JPS6236940A - Data communication equipment in automobile - Google Patents

Abstract

PURPOSE:To attain the transmissin of interruption request at data transmission in a synchronizing transmission protocol and to set a free idle period at data transmission in an asynchronizing transmission protocol by providing a control/ status signal path. CONSTITUTION:When a central unit 20 and terminal units 30, 40, n0 make data transmission while using an asynchronizing transmission protocol, the level of a control/status signal path 100 is brought into an L level and the data are sent. In this case, a unit sending a data sends an address ode, then an address code strobe signal is sent to the signal line 100 in place of an idle period for a prescribed time or over and a reception unit uses the signal to identify the head of a frame. Thus, the idle period is set freely between data in a frame. In sending a data by using a synchronizing transmission protocal, the signal line 100 is brought into a level H and when it is required to give interruption request for a unit not requiring high speed communication to the unit 20, a data is sent via the signal line 100.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data communication device that mutually transmits digital data between a plurality of devices in an automobile.

[Prior Art] As a conventional device of this type, there is one using a one-wire half-duplex series communication system. By the way, the inventor of the present invention particularly found that some of the plurality of terminal units have a communication speed of approximately several IQ.
A system as shown in FIG. 4 is being developed as a system including a unit that requires high-speed communication of kbps or higher. Here, the terminal unit refers to a device such as an air conditioner controller or a car stereo that performs data transmission with a central unit such as a control display system.

In the system shown in Fig. 4, the central unit and the terminal units that require high-speed communication between the central unit and the terminal unit are equipped with a multiprotocol serial communication interface that has two types of transmission protocols: asynchronous and synchronous. Terminal units that do not require high-speed communication with other units are equipped with an asynchronous serial communication interface.

In the figure, 10 is a transmission/reception data transmission line consisting of one bus for bidirectionally transmitting data between each device;
0 is a central unit such as a control display system that performs centralized control and centralized display of multiple devices, and in this central unit 20, 21 is an asynchronous type and a synchronous type (BI 5YNC) that interfaces with the data transmission line 10 for sending and receiving. 22 is a communication control means for controlling the multi-protocol serial ill(t) interface 21;

A terminal unit 30 is required to perform high-speed data communication with the central unit 20, and is, for example, a large-capacity storage device such as a floppy disk drive or a hard disk. 31 is a multiprotocol serial communication interface equipped with two types of transmission protocols, an asynchronous type and a synchronous type (B I 5YNC), which interfaces with the data transmission line 10 for sending and receiving in the terminal unit 30; 32 is a multiprotocol serial communication interface 3;
This is a communication control means that controls 1.

40 and nO are terminal units that do not require high-speed communication, such as devices such as an air conditioner controller or a curtain system. 41 and nl are terminal units 40. The asynchronous serial communication interfaces 42, n2 that interface with the transmitting/receiving data transmission path 10 in the terminal unit 40° are communication control means for controlling the asynchronous serial communication interfaces 41, nl in the terminal unit 40°no, respectively.

Next, the operation will be explained.

First, the terminal unit 40. which does not require high-speed communication with the central unit 20. The case where messages are exchanged with nO will be explained. Here, the message consists of one or more frames,
Each frame consists of multiple bytes of data.

First, the multiprotocol serial communication interface 21 of the central unit 20 is set to the asynchronous communication mode by the communication control means 22, and then the terminal unit 40. Data is transmitted with the nO using an asynchronous transmission protocol. The communication procedure at that time is as follows.

That is, each frame constituting a message is composed of a terminal unit identification address code (identification code), transfer data including the number of transfer data bytes, command parameters, etc., and an error check code. And each frame has data bits provided to identify the beginning of the frame.
After an idle period of more than a certain period of time in which 1'' continues, data transmission lines for transmission and reception are switched from the multi-protocol serial communication interface 21 and the asynchronous serial interface 41.nl, respectively, under the control of the communication control means 22 and 42.n2. 10.

Next, a case will be described in which messages are exchanged between the central unit 20 and the terminal unit 30 that requires high-speed communication. First, when high-speed communication is not required, the multi-protocol serial communication interface 21 of the central unit 20 and the terminal unit 30
and the multi-protocol serial communication interface 31 are respectively set to an asynchronous communication mode under the control of the communication control means 22 and 32, and mutually perform data transmission using an asynchronous transmission protocol. The communication procedure at this time is the same as the above-mentioned asynchronous method, and naturally the central unit 2
is a terminal unit 40 that does not require high-speed communication. n
Data transmission is also possible with O.

On the other hand, when high-speed communication is required, the multi-protocol serial communication interface 2 of the central unit 20
1 and the multi-protocol serial communication interface 31 of the terminal unit 30, respectively, by the communication control means 22.
．． 32 to set the synchronous (BI 5YNC) communication mode, and mutually perform data transmission using the synchronous (BI 5YNC) transmission protocol. Note that the communication procedure at this time is the same as in the asynchronous type, except that a two-character synchronization code for frame synchronization is provided at the beginning of each frame instead of an idle period of a certain time or more.

[Problem that the invention seeks to solve]

By the way, considering the ease of control in the communication control means, it is desirable to provide a predetermined idle period between each data in a frame, but in the above-mentioned in-vehicle data communication device, When data is transmitted using an asynchronous transmission protocol, if an idle period is provided between each piece of data within a frame, there is a risk that the idle period may be mistakenly recognized as the beginning of the frame. Another problem is that when data is transmitted using a synchronous transmission protocol, a terminal unit that does not require high-speed communication cannot send a transmission request (interruption) to the central unit.

This invention was made to solve the above-mentioned problems, and when transmitting data using an asynchronous transmission protocol, it is possible to freely set an idle period between each data in a frame, and To provide an in-vehicle data communication device in which a terminal unit that does not require high-speed communication can send a transmission request (interruption) to a central unit when transmitting data using a synchronous transmission protocol.

[Means for solving problems]

The in-vehicle data communication device according to the present invention includes a data communication device, that is, a signal line for data communication between a central unit and a plurality of terminal units.
In addition to the data transmission path for transmission and reception, a control/status signal path consisting of at least one signal line for sending control signals or status signals is provided.

[Effect]

In this invention, 'ζ is a strobe signal of the address code for terminal unit identification when transmitting data using an asynchronous transmission protocol via the control/status signal path, and a strobe signal of an address code for terminal unit identification when transmitting data using a synchronous transmission protocol. Sends interrupt signals, etc. for transmission requests from terminal units to the central unit that do not require high-speed communication.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 10 is a transmission/reception data transmission path consisting of one bus for bidirectionally transmitting data between each device;
00 is a control/status signal path for sending control signals or status signals between devices, 2
0 is a central unit that performs centralized control and centralized display of multiple devices, and in this central unit 20, 21 is an asynchronous type and a synchronous type (B I 22 is a communication control means for controlling the multiprotocol serial communication interface 21, which is equipped with two types of transmission protocols (5YNC) and can switch the transmission protocol by hardware or software.

30 is a terminal unit that needs to perform high-speed data communication with the central unit 20, and 3I is an asynchronous type and a synchronous type (BTSYNC) that interfaces with the data transmission path 10 for sending and receiving and the control/status signal path 100 in the terminal unit 30. A multi-protocol serial communication interface 32 is a communication control means for controlling the multi-protocol serial communication interface 31.

Both 40 and no are terminal units that do not require high-speed communication; 41. nl is terminal unit 4 respectively
0. 42. an asynchronous serial communication interface interfacing with the transmitting/receiving data transmission line 10 and the control/status signal line 100 at the nO; n2 are asynchronous serial JM communication interfaces 41.n2, respectively. nl
This is a communication control means that controls the

Next, the operation will be explained.

FIG. 2 is a diagram showing signal waveforms in each state of the transmitting/receiving data transmission path 10 and the control/status signal path 100 in this embodiment, where AI and B1.01 are the waveforms of the control/status signal path 100, A2. B2. C2
shows the waveform of the data transmission path 10 for transmission and reception. The states are that Al and A2 have switched the transmission protocol from asynchronous to synchronous, Bl and B2 are in asynchronous transmission protocol, and CI and C2 are in synchronous transmission protocol. Further, 201 is an address code signal, 202
203 is an address code strobe signal, and 203 is a transmission request interrupt signal.

First, central unit 20 and terminal unit 3
0,40. A case will be described in which data is transmitted using an asynchronous transmission protocol.

First, central unit 20 and terminal unit 3
0 multiprotocol serial communication interface 21.
31 transmission protocols are both set to non-same FJJ mode. Furthermore, the multi-protocol serial communication interface 21 of the central unit 20 is connected to the communication control means 2.
2 and control/status signal path 10.
0 to level “L” as shown in A/(period Ta) in FIG.
''. After the above settings, data is transmitted between the central unit 20 and the terminal units 30, 40.nO using an asynchronous transmission protocol.The communication procedure at this time is almost the same as the conventional one. However, when the unit sending out the data, that is, the central unit 20 or the terminal unit 30.40.no, sends out the address code, instead of an idle period of more than a certain time, as shown in B1 and B2, Address code strobe signal 20 is synchronized with address code signal 201.
2 on control/status signal path 100. The unit receiving the data identifies the address code, ie, the beginning of the frame, based on this strobe signal.

Next, the central unit 20 and the terminal unit 3
A case will be described in which data is transmitted using the synchronous (BISYNC) transmission protocol. Initially, the transmission protocols of the multiprotocol serial communication interfaces 21.31 of the central unit 20 and the terminal units 30 are both set to synchronous mode. Furthermore, the multi-protocol serial communication interface 21 of the central unit 20 is controlled by the communication control means 22, and the control/status signal path 100 is controlled by the control/status signal path 100 shown in FIG.
As shown in (T s between J'lf), the level is set to "H". After the above settings, data is transmitted between the central unit 2° and the terminal unit 30 using the synchronous (BISYNC) transmission protocol.The communication procedure at this time is the same as the conventional one, but the central unit 2° Terminal unit 4 that does not require high-speed communication during data transmission between and terminal unit 30
0. If a request for data transmission to the central unit 2o occurs in no, the terminal unit 40. nO is CI
, C2, the transmission request interrupt signal 203 is sent from the asynchronous serial communication interface 41 r n l.
to the control/status signal path 100,
Inform central unit 2o.

In the device of this embodiment, a control/status signal path is provided as a signal line for data communication in addition to the data transmission path for sending and receiving, so even when data is being transmitted using an asynchronous transmission protocol, the frame An idle period can be freely provided between each data in the data, and control by the communication control means can be facilitated. Also, when data is being transmitted using the synchronous transmission protocol, a terminal unit that does not require high-speed communication can send a transmission request to the central unit.

In the above embodiment, the multi-protocol serial communication interface of the central unit and the terminal unit that requires high-speed i1 communication includes both asynchronous and synchronous B.
A system with two types of transmission protocols (I5YNC) was shown, but the multi-protocol serial communication interface of each unit mentioned above has an asynchronous type and a synchronous type HDL.
C (formerly ghLevel Data Link Cont
Two types of transmission protocols may be provided. In this case, when performing high-speed communication between the central unit and the terminal unit that requires high-speed communication, the HDLC helloware uses the frame synchronization flag (code), end flag (code), error check code (cyclic・Redundancy code (CRC) etc. are automatically generated and address codes are automatically recognized, which reduces the burden on the communication control means of each unit and enables even more efficient data transmission.

Furthermore, in the above embodiment, a half-duplex single-line signal bus is provided as the data transmission path for transmission and reception, and data is transmitted in both directions. As shown in the figure, it may be configured with two buses, each viewed from the central unit 20, as a sending data transmission path 11 and a receiving data transmission path 12. In this case, the communication method is full duplex, and the transmission capacity is further increases.

〔Effect of the invention〕

As described above, according to the present invention, in addition to the data transmission line for transmission and reception, the signal line for data communication is used to send control signals or status signals between a central unit that performs data communication and a plurality of terminal units. A control rule consisting of at least one signal line/
Since a status signal path is provided, even when transmitting data using an asynchronous transmission protocol, it is possible to freely set an idle period between each data in a frame to facilitate control by the communication control means. When transmitting data using a transmission protocol, a terminal unit that does not require high-speed communication has the advantage of being able to send a transmission request (interruption) to the central unit.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an in-vehicle data communication device according to an embodiment of the present invention, FIG. 2 is a signal waveform diagram of a data transmission line for transmission/reception and a control/status signal path in the device, and FIG. 3 is a diagram of the present invention. FIG. 4 is a block diagram showing an in-vehicle data communication device developed by the inventor of the present invention. 10... Data transmission line for sending and receiving, 11... Data transmission line for sending, 12... Data transmission line for receiving, 100.
... Control/status signal path, 20... Central unit, 21... Multi-protocol serial communication interface, 22... Communication control means, 30...
・Terminal unit that requires high-speed communication, 31...
・Multi-protocol serial communication interface, 32・
...Communication control means, 40. nO...terminal unit that does not require high-speed communication, 41. nl...Asynchronous serial communication interface, 42. n2...Communication control means. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (4)

[Claims] (1) A data communication device that mutually transmits digital data between multiple devices in an automobile, including at least one cable for mutually transmitting digital data between a central unit and multiple terminal units. a data transmission line for sending and receiving data consisting of a bus; and a control/status signal line consisting of at least one signal line for bidirectionally transmitting control signals or status signals between the central unit and the plurality of terminal units. , a multi-protocol serial communication interface having two types of transmission protocols, asynchronous and synchronous, for interfacing the central unit with the transmitting/receiving data transmission path and the control/status signal path, and controlling the multi-protocol serial communication interface. and an asynchronous series interface between a terminal unit of the plurality of terminal units that does not require high-speed communication with the central unit, the data transmission path for sending/receiving, and the control/status signal path. A communication interface, a communication control means for controlling the asynchronous serial communication interface, a terminal unit of the plurality of terminal units that requires high-speed communication with the central unit, the data transmission path for sending and receiving, and the control/receiver. An automobile interior comprising: a multi-protocol serial communication interface having two types of transmission protocols, an asynchronous type and a synchronous type, for interfacing with a status signal path; and a communication control means for controlling the multi-protocol serial communication interface. Data communication equipment. (2) The transmission protocol of the multi-protocol serial communication interface in the central unit and the terminal unit that requires high-speed communication between the central unit and the central unit is two types: an asynchronous type and a BISYNC type. The in-vehicle data communication device according to item 1. (3) The transmission protocol of the multi-protocol serial communication interface in the central unit and the terminal unit which requires high-speed communication between the central unit and the central unit is two types: an asynchronous type and an HDLC type. The in-vehicle data communication device according to item 1. (4) In-vehicle data according to any one of claims 1 to 3, characterized in that the data transmission path for sending and receiving is composed of two buses, one for sending and one for receiving. Communication device.