JP2004135168A - Multiplex communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide multiplex communication equipment capable of shortening the start time of the multiplex communication equipment which is in a low power consumption operation mode. <P>SOLUTION: The multiplex communication equipment is provided with an input detection means which detects an input signal of a slave station, a sleep control means which sets an operating state of the slave station in the low power consumption operation mode when a communication signal is not detected continuously for over a prescribed time by a signal monitoring means which monitors presence/absence of a signal on a communication line and the input signal is not inputted continuously for over the prescribed time, a wake-up control means which restores the operating state of the slave station to a normal operation mode when the communication signal or the input signal is detected in the case of operation in the low power consumption operation mode and a wake-up signal output means which outputs a wake-up signal on the communication line prior to the wake-up control means. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multiplex communication device suitable for being incorporated in a vehicle, for example.
[0002]
[Prior art]
The vehicle incorporates various input devices including switches and sensors, and various load devices including lamps and actuators that are driven according to information provided from these input devices. In order to operate the input device and the load device in association with each other, a control device (ECU; electronic control unit) is provided in each part of the vehicle, and the control is performed while communicating information between these control devices. Things have also been done.
[0003]
FIG. 1 shows a schematic configuration of a vehicle LAN (multiplex communication device) constructed by connecting such control devices via a communication line. Reference numeral 1 denotes a various input device 2 provided in each part of the vehicle. It is a slave ECU that detects a state and drives various load devices 3. Reference numeral 4 denotes a master ECU that communicates information with a plurality of slave ECUs 1 via branch lines 5 and controls the operation of each slave ECU 1. Incidentally, the communication between the master ECU 4 and the slave ECU 1 is performed by, for example, a polling selecting method. A plurality of master ECUs 4 provided for various functions are configured to communicate with each other via a trunk line 6.
[0004]
By the way, the multiplex communication apparatus configured as described above is provided with a function of setting a low power consumption operation mode to reduce the power consumption (for example, see Patent Document 1). In the low power consumption operation mode, the power consumption is suppressed by lowering the frequency of the operation clock in each of the ECUs 1 and 4 or stopping the generation of the clock itself, and is called a sleep mode. Incidentally, this low power consumption operation mode (sleep mode) is set when there is no need for information communication between the ECUs 1 and 4.
[0005]
[Patent Document 1]
JP-A-6-292274
[Problems to be solved by the invention]
However, in the above-described multiplex communication device, when the slave ECU 1 in the low power consumption operation mode detects a change in a signal input from the input device 2 such as a sensor and shifts to the normal operation mode, the slave ECU 1 shifts to the normal operation mode. It is unavoidable that it takes time until the reference clock oscillator in the slave ECU 1 starts oscillating and its frequency stabilizes. Then, after the oscillation frequency is stabilized, a start signal (wake-up signal) is transmitted to the branch line 5 to urge the other slave ECUs 1 to return to the normal operation mode.
[0007]
Therefore, when the other slave ECU 1 receives the start signal, it starts the start operation to shift to the normal operation mode. Therefore, it takes a lot of time before communication between the plurality of slave ECUs 1 becomes possible. Since there is a time required for the activation, for example, a response delay until a predetermined load device (a lamp, an actuator, or the like) is operated by a human operating a switch or the like becomes large, giving an uncomfortable feeling to the person who performed the operation. There was a problem.
[0008]
In addition, since the above-described start signal is a pulse signal, when noise is superimposed on the branch line 5, the slave ECU 1 in the low power consumption operation mode erroneously wakes up and shifts to the normal operation mode. Was.
SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide a multiplex communication apparatus capable of shortening the startup time of a multiplex communication apparatus that has shifted to a low power consumption operation mode without causing a malfunction. Is to provide.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a multiplex communication device according to the present invention includes a master ECU serving as a master station and a plurality of slave stations (slave ECUs) connected to the master ECU via a communication line. Wherein the slave ECU includes an input detection unit that detects an input signal of the slave ECU, a signal monitoring unit that monitors presence or absence of a communication signal on the communication line, and a signal monitoring unit that continues for a predetermined time or more. Sleep control means for setting the operation state of the slave ECU to a low power consumption operation mode when a communication signal is not detected and the input means does not continuously detect an input signal for a predetermined time or more; When a communication signal or an input signal is detected during operation in the operation mode, the operation state of the slave ECU is returned to the normal operation mode. Wake-up control means, and wake-up signal output means for outputting a wake-up signal to the communication line prior to the wake-up control means when an input signal is detected during operation in the low power consumption operation mode. It is characterized by:
[0010]
Therefore, when the state of an input device such as a sensor or a switch connected to the slave ECU changes during operation in the low power operation mode, a wake-up signal is sent to another slave ECU connected to the branch line, and the sleep mode is switched to the sleep mode. Since the state is released and the wake-up is performed, it is possible to reduce the time required for shifting to the normal operation mode.
[0011]
Further, the wake-up signal output means is configured to transmit an activation signal maintaining a predetermined voltage level to the communication line for a predetermined time. Alternatively, a command signal composed of a plurality of bit strings is sent to the master ECU via a communication line. With this configuration, it is possible to prevent the wake-up process from being performed erroneously due to noise or the like.
[0012]
Therefore, according to the present invention, the startup time of the multiplex communication apparatus that has shifted to the low power consumption operation mode can be reliably reduced without causing a malfunction.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a multiplex communication device according to the present invention will be described with reference to the drawings. The multiplex communication device is configured to control the vehicle by transmitting and receiving signals between a control device, an actuator, and a sensor in the vehicle.
FIG. 2 is a diagram showing a schematic configuration of the multiplex communication device. The multiplex communication device includes a branch line 5 that connects the master ECU 4 and the plurality of slave ECUs 1 to perform mutual communication. The master ECU 4 is connected to a trunk line 6 that can connect other master ECUs (not shown) to each other and perform communication between the master ECUs.
[0014]
On the other hand, the slave ECU 1 includes an input device 2 including a sensor for detecting a state of the vehicle or a switch for receiving a human operation, and various load devices (a lamp, an actuator, and the like) 3.
Further, the slave ECU 1 is provided with an input detection circuit 11 for detecting a state of the input device 2 (for example, on / off of a switch, a vehicle speed, a rotation speed, and the like). A slave station control unit 12 that determines the state of the input device 2 obtained by the input detection circuit 11 and controls the various load devices 3 connected to the slave ECU 1 is provided in the slave ECU 1.
[0015]
The slave ECU 1 is provided with a communication interface circuit 13 so that the master ECU 4 and other slave ECUs 1 can communicate with each other via the branch line 5. The communication interface circuit 13 is connected via a branch line 5 from the master ECU 4 to a reception signal decoding circuit 14 for decoding the contents of the control command output to the slave ECU 1. The control command decoded by the reception signal decoding circuit 14 is given to the slave station control unit 12.
[0016]
The slave station controller 12 having received the control command is provided with an output circuit 15 for driving a load device (a lamp, an actuator, etc.) 3 connected to the slave ECU 1 and responds to the control command of the master ECU 4 described above. It plays a role of driving and controlling the load device 3.
Further, the slave ECU 1 is provided with a signal transmission circuit 16 for transmitting a state of the input device 2 detected by the input detection circuit 11 or a response signal to a control command issued from the master ECU 4 to the slave ECU 1 to the master ECU 4. ing. The response signal transmitted from the signal transmission circuit 16 is transmitted to the master ECU 4 via the communication interface circuit 13 and the branch line 5 described above.
[0017]
By the way, the slave station control unit 12 configured to control the slave ECU 1 configured as described above sets the low power consumption operation mode (sleep mode) for reducing the power of the slave ECU 1 and switches to the normal operation mode (wake up). It is configured as having a sleep control function and a wake-up control function for controlling the return.
[0018]
In the sleep mode, the power consumption of the slave station control unit 12 is reduced by lowering the frequency of an operation clock of, for example, a CPU (Central Processing Unit: not shown) or stopping the generation of the clock itself. It is to suppress.
Further, the slave ECU 1 is provided with a signal monitoring circuit 17 for detecting whether communication data is continuously output on the branch line 5 for a certain period of time or longer, or whether a wake-up signal is output. . After receiving the sleep request output by the master ECU 4, the slave ECU 1 detects that communication data has not been continuously output on the branch line 5 for a certain period of time by the signal monitoring circuit 17. 12 sets the slave ECU 1 to the sleep mode.
[0019]
On the other hand, the master ECU 4 is provided with a master station control unit 21 that controls the entire master ECU 4. The master ECU 4 is provided with a branch line communication interface circuit 22 that enables mutual communication with a plurality of slave ECUs 1 connected to the branch line 5. The master ECU 4 is provided with a trunk communication interface circuit 23 for performing mutual communication with a plurality of other master ECUs 4 (not shown) via the trunk 6. Further, the master ECU 4 includes a wake-up signal detection circuit 24 that detects that the slave ECU 1 has shifted from the sleep mode to the normal operation mode.
[0020]
Now, in the multiplex communication apparatus configured as described above, a feature of the present invention is that when the state of the input device 2 connected to the slave ECU 1 changes during the operation in the sleep mode (when there is an input signal). The slave ECU 1 is provided with a communication line wake-up signal output circuit 18 for transmitting a wake-up signal (start signal) to the branch line 5 before returning to the normal operation mode (wake-up).
[0021]
For this reason, in parallel with the wake-up process of the slave ECU 1 in which the state of the input device 2 has changed, the other slave ECUs 1n and the master ECU 4 connected to the branch line 5 perform a start-up process in advance of the start of mutual communication. Since it can be performed, it is possible to reduce the time required for wake-up.
The wake-up signal (start signal) output to the branch line 5 by the above-described communication line wake-up signal output circuit 18 is a pulse-like signal. More preferably, a malfunction caused by noise entering the multiplex communication device is prevented. Therefore, it is desirable to use a wake-up signal for continuously transmitting a signal of a predetermined voltage level according to the specifications of the branch line 5 over a certain period of time.
[0022]
Specifically, for example, when the branch line 5 takes a binary level of [12 V] and [0 V], the voltage level of the wake-up signal when the branch line 5 has no data (no signal) is [0 V]. Then, the wake-up signal output from the communication line wake-up signal output circuit 18 may be transmitted as a voltage level of [12 V] for several ms or more. This means that while a normal data signal transmitted to the branch line 5 changes in voltage level (binary level) within several ms or less, a signal that is kept at a fixed level and continues for a fixed time or longer is used as a wake-up signal. Thus, a normal data signal and a wake-up signal are distinguished from each other.
[0023]
Of course, in the above-described binary communication line, if the voltage level when there is no data on the branch line 5 (no signal) is [12 V], the wake-up signal output from the communication line wake-up signal output circuit 18 is output. Is set to [0 V], and a signal of this level may be transmitted for several ms or more. In short, the wake-up signal may be a level at which a normal data signal and a wake-up signal can be distinguished according to the voltage level of the branch line 5.
[0024]
Alternatively, the wake-up signal output from the communication line wake-up signal output circuit 18 may be configured using a plurality of bit strings indicating a wake-up signal. In this case, since a signal composed of a plurality of bit strings is used as a wake-up signal, noise can be reliably distinguished from a wake-up signal. Therefore, a malfunction of the wake-up process due to noise or the like can be more reliably prevented, which is preferable.
[0025]
More specifically, FIG. 3 will be described in detail based on a flowchart showing a control procedure of the multiplex communication apparatus according to the present invention.
First, data transmission is performed between the master ECU 4 and the slave ECU 1 operating in the normal mode via the branch lines 5 (step S1). At this time, when there is no data to be communicated between the master ECU 4 and the slave ECU 1 (step S2), the master ECU 4 outputs a sleep request to all the slave ECUs 1 to reduce the power consumption (step S3).
[0026]
The slave ECU 1 receiving the sleep request monitors by the signal monitoring circuit 17 whether data is continuously transmitted to the branch line 5 for a predetermined time or more (step S4). At this time, when data is transmitted to the branch line 5, the slave ECU 1 returns to the normal mode (step S1), and shifts to the sleep mode when data is not continuously transmitted to the branch line 5 for a predetermined time or more. (Step S5).
[0027]
The slave ECU 1 that has shifted to the sleep mode changes the state of the input device 2 (for example, a switch, a sensor, or the like) connected to the slave ECU 1 (there is an input signal), or sends a sleep cancel command from the master ECU 4. Until the sleep mode is maintained (step S6). In the sleep mode, as described above, the power consumption of the slave ECU 1 is suppressed by lowering the frequency of the operation clock or by stopping the generation of the clock itself.
[0028]
During the operation in the sleep mode, if the state of the input device 2 changes (there is an input signal), the communication line wake-up signal output circuit 18 sends a wake-up signal to the branch line 5 (step S7). Then, the other slave ECU 1n connected to the branch line 5 receives the wake-up signal and releases the sleep mode (step S8). That is, the operation clock in the slave ECU 1n is set to the frequency of the normal operation mode.
[0029]
On the other hand, the slave ECU 1 to which the signal is input from the input device 2 detects the input signal of the input device 2 by the input detection circuit 11 at the same time as sending the wake-up signal described above, and changes the frequency of the operation clock in the slave ECU 1. After shifting to the normal operation frequency and waiting until the oscillation frequency stabilizes (step S9), the operation shifts to the operation in the normal operation mode (step S1).
[0030]
Thus, in the multiplex communication device configured as described above, when the slave ECU 1 operating in the sleep mode receives the signal input from the input device 2, the communication line wakes up prior to the start processing of the slave ECU 1. The signal output circuit 18 sends a wake-up signal directly to the branch line 5. Therefore, the other slave ECUs 1n in the sleep mode can be returned to the normal operation mode without waiting for the sleep mode release command from the master ECU 4. Therefore, it is possible to reduce the time required to return from the sleep mode to the normal operation mode.
[0031]
Therefore, for example, in a vehicle device using the multiplex transmission device according to the present invention, after a human operates the input device 2 such as a switch provided in the vehicle device, a desired load device (a lamp, an actuator, or the like) is operated. 3) Since the time until 3 is activated can be shortened, it is possible to reduce discomfort related to the operation.
Since the wake-up signal transmitted by the slave ECU 1 is maintained at a predetermined level and is a signal transmitted over a predetermined time or a command signal composed of a plurality of bit strings, it can be easily distinguished from noise. For this reason, the slave ECU 1 does not wake up accidentally due to noise or the like.
[0032]
The multiplex communication apparatus according to the present invention can be applied not only to a vehicle apparatus but also to a communication apparatus having a sleep mode so as to shorten the start-up time.
As described above, the present invention can be implemented in various modifications without departing from the gist of the present invention, without being limited to the above-described embodiment.
[0033]
【The invention's effect】
As described above, according to the multiplex communication apparatus of the present invention, when detecting a state change of an input device such as a sensor or a switch connected to the slave ECU during operation in the low power operation mode, the multiplex communication device is connected to the branch line. Since the wake-up signal is transmitted to the other slave ECUs to release the sleep mode and wake up, the time required for the multiplex communication device to shift to the normal operation mode can be reduced.
[0034]
Further, since the wake-up signal is a predetermined level signal or a command signal composed of a plurality of bit strings, it is possible to easily distinguish the wake-up signal from noise. Is played.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of a multiplex communication apparatus including a plurality of master stations and a plurality of slave stations connected to the master station.
FIG. 2 is a diagram showing a schematic configuration of a master station and a slave station of the multiplex communication apparatus according to the present invention.
FIG. 3 is a flowchart showing a control procedure of the multiplex communication apparatus according to the present invention.
[Explanation of symbols]
1 Slave ECU (slave station)
4 Master ECU (master station)
5 branch line 6 trunk line 12 slave station controller 13 communication interface circuit

Claims (3)

A multiplex communication apparatus including a master station and a plurality of slave stations connected to the master station via a communication line,
The slave station, input detection means for detecting an input signal of the slave station,
Signal monitoring means for monitoring the presence or absence of a communication signal on the communication line,
When the communication signal is not detected for a predetermined time or more in the signal monitoring means, and the input signal is not detected for a predetermined time or more in the input detection means, the operation state of the slave station is set to a low power consumption operation mode. Sleep control means to be set;
Wake-up control means for returning the operation state of the slave station to the normal operation mode when a communication signal or an input signal is detected during operation in the low power consumption operation mode,
Wake-up signal output means for outputting a wake-up signal to the communication line prior to the wake-up control means when an input signal is detected during operation in the low power consumption operation mode. Multiplex communication device. 2. The multiplex communication apparatus according to claim 1, wherein said wake-up signal output means transmits a start signal for maintaining a predetermined voltage level to said communication line for a predetermined time. 2. The multiplex communication apparatus according to claim 1, wherein said wake-up signal output means sends a command signal composed of a plurality of bit strings to said communication line.

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