Applications and Experiments with
eBlocks – 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 of 15
Solution: A Simple “Embedded System”
 Blink LED in bedroom if garage
open at night

Homeowner sees LED before
bed
 Components needed






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 of 15
Possible solutions
 Alarm company -- too expensive
 Off-the-shelf


Low volume product: hard-to-find, costly
Inflexible: What if two garage doors;
notification in 2 places; audible alert?

Vendor can’t include everything
 Build it yourself



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



http://www.smarthome.
com
Battery drains in 2 days
Need packets and sleep - more skills
Experiment


50 skilled students (CS, EE) given weeks
60% did not complete


40%’s solutions were not power efficient
No way regular person could build it
Susan Cotterell and Frank Vahid
UC Riverside
4 of 15
What’s Needed
 The wood and nails of the sensor world
 So novices can build simple things and semi-skilled people even
more
Susan Cotterell and Frank Vahid
UC Riverside
5 of 15
Our Solution – Off-the-Shelf Easy-to-Use
Electronic Building Blocks -- eBlocks
 eBlocks – Electronic Building Blocks

 Enable people with no programming or
electronics expertise to build sensor-based
systems
 Basic block with predefined functions
 Standard plugs and communication
 Connected like Legos, interchangeable
 Battery powered (wall/other power optional)
First version: Boolean (“yes/no”) eBlocks (future:
Integer blocks)
 Sensors like motion, light, sound, button,
contact, etc., send Boolean (“yes” or “no”)
 Outputs like LED, beeper, electric relay, PC, etc.
 Compute blocks perform logic & state functions
Motion
Sensor
Button yes/no
yes/no
Light yes/no
Sensor
yes/no
yes/no
LED
Beeper
yes/no
yes/no
yes/no
Toggle
yes/no
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 of 15
Connect eBlocks to Build Application
 Basic blocks enable variety




Garage Open At Night Detector
Flexible: 2 garages, >1 alert...
Different applications w/ blocks
Enables mass production


Low cost: ~$4 (Harvard Bus.Sc.)
Available: next to wood/nails?
Light Sensor
wireless
TX
Outside
Magnetic
Contact
Switch
2-Input Logic
wireless
RX
LED
Inside house
At garage door
 2003-2004: ~100 prototypes, 15
types
Size: deck of cards

PIC processor and electronics

2+ years on 9-volt battery
Protocol/architecture: ISSS/CODES’03





Illusion of continuous communication,
but packets & sleep
Constraints & timeouts (data, alive)
ensure connect/disconnect response
LED
LED
Splitter
2-Input Logic
Toggle
Button
Button
Service Line
Kitchen
Hands-on -- intuitive, few abstractions

Enables step-by-step design: DEMO
Susan Cotterell and Frank Vahid
UC Riverside
7 of 15
1000s of Applications, Not Just Garages

Countless applications

Residential


Office/Commercial



Sleepwalker detection, hard-ofhearing sound alert, water leak
alert...
Environmental


Cafeteria food alert, front desk
notifier, conference rooms in use,
copy machine in use, visitor at
front gate, reserved parking spot
detector
Health


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


Endangered species photography
project with county
Developing an elder wellness home
monitoring project with major
company
Susan Cotterell and Frank Vahid
UC Riverside
8 of 15
eBlocks and “Traditional” Sensor Networks
 Each eBlock has specific function

User does not write programs



Only minor configuration may be required
Connecting blocks creates end-application
Programming is an option
Configured to
AB’
A
Motion
Sensor
Light
Sensor B

Beeper
or
or
2-Input Logic
Wireless
Transmitter
eBlock-only application
 Wired connections

Wireless
Receiver
Makes connectivity explicit (intuitive), less
power, lengthens distances (2 miles)
Wireless point-to-point link is an option
 eBlocks NOT a replacement for traditional
sensor network nodes; instead:
1. Some systems eBlocks only, or front (or
back)-end to PC or appliance
2. Front (or back)-end to sensor-network
nodes
3. Sensor-network nodes inside eBlocks
eBlock
Sensor
eBlock
Sensor
eBlock
Sensor
Node
Node
eBlock
State Block
Node
Node
eBlock
Logic Block
Node
Front/back-end to traditional sensor
network nodes
eBlock
Sensor
eBlock
Logic Block
Node
eBlock
Sensor
eBlocks implemented with
traditional sensor network nodes
Susan Cotterell and Frank Vahid
UC Riverside
9 of 15
Experiments

Can people of varying skill levels
build basic sensor-based systems
using eBlocks?
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
LED
Light
Sensor
Splitter
Button
2-Input Logic
Beeper
2-Input Logic
Toggle
Button
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 of 15
Experiments


Prototypes and graphical simulator
Users of varying skill




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

Thus, students not particularly motivated




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

Tests whether immediately understandable

Success improves with time
Susan Cotterell and Frank Vahid
UC Riverside
11 of 15
Results
yes
no
Sensor-with-state
Success
Rate
Success
Num.
Success
Num.
Rate
Students
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
Sensor-with-logic
AND B is
OR
yes
no
then the output is yes
All
experiments:
students had
less than 10
minutes to
complete
Good % given building systems
with multiple blocks, configuringBasic 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 of 15
Previous Work –
Programmable Products
LegoMindstorms
http://www.mindstorms.lego.com
 Customizable Solutions
 User selects sensors and
actuators, possibly connect to
central device
 Nodes or central device
programmed by the user
ir sensor
potentiometer
 Programmed via Visual Basic,
C/C++, Graphical languages,
etc.
temperature
sensor
Teleo
http://www.makingthings.com
 Domains



accelerometer
Education/Toys
 MIT Crickets, Lego Mindstorms
Industrial
 Phidgets, Teleo
Sensor networks
 Motes, Smart Dust
light sensor
joystick
Phidgets
http://www.phidgetsusa.com
 Requires user programming
Mica Motes
http://www.xbow.com
Susan Cotterell and Frank Vahid
UC Riverside
13 of 15
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
 Some intended for other domains




Kharma, N. and L. Caro.
MagicBlocks: A Game Kit for Exploring Digitial Logic.
American Society for Engineering Education Annual
Conference, 2002.
 Hobbyists
 Electronics education
Logiblocs http://www.logiblocs.com
Robobrix
Electronic Blocks
http://www.itee.uq.edu.au/~peta/_Electr
onicBlocks.htm
Logidules
http://diwww.epfl.ch/lami/teach/
logidules.html
http://www.robobrix.com
Susan Cotterell and Frank Vahid
UC Riverside
14 of 15
Summary and Future Work
 Summary
 Developed a set of electronic building blocks – eBlocks
 Discussed applications and relation to traditional sensor-network nodes
 Initial studies show that users can effectively build basic systems
 Present/Future Work
 Improved success rate through intuitive logic/state blocks (CHI’05 HCII’05
submitted)
 Extend eBlocks to integers (presently Boolean)
 Integer sensors, arithmetic compute blocks
 Wider-range of systems
 PC-based tools for more experienced users
 Programmable eBlock
 Automated design synthesis from simulator-based design
(DATE’05
submitted)
 Power sharing through wires
 CAD tools to build eBlocks themselves
Susan Cotterell and Frank Vahid
UC Riverside
(DATE’05 submitted)
15 of 15