Hardware Challenges and Their Resolution in Advancing WirelessHART

1. Hardware Challenges and Their Resolution in Advancing WirelessHART Authors:Xiuming Zhu1, Song Han1, and Aloysius Mok1 1The Department of Computer Science, the University of Texas at Austin Deji Chen2, and Mark Nixon2 2Emerson Process Management Presenter: Yi-Hung Wei1

2. Introduction • Wireless Personal Area Network(WPAN) • IEEE 802.15.4 • ZigBee • Industrial Wireless Network • Timing requirement, reliability, security concerns • WirelessHART • IEEE 802.15.4 • Hardware challenges 2003 2004 2005 2006 2007 2008 2009 IEEE 802.15.4 ZigBee WirelessHART FreeScale MC1322

3. Properties Real-Time • TDMA Technology • Centralized Network Management Reliability • Channel Hopping and Channel Blacklisting • Mesh Networking Security • Data Integrity on MAC Layer • Data Confidentiality on the Network Layer IEEE 9th International Conference on Industrial Informatics, INDIN'2011

4. WirelessHART Mesh Network IEEE 9th International Conference on Industrial Informatics, INDIN'2011

5. Outline • Hardware Challenges • Development of WirelessHART • Early Prototype • Wi-HTest • Current System • Future work IEEE 9th International Conference on Industrial Informatics, INDIN'2011

6. Hardware Challenge: MCU Speed • TDMA data link layer • Timeslot: 10ms • TsTxAckDelay: 1ms • Security mechanism • MAC layer related processing • Authenticate the incoming message • Generate authentication code WirelessHART Slot Timing IEEE 9th International Conference on Industrial Informatics, INDIN'2011

7. Hardware Challenge: Memory Size Network Layer Minimum Requirement Data Link Layer Minimum Requirement IEEE 9th International Conference on Industrial Informatics, INDIN'2011

8. Hardware Challenge: Clock Precision • WirelessHART network is a synchronized network • 10ppm drift rate of the MCU clock. • The maximum tolerance for drift is 1ms • Synchronize every 50secs between master and slave. • If the chain from time source is longer, the time to sync is shorter. IEEE 9th International Conference on Industrial Informatics, INDIN'2011

9. Outline • Hardware Challenges • Development of WirelessHART • Early Prototype • Wi-HTest • Current System • Future work IEEE 9th International Conference on Industrial Informatics, INDIN'2011

10. Early Prototype • 802.15.4 chips available in early day * J. Song, S. Han, A. K. Mok, D. Chen, M. Lucas, M. Nixon, and W. Pratt, WirelessHART: Applying Wireless Technology in Real-Time Industrial Process Control. Real-Time Technology and Applications Symposium, 2008. * J. Song, S. Han, X. Zhu, A. K. Mok, D. Chen, and M. Nixon, Demo of a Complete WirelessHART Network, ACM SenSys 2008 Demo Session. IEEE 9th International Conference on Industrial Informatics, INDIN'2011

11. Early Prototype - resolution • Some observations • MCU • Only tested with 20ms, 40ms timeslots • Software AES engine • MC1321 software AES engine • Transmitter • Maximum programmable transmit power is only 3dBm • RAM • 4KB is too limited 10ms Hardware AES 10dBm IEEE 9th International Conference on Industrial Informatics, INDIN'2011

12. Outline • Hardware Challenges • Development of WirelessHART • Early Prototype • Wi-HTest • Current System • Future work IEEE 9th International Conference on Industrial Informatics, INDIN'2011

13. Wi-HTest • Motivation • Assure the standard compliance of WirelessHART devices • Thorough tests for each layer of WirelessHART stacks are needed • Help vendors avoid expensive product recalls and technical support costs • Hardware architecture • FreeScale MC1320 • Physical layer, data link layer • ColdFireV1 MCU, 32-bit, 50.33MHz • 128KB FLASH • 16KB RAM • PC Box • Network layer S. Han, J. Song, X. Zhu, A. K. Mok, D. Chen, M. Nixon, W. Pratt, and V. Gondhalekar, Wi-HTest: Compliance Test Suite for Diagnosing Devices in Real-Time WirelessHART Network. Real-Time Technology and Applications Symposium, 2009.

14. Wi-HTest • Clock precision • ±2.5ppm oscillator as the external clock input • The drift is consistent in fixed environment • It is possible to compensate it with software • Security computation • CCM algorithm is still expensive • Parallel decoding • Pre-compute acknowledgement message • Flash Memory Usage IEEE 9th International Conference on Industrial Informatics, INDIN'2011

15. Outline • Hardware Challenges • Development of WirelessHART • Early Prototype • Wi-HTest • Current System • Future work IEEE 9th International Conference on Industrial Informatics, INDIN'2011

16. Current System • Hardware • FreeScale MC1322 • 32-bit 24MHz ARM7 MCU • 22mA typical RX current draw • 29mA typical TX current draw • Extensive sleep mode • MAC accelerator • Advanced AES hardware engine • Software • Complete WirelessHART mesh networking functionality IEEE 9th International Conference on Industrial Informatics, INDIN'2011

17. Current System – cont. • 10 devices and 1 AP in the system • Devices publish data to GW with different sampling rates (1sec – 8sec) • Retry happens but no packet loss is detected

18. Outline • Hardware Challenges • Development of WirelessHART • Early Prototype • Wi-HTest • Current System • Future work IEEE 9th International Conference on Industrial Informatics, INDIN'2011

19. For future work • Memory • 96K Flash for WirelessHART stack • 24K RAM for the data section • More space for application layer • Clock • High precision • Maintains precision when sleep • Power • More sensitive receiver • More deeper sleep mode • Encryption • Hardware AES engine or fast MCU • Open AES engine IEEE 9th International Conference on Industrial Informatics, INDIN'2011

20. Summary • Chronicle our work and provide our experience of the system design challenge of WirelessHART • Prototype • Wi-Htest • Complete WirelessHART mesh network • Provide hardware requirement for future industrial wireless embedded network chip IEEE 9th International Conference on Industrial Informatics, INDIN'2011

21. Thank You! Comments? IEEE 9th International Conference on Industrial Informatics, INDIN'2011