JPH11298504A - Communication control equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate the processing of emergency data by storing the data of a message corresponding to the class of the message to be received and transferring the stored data to a data processor corresponding to the class of the message. SOLUTION: The data message received by communication control equipment 20 is sampled by a sampling part 21 and assembled into bytes by a character buffer 22. Two bits of a CTL field are decoded by a CTL decoder 25 and in response to a signal from the CTL decoder 25, a selection part 28 is operated so that when these two bits show '11' (emergency), data bytes from the character buffer 22 are transferred to a first buffer 23 but when these two bits show '01' (non-emergency), the data bytes are transferred to a second buffer 24. A control part 26 receives a signal showing the emergency processing of the data message from the CTL decoder 25 and when the entire data are normally received and stored in the first buffer 23, an interruption request signal INT is preferentially sent to a CPU 11 at once.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control device which is provided between a computer and a data transmission line and controls data reception and transfer to a computer.

[0002]

2. Description of the Related Art Functions generally required between a computer and a data transmission line include 1) an electrical and physical interface with the line, 2) line connection control, 3) reception signal selection, Functions include 4) character assembly and disassembly, 5) data buffering, 6) error control, 7) matching of data transmission speed and computer processing speed, 8) transmission control, and 9) message assembly and disassembly. is there. The communication control device is provided between the computer and the data transmission line in order to share some or all of these functions and to enable the computer to perform only essential advanced data processing.

Depending on how the above-listed functions are shared with the computer, the communication control device determines the bit buffer system, the character buffer system, the block buffer system,
It is divided into message buffer systems.

In the bit buffer method, the communication control device is responsible for the function of assembling the received bits, and the processing after the character assembly is performed by the computer. In this method, bits are assembled into characters, and the completed characters are transferred to a main memory of a computer. The block buffer method is a method in which a communication control device buffers transmission blocks and transfers clean data to a memory of a computer. It is a method to perform. These methods can be further divided into more methods according to the detailed functions to be shared. As described above, the boundary between the communication control device and the computer changes depending on the system design.

In Japanese Patent Application Laid-Open No. 54-78039, buffer memories 7 and 7 '(FIG. 2) are provided between the communication control device 1 and the processing device 6 for each line, and the processing device 6 It describes processing, reading information from a buffer memory for each line, and performing batch processing.

[0006] JP-A-5-292102 and JP-A-5-316124 disclose an electronic control unit (ECU) in a vehicle-mounted data transmission system.
It is described that a communication control IC included in a communication unit controls transmission of a message to a network bus and reception of a message from the network bus.

[0007]

Normally, transmitted data includes urgent data and urgent data. For example, in an in-vehicle computer network described in JP-A-5-292102 and JP-A-5-316124, an engine ECU is used.
Since the data indicating the cooling water temperature transmitted from the transmission ECU to the transmission ECU does not relate to the parameter that changes instantaneously, there is no need to perform urgent processing. For example, a processing delay of about 1 second does not matter. On the other hand, for example, when the transmission ECU executes a shift, it is necessary to retard the ignition timing of the engine and temporarily reduce the output torque of the engine in order to smoothly engage the clutch. This process needs to be performed in about 1 millisecond, and therefore, the data required by the transmission ECU to lower the torque of the engine ECU must be urgently processed by the engine ECU.

[0008] The conventional communication control device does not perform such processing according to the urgency and type of data. If the frequency of transferring data from the communication control device to the data processing device is increased in accordance with highly urgent data, the load on the data processing device increases, and the performance of the entire data processing decreases.

Accordingly, it is an object of the present invention to provide a system for quickly processing urgent data without substantially increasing the load on a data processing device.

[0010]

In order to solve the above-mentioned problems, a communication control apparatus according to the first aspect of the present invention comprises a plurality of storage means for storing data of a message to be received, and a plurality of storage means for storing data of a message to be received. Selecting means for selecting any one of the plurality of storage means to store the data of the message, and controlling the transfer of the data stored in the storage means to the data processing device in accordance with the type. Take. Here, the plurality of storage units may be physically a single storage device, that is, a plurality of different storage areas may be allocated.

According to the first aspect of the present invention, data received by the communication control device is stored in different storage means according to its type, and transfer to the data processing device is controlled according to the type of data. Urgent data is urgently transferred to the data processing device, and non-urgent data is handled according to its type. Therefore, an efficient system can be provided without substantially increasing the load on the data processing device. Operation can be performed.

According to a second aspect of the present invention, in the communication control device of the first aspect, the message has a data field for storing data and a type field for storing a code representing the type, and the type field is provided in front of the data field. It is configured to be arranged.

According to the second aspect of the present invention, since the communication control device receives the code indicating the type of data before receiving the entire data, the communication control device can promptly prepare for an interrupt request to the data processing device. The system can be operated efficiently.

According to a third aspect of the present invention, there is provided a communication control apparatus comprising at least a first buffer for storing data of an urgent type message and a second buffer for storing data of a non-urgent type message. When data is stored in the first buffer, an interrupt request is preferentially issued to the data processing device, and at the time of data transfer, data in the second buffer is also transferred.

According to the third aspect of the present invention, when the urgent received message is stored in the first buffer, an interrupt request is issued to the data processing device with priority, and the data in the first buffer is transferred. Since the data in the second buffer is also transferred, the system can be operated in accordance with the urgency of the data without substantially increasing the frequency of interruption to the data processing device.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings, taking a vehicle-mounted computer network system as an example. The present invention is not limited to application to an in-vehicle computer network, but can be widely applied to a communication control device.

FIG. 1 shows an in-vehicle computer network.
FIG. 3 is a block diagram showing the overall configuration of the system, and includes a plurality of electronic control units (ECUs);
Hereinafter, it is called ECU. ) Are connected by a network bus 8. These plural electronic control units send messages to the network bus 8 in a message format described later, and exchange data with each other.

The engine ECU 1 is an ECU that controls the driving of the engine such as the fuel injection amount and the ignition timing of the engine in accordance with the driving condition of the vehicle. The engine ECU 1 stores a data processing device (CPU) 11 for executing calculations and a computer program. Non-volatile read-only memory (ROM) 12, EC
A random access memory (RAM) 13 which provides a work area for operation by the CPU when the U operates, temporarily stores various data and programs, and a communication control device 20 which receives a message from the network bus 8 and sends the message to the network bus 8 It has. CPU1
1, ROM 12, RAM 13, and communication control device 20
Are connected by a data bus 16.

The engine ECU 1 includes an intake pipe pressure sensor,
An output signal is received from various sensors 14 related to the engine, such as an air-fuel ratio sensor and an engine water temperature sensor. The engine ECU 1 executes a calculation using these parameters and sends a control signal to an actuator 15 such as a fuel injection valve or an igniter. The engine ECU 1 communicates with another E via the network bus 8.
Receiving data from the CU and performing calculations using it,
Further, parameters and other data generated by the engine ECU 1 are sent to other ECUs via the network bus 8.

An engine ECU is connected to the network bus 8.
1 Other than EAT: Electronic-Control Automatic Transmission (EAT)
ECU2, Traction control system (TCS: T
raction Control System) ECU3, 4 wheel drive (4WD: 4
Wheel Drive) ECU 4, 4 Wheel Steering (4WS: 4 Wheel Ste)
ering) ECU5, anti-lock brake system (AB
S: Anti-lock Braking System) ECU 6 and suspension control ECU 7 are connected.

The basic configuration of these ECUs is the same as that of the engine ECU 1, and includes a CPU, a ROM,
It comprises a RAM and a communication controller, receives signals from relevant sensors and sends control signals to relevant actuators. Like the engine ECU 1, these ECUs are connected to the network bus 8 from the engine ECU 1 and other ECUs.
And transmits the data to another ECU.

According to the general method, the ECU
The data transmitted between the ECUs is received by the communication control device of each ECU, temporarily stored in a buffer according to the above-described various buffer systems, issues an interrupt request to the CPU, and waits for processing by the CPU. FIG. 2 is a flowchart showing a general flow of such an interrupt process.
Taking U1 as an example, when interrupt processing is started,
The CPU 11 saves the information of the register including the operand of the operation being executed, the memory address being accessed, and the like in the memory (stack) (101), masks the interrupt so as not to accept other interrupts (102), The received data is read from the buffer of the communication control device 20 and R
The data is saved in the AM 13 (103), the mask of the interrupt is released (104), the data saved in step 101 is fetched from the memory (stack), returned to the original position, and the operation interrupted by the interrupt is restarted ( 105).

The data read from the communication control device 20 into the RAM 13 is used immediately in subsequent calculations. For example, when the data temporarily stored in the buffer of the communication control device 20 is data representing the temperature (oil temperature) of the transmission oil transmitted from the transmission ECU 2, the oil temperature data stores the oil temperature data in the RAM 13. The oil temperature data in the memory location is written in the RAM 13 in a rewritten form, and is used for subsequent calculations.

FIG. 3 is a block diagram of the communication control device 20 according to one embodiment of the present invention. The communication control device 20 samples a message received from the network bus 8 on a bit-by-bit basis, a character buffer 22 for assembling the sampled bits into one byte (for convenience, called a character), and a sampled bit, which will be described later. A CTL decoder 25 for detecting and decoding bits of the CTL field; a selector 28 for switching a transfer destination of data bytes from the character buffer 22 according to a value of the CTL field detected by the CTL decoder 25; Buffer 23 and second buffer 24 for receiving and temporarily storing
It has.

The CTL decoder 25 may be configured to receive the value of the CTL field not from the sampling circuit 21 but from the character buffer 22. The CTL field is a field for storing a code indicating the type of a message to be transmitted, as will be described in detail later. For example, the CTL field indicates a data type such as urgent data or urgent data.

The control unit 26 monitors the status of the data stored in the first buffer and the second buffer, and when a predetermined condition is reached, an interrupt request I is sent to the CPU 11.
Send NT. This operation will be described later in detail.

The data bytes from the character buffer are transferred to the error detector 27, where errors in the received message are detected. The error detection unit 27 also has a function of performing error detection and correction on the received message using a CRC (Cyclic Redundancy Check) code. In this embodiment, upon detecting an error, the error detecting section 27 sends an error message composed of continuous dominant bits to the network bus 8. In some embodiments, when an error is detected, a negative acknowledgment (NACK) may be sent to the sending node after the completion of message reception.

The communication control unit 20 includes a transmission buffer 30 for receiving and temporarily storing a message to be transmitted from the CPU 11, a character buffer 31 for receiving data in byte units from the transmission buffer 30, a character decomposing unit 32 for decomposing bytes into bits, and There is provided a bit transmitting unit 33 for transmitting the decomposed bits to the network bus 8.

FIG. 4A shows a format of a data message transmitted / received between a plurality of ECUs via the network bus 8. Since this embodiment relates to an in-vehicle computer network, the ECU is connected to the network. However, in general, a computer system or a communication control device of a terminal device is connected to the network to form a network system. A communication control device connected to such a network is called a node from the viewpoint of a communication network. Therefore, the term "node" may be used in the following description of communication, and this term corresponds to the communication control device of the ECU in this embodiment.

The SOM (Start Of Message) field is a field for storing one bit of a dominant indicating the start of a message. This SOM bit establishes synchronization of all nodes connected to the network system.

The TA (Next Token Address) field is a field for storing the address (4 bits) of the node that is the destination of the token. In this embodiment, the network system uses a token passing method, in which a node having a token has a right to transmit to the network, and transfers the token to each of a plurality of nodes in order. The present invention is not limited to the token passing method, and it goes without saying that the present invention can be applied to other communication methods.

The CTL (Control) field is a field for storing two bits indicating the type of the message. The type of the message represented by the two bits is as shown in FIG.
As shown in FIG. That is, 10 indicates that this message is for transferring the token to the next node. In this case, in the format shown in FIG. 4A, the DATA Unit field, the FCS field, and the DACK Field is not included in the message.

[0033] The CTL field 01 indicates that this message transmits data that does not require urgency. On the other hand, 11 indicates that this message is a message for transmitting urgent data.

DATA_UNIT is a field for storing data which is the content to be transmitted, and can store data of 32 bits (4 bytes) to 96 bits (12 bytes).

An FCS (Frame Check Sequence) field has a CRC (Cyclic Redundanc) for a data string from the SOM field to the DATA_UNIT field.
y Check) is a 15-bit field for storing the result of performing (Check).

The DACK (Data Acknowledge) field is a field for a node that has normally received data to acknowledge the data, and is composed of a first two bits of an acknowledge bit and a second two bits of a recessive (recessive) bit. . The transmitting node sends out four recessive bits in this field. DATA_UN
When the node specified in the destination node field included in the IT field receives data normally, this node sets the first two bits of this field to dominant (dominant).
Acknowledgment is made by overwriting the bit. The transmitting node monitors a message on the network, and if it detects a dominant bit in any of the first two bits of this field, it determines that there is an acknowledgment.

The TACK (Token Acknowledge) field is a field for the node specified by the TA field to acknowledge the receipt of the token. Like the DACK field, the first two bits of the acknowledge bit field and the second two bits are used. , And D
Used in a manner similar to ACK.

The EOM (End of Message) field is
In the field indicating the end of the message, the sending node is 6
Send out consecutive recessive bits of bits.

In the above description, the dominant bit represents a logical "1" by a dominant bit. The dominant bit is
The recessive bits can be overwritten, and if the dominant and recessive bits are placed on the bus at the same time, the bus becomes dominant bit logic. The recessive bit is the inferior bit and represents logic "0".

Here, returning to FIG. 3, the communication control device 20
Is received by the sampling unit 2
1 is sampled bit by bit, and the character buffer 22
Is assembled into bytes (8 bits). Two bits of the CTL field of the data message are decoded by the CTL decoder 25, and if these two bits are 11 (meaning data requiring urgency), the selector 28 responds to the signal from the CTL decoder 25 to It operates to transfer data bytes from the character buffer to the first buffer 23.

When two bits of the CTL field are 01
(Meaning data that does not require urgency), CTL
In response to the signal from the decoder 25, the selection unit 28 determines the transfer destination of the data from the character buffer 22 to the second buffer 24.
Set to. In FIG. 3, the selecting unit 28 is expressed as if it were a mechanical switch. Good.

The control unit 26 sends a signal indicating that the data message being received requires urgent processing to a CT signal.
When the data is received from the L decoder 25, the input state of the data to the first buffer 23 is monitored, and when the entire data is normally received and stored in the first buffer, the CPU 1
1 for the interrupt request signal INT.

As described with reference to FIG. 2, when the CPU 11 receives the interrupt request signal INT and reaches the stage where the process under operation can permit the interrupt, the CPU 11 starts the interrupt processing and stores it in the first buffer 23. RA data
Write to a predetermined memory location of M13. In this case, it is preferable that the CPU 11 write not only the data of the first buffer 23 but also the data of the second buffer 24 to the RAM 13. This is because it is more efficient to read all the data temporarily stored in the communication control device 20 by one interrupt processing than to perform frequent interrupt processing.

Upon receiving from the CTL decoder 25 a signal indicating that the data being received does not require urgent processing, the control unit 26 monitors the state of data input to the second buffer 24, and Then, an interrupt request signal INT is sent to the CPU 11 after a predetermined amount of data is accumulated. This predetermined amount is preferably set to the amount of data transmitted by a plurality of messages from a plurality of nodes. In addition, the control unit 26
In this case, if a predetermined time, for example, one second, elapses after the data of the first received data message is stored in the second buffer, an interrupt request is issued to the CPU 11 even if the data amount of the second buffer does not reach the predetermined amount. Signal INT
To send. The CPU 11 outputs the interrupt request signal I
Upon receipt of NT, interrupt processing is executed by the process shown in FIG. 2 in the same manner as described above.

The predetermined amount can be determined on the basis of the amount of data stored in, for example, 500 milliseconds in a normal vehicle driving situation. By doing so, non-urgent data is taken into the data processing device once every 500 milliseconds, and at least one
Once a second, the data is taken into the data processing device.

Although the engine ECU 1 has been described as an example, the RAM 13 has a predetermined memory location for each of the data transmitted from other ECUs. For example, the RAM 13 has an electronically controlled automatic transmission (EAT). The transmission oil temperature data sent from the ECU 2 is written in the first memory location so as to overwrite the oil temperature data previously stored therein, and the shift data is previously stored in the second memory location. The data is written in such a manner that the speed change data is overwritten.

Since the oil temperature of the transmission does not change rapidly, the oil temperature data is read out by the CPU 11 at a relatively slow rate, such as once every 500 milliseconds or once every second, and is used for calculation. Is done. On the other hand, it is necessary to control the ignition timing of the engine or the like instantaneously according to the content of the shift data, and thus the shift data is read out by the CPU 11 at a high rate such as once every millisecond to once every several milliseconds and used for the calculation. . In this example, the oil temperature data is the EAT
The shift data is transmitted from the ECU 2 to the engine ECU 1, and the shift data is transmitted from the EAT / ECU 2 to the engine ECU 1 as an urgent message.

FIG. 5 is a flowchart showing a process of generating an interrupt request by the communication control device according to the embodiment of the present invention. The CTL decoder 25 determines whether the data message being received is urgent or not (201). If the data message is urgent, the received data is written into the first buffer 23 (203) and the urgent message is written. If the message does not require
(Step 202). First buffer 2
3 is completed, the control unit 26
Sends an interrupt request signal INT to generate a reception interrupt (205).

On the other hand, if the message does not require urgency, the control unit 26 waits until a predetermined amount of data is accumulated in the second buffer 24, and when the message reaches the predetermined amount, the control unit 26 sends an interrupt request signal to the CPU 11 to receive it. An interrupt is generated (205).

Although the embodiment of the present invention has been described above by taking a vehicle-mounted computer network as an example, the present invention is not limited to such an embodiment, and can be widely applied to a communication control device in data transmission. it can.

[0051]

According to the first aspect of the present invention, the transfer of the data received and stored by the communication control device to the data processing device is controlled according to the type of data. Data that is transferred to the data processing device and that does not require urgency is handled according to its type, so that efficient system operation can be performed without substantially increasing the load on the data processing device.

According to the second aspect of the present invention, since the communication control device receives the code indicating the type of data before receiving the entire data, it can promptly prepare for an interrupt request to the data processing device. The system can be operated efficiently.

According to the third aspect of the present invention, the urgent received message is stored in the first buffer, and an interrupt request is issued preferentially to the data processing device. Since the data in the second buffer is also transferred, the system can be operated in accordance with the urgency of the data without substantially increasing the frequency of interruption to the data processing device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of an in-vehicle computer network.

FIG. 2 is a flowchart showing a general flow of interrupt processing by a CPU when data is received.

FIG. 3 is a block diagram showing an overall configuration of a communication control device according to one embodiment of the present invention.

FIG. 4 is a diagram showing a format of a data message in the embodiment of the present invention.

FIG. 5 is a flowchart showing an interrupt generation process in the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 11 CPU (data processing device) 20 Communication control device 23 First buffer (plurality of storage means) 24 Second buffer (plurality of storage means) 25 CTL decoder (selection means) 28 Selection unit (selection means) DATA_UNIT Data field CTL type field

Claims (3)

[Claims] 1. A plurality of storage means for storing data of a message to be received, and a selection means for selecting one of the plurality of storage means according to a type of the message to be received and storing the data of the message. A communication control device that controls transfer of data stored in the storage unit to the data processing device according to the type. 2. The message according to claim 1, wherein the message has a data field for storing the data and a type field for storing a code indicating the type, and the type field is arranged in front of the data field. Communication control device. 3. The first storage device according to claim 1, wherein said plurality of storage means stores at least data of a message of an urgent type.
And a second buffer for storing data of a non-urgent message type,
When data is stored in the buffer, an interrupt request is preferentially issued to the data processing device, and when transferring data in the first buffer, data in the second buffer is also transferred. 3. The communication control device according to 1 or 2.