Design and verification of physical layer architecture for a 1-wire sensor communication bus

ii To my family. iii People think it's an obsession. A compulsion. As if there were an irresistible impulse to act. It's never been like that. I chose this life. I know what I'm doing. And on any given day, I could stop doing it. Today, however, isn't that day. And tomorrow won't be either. Batman, in Brad Meltzer's Identity Crisis iv ACKNOWLEDGMENTS I would like to thank my committee members for serving on my committee. I would like to thank all of my colleagues at IIHR for their input, especially Dr. Jim Niemeier for helping me to understand the architecture of the soil moisture network that was previously deployed in Ames, Hamid Fahim Rezaei for discussing various communications topics that helped me to come up with new ideas, and Nick Sitter for his help with the parasitic power circuit, the build of the first hardware prototype, and advice on using the ATTiny45 chip. I would also like to thank IIHR for their financial support during the time that I was working on this project. Finally, I would like to thank my advisor, Dr. Anton Kruger, for his support. This development would not have happened if it were not for his ideas and our many long discussions about the fundamental issues of implementing this type of network. figure illustrates the objective of this thesis. A 1-wire bus where users can communicate asynchronously, simultaneously, and independent of other bus users, perhaps even at different rates.. Figure 2. IIHR Soil Moisture Network Overview from [21]. This network provides significant motivation for the bus described in this thesis. The network contains wireless nodes, each with its own instrument bus. Several soil moisture and temperature probes are connected to each instrument bus and communicate using Time Division Multiple Access in timeslots assigned by the local master.. Figure 3. Soil Moisture Network Sensor Bus Illustration from [21]. Annotations have been added to show relevant communication and sensor hardware and highlight the 1-wire communication bus. The bus master is responsible for assigning time-slots to the sensor probe controllers and relaying the data to a relay node that has a cellular modem.. Figure 4. The Open Systems Interconnection (OSI) Networking Model is shown here. This model is referred to throughout this thesis, especially the Physical Layer. See [4] and [17] for a general reference on networking and the OSI Figure 6. System Model Block Diagram. The block …