MODEL AND DESIGN OF DISTRIBUTED EMBEDDED SYSTEMS ____________________________________ A Thesis Presented to the Faculty of California State University, Fullerton ____________________________________ In Partial Fulfillment of the Requirements for the Degree Master of Science in Computer Engineering ____________________________________ By Thanga Nirmala Dasamoni Thesis Committee Approval: Michael Turi, Department of Computer Engineering, Chair Kiran George, Department of Computer Engineering Kenneth Faller, Department of Computer Engineering Fall, 2016 ABSTRACT Many model-based approaches have been suggested to improve and accelerate the development process of complex distributed embedded systems (DES) from design to deployment. In this approach, abstract models of the system are created and then transformed systematically into concrete implementations. Modeling focuses on commands and information being distributed reliably throughout the system with minimized latency to maintain acceptable QoS. In this research, an irrigation system is developed. Model-based development was used to model the architecture and communication of distributed nodes. However, the complexity of the Bluetooth Low Energy (BLE) communications used by the irrigation system requires a model with very high sophistication in the bottom-up modeling approach. A distributed irrigation system is implemented as a proof of concept using an experimental Bluetooth Low Energy based network topology and protocol, and the data was observed to verify the correct operations. ii TABLE OF CONTENTS ABSTRACT ................................................................................................................... ii LIST OF TABLES ......................................................................................................... v LIST OF FIGURES ....................................................................................................... vi ACKNOWLEDGMENTS ............................................................................................. viii Chapter 1. INTRODUCTION ................................................................................................ 1 2. MODEL BASED DEVELOPEMENT ................................................................. 4 Modeling Basics ................................................................................................... 4 Modeling Languages: UML and SysML ....................................................... 6 Generation of Low Level Representation in Modeling ................................. 10 Evaluation of Model Based DES .......................................................................... 10 Evaluation Criteria ......................................................................................... 11 Evaluation Process ......................................................................................... 13 3. DESIGN OF A DISTRIBUTED EMBEDDED SYTEM FOR IRRIGATION CONTROL............................................................................................................ 21 Distributed Embedded Systems ............................................................................ 21 Advantages of DES ........................................................................................ 22 Issues in DES ................................................................................................. 23 DES Models ................................................................................................... 23 Design and Development of Irrigation Controller: Proof of Concept .................. 24 Hardware Architecture .......................................................................................... 25 Soil Moisture Sensor ...................................................................................... 27 Temperature and Relative Humidity Sensor .................................................. 28 Software Architecture ........................................................................................... 28 BLE Based Communication Protocol Layer ................................................. 28 The Communication Topology ...................................................................... 41 Spanning Tree Algorithm .............................................................................. 43 Application Layer .......................................................................................... 47 Development of Irrigation Controller ................................................................... 51 Implementation of Spanning Tree Protocol ................................................... 52 iii Implementation of Application Layer ............................................................ 56 Testing ........................................................................................................... 67 4. CONCLUSION AND FUTURE WORK ............................................................. 59 Conclusion ............................................................................................................ 59 Future Work .......................................................................................................... 59 REFERENCES .............................................................................................................. 61 iv LIST OF TABLES Table Page 1. Required Parameters for Calculating ET ............................................................. 49 2. Crop Water Use Table for Checkbook Method ................................................... 50 3. BLE Advertising PDU Structure ......................................................................... 55 4. Application Advertising PDU Structure .............................................................. 55 5. Application Layer Classes: WeatherSense and ValveController ......................... 57 v LIST OF FIGURES Figure Page 1. Metamodeling ..................................................................................................... 5 2. UML diagram types ............................................................................................. 7 3. SysML diagram types .......................................................................................... 9 4. Use Case diagram of the Irrigation Controller. .................................................... 16 5. Pinger and Ponger capsules and their interactions ............................................... 17 6. Pinger state machine ............................................................................................ 18 7. Ponger state machine ........................................................................................... 18 8. Organization of a distributed system ................................................................... 22 9. Hardware architecture of the Irrigation Control system. ..................................... 26 10. Soil moisture sensor output Vs VWC .................................................................. 27 11. BLE protocol stack components and layers for a single mode device ................ 31 12. BLE channel arrangements .................................................................................. 32 13. Advertising and scanning timings ........................................................................ 35 14. BLE over-the-air frame packet ............................................................................ 36 15. BLE topology ....................................................................................................... 38 16. GATT attribute table ............................................................................................ 39 17. Bluetooth piconet topology and Spanning Tree topology ................................... 42 18. BLE API interface................................................................................................ 53 vi 19. Classes used in communication layer .................................................................. 54 vii ACKNOWLEDGMENTS It is with a deep sense of gratitude that I thank Dr. Mike Turi, Department of Computer Engineering, for his inspiring guidance and constant encouragement throughout the course of this work. I could not have asked for a better supervisor and a mentor than Prof. Turi, who was not only my sounding board but also showed infinite patience by allowing me to pursue my style of research. My heartfelt thanks is also extended to my thesis committee: Dr. Kiran George and Dr. Kenneth Faller for their insightful comments and encouragement. To my mother, my siblings, my husband, my children, and the community I live in, for their constant support and encouragement, I owe everything. viii 1 CHAPTER 1 INTRODUCTION Designing and building Distributed Embedded Systems (DES) is a challenging task. These systems are still developed in an ad-hoc manner as the block components and middleware required for building such applications are hard to find in formally verifiable and analyzable format [1]. Moreover, the design complexity of these systems increases tremendously with the need to adapt to the new processes quickly and to develop highly customizable applications that are mostly heterogeneous in specification and complexity. Application developers use standards-based QoS enabled component based middleware such as Common Object Request Broker Architecture (CORBA) to develop individual components and later compose them in a plug and play manner to realize the complete system. But this comes with significant