Applications and Experiments with e. Blocks – Electronic Blocks for Basic Sensor-Based Systems Susan Cotterell*, Kelly Downeyŧ, Frank Vahid*¥ * Department of Computer Science and Engineering ŧ Department of Electrical Engineering University of California, Riverside {susanc, kstephen, vahid}@cs. ucr. edu; http: //www. cs. ucr. edu/eblocks ¥ Also with the Center for Embedded Computer Systems at UC Irvine This work is being supported by the National Science Foundation and a Department of Education GAANN Fellowship
A Typical Problem Garage door . . . left open at night - Oops! Susan Cotterell and Frank Vahid UC Riverside 2
Solution: A Simple “Embedded System” w Blink LED in bedroom if garage open at night n Homeowner sees LED before bed w Components needed n n n LED Contact switch Light sensor Logic (no light AND switch not closed) Wireless transmitter Wireless receiver LED receive transmit AND light contact sensor switch Susan Cotterell and Frank Vahid UC Riverside 3
Possible solutions w Alarm company -- too expensive w Off-the-shelf n n Low volume product: hard-to-find, costly Inflexible: What if two garage doors; notification in 2 places; audible alert? l Vendor can’t include everything w Build it yourself n n n Should be feasible for semi-skilled person Hard! -- Find components (where? ), read datasheets (tough), program microcontrollers (much skill), build circuit boards (more skill) Low power issues l l n http: //www. smarthome. com Battery drains in 2 days Need packets and sleep - more skills Experiment l l 50 skilled students (CS, EE) given weeks 60% did not complete w l 40%’s solutions were not power efficient No way regular person could build it Susan Cotterell and Frank Vahid UC Riverside 4
What’s Needed w The wood and nails of the sensor world w So novices can build simple things and semi-skilled people even more Susan Cotterell and Frank Vahid UC Riverside 5
Our Solution – Off-the-Shelf Easy-to-Use Electronic Building Blocks -- e. Blocks w e. Blocks – Electronic Building Blocks w w Enable people with no programming or electronics expertise to build sensor-based systems w Basic block with predefined functions w Standard plugs and communication w Connected like Legos, interchangeable w Battery powered (wall/other power optional) First version: Boolean (“yes/no”) e. Blocks (future: Integer blocks) w Sensors like motion, light, sound, button, contact, etc. , send Boolean (“yes” or “no”) w Outputs like LED, beeper, electric relay, PC, etc. w Compute blocks perform logic & state functions Motion yes/no Sensor Button yes/no Light yes/no Sensor yes/no LED Beeper yes/no Toggle yes/no 2 -Input Logic in rst Other logic/state blocks “Opposite” Tripper “Once yes, stays yes” (until reset) “Yes prolonger” Button “Pulse generator” yes red means NO Button no yellow means ERROR green means YES Susan Cotterell and Frank Vahid UC Riverside About 15 basic blocks 6
Connect e. Blocks to Build Application w Basic blocks enable variety n n Garage Open At Night Detector Flexible: 2 garages, >1 alert. . . Different applications w/ blocks Enables mass production l l Low cost: ~$4 (Harvard Bus. Sc. ) Available: next to wood/nails? Light Sensor Outside Magnetic Contact Switch wireless TX 2 -Input Logic wireless RX LED Inside house At garage door w 2003 -2004: ~100 prototypes, 15 types Size: deck of cards n PIC processor and electronics n 2+ years on 9 -volt battery Protocol/architecture: ISSS/CODES’ 03 n w n n w Illusion of continuous communication, but packets & sleep Constraints & timeouts (data, alive) ensure connect/disconnect response LED Splitter 2 -Input Logic Toggle Button Service Line Kitchen Hands-on -- intuitive, few abstractions n Enables step-by-step design: DEMO Susan Cotterell and Frank Vahid UC Riverside 7
1000 s of Applications, Not Just Garages w Countless applications n Residential l n Office/Commercial l n n Sleepwalker detection, hard-ofhearing sound alert, water leak alert. . . Environmental l n Cafeteria food alert, front desk notifier, conference rooms in use, copy machine in use, visitor at front gate, reserved parking spot detector Health l n Wireless doorbell, mail alert, gate open, motion on property, package on porch, customized motion lights, carpool alert Temperature logging, animal tracking, . . . And others… Current projects l l Endangered species photography project with county Developing an elder wellness home monitoring project with major company Susan Cotterell and Frank Vahid UC Riverside 8
e. Blocks and “Traditional” Sensor Networks w Each e. Block has specific function n User does not write programs l l l Only minor configuration may be required Connecting blocks creates end-application Programming is an option Configured to AB’ Motion Sensor Light Sensor A 2 -Input Logic B w Wired connections n n Makes connectivity explicit (intuitive), less power, lengthens distances (2 miles) Wireless point-to-point link is an option w e. Blocks NOT a replacement for traditional sensor network nodes; instead: 1. Some systems e. Blocks only, or front (or back)-end to PC or appliance 2. Front (or back)-end to sensor-network nodes 3. Sensor-network nodes inside e. Blocks Wireless Receiver e. Block Sensor Node Wireless Transmitter Beeper or or e. Block-only application e. Block State Block Node e. Block Logic Block Node Front/back-end to traditional sensor network nodes e. Block Sensor e. Block Logic Block Node e. Block Sensor e. Blocks implemented with traditional sensor network nodes Susan Cotterell and Frank Vahid UC Riverside 9
Experiments w Can people of varying skill levels build basic sensor-based systems using e. Blocks? Button Motion Sensor Beeper Toggle Front Desk Notifier in Button Light Sensor Magnetic Contact Switch LED rst Tripper Beeper Package Delivery Alert 2 -Input Logic Sensors-with-state Garage Open at Night LED Light Sensor Button Splitter 2 -Input Logic Beeper 2 -Input Logic Toggle Button Daytime Doorbell Service Line Sensors-with-logic Cafeteria Food Alert Kitchen Sensors-with-logic-and-state Susan Cotterell and Frank Vahid UC Riverside 10
Experiments w w Prototypes and graphical simulator Users of varying skill n n n w Beginners: non-science/non-engin. majors in required computer applications course Intermediate: first year programming course Advanced: upper-division embedded systems course Just 1 -minute introduction, no grade n Thus, students not particularly motivated l l n w But we didn’t want to influence the results Motivated people performed much better No assistance (from us or others) Short time: 8 -10 minutes n Tests whether immediately understandable l Success improves with time Susan Cotterell and Frank Vahid UC Riverside 11
Results Sensor-with-logic Sensor-with-state Success Rate Success Num. Rate Students Num. Students Sensor-with-logicand-state Beginner 35 % 86 100 % 2 0% 2 Intermediate 47 % 113 56 % 101 0% 21 Advanced 85 % 82 80 % 65 28% 16 54 % 281 66 % 168 12 % 39 Overall When A is All experiments: students had less than 10 minutes to complete yes AND B is no OR yes no then the output is yes Good % given building systems with multiple blocks, configuring. Basic state blocks seem intuitive. logic, in just a few minutes Combine A A When A the input A A is B yes no B B The B output B should be out Combine Success rate increases with experience level. Also, plenty of close solutions. Students need more time to build more complex systems Susan Cotterell and Frank Vahid UC Riverside 12
Previous Work – Programmable Products Lego. Mindstorms http: //www. mindstorms. lego. com w Customizable Solutions w User selects sensors and actuators, possibly connect to central device w Nodes or central device programmed by the user ir sensor potentiometer w Programmed via Visual Basic, C/C++, Graphical languages, etc. temperature sensor Teleo http: //www. makingthings. com w Domains accelerometer w Education/Toys w MIT Crickets, Lego Mindstorms w Industrial w Phidgets, Teleo w Sensor networks w Motes, Smart Dust light sensor joystick Phidgets http: //www. phidgetsusa. com w Requires user programming Mica Motes http: //www. xbow. com Susan Cotterell and Frank Vahid UC Riverside 13
Previous Work – Board & Block Products Electronic components Users connect components to build systems Functionality defined within individual block Some too simplistic for building sensor based systems – intended for younger audiences w Some intended for other domains w w Kharma, N. and L. Caro. Magic. Blocks: A Game Kit for Exploring Digitial Logic. American Society for Engineering Education Annual Conference, 2002. w Hobbyists w Electronics education Logiblocs http: //www. logiblocs. com Robobrix Electronic Blocks http: //www. itee. uq. edu. au/~peta/_Electr onic. Blocks. htm Logidules http: //diwww. epfl. ch/lami/teach/ logidules. html http: //www. robobrix. com Susan Cotterell and Frank Vahid UC Riverside 14
Summary and Future Work w Summary w Developed a set of electronic building blocks – e. Blocks w Discussed applications and relation to traditional sensor-network nodes w Initial studies show that users can effectively build basic systems w Present/Future Work w Improved success rate through intuitive logic/state blocks (CHI’ 05 HCII’ 05 submitted) w Extend e. Blocks to integers (presently Boolean) w Integer sensors, arithmetic compute blocks w Wider-range of systems w PC-based tools for more experienced users w Programmable e. Block w Automated design synthesis from simulator-based design (DATE’ 05 submitted) w Power sharing through wires w CAD tools to build e. Blocks themselves Susan Cotterell and Frank Vahid UC Riverside (DATE’ 05 submitted) 15
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