Communication apparatus

Abstract

An airbag ECU includes a communication bus connection circuit for connecting communication buses to communication circuits. A central control circuit connects some of the communication buses to the communication circuits with the communication bus connection circuit and sets addresses for some of slave sensor devices. When those addresses are set, the other communication buses are connected to the communication circuits by the communication bus connection circuit, and addresses for the other slave sensor devices are set. Thus, a circuit can be made simpler without any influence on address setting, thus reducing cost and size of an airbag apparatus.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

FIG. 1 is a schematic plan view of a vehicle having a communication apparatus according to a first embodiment of the invention;

FIG. 2 is a block diagram of the communication apparatus in the first embodiment;

FIG. 3 is a block diagram of slave sensors of the communication apparatus in the first embodiment;

FIG. 4 is a block diagram of a communication apparatus according to a second embodiment of the invention;

FIG. 5 is a block diagram of a communication apparatus according to a third embodiment of the invention; and

FIG. 6 is a block diagram of a communication apparatus according to a fourth embodiment of the invention.

Claims

1. A communication apparatus comprising: a master device having a communication circuit for transmitting and receiving serial data;a plurality of communication buses over which serial data are transmitted; anda plurality of slave devices daisy-chain-connected to the communication circuit through respective ones of the communication buses for transmitting and receiving serial data to and from the communication circuit,wherein the communication circuit sets addresses for the slave devices through the plurality of communication buses at the time of initial setting, and thereafter transmits and receives serial data to and from the plurality of slave devices using the set addresses, andwherein master device further has a communication bus connecting circuit for sequentially connecting the plurality of communication buses to the communication circuit.

2. The communication apparatus according to claim 1, wherein the master device connects one of the communication buses to the communication circuit by the communication bus connecting circuit to set an address for one of the slave devices daisy-chain-connected to the one of the communication buses, and sequentially connects another of the communication buses to sequentially set addresses for another of the slave devices daisy-chain-connected to the another of the communication buses after the address is set for the one of the slave devices.

3. The communication apparatus according to claim 1, wherein the communication bus connecting circuit includes: a connection wiring for connecting one of the communication buses to the communication circuit;a plurality of switches for switchably connecting other of the communication buses to the communication circuit; anda switch control circuit for controlling switching operations of the switches.

4. The communication apparatus according to claim 1, wherein the communication bus connecting circuit includes: a plurality of switches for switchably connecting respective ones of the plurality of communication buses to the communication circuit; anda switch control circuit for controlling switching operations of the plurality of switches.

5. The communication apparatus according to claim 4, wherein the switch control circuit turns off, when any of the slave devices fails, the switch connecting the communication bus connected to the slave device having a failure to the communication circuit.

6. The communication apparatus according to claim 3, wherein the communication circuit, the plurality of switches and the switch control circuit are provided in an integrated circuit.

7. The communication apparatus according to claim 4, wherein the communication circuit, the plurality of switches and the switch control circuit are provided in an integrated circuit.

8. The communication apparatus according to claim 1, wherein: the plurality of slave devices are sensors for detecting information on a collision of a vehicle; andthe master device is an electronic controller for controlling passenger protection unit in the vehicle based on the information on the collision of the vehicle detected by the plurality of slave devices.