JPH04160932A - Communication interface unit - Google Patents

Abstract

PURPOSE:To enable a communication interface to easily cope with a different communication medium easily by fabricating the communication control section and communication driver/receiver of a communication interface using separate integrated circuits to constitute a physically separated communication interface. CONSTITUTION:By separating a communication interface to the communication control IC33 and the communication driver/receiver IC32, it is possible to adapt the communication interface to a different transmission medium of communication BUS 14. For example, for differential transmission, although twist pair line is usually used as communication BUS 14, when optical communication cable is used as communication BUS 14, the use of an electric/optical converter for communication driver/receiver IC32 can adapt to a different communication medium without changing other constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication interface device, and particularly to a communication interface device suitable for use as a connection network for a vehicle-mounted AV (audio-visual) system.

[Conventional technology]

In recent years, in-vehicle audio systems have been evolving from systems that simply listen to music to systems that include visual elements. A system having not only audio but also visual functions is known as an AV system.

An in-vehicle AV system is constructed from a wide variety of elements. For example, audio elements include a cassette tape deck, radio tuner, CD (compact disc) player, etc., and visual elements include:
It includes a TV (television) tuner, navigation device, etc.

The audio playback signals output from each of these elements are played back from the speakers installed in the car via an amplifier.
The image reproduction signal is similarly output as a video onto a display mounted inside the vehicle. Today, each of these elements is controlled by digital technology, and the control is performed by a controller using a microcomputer.

In order to operate each of the above elements systematically, it is necessary to control each element in an integrated manner. Therefore,
In an in-vehicle AV system, the controllers of each of the above-mentioned elements are connected through a bus-type network, and mutual control data is sent and received via a communication bus that constitutes the network.

The controllers of each of the above elements are connected to a communication bus via a communication interface. Conventionally, the communication interface was L5I (LaBe5caleln+eHat
ion). Communication interface IC
is a communication driver/receiver unit for sending communication data issued from the controller onto the communication bus and receiving communication passscala communication data, and for controlling communication operations of this communication driver/receiver unit. It is broadly divided into the communication control section and the communication control section. Generally, the communication driver/receiver section uses bipolar transistors with high current supply capability to drive the communication bus.

On the other hand, a CMOS transistor is used in the communication control section to suppress power consumption during operation. Therefore, in terms of transistor configuration, the conventional communication interface IC is a so-called Bi-CMO8LSI.
It is.

[Problems to be Solved by the Invention] The problems with the above-mentioned conventional communication interface LSI are: firstly, there are limitations on the transmission medium used in the communication bus, and secondly, there is a problem with disturbance noise mixed in from the communication bus etc. Examples include poor maintainability and lack of reliability against the resulting failures.

In other words, regarding the first point above, although twisted pair wires of metal conductors are used as the transmission medium used in conventional communication buses, the transmission medium is not only electrical.
The use of optical transmission cables must also be considered. However, in the case of the above-mentioned conventional communication interface device, a converter (hereinafter referred to as an electrical/optical converter) is required to convert electrical signals into optical signals and perform the inverse conversion between the communication bus and the communication bus. becomes. Regarding the second point above, especially when installed in a car, there is a risk that the communication interface LSI will be destroyed by the incorporation of noise, as there are many noise sources such as the engine in the car. . However, it is often the communication driver/receiver that is destroyed by disturbance noise. Even in this case, conventionally, the communication control section and the communication driver/receiver section were formed in one LSI, so local conversion was impossible and the LSI itself had to be replaced, making it economical. There are problems in terms of performance and maintainability.

An object of the present invention is to provide a communication interface device that can easily support different communication media and can minimize the influence of disturbance noise.

[Means to solve the problem]

In order to solve the above problems, as shown in FIG. An interposed communication interface device (A) that controls a communication driver/receiver section (D) that transmits and receives communication data to and from the communication bus (B), and a communication operation of this communication driver/receiver section (D). The communication control unit (C) is physically separated from each other using separate integrated circuits.

[Effect]

According to the present invention, the communication interface device (A) includes a communication control unit (C) and a communication driver/receiver (D
) are physically separated by separate integrated circuits, so the communication driver/receiver section (D)
The integrated circuit can be removed at will, making it easy to change the communication bus to a different transmission medium (for example, an optical transmission cable), and even if only the communication driver/receiver section (D) fails due to external factors It can also be replaced easily and within a minimum range.

〔Example〕

Next, preferred embodiments of the present invention will be described based on the drawings.

Power supply system for AV system In a preferred embodiment, the present invention is applied to a vehicle-mounted AV system. As shown in FIG. 2, the AV system 103 receives power from the car battery 101 via the ACC switch 102. The ACC switch 102 is a switch that is linked to the engine key of the automobile, and by rotating the engine key to the position of the ACC switch 102, power is supplied to accessories in the automobile. Therefore, in general, the AV system 103
Power is supplied 0N10FF every time the engine key is turned.
will be repeated.

Configuration Example of AV System FIG. 3 shows a configuration example of an AV system to which the present invention is applied. In the example shown in FIG. 3, the audio playback device is a tape deck 6 that plays back recording signals from a cassette tape 1.
, a multi-CD player 9 including an FM tuner 7 for reproducing radio waves received by the antenna 2, a CD player 8 for reproducing recorded signals from a CD 3, and an autochanger 5 for reproducing recorded signals from each CD of a multi-CD 4. ing. As a visual reproduction device, antenna 2
A TV tuner (assumed to be built in the tuner 7) that plays back the TV radio waves received by the TV tuner, or a CD player 8 or a CD-ROM, outputs the recorded still image as an image via the CD player 8. display 1
Contains 2 etc. A typical example of using a CD-ROM is a navigation device. The external commander 10 consists of a keyboard for inputting various operation commands from the outside. The input device 13 can also be incorporated into the external commander 10.

Each of the above devices has a controller for controlling its own operation, and the controllers are connected to each other via a communication BUS 14 to form a bus-type control network. The configuration of this network is shown in FIG. 4, and the details will be described later.

On the other hand, the playback signal from the audio playback device is selectively input to the digital amplifier 16 via the selector 15, amplified by a predetermined amount, and then radiated from the speaker 17. The digital signal system circuit included in the digital amplifier 16 is also controlled by a built-in controller, and this controller is also connected to the communication BUS 14.

AV System Control Network FIG. 4 shows an example of an AV system control network. Here, for convenience of explanation, communication BU
The general expression for each device connected to S14 is “
unit. As shown in Figure 4,
Each unit is connected to the communication BUS 14 in parallel. One of the units is used as a "mask" to collectively control the network, and this is indicated by a master unit 200. All other remaining units are "slaves" and are referred to as slave unit 2.
00. ~200-n-? ? show.

The mask controller 18 built in the mask unit 200 communicates with B via the communication interface IC25.
Connected to US 14. In this example, the mask controller 18 is designed to control both the tape disk 6 and the tuner 7. Further, the tape deck 6 control portion of the mask controller 18 also controls the autochanger 5. Slave unit 200. The slave controllers 19 to 24 built in ~200-□ are similarly connected to the communication BUS 14 via communication interface ICs 25 to 31.

FIG. 5 shows a mask unit 200 and a slave unit 2.
A specific example of the connection state with 00 is shown below. As shown in FIG. 5, the mask unit 200 and the slave unit 200 are connected via the communication BUS 14. The communication BUS 14 uses twisted pair wires consisting of two wires. Communication data DT sent and received via communication BUS 14 is sent to mask unit 2.
00 and slave unit node 200 communication interface IC25 and n communication interface IC31.

The communication interface IC 25 is separated into a communication driver/receiver IC 32 and a communication control IC 33, and similarly the communication interface IC 31 is separated into a communication driver/receiver IC 35 and a communication control IC 36. In this regard, conventionally, they have been provided integrally within one IC. Communication control IC33 is CMO
Communication driver/receiver I
C32 is formed of a bipolar transistor with high current driving ability. The same applies to the communication driver/rember IC 35 and the communication control IC 36.

In this way, regarding the communication interface IC 25, by separating it into the communication control IC 33 and the communication driver/receiver IC 32, the communication BUS 14
This makes it possible to respond to changes in transmission media. For example, in the example shown in FIG. 5, a twisted pair wire is used as the communication BUS 14 for differential transmission, or when an optical communication cable 40 is used as the communication BUS 14 as shown in FIG. Electric instead of /
By using the optical converter 38, this can be handled without changing the other configurations. In addition, malfunctions that occur in the mask unit 200 are largely due to disturbance noise mixed in from the communication BUS 14, and even if an excessive signal is mixed in for some reason, it is often only a failure of the communication driver/receiver IC 32, and the communication This is advantageous in terms of maintenance, as it is easy to return to the current state by replacing only the driver/receiver IC 32.

This is particularly effective in the case of in-vehicle AV systems, since there are many opportunities for noise to be mixed in from the engine system of the vehicle.

In addition, from the viewpoint of IC manufacturing, it is easier to manufacture and cost-effective to separate into ICs of CMO8h transistor and bipolar transistor, which have different manufacturing processes, than to have a Bi-cMO3IC configuration.

In addition, although the above explanation was about the communication interface IC 25, other slave units 200. ~2
00. The communication interface ICs 26 to 31 are similarly separated into a communication control IC and a communication driver/receiver IC.

Transmission format of communication data DT Next, the transmission format of communication data DT will be explained.

FIG. 7 shows an example of the transfer format of communication data DT. As shown in FIG. 7, the communication data DT includes mask address data MA indicating the address of the mask unit 200 from the beginning, slave units 200-1-200.
, message length data N1 indicating the message length of data D, classification data TP indicating the type of data D, and data D indicating the transfer content.

The structure of data D is the content of communication data DT, that is,
It differs depending on the classification data TP, and can be roughly divided into three types of format configurations. As shown in FIG. 10, the first format is a format for connection confirmation, the second format is a format for keys, display data, etc., and the third format is a format for sending the result of check sum C8. It is. Furthermore, the format for connection confirmation is to send the communication data DT to the slave unit 200. ~200-. There are differences between the case of transferring the data from to the master unit 200 and the case of transferring the data vice versa. Note that in FIG. 10, in the format of keys and display data, all of the data configurations from physical status data PS to logical mote data LM are the same, so illustration is omitted.

The classification data TP is placed at the beginning of the communication data DT,
This is a data area representing the type of data D following the classification data TP. The classification data TP is composed of major classification data and minor classification data. The major classification data represents the type of data D, as shown in FIG. Regarding bit allocation, when the entire classification data TP is 8 bits, the upper 4 bits are allocated. As shown in FIG. 9, the minor classification data is mainly used to identify the format of data D.
The lower 4 bits are allocated.

As shown in FIGS. 11 and 12, the physical address data PA is used for communication on the communication BUS 14 to identify the communication interface ICs 25 to 200-1 to 200-n-31 of each mask unit 200 to slave units 200-1 to 200. This is the address above, and the mask unit 200, slave units 200, ~20
This is an address indicating 0. This physical address data P
Of A, physical address data PA specifying the master unit 200 is always fixed. Basically, one physical address data PA is assigned to one unit. FIG. 15 shows an example in which physical address data PA is assigned in association with the unit configuration of FIG. 4. In FIG. 15, the physical address data PA is also set in the mask controllers 18 to 24, but this is because one controller mask controller 18 has two tape decks 6 and a tuner 7, like the mask unit 200. This takes into consideration the case where functional elements are connected. When combining one function with one controller, slave controllers 19 to
24, the physical address data PA and the logical address data LA are the same address.

The physical status data PS is stored in the master unit 200, slave unit h200. ~200 status information about the unit ~n, and the functional address of the unit (i.e.
This data indicates the number of logical address data (LA) to be described later.

As shown in FIG. 13, logical address data LA is transmitted to mask unit 200, slave unit 200 . ~20
0, the functions that the unit has (i.e., tuner,
This data indicates the tape deck) and is assigned to each function.

The number of logical address data LA is equal to the number of functions handled by the controller determined by the physical address data PA.
A, XLA2, etc. are added, so it is not a fixed number. FIG. 14 shows an example in which logical address data LA is assigned in association with the unit configuration of FIG. 4.

The talker address φ data TL indicates the address of the transmission source (speaker) that transmits the communication data DT.

The listener address data LN indicates the address of the destination (listener) that receives the communication data DT.

Logical status data LS represents the state of the function corresponding to each logical address LA.

Logical mode data LM represents the operating state (mode) of the function corresponding to each logical address.

The checksum data C8 is error detection data added to improve the reliability of the data D.

Communication operation In the AV system described above, for example, the mask unit 200 and the slave unit 200, ~200
−． The operation when communication data DT for connection confirmation is communicated with is explained below.

A specific example is shown in FIG. FIG. 15 shows TV/
This figure shows an example of a connection confirmation sequence when the slave unit accesses its own AV system between a slave unit including an FM tuner and a master unit to confirm connection to its own AV system.

In this network, unlike the conventional polling method, all slave units self-report their own units to the master unit. The master unit does not actively access the slave unit side.

Now, in FIG. 15, the slave knee unit issues communication data DT1 and transmits it to the master unit via the communication BUS 14 in order to request connection confirmation (self-report). At this time, the communication data DT1 sets its own physical address data PA to "123H" (H is hexadecimal hexadecimal).
, the physical address data PA of the other party's mask unit is set to "100H", and the logical address data LA,=05 indicates that the own slave unit has a configuration including a TV tuner and an FM/AM tuner, and the logical address data LA,=05. 07 (see Figure 13). With this communication data DTl, the mask unit 200 outputs PA=12.
At 3H, it is registered that a unit having the functions of LA=05 and LA2=07 is connected to the communication BUS 14, and henceforth this unit will be treated as an AV system constituent member. When the communication data DT1 is transmitted, the master unit returns return data RDT to the slave unit to indicate that it has received the communication data DT. Next, in order to inform the newly connected slave unit of the constituent members of the AV system, system connection information DT2 is transmitted to the slave unit side. The slave unit that received this system connection information DT2 sends return data RD to confirm reception.
T2 is returned to the mask unit side.

Then, after a predetermined period of time has elapsed, the slave unit again sends the communication data DT of the connection confirmation request (self-report).

is sent to the master unit. In the case of an in-vehicle AV system, the communication data DT requesting connection confirmation is sent again after a predetermined period of time has elapsed, when the power supply is turned ON/OFF.
This is because FF depends on ON/OFF of the ACC switch, so it is necessary to periodically check the connection.

In this way, communication data DT always includes either physical address data PA or logical address data LA, and since physical address data PA and logical address data LA are mutually independent data, they can be combined in any combination. Communication data DT can be sent to any destination.

Although the above operation example describes an example of communication between a slave unit and a master unit, communication is possible between other slave units as well.

In addition, by separating the format of the communication data DT and assigning addresses to each unit into the physical address PA and the logical address LA as described above, even if the physical address PA is unknown, the logical address LA can be used.
If it is clearly set, it is possible to connect a new unit, and it is possible to communicate with the already connected unit.

That is, as shown in FIG. 16, it is assumed that m new slave units 200 are connected to the communication BUS 14. In this case, the slave unit 200
Even if physical address data PA = 101 is assumed, if the function is a "display function", the same function or logical address already registered in the slave unit 200 is used. Since the data LA=01 exists, the logical address data LA can be accessed, and therefore the slave unit 200 can be connected. This will contribute to improving the expandability of the AVm system.

〔Effect of the invention〕

As described above, according to the present invention, in the communication interface device, the communication control section and the communication driver/receiver are configured to be physically separated by separate integrated circuits, so that the communication control section and the communication driver/receiver section are physically separated. The circuit is optionally removable and can be used to connect the communication bus to a different transmission medium (
For example, the optical transmission cable (optical transmission cable) can be easily changed, and even if only the communication driver/receiver section breaks down due to external factors, it can be easily replaced within a minimum range.

Therefore, according to the present invention, it is possible to provide a communication interface device that can easily accommodate different communication media and can minimize the influence of disturbance noise.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a power supply system diagram of the AV system, Fig. 3 is an overall configuration diagram of the AV system, Fig. 4 is a block diagram of the control network of the AV system, and Fig. 5 is a diagram of the control network of the AV system. FIG. 6 is a block diagram showing a specific example of the connection state between the mask unit and slave unit; FIG. 6 is a block diagram showing another example of the connection state between the mask unit and slave unit; FIG. 7 is an explanatory diagram showing the transfer format of communication data. , Fig. 8 is an explanatory diagram showing the contents of classification data (major classification), Fig. 9 is an explanatory diagram showing the contents of classification data (minor classification), Fig. 10 is an explanatory diagram showing the basic data format, Fig. 11 is an explanatory diagram showing an example of a physical address, FIG. 12 is an explanatory diagram showing an example of a physical address, FIG. 13 is an explanatory diagram showing an example of a logical address, and FIG. 14 is an explanatory diagram showing an example of physical address and logical address assignment. Block Diagram FIG. 15 is an explanatory diagram showing an example of communication operation, and FIG. 16 is a block diagram when an additional slave unit is connected. ADR...Address data B...Communication BUS C8...Check sum data D...Data DT...Communication data LA, LA, ~LAn...Logical address data M...
・Mask devices PA, PA, ~PAn...Physical address data PS・
...Physical status data S1 to S0...Slave device TP...Classification data 101...Car battery 102...ACC switch 103...AV system 200...Mask unit 200-1 to 200□... - Slave unit - Cassette tape 2 - Antenna 3 - CD 4 - Multi-CD 5 - Auto changer 6 - Tape deck 7 - Tuner 8 - CD player 9 - Multi-CD player 10...External commander 11...Display 12...Display 13...Input device 14...Communication BUS 15...Selector 16.16A...Digital amplifier 17...Speaker 18... Mask controller 19...Slave controller 20...Slave controller 21...Slave controller 22...Slave controller 23...Slave controller 24...Slave controller 25...Communication interface IC 26...Communication Interface IC 27... Communication interface IC 28... Communication interface IC 29... Communication interface IC 30... Communication interface IC 31... Communication interface IC 32... Communication driver/receiver IC 33... Communication Control IC 34...Controlled part 35...Communication driver/receiver IC36...Communication control IC 37...Controlled part 38...Electronic/optical converter 39...Electric/optical converter application Human agent Yasushi Ishikawa Oo (Sold in August) B Month Tenguchi Figure 1 AV system↑Mu's Hayabusa coin connection old Figure 9 DG Nerf D basic and cloak Figure 10 Physics 7￥Res 9'1 Fig. 11 Work is OK, Dore X's 4ri 1) Fig. 12 Shijiri Address Child 11 Fig. 13 I Yes No Fig. 15 by I7U

Claims (1)

[Claims] A communication interface device interposed between a communication bus and a communication device that transmits and receives communication data via the communication bus, the communication interface device comprising: a communication driver that transmits and receives communication data to and from the communication bus; A communication interface device characterized in that a receiver section and a communication control section that controls communication operations of the communication driver/receiver section are physically separated by separate integrated circuits.