CN1848790A

CN1848790A - Vehicle instruments internal data transmitting method based on CAN technology

Info

Publication number: CN1848790A
Application number: CN 200510025094
Authority: CN
Inventors: 杨毅; 施麟范; 刘志强; 李巍
Original assignee: Shanghai Delco Electronics & Instrumentation Co Ltd
Current assignee: JILIN DEKE ELECTRONIC CO., LTD.
Priority date: 2005-04-14
Filing date: 2005-04-14
Publication date: 2006-10-18
Anticipated expiration: 2025-04-14
Also published as: CN100377543C

Abstract

A method for transmitting internal data of automobile instrument based on CAN technique includes storing data using byte as unit from bus to bottom register ( BR ), taking data out from said register to place it as per byte order into array of storing region at internal memory ( IM ) to form structure body being sent to communication layer ( CL ) of node when data is received by node; sending data out by node CL, storing data using structure body as unit in storing region of IM, placing data in structure body as per byte in array into BR and entering data from register to bus in mode of byte when data is sent by node.

Description

A kind of vehicle instruments internal data transmitting method based on the CAN technology

Technical field

The present invention relates to a kind of vehicle instruments internal data transmitting method based on the CAN technology.

Background technology

At present, from the communication angle, the automobile instrument system of China exists several types: not with the low-grade instrument system of any communication function, the instrument system that has the instrument system of simple communication function and have the complex communication function.

In low-grade instrument system, the running status of automobile each several part, be transducer by each several part with various non-electric charge quantity signallings, as signals such as temperature, pressure, change into analog electrical signals such as voltage, electric current or pulse.Because the transmission characteristic of analog signal self makes instrument exist the shortcoming that computational speed is poor, precision is low for the analysis of the state of vehicle body various piece.And the transmission of signal adopts mode one to one, thus when the car body component that needs transmission signals is many, the corresponding also corresponding increase of transmission channel, this has not only increased production cost, and has increased the risk of phase mutual interference between signal.

Also have a kind of instrument system, it observes low side communication protocol, as K-line, LIN etc.Possessed communication function though observe the instrument of these agreements, this ability is local.For example utilize the LIN agreement can realize the communication of instrument and other parts of vehicle body, but this agreement has only been stipulated the signal parameter of physical layer, and do not had to determine treatment mechanism message.Its concrete message processing facility is by automobile production producer and its product vendor is inner determines.And the product of other manufacturers can't match, and does not promptly have opening.

The CAN standard is a kind of serial, many main open bus protocols.Observe and to realize remote (the longest 10km of reaching) high speed communication (the fastest 1Mbit/s of reaching) between the parts (in agreement, being called node) of this agreement; And owing to the regulation assurance data of agreement self can accurately be transmitted between the peer protocol layer of two nodes.Therefore, the node that utilizes the CAN bus all can be followed agreement utilizes one or two transmission lines to couple together, and can realize real-time control between node.Because the data field of message is that unit transmits with the byte on the bus, if the Communication Layer of node is directly handled byte, data transmission efficiency can be very low so, can additionally increase software overhead, causes the automobile instrument cost to promote.

Summary of the invention

The purpose of this invention is to provide a kind of vehicle instruments internal data transmitting method, alleviate the node Communication Layer and data are reorganized and decompose self need send the information burden, improve efficiency of transmission based on the CAN technology.

Each parts of automobile are the node on the bus, and the instrument of automobile also is a node on the bus.Each automobile component node the required various performance parameter data of instrument, sends on the bus with transmitter by the CAN bus control unit of self.Be delivered to the instrument place through bus again, instrument receives data by receiver, and instrument all will utilize the transmitter of instrument node to promise signal by bus to other parts transmission after correctly receiving data at every turn.The expression data that it sent are successfully received after certain parts node is received answer signal by receiver, otherwise it will resend data.

The present invention has opened up a memory block in the memory field of instrument system.The effect of an interface logically between bottom register and Communication Layer program, is played in this zone, promptly is to carry out exchanges data by the memory block of internal memory between register and the node Communication Layer.

At first, between bottom register and the memory storage area being is connection object with the byte; Be operand with the structure between memory storage area and the Communication Layer program.And do not carry out directly transfer of data between bottom register and the node Communication Layer program.Association of program definition.One and the corresponding structure of other node in association, have been defined.The different members of structure inside has been described the different attribute of this node respectively.

In association, define an one dimension character type array identical again with structure size.Because all bytes in association inside are shared identical application heap,, one or several elements in the array finish certain member in the structure body so forming.

When data are that unit stores with the byte when bus enters bottom register, program is taken out data from register, put into the array of memory storage area by certain byte order after, the byte data of reflection node has constituted can be by the convenient structure that uses of Communication Layer program.These structures are sent in the Communication Layer of instrument node then.

Equally, when the Communication Layer of instrument node will send information, it deposited information in the memory storage area in the structure form, and the bottom program is put into bottom register with member in the structure singly by the element in the general array.Subsequently, data are transmitted on bus with the form of byte, are received by respective nodes.

Beneficial effect of the present invention is, alleviated Communication Layer widely and data are reorganized and decomposed the burden that self need send information.Simultaneously, the readability and the level of program strengthen greatly, and this improvement for following program provides a safety and environment and standard easily.In addition, Communication Layer and application layer data adhere to two modules separately, between function call mutually, must not shared variable, can only transmit information by intermediate function, increased system reliability, convenient simultaneously test.

Description of drawings

Fig. 1 is automotive interior bus structures figure

Fig. 2 is intra-node data transmission structure figure

Fig. 3 is the data transfer logic structure chart

Embodiment

As shown in Figure 1, each parts (node) of automobile as engine, fuel tank, car light, instrument etc., all are nodes on the automobile CAN-bus, and they are connected on the bus.As shown in Figure 2, each node by self the CAN bus control unit and transmitter the required various performance parameter data of instrument, send on the bus.Arrive the instrument place through bus transfer again, instrument receives data by receiver, and instrument all will utilize the transmitter of instrument node to promise signal by bus to the respective nodes transmission after correctly receiving data at every turn.The expression data are successfully received after this node is received answer signal by receiver, otherwise it will resend data.

For example, as shown in Figure 3, when the engine node will send engine speed information to instrument,, information is sent to bus by transmitter after the bus arbitration success.

When rotary speed information when bus enters the bottom register of instrument, be that unit stores with the byte, program is taken out data from register, put into memory storage area by certain byte order.In memory storage area, association of program definition.In association, defined a structure relevant with rotary speed information.Rotary speed information is a member in the structure.In association, define an array identical again with structure size.Because all members in association inside share identical application heap,, one or several characters in the array finish certain member in the structure body so forming.Like this, the byte data of reflection rotary speed information has constituted the part that can be made things convenient for the structure that uses by the Communication Layer program.The structure that contains rotary speed information is transferred into the instrument Communication Layer.

At last, automobile instrument shows on instrument the data of coming from the CAN bus transfer after treatment.By gauge pointer, LCD or LED etc., the driver can learn a series of vehicle condition information.When engine speed changes, utilize identical preceding method to send the change data to instrument.

Miscellaneous part also is by aforementioned identical data transmission method the state information of self to be delivered on the instrument on the automobile.

Claims

1. the vehicle instruments internal data transmitting method based on the CAN technology comprises that node receives data step and node sends data step, it is characterized in that adopting following step:

When node received data, data were that unit deposits in the bottom register from bus with the byte, and data are taken out from bottom register, put into the array of memory storage area by byte order, formed structure, and structure is transferred into the Communication Layer of node;

When node sent data, the node Communication Layer sent data, is that the data of unit deposit memory storage area earlier in the structure, and data are put into bottom register by the byte in the array in the structure, and data enter bus with the byte form from register.

2. the vehicle instruments internal data transmitting method based on the CAN technology as claimed in claim 1 is characterized in that, in the middle of the data transaction in the interval of bottom register and memory, and association of definition earlier; Defined one and the corresponding structure of physical entity in association, the byte of structure inside is described the different attribute of physical entity respectively; Defining an array identical with structure size in association again, is the physical relation of byte to byte between this array and the structure.