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An Inter-ORB Protocol for CORBA-based Embedded Systems on the CAN Bus

An Inter-ORB Protocol for CORBA-based Embedded Systems on the CAN Bus. 김기문, 전광일, 홍성수, 김선일, 김태형 발표자: 홍성수 교수 서울대 전기공학부 실시간 운영체제 연구실. Presentation Outline. Motivations Design Goals Controller Area Network (CAN) Design Overview Publisher/Subscriber Protocol for CORBA

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An Inter-ORB Protocol for CORBA-based Embedded Systems on the CAN Bus

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  1. An Inter-ORB Protocol for CORBA-based Embedded Systems on the CAN Bus 김기문, 전광일, 홍성수, 김선일, 김태형 발표자: 홍성수 교수 서울대 전기공학부 실시간 운영체제 연구실

  2. Presentation Outline • Motivations • Design Goals • Controller Area Network (CAN) • Design Overview • Publisher/Subscriber Protocol for CORBA • Embedded Inter-ORB Protocol (EIOP) • Conclusions

  3. Motivations (1/2) • Increased Demand for Distributed Embedded Systems Centralized System A single computer connects every peripherals. Distributed System a network of specialized micro-controllers • expensive • point-to-point wiring • limited scalability • cost-effective • modular • extensible

  4. Motivations (2/2) • Component S/W for Distributed Embedded Systems All-in-one System Component-based System • low-level languages • no OS and middleware • hand-tuning • mixed-up modules • object-orientation • platform independence • extensible interfaces • high reusability

  5. Design Goals • Customization of CORBA for Embedded Networks Customization CORBA CAN-based CORBA • Target Network: CAN (Controller Area Network) • Redesign the inter-ORB protocol (IOP) of CORBA • Support the group communication model • Reduce resource demands

  6. Controller Area Network (CAN) (1/3) • ISO-IS 11898 Standard for Real-time Control Networks • Bounded message transfer latency • Non-destructive priority-based bus arbitration • Highly resistant toelectro-magnetic interference

  7. Power Locks FCU Air Con- dition FCU C A N Dash Board C A N CAN CAN CAN CAN CAN Power Win- dows FCU Power Seats FCU Airbag FCU Controller Area Network (CAN) (2/3) • Embedded Control Network (ECN) • Functional Control Unit (FCU) Anti- Lock Brakes FCU Engine Control FCU Lighting FCU CAN CAN CAN ECN 1 ECN 2 CAN CAN Trans- mission Control FCU Active Suspen- sion FCU

  8. Controller Area Network (CAN) (3/3) • Unique Features Slow Serial Bus Group Communication • 1 Mbps bandwidth • 8 bytes payload • n by n • subject-based addressing • h/w based message filtering

  9. Design Overview

  10. Publisher/Subscriber Protocol for CORBA (1/4) • Protocol Header for CAN 2.0A • TxNode + TxPort = global port address

  11. Publisher/Subscriber Protocol for CORBA (2/4) • Conjoiner-based object binding scheme

  12. Publisher/Subscriber Protocol for CORBA (3/4) • Example Subscriber Code

  13. Publisher/Subscriber Protocol for CORBA (4/4) • Example Publisher Code

  14. Embedded Inter-ORB Protocol (EIOP) (1/4) • Compact Common Data Representation (CCDR) • no alignment • no padding bytes. • variable-length integer • For every 32-bit integer, saves two or three bytes.

  15. Embedded Inter-ORB Protocol (EIOP) (2/4) • Simplified Message Types of EIOP • merely two message types supported • removed message types • location forward and connection management • LocateRequest, LocateReply, CloseConnectionand Fragment • Bi-directional synchronous communication • Reply and MessageError

  16. Embedded Inter-ORB Protocol (EIOP) (3/4) • Reduce the message header length of the Request type.

  17. Embedded Inter-ORB Protocol (EIOP) (4/4) • Magic is reduced into one byte. • Merge GIOP_version, flags and message_types into the one-byte flags. • Use integer-based identifiers for object_key and operation. • Note that the resulting message fits in one CAN frame.

  18. Conclusions • Summary • environment specific CORBA for embedded control networks. • anonymous publisher/subscriber communication. • minimized network resource demand. • IDL-level compliant to the standard CORBA. • Future Works • performance number report. • inter-operability with standard ORBs.

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