320 Send signal

[0063] 325 Signal received AND not yet initialized?

[0064] 330 Acknowledge signal

[0065] 335 Exchange parameters

[0066] 340 Initialize

[0067] 345 Close daisy chain 350 Confirm initialization

[0068] 355 Confirmation received

[0069] 360 timeout

[0070] 365 System initialized 370 Request interrupt

[0071] 375 Treat interruption

Claims

PATENT CLAIMS 1. A method (300) for initializing a system (105) having a primary (110) and at least one secondary electronic module (115), wherein the secondary modules (115) are connected to the primary module (110) by means of a signal line (125) in the manner of a daisy chain; wherein the method (300) comprises the following steps: a) opening (310) the signal line (125) in all secondary modules (115); b) providing (320) an initialization signal on the signal line (125) by the primary module (110); c) initializing (340) a secondary module (115) which receives the initialization signal and is not yet initialized; d) closing (345) the signal line (125) by the last initialized secondary module (115); and e) repeating steps b) to d) until all secondary modules (115) are initialized.

2. The method (300) of claim 1, wherein initializing (340) a secondary module (115) comprises communicating (335) with the primary module (110).

3. The method (300) of claim 2, wherein a software component of the secondary module (115) is updated by the primary module (110).

4. The method (300) according to claim 2 or 3, wherein the secondary modules (115) are additionally connected to the primary module (110) by means of a data bus (120); wherein the communication takes place via the data bus (120).

5. The method (300) according to any one of claims 2 to 4, wherein the initialization is terminated (365) if no communication (360) takes place between the primary module and a not yet initialized secondary module (115) during a predetermined time after the provision of an initialization signal.

6. The method (300) according to any one of claims 2 to 5, wherein the communication (335) comprises transmitting a configuration from the secondary module (115) to the primary module (110); the primary module (110) determines a topology of secondary modules (115) in the system (105) based on received configurations.

7. The method (300) according to any one of the preceding claims, wherein, after all modules (110, 115) are initialized, one of the modules (110, 115) connects (370) the signal line (125) to a predetermined potential to provide an interrupt request.

8. Electronic module (110) comprising: - an output (210) for connection to a signal line (125) in the manner of a daisy chain; and - a processing device (230) which is configured to provide an initialization signal to at least one further electronic module (115) via the signal line (125).

9. Electronic module (115) comprising: - an input (205) and an output (210) for a signal line (125) in the manner of a daisy chain; - a switch (215) between the input and the output; and - a processing device (230) which is configured to detect an initialization signal at the input when the switch (215) is open, to initialize the module (115); and to close the switch (215).

10. The module (115) of claim 9, further comprising another switch (225) for connecting the signal line (125) to a predetermined potential to provide an interrupt request.

11. System (105), comprising: - a primary electronic module (110) according to claim 8; - at least one secondary electronic module (115) according to claim 9 or 10; and - a signal line (125) which connects the secondary modules (115) to the primary module (110) in the manner of a daisy chain.

12. Electrical device (100) comprising a system (105) according to claim 11.

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