Download CDR - UCF EECS

Group 32
Watts The Matter?
Home Power Consumption Monitor
CpE: Daniel Allen
EE: Jonathan Nguyen
CpE: Richard Velez
Motivation
Many people are aggravated at the end of the month when they see
their electric bill and have no idea why it is so high
There is a curiosity as to what consumes the most power in a
house or apartment and while many people have a good idea as to
what devices do, they do not know the exact numbers
In an effort to reduce power consumption in a reasonable manner it
would be useful to have a system in place that can report in a
familiar measurement (kW/h) as to how much is being used
Goals & Objectives
Measure and report power consumed by each device plugged into an
outlet
Give users the ability to set goals that can be met during a month or longer
period
Forecast power consumption and turn off offending devices (with
permission) that will prevent the user from reaching previously set goals
Accurately predict the users bill given the kWh rate by the user as well as
their billing cycle
Record a users history for long term storage so that it can be reflected on
in the future through the use of graphs and other analysis
Block Diagram
Microcontroller
Parallax P8X32A-Q44
44-Pin Quad Flat Package (QFP) Chip (32 GPIO)
8 Independent Cores running on same system clock
System Clock Speed: DC to 80 MHz
32 KB Ram + 32 KB ROM
Up to 40 mA per I/O
VDD 3.3 V
Capable of producing VGA/NTSC/PAL signal
Can run assembly and C within the same program, support for other
languages as well
MSRP $7.99
How Efficient?
EEPROM
Microchip Technology IC EEPROM
512K (64K x 8)
400kHz
Interfaces with I²C
Requires 2.5 ~ 5.5V (will use 3.3V)
8 pin SOIC package
Will be used for holding the main program and the
users history
Programming the Microcontroller
There were two routes that could
be taken and those include USB or
serial
The option selected was a 9 pin D
Sub connector to allow
programming over a serial
connection
Programming is completed upon
booting the microcontroller if serial
connection exists
Displaying Content to User
The use of a DE-15 connector
will be needed to output a
VGA signal to an LCD screen
Requires 5V on pin 9
8 resistors will be used to get
the appropriate timings for the
RGB signals
LCD Screen
7” Resistive Touch LCD panel
Inputs include HDMI, VGA, and 2
AV sources
Driver Board Included
640x480 Resolution
Touchscreen used to eliminate the
need of a mouse or keyboard
4 Pin FFC Connector
Flat flex cable connector is needed to
obtain the input from the resistive touch film
from the LCD panel
Analog signal will need to be converted to
digital using two 1nF capacitors, a 100kΩ
resistor, and two pins on the microcontroller
in conjunction with the cog counters
Sigma Delta conversion will be used
Quad 1-2 Demultiplexer
Used to change inputs on the
touch screen
Supply voltage: 4 - 5.5V
Less than 0.25ns max delay
through switch
No circuit bounce
Close to 0 standby current
Real Time Clock
Maxim DS1302
Accept to voltage inputs from battery and power source
Selects the greater of two sources
Use with 32.768 kHz crystal
Trickle Charger
2.0V to 5.5V
CR1220 Battery used
3 wire serial interface
Power Source
CUI Inc Barrel Power Connector (SMT)
Rated for 16VDC and 5A
2.1mm ID, 5.5mm OD
CUI Inc Wall Adapter
Can accept 90-264 VAC
Outputs 12V and 2A
2.1mm ID, 5.5mm OD
Power Regulation
Step down from 12VDC 2A to 5V 2A and with slight modification 5V to 3.3V 2A
Power Regulation Cont
Texas Instruments TPS54331 Switching Regulator
Capable of handling 3.5V to 28V input
Transient voltage protection
Small Outline Integrated Circuit (SOIC) 8 package
Supported by SwitcherPro software
Includes PowerPAD technology for better cooling
High Efficiency at Light Loads
Initial Startup
Program Flow
Schematic (Main Board)
Kilowatt Hour Meter
Determine power drawn from appliances
Transmit data back to central hub
Correctly read in Voltage and Current
Capable of cutting off power to an outlet
Kilowatt Hour Meter
Connects directly to live and neutral wires
of outlet
Break in both the live and neutral line for
the design
Location will be between outlet and device
being monitored
Microcontroller
Name
Frequency
GPIO
ADC
Flash
ATMega32
16 MHz
32
8
32 KBytes
ATMega382
20 MHz
23
8
32 KBytes
MSP430AFE
12 MHz
11
3
8 KBytes
Parallax
Propeller
80 MHz
32
0
64 KBytes
Microcontroller
Parallax P8X32A-Q44
Same microcontroller as
VGA Board
Working knowledge
Uniformity between device
and VGA
Voltage/Current Measurement
HCPL-7800
Isolation Amplifier
Ignores High CMSR (at
least 10kV/ms)
Sigma Delta / Analog
Digital Converters
Voltage/Current Measurement
Voltage Divider (1001:1)
• 1 MOhm : 1 kOhm
• Used to step down AC voltage to a safe level from
170V to 0.17VPP
Vline = 1001*Vdivider
Current Sensing Resistor (0.2 Ohm)
I = Vcurrent/(0.2)
Voltage, Current, Power Calculations
𝑽𝑹𝑴𝑺 =
𝑰𝑹𝑴𝑺 =
𝟏𝟎𝟎𝟏𝟐
𝒚
𝟐
𝒗
𝒙=𝟏
𝒙
𝒚
𝒚
𝟐
𝑽
𝒙
𝒙=𝟏 𝑰
𝟎. 𝟐 𝟐 𝒚
𝑷 = 𝑽𝒓𝒎𝒔 ∗ 𝑰𝒓𝒎𝒔
𝟏𝟎𝟎𝟏
𝒚
𝑷=
𝒙=𝟏 𝑽𝒓𝒎𝒔 ∗ 𝑰𝒓𝒎𝒔
𝐲∗(𝟎.𝟐)
VI=Voltage across current sensor
y = sample size (1000 in this case)
COM-10924 Relay SPDT
Used to manual and automatically turn off
power to an outlet
Located inside outlet casing
Feed 5VDC signal to trigger relay
Single Pole - Double Throw
Rated up to 2000VAC @ 20A
GFCI Outlet
Ground Fault Circuit Interrupters
Used as a safety hazard
Will cut power in the event of a ground fault
Reacts within as little as 1/40 of a second
Reacts when a difference of 5mA is detected
between current and entering and leaving device
KWH Schematic
Software Process
Foreground and Background process
Foreground will initialize all hardware and
software components
UART, ADC, Clock, I/O, Timer, etc
Background will handle the data/sample collection
In order for this system to operate, it needs to
communicate between each of the
microprocessors and the central hub to relay
the data to be displayed.
Since we will be tracking multiple outlets in
different parts of the room, it becomes
necessary to use radio transmitters to
accomplish this.
The XBee Series
LINX NT Series
Atmel RF
Multitudes of choices on Amazon/Ebay
Attributes vary, but so too does the quality and reliablility.
Name
Frequency
Power Output
Max Range
RF Data Rate
Xbee Pro 900
HP
900 MHz
250 mW
15.5 km
200 Kbps
Linx TRM 900
NT
900 MHz
18 mW
914m
56 – 300 Kbps
Atmel
AT86RF212B
769- 900 MHz
10 mW
1 km
1 Mbps
MX-05V RF
(eBay)
433MHz
10mW
200m
4Kbps
Can handle supply voltages up to 2.8-3.4
VDC
Has a range of up to 100m line-of-sight
Frequency Band of 2.4 GHz
Tiny and easily programmable
Uses Universal Asynchronous Receiver
Transmitter (UART) @ 250 Kbps
Power Down adjusts power levels to extremely low levels
• (< 10.0uA)
Operates on 2.8-3.4V
Data_IN
• Logic Low: 0.3V to (0.2V*Vcc)
• Logic High: (0.7V*Vcc) to 5.5V
Data_Out
• Logic Low: 0.3V to 0.4V
• Logic High: (0.5*Vcc) to (Vcc-0.4V)
Absolute Max voltage: 3.4V
Max Temperature: 85° C
Possible Bluetooth capability
Ability to transmit to smartphone devices able to
pick up the signal
An app could then be created to simulate the same
display and touch capabilities of the main screen.
Paralax Propeller development to be used for
main system
Eclipse equipped with Android tools would be
used for the development of the app if that
option is taken
• Both chosen for familiarity with language and
convenience.
Product
Quantity
Price
LCD Screen
(1)
$78.55
Xbee Series 1
(3)
$54.00
HCPL-7800
(4)
$5
Parallax
(2)
$15.00
Voltage Regulator
(DC-DC)
(4)
$6.88
PCI Serial Port
Card
(1)
$16.95
Real Time Clock
(1)
$3.05
24LC512 EEPROM
(8)
$12.48
AC/DC Adaptor
(3)
$38.89
Misc: Resistors,
Capacitors, Diodes
~$90
PCB Fabrication
~$300
Total Spent
-----
------
Budget
($1433.12)
~$800
Distribution of Work
Jon
Daniel
Richard
VGA Display
X
X
RF Transmission
X
X
Circuit Breaker
X
X
kWh Meter
X
X
Questions?