CDR Presentation
Thursday February 28, 2013
Reviewed by: Prof. Bardin & Prof. Gao
Paulo Leal, Kevin Okiah, Chris Finn
& Tim Mirabito
Department of Electrical and Computer Engineering
Outline
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MDR Recap
CDR Goals/Progress
Design Choices
FPR Goals
Demos
Cost Breakdown
Questions?
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Project Recap
 Project Goal
Give people a means to monitor and control the
electrical devices within their households.
 Motivation
• Energy conservation has a significant social &
economic impact.
• It is hard to conserve energy because
• Limited quantitative data
• Limited social awareness
• Limited residential control
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MDR Recap: Block Diagram
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MDR Recap: Communication Flow
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Tim’s MDR Review
 At MDR I had reverse engineered the critical
components of the P4400 Kill-a-Watt device.
 From this process, circuit schematics for each
subsystem of the device were generated.
 In addition, a proprietary design for a
transformerless power supply was created,
simulated and laid out on a PCB.
• The specifications of were designed to match the power
requirements for our components.
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Tim’s Proposed CDR Goals
 Prototype modified “Tweet-a-Watt” for real-time
data
 Complete proprietary design of watt meter
subsystems
 Integrate relay and XBee layouts into proprietary
design
 Complete schematic and PCB layouts for a fully
functioning system
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Initial Power Supply Design
Initial PCB layout for the transformer less power supply design schematic with a 15V
and 50mA output.
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Design Revision: Power Supply
 Initial design for a
transformerless power
supply presented
efficiency & fail safe
challenges.
• Conversion Efficiency of
~10%
CUI Series VSK-S1 Model 5U
 Opted instead for a
commercial power
supply in a fail safe
configuration.
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Design Revision: Power Supply
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Design Choice: Relay Circuit
The simulation results for the XBEE
trigger showing relay control
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Design Choice: Current & Voltage Sense
Utilization of the INA128P instrumentation amplifier from Texas Instruments
was chosen due to the design being specifically applicable to our objective
and high CMRR of 130dB.
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Current & Voltage Sense Subsystem
Circuit schematic and simulation output from the implemented
design show the voltage values corresponding to current and
voltage readings being sent to the XBEE.
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Paulo’s Goals/Progress
 Build Tweet a Watt
 Networking Circuit
• Setup XBee Network
• Transmit data wirelessly from model A to B
• Control Switching Mechanism
 Relay Circuit
• Design & Test
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Overview - Design Choice: Tweet a Watt
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Overview - Design Choice: XBee Wireless Radios
 XBee Series 1
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Indoor Range: 100ft.
RF Data Rate: 250Kbps
Frequency: 2.4 GHz
AES encryption
Analog to Digital converter
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Overview – Previous Design Choice: Relay CKT
 PowerSwitch Tail for 110-120vac
• Provide single pole switching at 20
amps
• 5300vrms isolation
• Driving voltage as little as 3vdc @ 3ma
• Cost: $18.50
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New Design – Relay Circuit
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Outlet Switching Circuit
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Relay – 220V @ 20A
NPN transistor controls coil current (80mA)
R1 pulls the trigger pin to ground so if
anything goes haywire the relay will remain
in the safe (Off)
Diode – protects power supply and nearby
parts
Cost: $5
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Christopher’s CDR Goals/Progress
 Parse XBee input
 Allow connection from user interface to database
• Over internet via port forwarding
 Relay circuit control
• Integrated with user interface buttons
 Security
• SSL for apache server
• User account database/login system
• AES XBee communication encryption
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Quick Review of Design Choices
 Raspberry Pi
• 700 MHz ARM computer
• Runs custom Debian Linux
• Utilize Linux packages
 LAMP Server
 Python
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Serial communication to/from XBee
Data processing
Database interactions
Raspberry Pi GPIO control
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Security
 Generated Self-Signed SSL Certificate
• Has to be manually trusted by browser to suppress
warnings
 Login system
• Table of user/md5(password) combos
• PHP sessions
 XBee 128bit AES encryption
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Data Flow: Outlet Data
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Data Flow: Relay Control
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Additional Design Notes
 Physical Storage Requirements
• Trade off between accuracy & storage size
• Past Year
• Minute intervals => 4.2MB per outlet per year
• >1 Year
• Fifteen Min. intervals => 280KB per outlet per year
• Total per outlet = 4.2MB + 4*280KB = 5.3MB
• Est. Household Total (5 yr, 100 outlets) = ~0.5GB
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Kevin’s MDR Recap /CDR Goals
 Developed a Basic user interface prototype
that is functional across all operating system
Network
Interface
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Kevin’s MDR Recap /CDR Goals Continued
Plotting functionality
FLOT
AwesomeChartJS
Demonstrated plotting data by successfully querying the
database
User Interaction with the system was Limited
Function to receive and send relay Signal
Develop a function to assimilate new devices to the system
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PROGRESS
Programing Languages
 HTML5
 CSS
 JavaScript
 PHP
 JQUERY
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Progress continued
Main Functions
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Real-time data
Account summary
Usage History
Your Energy Cost
Devices
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Demos!
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FPR Group Goals
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Chris
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Multi-room integration (via HomePlug)
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User defined storage intervals
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Downloadable ZIPs of table data
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Optimize data calculations
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Code revisions
• Clean up & optimize
Tim
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Professor review of preliminary PCB layout for manufacture.
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Implementation of scalability functions:
• Multiple 120V Outlets
• 240V Outlet Interface
• Increased Sampling Rate
Paulo
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Expand Wireless Network to multiple rooms
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Finalize Integration Process within blocks
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Design a safe and minimized final enclosure
Kevin
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Seamless assimilation of new devices to the PowerPi system
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Expand my plotting functionality to accommodate more than one device/ outlet.
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Improve user interaction by giving users more control over the system
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Full Circuit Schematic
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XBee Explorer
Using the current design of the XBee Explorer as a foundation, the final
implementation of the watt meter PCB will have a subsystem with pin out
headers for easy upgradability.
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Full Circuit PCB Layout
 PCB layout done
via Cadsoft’s
EAGLE
 Top & Bottom
Layered with
copper
grounding.
 Part outlines
established via
silk screening.
 Board Size:
119mm x
105mm
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PCB Fabrication
 PCB fabrication can be done at many companies;
some of the ones I’ve looked at:
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Custom Circuit Boards, LLC. in AZ
E-Teknet, Inc. in AZ
PCB Solutions LLC in NV
Fineline Circuits & Technology, Inc. in CA
PCB FAB EXPRESS in CA
 The cost to fabricate a single board will cost $60$100 dependent on board layering, and size.
 The turn around time varies from 3 to 10 days.
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Cost Breakdown
QTY
UOM
Unit Price
Description
Total
1
1
$35.00
Raspberry PI Model B
$35.00
3
1
$19.49
P3 International P4400 Kill A Watt Electricity Usage Monitor
$58.47
1
1
$49.99
Actiontec PWR511K01 500 Mbps HomePlug HD Power line
Wall Plug Network Adapter
$49.99
1
1
$3.95
Jumper Wires Premium 6“ M/F Pack of 10
$3.95
1
1
$3.95
Jumper Wires Premium 6" F/F Pack of 10
$3.95
3
1
$3.00
T9A Series Relay
$9.00
2
1
$19.00
XBee Series 1 XB24-AWI-001
$38.00
5
1
$21.00
Prototype PCB
$105.00
5
1
$11.01
VSK-S1 Power Supply
$55.05
Total
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$358.41
35
Questions
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