JP2004179773A - On-vehicle communication system and on-vehicle communication interrupting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-vehicle communication system capable of maintaining data transmission between all apparatuses even when there exists an apparatus whose communication is disabled. <P>SOLUTION: In the on-vehicle communication system connected with a plurality of apparatuses 1 to 5, 7, 8, and 10 mounted on a vehicle, the apparatuses 1 to 5, 7, 8, and 10 are connected in a ring, the display apparatus 10 is provided with an interruption switch for interrupting the connection between the display apparatus 10 and the sub display apparatus 7, and when the connection between the display apparatus 10 and the sub display apparatus 7 is interrupted by the interruption switch, the apparatuses 1 to 5, 7, 8, and 10 are brought into daisy chain connection. Further, when there is an apparatus whose communication is disabled, the interruption switch is switched to connect the display apparatus 10 and the sub display apparatus 7, thereby bringing the apparatuses 1 to 5, 7, 8, and 10 into a state of daisy chain connection. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an in-vehicle communication system and an in-vehicle communication cutoff device to which devices mounted on a vehicle are connected.
[0002]
[Prior art]
2. Description of the Related Art Various devices such as a navigation system, a camera, a display, and a speaker are mounted on an automobile. In some cases, these in-vehicle devices are connected to each other to construct an in-vehicle LAN (in-vehicle communication system). For example, an in-vehicle LAN compliant with IEEE (Institute of Electrical and Electronic Engineers) 1394 can be constructed. By constructing an in-vehicle LAN compliant with IEEE 1394, high-speed data transmission of, for example, 400 Mbps can be performed, and additional connection of devices compatible with IEEE 1394 can be easily performed (for example, see Patent Document 1).
[0003]
FIG. 12 shows a configuration example of the in-vehicle LAN. In the example of FIG. 12, a tuner 1 such as a digital broadcast tuner, a camera 2 for photographing a situation around the vehicle (for example, behind the vehicle), and various data such as reception data of the tuner 1 or photographing data of the camera 2 are stored. A storage device 3 such as a hard disk, a DVD (Digital Video Disk) player 4, a navigation system 5, a display 6 with an operating device such as a touch panel type liquid crystal display arranged around the instrument panel, a front seat back, etc. A sub display 7 with an operation device such as a touch panel type liquid crystal display and a speaker 8 are mounted on the vehicle, and the devices 1 to 8 are connected in a chain (daisy chain connection). In an in-vehicle LAN conforming to IEEE 1394, data such as a command for device control is transmitted as asynchronous, and moving image data (video data and audio data) is transmitted as isochronous (isochronous).
[0004]
[Patent Document 1]
JP 2002-16614 A
[0005]
[Problems to be solved by the invention]
Since each device of the in-vehicle LAN is daisy-chain connected, if any device or connection cable fails, communication between all devices cannot be performed. For example, if a cable connection failure occurs at port B of port A (connected to camera 2) and port B (connected to DVD player 4) of storage device 3 shown in FIG. 12, as shown in FIG. The connection between the device 3 and the DVD player 4 is cut off. In this case, the tuner 1, the camera 2, and the storage device 3 are daisy-chain connected (network 1) and can communicate with each other. The DVD player 4, the navigation system 5, the display 6, the sub-display 7, and the speaker 8 are daisy-chained (network 2) and can communicate with each other.
[0006]
However, communication between the network 1 and the network 2 cannot be performed. For example, the video taken by the camera 2 cannot be output to the display 6 or the digital broadcast received by the tuner 1 cannot be output to the sub-display 7 and the speaker 8. If the image captured by the camera 2 is not displayed on the display 6, the driver cannot confirm the situation around the vehicle such as behind the vehicle, and the driving safety may be reduced. In addition, when the received image of the tuner 1 is not output to the sub-display 7 and the speaker 8, the driving is not affected, but there is a high possibility that the satisfaction or evaluation of the product is reduced.
[0007]
As a countermeasure against the communication failure between the devices, a method of duplicating the connection between the devices as shown in FIG. 14 can be considered. However, in the case of duplexing, it is necessary to provide each device with two types of connection ports for normal use and standby, and to perform switching processing from normal use to standby use, thereby increasing costs. Further, since two sets of connection cables are required, the cost is increased, and the wiring work and the wiring space are increased. Therefore, it is difficult to duplicate the connection, which is not practical.
[0008]
The present invention has been made in view of such circumstances, and in a plurality of devices connected in a ring shape, a disconnection unit that disconnects a connection between adjacent devices and causes all devices to be in a daisy chain connection state. , Even if there is a device that has become unable to communicate, the on-vehicle communication system capable of maintaining the state in which all the devices are connected in a daisy chain by switching the adjacent devices from the cutoff state to the connection state. And an on-vehicle communication cutoff device.
[0009]
In addition, the present invention includes a communication failure detection unit that detects a communication failure device from among a plurality of devices, so that it is possible to detect a communication failure device and quickly return to a state in which all devices are connected in a daisy chain. Another object of the present invention is to provide a vehicle-mounted communication system and a vehicle-mounted communication cutoff device that are possible.
[0010]
In addition, the present invention includes a response request unit for requesting a response from each device and a response confirmation unit for confirming a response from each device, so that it is possible to detect an uncommunicable device based on a response confirmation result. Another object of the present invention is to provide an in-vehicle communication system.
[0011]
Further, the present invention includes a storage unit in which connection state information of each device is stored, and an acquisition unit for acquiring connection mode information, so that the connection state information stored in the storage unit and the acquisition unit acquire the connection state information. Another object of the present invention is to provide an in-vehicle communication system capable of detecting an uncommunicable device based on a difference from connection state information.
[0012]
Further, according to the present invention, the state (connection or disconnection) of the blocking unit at the time of system startup is determined based on the connection mode information stored in the storage unit, thereby minimizing the initial processing at the time of system startup. Another object of the present invention is to provide an in-vehicle communication system capable of performing the following.
[0013]
It is another object of the present invention to provide an in-vehicle communication system that can easily and inexpensively configure a blocking unit using an analog switch or an AND circuit.
[0014]
In addition, the present invention includes stop detection means for detecting that the vehicle is stopped, so that switching of connection / disconnection of the cutoff means can be performed when the vehicle is stopped, thereby enhancing safety. Another object of the present invention is to provide an in-vehicle communication system.
[0015]
[Means for Solving the Problems]
An in-vehicle communication system according to a first aspect of the present invention is an in-vehicle communication system in which a plurality of devices mounted on a vehicle are connected, wherein the plurality of devices are connected in a ring shape and cut off a connection between adjacent devices. And a shut-off unit for setting the plurality of devices in a daisy-chain connection state.
[0016]
A vehicle-mounted communication system according to a second invention is characterized in that, in the first invention, the plurality of devices are devices that perform data transmission conforming to IEEE 1394.
[0017]
The in-vehicle communication system according to a third invention is the communication system according to the first or second invention, further comprising a communication failure detecting unit for detecting a communication failure device from among the plurality of devices, wherein the blocking unit connects the adjacent devices. When a communication-disabled device is detected by the communication-disabled detecting means in a state where the communication is interrupted, the disconnection of the connection between the adjacent devices is released.
[0018]
The in-vehicle communication system according to a fourth aspect is the third aspect, further comprising: response request means for requesting a response from the plurality of devices; and response confirmation means for confirming a response from the plurality of devices; The means is adapted to detect a communication-disabled device based on a result of the response confirmation by the response confirmation means.
[0019]
A communication system mounted on a vehicle according to a fifth invention is the communication system according to the third invention, further comprising: a storage unit that stores connection mode information of the plurality of devices; and an obtaining unit that obtains connection mode information of the plurality of devices. The impossibility detecting means is adapted to detect a communication-disabled device based on a difference between the connection form information stored in the storage unit and the connection form information acquired by the acquisition means.
[0020]
The in-vehicle communication system according to a sixth aspect is the vehicle-mounted communication system according to the fifth aspect, wherein a difference detecting unit that detects a difference between the connection mode information stored in the storage unit and the connection mode information acquired by the acquiring unit, And an updating unit for updating the connection form information stored in the storage unit to the connection form information acquired by the acquisition unit when a difference is detected by the acquisition unit.
[0021]
In a vehicle-mounted communication system according to a seventh invention, in the sixth invention, in accordance with the sixth invention, when the system is activated, the disconnection unit disconnects the connection between the adjacent devices according to the connection mode information stored in the storage unit. It is characterized by being done.
[0022]
An in-vehicle communication system according to an eighth aspect of the present invention is the vehicle-mounted communication system according to any one of the third to seventh aspects, wherein the shut-off means is provided between the adjacent devices in accordance with the presence or absence of a communication disabled device detected by the communication disabled detection device. An analog switch for switching between connection and disconnection is provided.
[0023]
In a vehicle-mounted communication system according to a ninth aspect, in any one of the third to seventh aspects, the blocking means includes: a binary signal corresponding to the presence or absence of a communication disabled device detected by the communication disabled detection means; And an AND circuit for receiving an input of a data signal transmitted between the devices, and switching between output and stop of the output of the data signal according to the binary signal.
[0024]
An in-vehicle communication system according to a tenth aspect of the present invention is the vehicle-mounted communication system according to any of the third to ninth aspects, further comprising stop detection means for detecting that the vehicle is stopped, wherein the cutoff means establishes a connection between the adjacent devices. In a disconnected state, when the communication-disabled device is detected by the communication-disabled detecting means and the stop of the vehicle is detected by the stop detecting means, the disconnection of the connection between the adjacent devices is released. It is characterized by.
[0025]
An on-vehicle communication disconnection device according to an eleventh aspect of the present invention is an on-vehicle communication disconnection device that is connected between devices in an on-vehicle communication network to which a plurality of devices mounted on a vehicle are connected, and disconnects the connection between the devices. Disconnecting means for interrupting the connection between the devices, and communication-disabled detecting means for detecting a communication-disabled device from among the plurality of devices; When an incommunicable device is detected by the incompatibility detecting means, disconnection of the connection between the devices is released.
[0026]
In the first invention, an in-vehicle communication system (in-vehicle LAN) in which a plurality of devices mounted on a vehicle are connected in a ring shape is constructed. Blocking means is provided for bringing the plurality of devices into a daisy chain connection. The blocking means can be provided around the connector of any of the adjacent devices, or can be provided as an independent device (vehicle communication blocking device) between the adjacent devices. When the connection between the adjacent devices is interrupted by the interrupting means, all devices are in a daisy-chain connection state. Further, when any one of the respective connections between the devices is cut off, the cut-off state of the cut-off means is released and the adjacent devices are connected to each other, so that all the devices are connected in a daisy chain.
[0027]
In the second invention, the plurality of devices can perform data transmission conforming to IEEE 1394. In a state where the plurality of devices are connected in a ring shape, data transmission according to IEEE 1394 cannot be performed, but all devices are connected in a daisy chain by disconnecting the connection between adjacent devices by a disconnection unit. In this state, the plurality of devices can perform data transmission conforming to IEEE 1394. Also, when any one of the connections between the devices is interrupted, data transmission between all the devices cannot be normally performed. However, by releasing the interruption of the interruption means and connecting the adjacent devices, all the devices can be connected. Are connected in a daisy chain, and data can be transmitted between all devices.
[0028]
In the third or eleventh aspect, a communication-disabled device is detected from the plurality of devices by a communication-disabled detecting unit. When the communication-disabled detecting unit detects the communication-disabled device in a state where the connection between the adjacent devices is disconnected, the disconnection unit cancels the disconnection of the connection between the adjacent devices. When an uncommunicable device is detected, data transmission between all devices cannot be normally performed.However, when all devices are connected in a daisy chain by disconnecting the blocking means and connecting the adjacent devices. And data transmission between all devices becomes possible.
[0029]
In the fourth aspect, a response request unit requests a response from each device, and a response confirmation unit confirms a response from each device. The communication failure detecting means detects the communication failure equipment based on the result of the confirmation of the response by the response confirmation means. For example, if there is a device that has not responded, the communication failure detecting unit determines that the device has become unable to communicate. Preferably, the response request is made periodically.
[0030]
In the fifth invention, information (connection form information) relating to the topology of each device is stored in the storage unit. Further, the current topology of each device is obtained by the obtaining unit. The communication failure detection means detects a communication failure device based on a difference between the topology stored in the storage unit and the topology acquired by the acquisition means. In the storage unit, for example, a topology at the time of shipping the vehicle is stored in advance, and a communication-disabled device is detected based on a change in the topology from the time of shipping the vehicle. In this case, since the topology stored in the storage unit is fixed, it is suitable when almost no device is added to or removed from the in-vehicle LAN.
[0031]
In the sixth aspect, a difference between the current topology acquired by the acquisition unit and the topology stored in the storage unit is detected by the difference detection unit, and when a difference is detected, the difference is stored in the storage unit by the update unit. The updated topology is updated to the topology acquired by the acquisition unit. In this case, since the topology stored in the storage unit is updated to the latest state, it is suitable when the device is frequently added to or removed from the in-vehicle LAN.
[0032]
In the seventh invention, the disconnection unit connects or disconnects the adjacent devices based on the connection form information (topology) stored in the storage unit when the system is started. For example, when the adjacent devices are connected in the topology stored in the storage unit, the disconnection unit at the time of starting the system is set to the connection state. By matching the state (connection or disconnection) of the blocking means at the time of system startup with the topology stored in the storage unit, the topology of the vehicle-mounted LAN can be maintained at the state of the previous operation even at the time of system startup. Become. In this case, since the in-vehicle LAN has the same topology as that at the time of the previous operation, no communication-disabled device or the like is not detected, and data transmission can be started only by performing minimum initial processing.
[0033]
In an eighth aspect, the disconnection unit includes an analog switch that switches connection and disconnection between the adjacent devices according to the presence or absence of a communication-disabled device detected by the communication-disabled detection unit. For example, when switching connection and disconnection between the connector A of the device X and the connector B of the device Y, it is possible to insert an analog switch into a connection line between the device X main body and the connector A. In this case, it is possible to switch connection and disconnection between the device X main body and the connector A (connected to the connector B of the device Y) by the analog switch.
[0034]
In the ninth invention, the blocking means receives a binary signal corresponding to the presence or absence of a communication failure device detected by the communication failure detection means and a data signal transmitted between the adjacent devices, and inputs the binary signal. And an AND circuit for switching between outputting and stopping output of the data signal in accordance with the signal. For example, when connection and disconnection between the connector A of the device X and the connector B of the device Y are switched, an AND circuit can be provided in a digital signal output unit of the device X corresponding to the connector A. In this case, by inputting a digital output signal and a binary signal corresponding to the presence or absence of a communication disabled device to the input of the AND circuit, if there is a communication disabled device (the binary signal is “1”), the digital output signal is The digital output signal is not output from the connector A when the signal is output from the connector A (connected to the connector B of the device Y) and there is no communication disabled device (the binary signal is “0”).
[0035]
In the tenth aspect, the stop detecting means detects that the vehicle is stopped. In a state where the stop of the vehicle is detected by the stop detecting means, if the communication-disabled detecting means detects a communication-disabled device, the blocking state of the blocking means is released to connect the adjacent devices. When the connection / disconnection between the adjacent devices is switched by the disconnection unit, for example, a bus reset occurs in the in-vehicle communication network (in-vehicle LAN) to cope with a new topology. May be unstable. In a state where the vehicle is stopped, it is possible to minimize the influence on driving when the operation of the in-vehicle LAN becomes unstable due to the bus reset.
[0036]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be specifically described with reference to the drawings showing the embodiments.
(First Embodiment)
FIG. 1 shows a configuration of a vehicle-mounted communication system (hereinafter, referred to as a vehicle-mounted LAN) according to the present invention. The vehicle includes a tuner 1 such as a digital broadcast tuner, a camera 2 that captures a situation around the vehicle (for example, behind the vehicle), and a hard disk that stores various data such as reception data of the tuner 1 or photography data of the camera 2. Storage device 3, a DVD (Digital Video Disk) player 4, a navigation system 5, a display 10 with an operating device such as a touch panel type liquid crystal display arranged around the instrument panel, and a rear seat, etc. A sub-display 7 with an operating device such as a touch panel type liquid crystal display and a speaker 8 are mounted, and the devices 1 to 5, 7, 8, and 10 are connected in a ring shape.
[0037]
In the present embodiment, of the port A (connected to the navigation system 5) and the port B (connected to the sub-display 7) of the display 10, the connection between the sub-display 7 and the display 10 is cut off on the port B side. A switch is provided.
[0038]
FIG. 2 shows the configuration of a portion around the cutoff switch of the display 10. The display 10 has an internal bus to which a liquid crystal display device main body and an operation device (touch panel) main body are connected. The internal bus includes a CPU (Central Processing Unit) 11, a RAM (Random Access Memory) 12, and a ROM (Read Only). Memory 13 and a 1394 / LINK / IC 14 that performs data transmission processing related to the link layer of IEEE 1394.
[0039]
The display 10 has a connector CA corresponding to the port A and a connector CB corresponding to the port B. The connector CA is connected to the 1394 / PHY / IC 15 which performs data transmission processing relating to the physical layer of IEEE1394. I have. The 1394 PHY IC 15 is connected to the 1394 LINK IC 14. The connector CB is connected to the 1394 / PHY / IC 15 through the cutoff switch 16. The disconnection switch 16 is connected to the CPU 11, and the CPU 11 controls connection / disconnection switching.
[0040]
FIG. 3 shows the configuration of the cutoff switch 16. In FIG. 3, only the cutoff switch 16, the connector CB, the 1394 / PHY / IC 15 and the CPU 11 are shown. The 1394 PHY IC 15 includes a receiving circuit 15a and a transmitting circuit 15b for performing voltage conversion and the like, and the cutoff switch 16 includes a receiving analog switch 16a and a transmitting analog switch 16b. The connection line L1 between the connector CB and the cutoff switch 16 shown in FIG. 2 has a reception connection line L1a and a transmission connection line L1b as shown in FIG. 3, and the reception line between the connector CB and the reception analog switch 16a is received. The connection CB and the transmission analog switch 16b are connected by a transmission connection line L1b. The connection line L2 between the cutoff switch 16 and the 1394 PHY IC 15 shown in FIG. 2 has a reception connection line L2a and a transmission connection line L2b as shown in FIG. The receiving circuits 15a are connected by a receiving connecting line L2a, and the transmitting analog switch 16b and the transmitting circuit 15b are connected by a transmitting connecting line L2b.
[0041]
The analog switch for reception 16 a and the analog switch for transmission 16 b are connected to the CPU 11. For example, when a signal is input from the CPU 11, the analog switch is connected, and when no signal is input, the analog switch is cut off. Normally, the CPU 11 does not input a signal to the cutoff switch 16 and the connection between the connector CB and the 1394 / PHY / IC 15 is cut off. For this reason, as shown in FIG. 4, the display 10 and the sub-display 7 of the in-vehicle LAN are shut off. In this case, each device is in a daisy chain connection state having the display 10 and the sub-display 7 at both ends.
[0042]
In the state of the daisy chain connection shown in FIG. 4, for example, IEEE 1394 data transmission is performed between the devices. In the case of an in-vehicle LAN, for example, the power of each of the devices 1 to 5, 7, 8, and 10 is turned on by operating an ignition key or the like (the system is activated), and a bus reset of the in-vehicle LAN occurs. By the bus reset, recognition of connected devices or recognition of a connection state is performed according to a general IEEE 1394 initial sequence (initial procedure), and a parent-child relationship between devices or a connection form (topology) is determined. Done. Each device obtains the result of the determination based on the initial sequence, and performs data transmission between the devices. The initial sequence is, for example, IEEE1394. a or IEEE 1394. b. The CPU 11 operates as a means for acquiring the topology of the in-vehicle LAN, and stores acquired topology information (connection form information) on the acquired topology in the RAM (storage unit) 12.
[0043]
Further, setting topology information relating to the topology of the in-vehicle LAN shown in FIG. 4 is stored in the RAM 12 in advance. The RAM 12 includes, for example, a non-volatile memory such as a flash memory, and the set topology information is stored in the flash memory, and is stored even when the power of the display 10 is off. For example, the set topology information relating to the topology at the time of vehicle shipment is stored in the RAM 12 (flash memory). Further, it is of course possible to store the set topology information in the ROM 13, for example.
[0044]
In addition, the CPU 11 operates as a unit that detects that the other devices 1 to 5, 7, and 8 have become unable to communicate. In the present embodiment, the CPU 11 periodically requests a response from each of the other devices 1 to 5, 7, and 8, and checks a response from each of the other devices 1 to 5, 7, and 8. And detects that each of the devices 1 to 5, 7, and 8 has become unable to communicate based on the presence or absence of a response.
[0045]
When a communication-disabled device (communication-disabled device) is detected, the CPU 11 switches the cutoff switch 16 from the cutoff state to the connection state. In the example of FIG. 3, signal input from the CPU 11 to the analog switch for reception 16a and the analog switch for transmission 16b is started, the cutoff switch 16 is switched to the connected state, and the connected state is maintained. In this case, the display 10 and the sub-display 7 are connected.
[0046]
Next, the operation of the in-vehicle communication system according to the present invention will be described. FIG. 5 shows a procedure for switching the cutoff switch when an uncommunicable device is detected. When the power of each device of the in-vehicle LAN is turned on (the system is started) by the driver starting the engine (S10), a bus reset of the in-vehicle LAN occurs and a general IEEE 1394 initial sequence starts. Is performed (S12). Since the topology of the in-vehicle LAN is determined by the initial sequence, the CPU 11 of the display 10 obtains the determined topology and updates the obtained topology information stored in the RAM 12. The CPU 11 compares the updated acquired topology information with the set topology information (the topology shown in FIG. 4), and when the topology is different (S14: YES), switches the cutoff switch 16 from the cutoff state to the connection state (S14: YES). S22). When the cutoff switch 16 is switched to the connection state, a bus reset of the in-vehicle LAN occurs (S24).
[0047]
For example, as shown in FIG. 6, when port B of the storage device 3 out of the port A (connected to the camera 2) and the port B (connected to the DVD player 4) has a poor connection, the display 10 displays the DVD player 4, the navigation Only the network to which the system 5 and the display 10 are connected can be recognized. In this case, a difference between the acquired topology information and the set topology information (the topology in FIG. 4) is detected by the CPU 11, and the cutoff switch 16 is switched to the connected state by the CPU 11 that has detected the difference, and as shown in FIG. And the sub-display 7 are connected. In this case, each of the devices 1 to 5, 7, 8, and 10 is in a daisy chain connection state having the DVD player 4 and the storage device 3 at both ends. In this state (FIG. 7), a bus reset occurs, a parent-child relationship or a topology is determined by a general IEEE 1394 initial sequence, and data transmission between the devices (all devices) is performed.
[0048]
Further, even if the acquired topology is the same as the topology shown in FIG. 4 (S14: NO), the CPU 11 periodically checks the response with each of the devices 1 to 5, 7, and 8 (S16). If no response is obtained and the CPU 11 detects a device that cannot communicate (S18: YES), the CPU 11 switches the cutoff switch 16 to the connected state (S22). Switching of the cutoff switch 16 causes a bus reset of the in-vehicle LAN (S24). For example, as shown in FIG. 6, when a connection failure occurs in the port B of the storage device 3, the CPU 11 cannot obtain a response signal from the storage device 3, the camera 2, the tuner 1, the speaker 8, and the sub-display 7. , And detects a device that cannot communicate.
[0049]
If no communication-disabled device is not detected (S18: NO), the CPU 11 periodically turns off the power of each device of the vehicle-mounted LAN (stops the system) by stopping the engine by the driver (S20: YES). The confirmation of the response and the detection of the uncommunicable device are repeatedly repeated (S16, S18: NO, S20: NO).
[0050]
In the embodiment described above, the set topology information is fixed to, for example, the topology shown in FIG. 4, but it is also possible for the CPU 11 to update the set topology information to the latest acquired topology information. For example, in the case of the above-described embodiment, the CPU (difference detecting means) 11 detects a difference between the acquired topology (acquired topology information) shown in FIG. Can be updated to the topology (acquired topology information) shown in FIG.
[0051]
Further, the state (connection or disconnection) of the disconnection switch 16 at the time of starting the system can be determined by the CPU 11 based on the updated and stored configuration topology information. For example, in the case of the above-described embodiment, the CPU 11 turns on the disconnection switch 16 (the state shown in FIG. 7) based on the set topology information stored in the RAM 12 at the next system startup (when the power is turned on). Therefore, a change in topology or the like is not detected after the initial sequence, and the initial processing at startup is completed in a short time.
[0052]
In the above-described embodiment, a communication-disabled device is detected by the response confirmation from each device. However, some devices of the in-vehicle LAN stop their functions and do not return a response when the power is turned off, for example. Some, however, maintain the connection of the IEEE 1394 bus. For example, when the user turns off the power of the tuner 1, the tuner 1 stops functioning and does not respond, but the connection between the camera 2 and the speaker 8 may be maintained. In this case, since there is a response from the speaker 8 or the sub-display 7, the CPU 11 of the display 10 determines that only the main body of the tuner 1 is stopped. By transmitting a stop notification from the tuner 1 to the display 10 when the power is turned off, the CPU 11 can also recognize that the main body of the tuner 1 is stopped. It is preferable that each device of the in-vehicle LAN transmits a stop notification to the display 10 when service provision such as power-off is stopped.
[0053]
In the above-described embodiment, the cutoff switch 16 is provided on the display 10; however, the cutoff switch 16 can be provided on any of the devices 1 to 5, 7, and 8 of the in-vehicle LAN. As shown in FIG. 8, it is also possible to connect a disconnection device (in-vehicle communication disconnection device) 20 including the disconnection switch 16 to the in-vehicle LAN. The configuration of the shutoff device 20 is substantially the same as the configuration of the portion around the shutoff switch 16 of the display 10 shown in FIG.
[0054]
In the above-described embodiment, the cutoff switch 16 is disposed between the connector CB and the 1394 PHY IC 15. However, the cutoff switch 16 may be integrated with the connector CB, or the cutoff switch 16 may be connected to the 1394 PHY. It is also possible to configure integrally with the analog input section of the IC 15.
[0055]
Further, the cutoff switch 16 is not limited between the connector CB and the 1394 / PHY / IC 15, but may be arranged between the 1394 / PHY / IC 15 and the 1394 / LINK / IC 14, for example, as shown in FIG. . FIG. 10 shows an example of the cutoff switch 17 shown in FIG. FIG. 10 shows only the cutoff switch 17, the 1394 / LINK IC 14, the 1394 / PHY IC 15 and the CPU 11. The cutoff switch 17 includes a reception AND circuit 17a and a transmission AND circuit 17b.
[0056]
The connection line L3 between the 1394 PHY IC 15 and the cutoff switch 17 shown in FIG. 9 has a reception connection line L3a and a transmission connection line L3b as shown in FIG. 10, and the reception circuit of the 1394 PHY IC 15 15a and the first input of the receiving AND circuit 17a are connected by a receiving connecting line L3a, and the transmitting circuit 15b of the 1394 PHY IC 15 and the output of the transmitting AND circuit 17b are connected by a transmitting connecting line L3b. I have. The connection line L4 between the cutoff switch 17 and the 1394 / LINK / IC 14 shown in FIG. 9 has a reception connection line L4a and a transmission connection line L4b as shown in FIG. The output and the 1394 LINK IC 14 are connected by a reception connection line L4a, and the first input of the transmission AND circuit 17b is connected to the 1394 LINK IC 14 by a transmission connection line L4b.
[0057]
The second input of the reception AND circuit 17a and the second input of the transmission AND circuit 17b are connected to the CPU 11, for example, when a signal is input from the CPU 11, the first input is output as it is (connection state), and the signal is input. If not, the first input is not output at all (cutoff state). Normally, the CPU 11 does not input a signal to the cutoff switch 17, and the 1394 / PHY IC 15 and the 1394 / LINK IC 14 are cut off. The display 10a shown in FIG. 9 can switch the connection / disconnection of the connection with the sub-display 7 similarly to the display 10 shown in FIG.
[0058]
In the above description, the cutoff switch 17 is arranged between the 1394 PHY IC 15 and the 1394 LINK IC 14, but the cutoff switch 17 may be integrally formed with the digital signal input / output unit of the 1394 PHY IC 15, The shut-off switch 17 can be integrally formed with the digital signal input / output unit of the 1394 / LINK / IC 14. It is also possible to switch between use and non-use of the port B by software in the 1394 link IC 14. For example, when a port B unused instruction signal is transmitted from the CPU 11 to the 1394 LINK IC 14, the 1394 LINK IC 14 may skip the port B initial sequence without performing the process related to the port B. .
[0059]
(Second embodiment)
In the above-described embodiment, when the incommunicable device is detected, the cutoff switch 16 is immediately switched to the connection state by the CPU 11, but the switching of the cutoff switch 16 causes a bus reset. May be temporarily unstable. Therefore, it may be preferable to switch the cutoff switch 16 while the vehicle is stopped. FIG. 11 shows an example of an in-vehicle LAN that switches the cutoff switch 16 while the vehicle is stopped. The in-vehicle LAN shown in FIG. 11 has a configuration similar to that of the first embodiment. In the present embodiment, a speedometer 9 for displaying the vehicle speed is connected to the in-vehicle LAN.
[0060]
The speedometer 9 is connected to a vehicle speed sensor (stop detecting means) (not shown) and displays a speed according to a vehicle speed detection signal output from the vehicle speed sensor. Vehicle speed information on the vehicle speed is transmitted from the speedometer 9 to the display 10. For example, the digital value of the vehicle speed displayed on the speedometer 9 is transmitted to the display 10 as vehicle speed information.
[0061]
When the vehicle speed is lower than the reference value, the CPU 11 of the display 10 determines that the vehicle is stopped. When the CPU 11 detects a device that cannot communicate, the CPU 11 switches the cutoff switch 16 after determining that the vehicle is stopped based on the vehicle speed information. The stop of the vehicle can also be obtained from the state of the side brake. Further, instead of the vehicle being stopped, it is also possible to switch the cutoff switch 16 in response to the detection of the uncommunicable device in a state in which each device of the in-vehicle LAN is not executing a process.
[0062]
【The invention's effect】
According to the first or second aspect of the present invention, even in the case of a device connected in a ring shape (actually in a daisy chain connection), even if there is a device in which communication is impossible, the disconnection unit is switched from the disconnection state to the connection state, and all devices are connected. It is possible to maintain the daisy-chain connection of, and to continue, for example, data transmission in accordance with IEEE 1394 between all devices. It is possible to prevent the data transmission from being stopped due to the inability to communicate between the devices, to improve the driving safety, and to increase the availability of the product. In addition, the present invention requires only adding a disconnecting means and a connection cable between devices whose connection is to be interrupted, and can increase reliability simply and at low cost as compared with a case where connections between devices are duplicated. It is.
[0063]
According to the third or eleventh aspect of the present invention, by detecting a communication-disabled device by the communication-disabled detecting means, the daisy-chain connection disconnected at the communication-disabled device portion can be quickly returned to a state in which all devices are daisy-chain connected. It is possible to do. It is possible to promptly respond to the occurrence of the uncommunicable device and minimize the data transmission stop time by the uncommunicable device.
[0064]
According to the fourth aspect, the response requesting unit requests a response from each device, and the response confirming unit confirms the response from each device, thereby detecting the incommunicable device based on the response confirmation result. It is possible. A device that does not respond is constantly monitored, and if there is a device that does not respond, it is possible to quickly switch the cutoff means.
[0065]
According to the fifth aspect, based on the difference between the topology stored in the storage unit and the topology acquired by the acquisition unit, the communication-disabled device is detected by the communication-disabled detection unit, and based on the change in the topology, It is possible to detect a device that cannot communicate. The topology is constantly monitored, and when the topology changes, the switching means can be quickly switched.
[0066]
According to the sixth aspect, a difference between the topology information acquired by the acquisition unit and the topology information stored in the storage unit is detected by the difference detection unit. When the difference is detected, the difference is stored in the storage unit by the update unit. By updating the used topology information to the topology information obtained by the obtaining means, it is possible to detect a communication-disabled device based on a real-time topology change.
[0067]
According to the seventh aspect, at the time of system startup, the on-board communication system is started up in the same topology as the previous use by setting the blocking unit to the connection state or the blocking state based on the topology information stored in the storage unit. Is done. Therefore, an uncommunicable device or the like is not detected, and the time required for the initial processing at the time of starting the system can be reduced.
[0068]
According to the eighth or ninth aspect of the present invention, an analog switch that switches connection and disconnection between the adjacent devices is used as the disconnection unit according to the presence or absence of a communication-disabled device detected by the communication-disabled detection unit. A binary signal corresponding to the presence / absence of a communication failure device detected by the failure detection means and a data signal transmitted between the adjacent devices are input, and output and stop of the data signal are stopped according to the binary signal. By using an AND circuit that switches between the two, it is possible to simply and inexpensively configure the cutoff means.
[0069]
According to the tenth aspect of the present invention, when the stop of the vehicle is detected by the stop detecting means, the connection and the cutoff between the adjacent devices are switched by the cutoff means, so that the stability of the in-vehicle LAN due to the topology change is reduced. The effect on driving can be minimized.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a vehicle-mounted communication system (vehicle-mounted LAN) according to the present invention.
FIG. 2 is a block diagram showing a configuration around a cutoff switch of the display.
FIG. 3 is a block diagram showing a configuration of a cutoff switch.
FIG. 4 is a diagram illustrating an example of a connection state of an in-vehicle LAN.
FIG. 5 is a flowchart showing a procedure for switching a cutoff switch.
FIG. 6 is a diagram illustrating an example of a connection state of an in-vehicle LAN.
FIG. 7 is a diagram illustrating an example of a connection state of an in-vehicle LAN.
FIG. 8 is a diagram showing another configuration of the in-vehicle LAN according to the present invention.
FIG. 9 is a block diagram showing another configuration of a portion around a cutoff switch of the display.
FIG. 10 is a block diagram showing another example of the cutoff switch.
FIG. 11 is a diagram showing still another example of the in-vehicle LAN according to the present invention.
FIG. 12 is a diagram illustrating a configuration example of a conventional in-vehicle communication system (in-vehicle LAN).
FIG. 13 is a diagram showing an example of a connection state of a conventional in-vehicle LAN.
FIG. 14 is a diagram showing another configuration example of a conventional in-vehicle LAN.
[Explanation of symbols]
9 Speedometer
11 CPU (communication failure detection means, response request means, response confirmation means, acquisition means, difference detection means, update means)
12 RAM (storage unit)
13 ROM
14 1394 ・ LINK ・ IC
15 1394 ・ PHY ・ IC
16, 17 cut-off switch (cut-off means)
16a, 16b analog switch
17a, 17b AND circuit
20 Breaking device (Vehicle communication breaking device)
CA, CB connector
L1, L2, L3, L4 connection line

Claims (11)

In an in-vehicle communication system in which a plurality of devices mounted on a vehicle are connected,
The plurality of devices are connected in a ring shape,
An in-vehicle communication system, comprising: a disconnection unit that disconnects a connection between adjacent devices to set the plurality of devices in a daisy-chain connection state. The in-vehicle communication system according to claim 1, wherein the plurality of devices are devices that perform data transmission conforming to IEEE 1394. Comprising a communication failure detecting means for detecting a communication failure device from among the plurality of devices,
The disconnection unit is configured to release the disconnection of the connection between the adjacent devices when the connection failure between the adjacent devices is detected by the communication failure detection unit in a state where the connection between the adjacent devices is interrupted. The in-vehicle communication system according to claim 1 or 2, wherein: Response request means for requesting a response from the plurality of devices;
Response confirmation means for confirming a response from the plurality of devices, wherein the communication failure detecting means detects the communication failure device based on a result of the response confirmation by the response confirmation means. The in-vehicle communication system according to claim 3. A storage unit in which connection mode information of the plurality of devices is stored,
Acquiring means for acquiring the connection form information of the plurality of devices, wherein the communication failure detection means communicates based on a difference between the connection form information stored in the storage unit and the connection form information acquired by the acquisition means. 4. The in-vehicle communication system according to claim 3, wherein the in-vehicle communication device is configured to detect a disabled device. A difference detection unit that detects a difference between the connection mode information stored in the storage unit and the connection mode information acquired by the acquisition unit,
6. The apparatus according to claim 5, further comprising: an updating unit configured to update the connection mode information stored in the storage unit to the connection mode information acquired by the acquisition unit when a difference is detected by the difference detection unit. In-vehicle communication system. 7. The in-vehicle communication according to claim 6, wherein the disconnection unit is configured to disconnect the connection between the adjacent devices according to the connection mode information stored in the storage unit when the system is started. system. The apparatus according to claim 3, wherein the disconnection unit includes an analog switch that switches connection and disconnection between the adjacent devices according to the presence or absence of a communication failure device detected by the communication failure detection unit. An in-vehicle communication system according to any one of the above. The blocking unit receives a binary signal corresponding to the presence / absence of a communication-disabled device detected by the communication-disabled detection unit and a data signal transmitted between the adjacent devices, and responds to the binary signal. The in-vehicle communication system according to any one of claims 3 to 7, further comprising an AND circuit that switches between outputting and stopping output of the data signal. Stop detection means for detecting that the vehicle is stopped,
The disconnecting unit is configured to disconnect the connection between the adjacent devices, and when the communication-disabled device detects the communication-disabled device and the stop detection unit detects that the vehicle has stopped, the adjacent device is disconnected. The in-vehicle communication system according to any one of claims 3 to 9, wherein the disconnection of the connection between them is released. A vehicle-mounted communication cutoff device that is connected between devices in a vehicle-mounted communication network to which a plurality of devices mounted on a vehicle are connected, and that cuts off connection between the devices.
Blocking means for blocking the connection between the devices,
A communication failure detection unit that detects a communication failure device from among the plurality of devices, wherein the blocking unit disconnects the connection between the devices, and when the communication failure detection unit detects the communication failure device, An on-vehicle communication disconnection device, wherein the disconnection of the connection between the devices is released.

Images