Detection method of bus termination

• US 5,939,997 A
• Filed: 10/31/1996
• Issued: 08/17/1999
• Est. Priority Date: 10/31/1996
• Status: Expired due to Term

• Current Assignee: Sony Transcom Incorporated (Rockwell International Corporation), Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Transcom Incorporated (Rockwell International Corporation), Sony Corporation (Sony Group Corp.)
• Inventors: Sekine, Kazutoyo, Lotocky, Daniel
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): Dalencourt, Yves
• Application Number:
  US08/739,874
• Time in Patent Office: 1,020 Days
• Field of Search: 340/825.16, 340/825.08, 340/825.77, 340/825.78, 340/825.06, 340/825.05, 370/489, 370/257, 381/77, 381/80, 381/82, 381/86
• US Class Current: 340/3.43
• CPC Class Codes: G06F 13/4086 Bus impedance matching, e.g. termination

Abstract

A system for detecting whether a bus used to connect units in an in-flight entertainment system is properly terminated. A detection circuit generates a bus termination signal when a terminating cap properly terminates the bus. Prior to installation of the terminating cap, a bus coupling contact of the detection circuit is maintained in a logic high or asserted state. A detection loop in the terminating cap grounds or deasserts the bus coupling contact when the terminating cap is properly installed. A microcontroller determines whether the bus coupling contact is grounded and signals a managing unit of the condition. The managing unit may display an appropriate error message to notify service personnel of the improper termination.

Claims

1. An in-flight entertainment system including a system for detecting whether an interconnect bus is properly terminated, said in-flight entertainment system comprising:

a plurality of electronic units, each electronic unit having a bus connector for coupling said electronic unit to said interconnect bus;

a terminating cap coupled to a final bus connector, said terminating cap coupling a detection loop to a bus coupling contact, said detection loop designed to ground a bus coupling contact of said final bus connector thereby indicating a proper termination; and

a monitoring circuit coupled to said interconnect bus, said monitoring circuit verifying that said bus coupling contact has been grounded.

2. The in-flight entertainment system of claim 1 wherein said plurality of electronic units controls audio and video signals traveling to passengers using said in-flight entertainment system.

3. The in-flight entertainment system of claim 1 wherein said detection loop couples said bus coupling contact to a ground contact in said final bus connector causing a bus termination signal to be generated which indicates that said terminating cap is coupled to said final bus connector.

4. The in-flight entertainment system of claim 1, wherein said monitoring circuit receives said bus terminating signal resulting from grounding of the bus coupling contact, said monitoring circuit processing said bus terminating signal and generating a control signal for transmission along said interconnect bus.

5. A system for detecting whether an interconnect bus is properly terminated, said system comprising:

a plurality of electronic units, each electronic unit having a bus connector for coupling said electronic unit to said interconnect bus;

a terminating cap coupled to a final bus connector, said terminating cap coupling a detection loop to a bus coupling contact, said detection loop designed to ground a bus coupling contact of said final bus connector thereby indicating a proper termination; and

a monitoring circuit coupled to said interconnect bus, said monitoring circuit verifying that said bus coupling contact has been grounded.

6. The system of claim 5 wherein said detection loop couples said bus coupling contact to a ground contact in said final bus connector causing a bus termination signal to be generated which indicates that said terminating cap is coupled to said final bus connector.

7. The system of claim 5, wherein said monitoring circuit receives said bus terminating signal resulting from grounding of the bus coupling contact, said monitoring circuit processing said bus terminating signal and generating a control signal for transmission along said interconnect bus.

8. The system of claim 7 wherein said monitoring circuit comprises a microcontroller.

9. The system of claim 7 wherein said monitoring circuit comprises a plurality of logic gates.

10. The system of claim 5 wherein said monitoring circuit comprises a microprocessor.

11. The system of claim 5 wherein said detection loop couples said bus coupling contact to a shield of said final bus connector.

12. The system of claim 5 further comprising an auxiliary power supply which supplies power to said bus coupling contact.

13. A method of determining whether a bus is properly terminated comprising the steps of:

applying a voltage to a bus coupling contact;

grounding said bus coupling contact if a terminating cap is coupled to a bus connector;

generating a bus termination signal based on the potential of said bus coupling contact.

14. The method of claim 13 further comprising the steps of:

processing said bus termination signal and generating a control signal indicating proper termination if said terminating cap is coupled to said bus connector;

transmitting said control signal along said bus.

15. The method of claim 13 when said grounding step is executed by coupling said bus coupling contact to a bus ground contact located in a final bus connector.

16. The method of claim 13 wherein said grounding step is executed by coupling said bus coupling contact to a shielding of said bus.

17. The method of claim 14 further comprising the steps of:

receiving said control signal at a managing unit; and

,

displaying an error signal on a display device if said bus is not properly terminated.

18. The method of claim 14 wherein said method further includes the step of:

transmitting an address of an electronic unit which improperly terminates said bus.

19. An electronic system, the system configured to simplify maintenance procedures, said system comprising:

a plurality of electronic units connected via a serial bus;

a final electronic unit coupled to the bus, said final electronic unit including a terminating cap having a connection which deasserts an asserted signal to indicate to a processor in said final electronic unit that the final electronic unit is properly terminated.

20. The electronic system of claim 19 wherein said processor transmits a signal to a system manager unit which simplifies maintenance procedures by causing said system manager unit to notify service personnel that said final electronic unit is improperly terminated.

21. The electronic system of claim 19 further comprising a network server hub which directs information flow between a system manager unit and the final electronic unit.

22. The electronic system of claim 20 further including a second daisy chain of electronic units, said second daisy chain of electronic units coupled to a second final electronic unit sending a second signal indicating proper termination of said second final electronics unit.