Communication apparatus and method

• US 20060235593A1
• Filed: 04/07/2006
• Published: 10/19/2006
• Est. Priority Date: 04/11/2005
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Mayumi, Nobuo
• Granted Patent: US 7,804,843 B2
• Time in Patent Office: Days
• US Class Current: 701/45
• CPC Class Codes: B60R 2021/01068 between different sensors and airbag control unit
• CPC Class Codes: B60R 2021/01115 specific data frames
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 2012/40273 the transportation system being a vehicle
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols

Abstract

A communication apparatus in an airbag system includes an airbag ECU as a master unit, sets of communication lines and slave sensor devices. The slave sensor devices are respectively connected to the airbag ECU through the set of communication lines. The airbag ECU transmits data transmission request commands to the respective sets of communication lines at timings which are different from each other. Thus, transmission timings in the respective sets of communication lines are prevented from being synchronized, and noise which develops in consequence of the data communications between the master unit and the slave sensor devices can be reduced.

Claims

1. A communication apparatus comprising:

a master unit;

a plurality of sets of communication lines connected to the master unit; and

a plurality of slave units connected to the respective sets of communication lines,

wherein the master unit serially transmits data transmission request commands each of which specifies the master device as a subject for communications and makes a request for transmission of data to the respective sets of communication lines in synchronism with a clock of predetermined period,

wherein each of the slave units determines whether it is the subject for communications on the basis of the data transmission request command, and in case of the subject for communications serially transmits the data corresponding to the data transmission request command to the master unit, and

wherein the master unit serially transmits the data transmission request commands at timings which are different in a predetermined time interval from each other among the sets of communication lines.

2. The communication apparatus as defined in claim 1, wherein the predetermined time interval is other than integer times of the predetermined period.

3. The communication apparatus as defined in claim 2, wherein the predetermined time interval is changed each time the data transmission request command is serially transmitted.

4. The communication apparatus as defined in claim 2, wherein the predetermined time interval is one half of a cycle period of the clock.

5. The communication apparatus as defined in claim 1, wherein the master unit, the sets of communication lines and the slave units are mounted on a vehicle so that the master unit activates airbags in response to detection of accelerations by the slave units.

6. A communication method in a vehicle having a master unit, a first group of slave units, a second group of slave units, a first communication line connecting the master unit and the first group of slave units, and a second communication line connecting the master unit and the second group of slave units, the method comprising:

generating a clock at every predetermined interval;

transmitting first data request commands from the master unit to the first group of slave units through the first communication line serially at first timings which are in timed relation with the clock; and

transmitting second data request commands from the master unit to the second group of slave units through the first communication line serially at second timings which are in timed relation with the clock, the second timings are delayed from the first timings a delay period which is other than an integer times of the predetermined interval.

7. The communication method as defined in claim 6, wherein the delay period is less than the predetermined interval.

8. The communication method as defined in claim 7, wherein the delay period is about one half the predetermined interval.