JP4029826B2 - LIN communication device - Google Patents

Description

  The present invention relates to a LIN communication apparatus that performs communication based on a LIN (Local Interconnect Network) communication protocol, which is used, for example, for communication control of in-vehicle devices.

  Conventionally, various types of signals have been transmitted and received between in-vehicle devices using various serial communication protocols in a vehicle. As this type of communication circuit, there is one in which the number of parts is reduced and the communication circuit is simplified (see Patent Document 1 and Patent Document 2).

Further, in the vehicle, for example, an engine control device that controls the engine, detects the state of the engine and notifies other devices, a brake control device that controls the brake based on the received signal, controls an air suspension, An air suspension control device that detects the state of the air suspension and notifies other devices, a body control device that detects the user's boarding operation such as unlocking operation and door opening by a remote switch, and notifies other devices, etc. Communication is performed via an in-vehicle LAN (Local Area Network). As a serial communication protocol for the in-vehicle LAN, for example, CAN (Controller Area Network), LIN, and the like are used, and LIN is attracting attention as an inexpensive communication protocol.
JP 2002-33740 A JP 2002-325085 A

  FIG. 7 shows a circuit configuration studied by the present inventors for the LIN communication apparatus using the LIN communication protocol described above. The LIN communication protocol is a master / slave type (main / slave device) serial communication system. In this example, a LIN driver circuit 110 and a microcomputer (hereinafter referred to as a microcomputer) 120 as a control circuit are used as a master 100. The slaves 200, 300, etc., which are arranged at various parts in the vehicle, are connected via the LIN bus 400 connected to the LIN port (terminal) of the driver circuit 110. These slaves 200, 300, and the like are also configured by a LIN driver circuit and a microcomputer similarly to the master 100, and bidirectional serial communication is performed between the master 100 and the slaves 200, 300, and the like.

  As shown in FIG. 7, the master 100 is connected to the in-vehicle battery 1 and the ignition switch 2 and is opened by a lock detection circuit 3 that detects lock presence / absence information from a remote switch (not shown) owned by the vehicle user. A transistor 4 that is turned on when receiving a lock signal and applies an L level signal to the master 100 is connected.

  In addition, the microcomputer 120 in the master 100 has a wakeup mode in which a wakeup is performed when an H level signal is applied to the WAKE2 port, and a sleep mode in which operation is suspended when an L level signal is applied. is doing.

  Switching between both modes of the microcomputer 120 is performed using a mode switching circuit composed of external circuit elements provided independently of the LIN driver circuit 110. In this case, the mode switching circuit is composed of a logical sum circuit composed of diodes 31 and 32 and a PNP transistor 33. When an unlock signal of the remote switch or an L level signal from the LIN bus 400 is input, the transistor 33 is turned on and H A level signal is supplied to the WAKE 2 port, and the microcomputer 120 is switched to the wake-up mode. The diode 34 generates a sufficient voltage between the emitter and collector of the transistor 33 to ensure that the transistor 33 operates reliably.

  As described above, in the LIN communication apparatus shown in FIG. 7, an operation mode switching circuit composed of external circuit elements is required to switch the operation mode of the microcomputer 120, resulting in an increase in cost of the LIN communication apparatus.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a LIN communication device that can reduce external circuit elements for switching operation modes.

  In order to achieve the above object, the present invention employs the following technical means.

According to the first aspect of the present invention, the microcomputer includes the LIN driver circuit that performs serial communication with the outside via the LIN bus using the LIN communication protocol, and the microcomputer that controls the communication operation through the LIN driver circuit. A LIN communication device having a wake-up mode for wake-up in response to a signal applied to the second WAKE port and a sleep mode for suspending operation;
A signal detection circuit is provided for externally supplying a trigger signal to the first WAKE port of the LIN driver circuit. The LIN driver circuit wakes up from a predetermined port in accordance with a trigger signal input from the signal detection circuit to the first WAKE port. Configured to provide an activation signal to the second WAKE port of the microcomputer to indicate up;
The trigger signal from the signal detection circuit is a signal that falls from the H level to the L level, and the LIN driver circuit outputs a signal that rises from the L level to the H level according to the trigger signal.
The microcomputer is characterized in that it receives, as an operation signal, a signal that rises from an L level to an H level output from a LIN driver circuit.

  Thus, by effectively utilizing the port configuration unique to the LIN driver circuit, an operation signal of a predetermined level (wake-up signal) according to the trigger signal from the outside, that is, an operation signal for switching the microcomputer to the wake-up mode, This can be generated from the LIN driver circuit, and the number of external circuit elements that are specially provided for this purpose can be reduced.

  According to the second aspect of the present invention, it is possible to configure an in-vehicle communication network in which both the LIN driver circuit and the microcomputer are mounted, and communication between the master and the slave is performed using the LIN communication protocol.

  According to the third aspect of the present invention, the signal detection circuit detects the timing information when the vehicle user gets on the vehicle and generates the trigger signal, so that the LIN communication device is waked in accordance with the timing at the time of boarding. As the timing information, the trigger signal is detected by detecting the unlocking signal of the remote switch operated by the vehicle user or the opening signal indicating the opening of the vehicle door as the timing information. By generating, it becomes possible to match the boarding timing more reliably.

  According to the fifth aspect of the present invention, a slave connected via the LIN bus is provided, and the microcomputer makes an inquiry to the slave before entering the sleep mode, and enters the sleep mode when the slave sleep condition is satisfied. By shifting, it becomes possible to shift to the sleep mode when the entire vehicle including the master and the slave satisfies the sleep condition, and balanced and stable operation mode switching can be performed.

  According to the invention described in claim 6, when the microcomputer determines that the sleep condition for shifting to the sleep mode is established, the microcomputer gives the sleep permission information to the microcomputer, and the sleep confirmation information is obtained from the LIN driver circuit. By having the operation mode determination means for shifting to, the microcomputer and the LIN driver circuit can switch to the sleep mode in time.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram illustrating an overall configuration of a LIN communication apparatus that is applied to transmission / reception (communication) between various devices mounted on a vehicle and uses a LIN protocol. This LIN communication device is a single master system of master / slave (main / slave device), and data cannot be transmitted from the slave unless instructed by the master, but there is no restriction on the receiving operation, and other slaves transmit. You can receive even when you are. That is, the master response (talk turn) and the slave response (talk turn) exchange information on a regular alternating schedule.

  In the present embodiment, 100 is set as a master, and the master 100 is usually composed of a LIN driver circuit 110 that is constituted by one dedicated IC and a microcomputer 120 that is a control circuit. Similarly to the master 100, the slaves 200 and 300 are also configured by a LIN driver circuit and a microcomputer, and bidirectional serial communication is performed between the master 100 and the slaves 200 and 300. For example, the master 100 corresponds to a vehicle instrument control unit, and the slaves 200 and 300 correspond to door rotation (side mirror, power window control, etc.), roof rotation (sunroof, light control, etc.) and steering rotation (wiper, direction indication control, etc.). .

  The in-vehicle battery 1 and the ignition switch 2 are connected to the master 100. Further, the transistor 4 is connected and turned on when receiving an unlocking signal indicating the timing when the vehicle user gets on the vehicle from the locking detection circuit 3 for detecting the presence or absence of locking from a remote switch (not shown), and changes to the H level. Thus, an L level signal is applied to the master 100.

  Next, a circuit configuration in the master 100 will be described.

  The diodes 11, 12, 13, and 27 are for protection against a negative surge voltage, and the diode 14 and the resistors 15 and 16 constitute a supply path for the battery voltage VB. The signal path including the resistor 17 from the transistor 4 detects a timing at which the vehicle user gets on the vehicle in response to the unlocking signal from the locking detection circuit 3 and generates a detection signal (trigger signal) that falls from the H level to the L level. A signal detection circuit 140 is provided to the WAKE1 port of the LIN driver circuit 110.

  The signal path including the resistors 18 and 19 constitutes a signal transmission path from the INH port of the LIN driver circuit 110 to the WAKE2 port of the microcomputer 120. In this case, when a trigger signal is received at the WAKE1 port, the INH port changes from L level to H level, and this H level signal is applied to the WAKE2 port of the microcomputer 120. The resistors 17, 18, 19, 20, 22, 23, 24, 25, and 26 are for input protection.

  The NPN transistor 21 is for fixing the signal level of the transmission signal from the TX2 port to the L level when the H level signal is output to the BRAK port of the microcomputer 120. Usually used when the baud rate of the transmission signal from the TX2 port is temporarily changed. The constant voltage circuit 130 applies a predetermined voltage VD to the VD port of the microcomputer 120. Both the LIN driver circuit 110 and the microcomputer 120 are configured to be supplied with power even when the ignition switch 2 is OFF.

  The LIN driver circuit 110 is a transceiver (transceiver) for LIN communication using the LIN protocol, and the configuration thereof will be described with reference to FIGS. The TX1 port is a port that receives a transmission signal transmitted from the microcomputer 120 to the slaves 200 and 300, drives the output driver unit 110a according to the received transmission signal, and outputs a transmission signal from the LIN port. Specifically, the output stage transistor 110a1 shown in FIG. 4A is turned on / off, and an H level / L level signal is put on the LIN bus 400.

  The WAKE1 port is a port that activates the wakeup unit 110c and generates an H level signal from the INH port when a falling or rising signal is received from the signal detection circuit 140. The EN port is a port that activates the wakeup unit 110c when receiving a signal of a predetermined level from the microcomputer 120 and generates a signal of the same level as the input signal level from the INH port. The RX1 port is a port that drives the receiver unit 110b in accordance with the received signal from the slaves 200 and 300 received at the LIN port, and transmits the received signal that has been subjected to signal processing with reference to the reference voltage Vref of the Vref unit 110d to the microcomputer 120. It is. The GND1 port is a port for supplying a ground (ground) potential, and the VSUP port is a port for supplying a battery voltage VB to the Vref unit 110d. The LIN port and INH port are as described above.

  Next, the LIN communication function by the LIN driver circuit 110 and the microcomputer 120 will be described.

  As shown in FIG. 1, the microcomputer 120 has two UART (Universal Asynchronous Receiver Transmitter) ports, TX2 port and RX2 port for serial communication, and communication between the microcomputer 120 and the LIN driver circuit 110 This is done using the UART port. At that time, the LIN driver circuit 110 outputs a transmission signal generated from the TX2 port of the microcomputer 120 and received at the TX1 port from the LIN port, while receiving from the LIN bus 400 and received at the LIN port of the LIN driver circuit 110. The signal is output from the RX1 port to the RX2 port of the microcomputer 120.

  The microcomputer 120 is configured such that when the transmission of the transmission signal (transmission data) from the TX2 port is stopped, the voltage level of the TX2 port becomes the H level. Until the start of transmission, a continuous H level signal is output to the TX1 port of the LIN driver circuit 110.

  FIG. 3 shows the structure of a message frame of the LIN communication protocol in the TX1 port, the RX1 port, and the LIN port of the LIN driver circuit 110. As shown in FIG. 3, the message frame (MESSAGE FRAME) includes a header (HEADER) including a sync break part (SYNC Brake), a sync part (SYNCH FIELD), an identification part (IDENTIEFIRE FIELD), and a plurality of data parts (DATA). Field) and a response (RESPONSE) including a checksum field (CHECKSUM FIELD). A response space (RESPONSE SPACE) is provided between the header and the response.

  The sync break part is an area for indicating a message frame transmitted from the microcomputer 120 of the master 100, and the number of bits is a minimum of 13 bits. There is no definition of the maximum number of bits of the sync break part, and the maximum number of bits of the sync break part is limited by the specification of the time of the entire message frame.

  In the LIN communication, the LIN bus 400 connected to the LIN port of the LIN driver circuit 110 uses the in-vehicle battery 1 (voltage VB) as it is as shown in FIG. (Input / output stage of the LIN driver circuit 110) 110a1 and a single wire using only the pull-up resistor 15 are used. Further, as shown in FIGS. 4B, 4C, and 4D, the signal level of the LIN bus 400 is determined by setting the determination level of the communication signal at the time of transmission and reception. A value 0 (L level) is represented by dominant, and a digital value 1 (H level) of the digital signal is represented by recessive.

  Each of the identification section, each data section, and the checksum section is 8 bits, and an L level start bit and an H level stop bit are added to each.

  Further, there are arbitrary bit intervals between the sync break portion and the sync portion, between the sync portion and the identification portion, between each data portion, and between the data portion and the checksum portion, and this portion is set to the H level. The H level is also set in the response space between the header and the response.

  Next, switching operation of the operation mode (wake-up mode, sleep mode) of the microcomputer 120 which is a communication control circuit will be described together with the operation of the LIN driver circuit 110.

  First, the wake-up process of the microcomputer 120 will be described using the flowchart shown in FIG. When the occupant is not in the vehicle, such as when parked, the ignition switch 2 is normally turned off, but power is always supplied to the LIN driver circuit 110 and the master 100 via the path of the diode 13, and the slaves 200, 300 are also supplied. Is also powered in the same way. Therefore, the master 100 and the microcomputer 120 in each of the slaves 200 and 300 are also in the normal sleep mode. At this time, the LIN port 400 and the LIN port of the LIN driver circuit 110 are maintained in the H level signal state.

  In the OFF state of the ignition switch 2, when the vehicle user unlocks the remote switch for getting on, the lock detection circuit 3 generates an unlock signal and turns on the transistor 4. As a result, a trigger signal that falls from the H level to the L level is input to the WAKE 1 port of the LIN driver circuit 110 on the collector side of the transistor 4. In response to this, an H level signal is output from the INH port (usually for a short period), and this H level signal is applied to the WAKE2 port of the microcomputer 120, thereby forcibly switching the microcomputer 120 to the wake-up mode, for example, for interrupt processing. Start the process.

  The flowchart shown in FIG. 5 shows a wake-up process when the microcomputer 120 is activated. When the microcomputer 120 is activated by the input of the H level signal to the WAKE2 port, it first communicates with the LIN driver circuit 110 to confirm whether it can be woken up as a LIN communication device. Therefore, in step 131, an H level signal is supplied from the OUT port of the microcomputer 120 to the EN port of the LIN driver circuit 110. In step 132, whether or not an H level signal is output from the INH port to the WAKE2 port of the microcomputer 120 accordingly. Determine. When it is determined in step 132 that the H level signal is output, it is determined that the wake-up process has been performed satisfactorily, and in step 133, LIN communication is started. On the other hand, when it is determined in step 132 that the H level signal is not output, the wakeup process shown in FIG. 5 is repeated again.

  Next, sleep processing by the microcomputer 120 and the LIN driver circuit 110 will be described using the flowchart shown in FIG. The microcomputer 120 determines the ON / OFF state of the ignition switch 2 based on the voltage level of the signal input to the IN2 port. In the sleep process shown in FIG. 6, the ignition switch 2 is in the OFF state and This is executed when there is no communication with the remote switch that is not connected and the H level signal is fixed to the IN port of the microcomputer 120. At that time, when the microcomputer 120 determines, for example, the OFF state of the ignition switch 2 or the like, sleep permission information for permitting sleep is placed at a specific position of a message frame that is LIN communication information.

  Therefore, in step 141, it is determined whether there is sleep permission information in the message frame. When there is sleep permission information, in step 142, the slaves 200 and 300 are inquired about whether or not to sleep, and when sleep is allowed, the sleep frame (sleep confirmation information) is placed at the corresponding position in the message frame. To instruct. This message frame is output as a transmission signal from the TX2 port to the TX1 port of the LIN driver circuit 110, and is transmitted from the LIN port to each of the slaves 200 and 300 via the LIN bus 400.

  Communication information from each of the slaves 200 and 300 is received by the LIN port of the LIN driver circuit 110 and is output from the RX1 port to the RX port 2 of the microcomputer 120. Therefore, in step 143, if all the sleep confirmation information of the master 100 and each slave 200, 300 is prepared from the communication information, it is determined that the sleep condition is satisfied. At this time, the determination is made without considering the signal level of the WAKE2 port, and the determination is made in a later step.

  When the sleep condition is satisfied in step 143, an L level signal is given to the EN port of the LIN driver circuit 110 from the OUT port to perform confirmation processing for entering the sleep as the LIN communication device, and in step 145, the INH port Thus, it is determined whether or not the L level signal is output to the WAKE2 port of the microcomputer 120. If it is determined in step 145 that the L level signal is output, the process shifts to the sleep mode in step 146. On the other hand, when the sleep condition is not satisfied in steps 141 and 143, or when it is determined in step 145 that the L level signal is not output, the sleep processing shown in FIG. 5 is repeated again.

  Here, steps 143 to 146 correspond to the operation mode determination means described in claim 6.

  In the above embodiment, even when the vehicle is not in use, when power is always supplied from the in-vehicle battery 1 and the entire LIN communication device is in the sleep mode, the lock detection circuit 3 and the signal detection circuit 140 are used to wake it up. It was done by the unlock signal of the remote switch. In addition, an opening signal indicating the opening operation of the vehicle door on the driver's seat or passenger's side, a signal indicating the opening operation of the trunk, or an unlocking instruction from a mobile phone when the vehicle is equipped with a telephone communication device The microcomputer 120 of the master 100 may be woken up by detecting a signal or the like. In any case, since the LIN communication device needs to be operated during the sleep mode, it is configured using hardware (external circuit) without depending on the LIN communication function.

  Further, as conditions for the LIN communication device to shift from the wake-up mode to the sleep mode, in the above embodiment, the OFF state of the ignition switch 2, the state of no communication signal with the remote switch, and the sleep allowable state of the LIN driver circuit 110 are confirmed. Was. In addition to this, a combination of a plurality of states, such as the closed state of the vehicle door, the continuation state without LIN communication, and the continuation state of the ignition switch OFF, is used to judge the vehicle usage status more accurately. May be shifted to the sleep mode.

  The LIN driver circuit 110 has a function and a configuration that are normally standardized in accordance with the LIN communication protocol. In addition to the trigger signal that falls from the H level to the L level, the LIN driver circuit 110 starts from the L level. Even if a trigger signal rising to H level is given, it is possible to take out the H level signal from the INH port. Therefore, the configuration of the lock detection circuit 3 and the signal detection circuit 140 may be changed so that a rising trigger signal is applied to the WAKE1 port of the LIN driver circuit 110.

1 is an overall configuration diagram showing an embodiment of a LIN communication apparatus according to the present invention. 2 is a block diagram showing a configuration of a LIN driver circuit 110. FIG. It is a figure which shows the structure of the message frame of a LIN communication protocol. FIG. 3 is a diagram for explaining communication signals transmitted / received by a LIN bus 400. It is a flowchart which shows the wake-up process for putting the microcomputer 120 into wake-up mode. It is a flowchart which shows the sleep process for making the microcomputer 120 into sleep mode. It is a whole lineblock diagram showing the LIN communication device which the present inventors examined.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle-mounted battery 2 Ignition switch 3 Locking detection circuit 100 Master 200, 300 Slave 110 LIN driver circuit 110a Output driver part 110b Receiver part 110c Wakeup part 120 Microcomputer (control circuit)
140 Signal Detection Circuit 400 LIN Bus

Claims (6)

A LIN driver circuit that performs serial communication with the outside via the LIN bus using a LIN communication protocol, and a microcomputer that controls a communication operation through the LIN driver circuit, are provided to the second WAKE port. A LIN communication device having a wake-up mode for wake-up in response to a sleep mode and a sleep mode for suspending operation,
A signal detection circuit for applying a trigger signal from the outside to the first WAKE port of the LIN driver circuit is provided, and the LIN driver circuit is responsive to the trigger signal input from the signal detection circuit to the first WAKE port. And an operation signal for instructing wake-up from a predetermined port is provided to the second WAKE port of the microcomputer ,
The trigger signal from the signal detection circuit is a signal that falls from an H level to an L level, and the LIN driver circuit outputs a signal that rises from an L level to an H level in response to the trigger signal,
The LIN communication apparatus , wherein the microcomputer receives a signal rising from an L level output from the LIN driver circuit to an H level as the operation signal .   2. The LIN according to claim 1, wherein the LIN driver circuit and the microcomputer are mounted on a vehicle, and an in-vehicle communication network that performs communication between a master and a slave using a LIN communication protocol is configured. Communication device.   The LIN communication apparatus according to claim 2, wherein the signal detection circuit is configured to detect timing information when a vehicle user gets on and generate a trigger signal.   4. The LIN according to claim 3, wherein the signal detection circuit generates the trigger signal by detecting an unlocking signal of a remote switch operated by a vehicle user or an opening signal indicating opening of a vehicle door. Communication device.   The slave connected via the LIN bus is provided, and the microcomputer interrogates the slave before entering the sleep mode, and enters the sleep mode when the slave sleep condition is satisfied. The LIN communication apparatus according to claim 2, wherein the LIN communication apparatus is characterized.   The microcomputer determines whether a sleep condition for shifting to the sleep mode is satisfied, gives sleep permission information to the LIN driver circuit, and shifts to the sleep mode when sleep confirmation information is obtained from the LIN driver circuit. The LIN communication apparatus according to claim 1, further comprising a determination unit.

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