Pluggable Realworld Interfaces
This document proposes pluggable real world interfaces that allow objects to have embedded software and sensors. It describes a two-step approach where real world interfaces with hardware are first deployed to objects, giving them awareness of their context, and then logic can be deployed through a network. This would allow objects like chairs to have code stored in them to recognize their state and interact in an office environment. The implementation uses small sensor nodes and a Java virtual machine to execute code on the objects. An evaluation shows the overhead is small and sensors can easily fit on low-cost memory. The conclusion is that context-awareness can be achieved by storing code in physical objects, and embedded systems can benefit from virtual machine abstraction.
Pluggable Realworld Interfaces
- 1. Pluggable Real World Interfaces Till Riedel*, Phillipp Scholl*, Christian Decker*, Martin Berchtold* and Michael Beigl** (*TecO, University of Karlsruhe, **DUS, University of Braunschweig)
- 2. Smart Items Interface the world (context awareness) Push Logic to the Item (ad-hoc collaboration) Example: − Chairs − Pen − Sponge − Doorplate − White board camera AwareOffice / 2
- 3. Logic on the Item should extensible and adaptable should be sensor hardware independent needs execution and communication platform / 3
- 4. Real World Interfaces recognize static and dynamic context of object − e.g. so. I am a chair and so. is sitting on me, ... depends on sensor types − Acceleration sensors, pressure sensor, ball switches depends on sensor placement − Direction, seat/arm rest depends on mechanical model − swivel chair, easy chair, stool / 4
- 5. Key Ideas Execute instead of describing sensor semantics − Unlike SensorML, IEEE 1451 Abstract Real World Interfaces − As High-Level Interfaces − accessible through Programming Language − Use type hierarchies and reflection Bundle Software and Hardware − Enable production of Smart Objects − Physically enabled code deployment / 5
- 6. 2-Step Approach Deploy Real World Interfaces with Hardware (Sensors+Interpretation) Deploy Logic with Network Architecture / 6
- 7. Implementation Load code from object into (virtual) machine Execute Static Initializers Item becomes “aware” Discover Deploy Logic / 7
- 8. Platform Particle Sensor Nodes − PIC18F6720: 8bit, 5MHz − TR1001 low power radio 21-Pin FCI Conan Connector Various Sensors Boards − SPI, I²C, PWM, 1Wire, Analog Particle Java VM − supports javac − code compression − class loading / 8
- 9. Evaluation Execution overhead : 30x (from external flash) Object overhead: 3 byte Code size for Sensors − ADXL210: 167 byte − Ballswitch: 29 byte − TC74: 120 byte − Microphone: 49 byte − TSL2550: 295 byte − TSOP36236: 49 byte Fits easily on cheap ROM/Flash / 9
- 10. Conclusion software engineering needs to consider “hardware context” context-awareness can be just storing code in the right place embedded design can profit from virtual machine abstraction / 10
- 11. Thank you! / 11