Timing Analysis of Communication Cycle on Vehicular FlexRay Network

Chau-Chung Song*, Wei-Chi Chen, and Wei-Chang Chen Institute of Aviation and Electronic Technology

National Formosa University Yunlin, Taiwan, R. O. C.

*E-mail: ccsong@nfu.edu.tw

Abstract—In this paper, the systematic timing analysis of communication cycle is studied and verified for the vehicular FlexRay network. The executing timing sequences of static and dynamic segments are discussed and analyzed by performing the specific experiments for synchronous and asynchronous FlexRay system. It is found that the working time of application task should be advanced for certain time interval to guarantee the task might be successfully executed in the scheduled time slot for synchronous system. The advanced time interval depending on the design architecture of Communication Controller in FlexRay chip is to be derived from some available experiments and estimated at about one slot time for both static and dynamic segments. Furthermore, the testing platform is proposed and implemented to construct a Drive-by-Wire system which is integrated with the steer-by-wire and throttle-by-wire functions, based on FlexRay Protocol. This networking system consists of four ECU nodes to achieve the steer-by-wire, and throttle-by-wire control. In conclusion, the practical timing configuration of communication cycle is implemented and analyzed to verify and evaluate the system performance and reliability of proposed Drive-by-Wire architecture on vehicular FlexRay network.

Keywords- Timing analysis, communication cycle, FlexRay network, synchronous system, Drive-by-Wire

I.

(Electronic Control Unit ECU)

(ECU)ECU

X-by-Wire

X-by-Wire (throttle-by-wire) (brake-by-

wire) steer-by-wire

[1] FlexRay

[2]FlexRay CAN

FlexRayFlexRay

FlexRayFreescale MPC5567

ECU [3] FlexRay

Drive-by-WireFlexRay

FlexRay

FlexRayFlexRay

FlexRay FlexRay (Time Slot)

FlexRay

II. FLEXRAY FlexRay TDMA Time Division Multiple

Access

10 Mbps 20Mbps

FlexRay

978-1-4244-8039-5/11/$26.00 ©2011 IEEE

FlexRay (Time Slot)

FlexRay Host Communication Controller Bus Guardian Bus Driver

1 [4] Bus Driver Host

Communication ControllerHost Communication Controller

Communication Controller Bus Driver Bus Driver Communication Controller

Bus Driver Bus Communication Controller Bus Driver Host

Host Bus Driver Bus Driver Bus Guardian

1 FlexRay [4]

FlexRay (Bus Network) (Star Network)

(Hybrid Network) 2 [5]

2 FlexRay [5]

III. FLEXRAY FlexRay

FlexRay Bus Host ProcessorController Host Interface (CHI)(Communication Controller) (Application Layer)

(Data Link Layer)(Synchronous, SYNC) (Asynchronous,

ASYNC) CHIFlexRay

FlexRay[6]

A. FlexRay

FlexRay Slot

FlexRay

ECU ttask_work (1)

SSprepareworkAp

buffertxworkApworktask

Ttt

ttt

_

___ (1)

tAp_work ECUttx_buffer Host

Bus Driver tprepare

TSS

FlexRay 13 154MTSlot 216MT ttx_buffer 62MT

68 sBus Driver

2 TSS

2 TSS 1 TSS 151MT Slot 216MT

ttx_buffer 65MT 71 s

1 FlexRay

3 FlexRay

B.

FlexRay Host

( )(2)

DYprepareworkApDyn

buffertxDynworkApDyntaskDyn

Ttt

ttt

__

_____ (2)

TDyn_task tDyn_Ap_work

tDyn_tx_buffer Host Bus Driver Tprepare

TDY FlexRay 2 4

2 FlexRay

4 FlexRay

FlexRay

HostCommunication Controller THost_to_CC

= 11MT Ttx_data = THost_to_CC + Static Slot

Ttx_data = THost_to_CC + TCC_to_BD

IV.

A. Freescale MPC5567 FlexRay

5 FlexRay (Steering-by-

wire) (Throttle-by-wire)

5 FlexRay

ECU 6 (On-board Computer)

(Driving Sensor Unit) /FlexRay

(Speed Control Unit) FlexRay

(Steering Control Unit) Node3 FlexRay

6

FlexRay Slot FlexRay

FlexRay FlexRay

FlexRay 3

IDECU /

4

3 FlexRay

4 FlexRay

B.

ADC eSCI eMIOSADC

/3 channel ADC 3 channel ADC 81.5 s 7 3( )

1 channel ADC 1 channel ADC 34 s 8 3( )

7 3 channel ADC

8 1 channel ADC

eSCI FlexRay RS-232RS-232

15 s 9 3( )

9 RS-232

eMIOSeMIOS

1.6 s 10 3( )

10 eMIOS

C.

FlexRay

V. FlexRay

FlexRayFlexRay

FlexRayFlexRay FlexRay

FlexRay (1)

(2) Ttx_data = THost_to_CC + Static Slot

THost_to_CC = 11MT (3) Ttx_data = THost_to_CC +

TCC_to_BD

This research was supported by the National Science Council, Taiwan, R.O.C. under Grants: NSC 97-3114-E-009-002, NSC 98-2218-E-009-017 and NSC 99-2218-E-009-004.

REFERENCES [1] Jianmin Duan, Liang Zhu, and Yongchuan Yu, “Research on FlexRay

communication of Steering-by-Wire system,” Proc. 2009 IEEE Intelligent Vehicles Symposium, 3-5 June, 2009, pp. 824-828.

[2] Tae-Yoon Moon, Suk-Hyun Seo, Jin-Ho Kim, Sung-Ho Hwang and Jae Wook Jeon, “Gateway System with Diagnostic Function for LIN, CAN and FlexRay,” Proc. International Conference on Control, Automation and Systems, 17-20 Oct.,2007, pp. 2844-2849.

[3] Freescale Semiconductor Corp. MPC5567 Microcontroller Reference Manual, 2007.

[4] FlexRay Communications System Protocol Specification v2.1 Revision A, 2005.

[5] FlexRay Communications System Electrical Physical Layer Specification v.2.1 Revision B, 2006.

[6] Inseok Park and Myoungho Sunwoo, “FlexRay Network Parameter Optimization Method for Automotive Applications,” IEEE Transactions on Industrial Electronics, Issue 99, 2010, pp. 1-11.

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