BeHāv
Student Behavior FeedbackSystem
Overview
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Team
BeHāV Overview
Schematic
Parts
Software
Hub
Timeline
Budget
Team Members
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Matthew Fargano
Joshua Fedders
Terrell Jones
Nicholas Miller
Mohamed Siddig
Joseph Esler*
*Software Systems Development Member
What is BeHāv?
• A Wireless System for Modifying Learning
Disabled Students Behavior
• A System for Tracking the Progress of
Learning Disabled Students
Features
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Wireless
Small Size
Long Battery Life
Easy to Use Interface
Schematic
Schematic- USB & Transceiver
Schematic- Real Time Clock
Key Fob
Originally we were considering using pre-programmable key fobs.
However, this approach was unwarranted since we would have to reverse
engineer the key fobs in order to make our transceiver on the other end
communicate with it. Due to the synergy of the project, the key fob
transmitter is similar in communication function compared to the receiver.
This allows us to produce a transmitter almost directly from our receiver
schematic. The major differences are:
•Key fob uses 2 buttons
•No Buzzer or Display
Microcontroller- MSP430F2272
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Processes incoming events.
Applies timestamp
Stores data
Outputs data to external PC
MSP430F2272 Advantages
• Large Flash Memory
– 32kB of Flash Memory
• Low Power Consumption
• UART, SPI, and I2C
compatible interfaces
• Flash Memory Program
Execution
Transceiver- MiRF v2
•Low cost
•Low Power (Requires Switch Converter works with 3.3-7 V input)
•Works with in our required area (30ft Radius)
•125 Channels (Between 2.4MHz – 2.525 MHz)
•Works in Open band (2.4GHz range)
•Built in Antenna
•Compact size
•Readily available
•Standby mode to save power
Transceiver- Dev Board
•Look at data sent and received over the wireless link.
•Can tweak firmware on the MiRF v2 (change channel used)
•Preloaded firmware for testing.
•Low Cost Dev Board
LED- Score Display
•Lite-on LTD-2701 7-segment LED
•Lower Power
•7mm digit height
•High Contrast
•Wide Viewing Angle
•Low Cost
•Requires BCD
BCD to 7-segment Driver
• TI CD4511BE
• CMOS
• Latches input
Vibrator- DC Motor G13566
•Costs less than $1 when bought in bulk
•11 mm x 4.5 mm
•Runs on as low as 1V DC (.05W)
•Will require a MOSFET to power
Power Regulator
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ADP2105
Buck Converter
2.7V - 5.5V input range
3.3V output
~96% Efficiency
1 A max load current
Real Time Clock- MT41T0
Features:
• Seconds, minutes, hours, day, date, month, years,
and century
• 32KHz crystal oscillator
• Serial interface supports I2C bus
• Low standby current 0.9μA (typ@3V)
• 2.0 to 5.5V clock operating voltage
Time Stamp Format
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Memory Capacity
Flash Memory =
32kB
Firmware =
10kB
Event Logging Space =
22kB
# of Bytes for a event =
555B
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# of events that could be recorded =
4553
Or 10 Days of 1 event/min for 8 hours a day
Software
Architecture
Spec.
Sequence Diagram - Feedback
To hub or not to hub?
Hub Advantages
• Single station for
devices
Hub Disadvantages
• Limited mobility
• Higher cost
• Limited expansion
Proposed USB
Connect the Receiver directly to an external
PC via USB.
– Increased Mobility
– Less Expensive
– Supports any number of devices
USB Port Interface
Allows communication between our devices and the PC through Mini USB
connection. This allows a easier form of programming and data retrieval than
original base station design. This connector interfaces directly with the
MSP430’s UART. This provides the option to incorporate a rechargeable
battery by connection to the USB.
•5 V input from USB bus (for rechargeable battery)
•Variable baud rate
•100mA maximum output current
Project Costs
Real Time Clock
$20.00
7 segment LED
$15.00
PCB
$120.00
MSP430F2270
Sampled
MSP430F2270 Dev Board
Provided
Transceiver+Dev board
$100.00
USB Interface
$40.00
Stripboard
$11.00
G13566 Motor
$3.00
Voltage Regulator
$2.25
Documents
$60.00
Other
$28.75
Total
$400.00
Receiver Unit Cost
MSP430F2272
$3.00
$3.00
DC Vibrator
$1.00
$1.00
Transceiver
$28.00
$6.00
7-Segment LED
$6.50
$2.00
Real Time Clock
$5.00
$5.00
USB Interface
$25.00
$7.00
PCB
$40.00
$40.00
Voltage Regulator
$2.25
$2.25
Total
$110.75
$66.25
Milestone 1
• Wire wrap constructed system.
• Able to receive input from external Key Fob
source.
• Timestamp and store events in internal flash.
• Can retrieve data from system via USB
connection.
Milestone 2
• PCB board assembled, debugged, and
working.
• Displays score through 7-segment LED
display.
• Data interfaces with Microsoft Excel.
Capstone Expo
• Delivers a single unit working BeHāv system
with following features.
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USB Interface
Time stamped events
7-segment LED display of current score
Vibrating receiver for feedback
Schedule
Tasks
Mutual Tasks: Documentation, Tech manual, User manual
Matt: Transceivers, MSP430 Firmware, and Proto-board lay out
Josh: MSP430 Firmware, LED display, BCD
Nick: Computer interface, USB, MSP430 Firmware, Real Time Clock
Terrel: PCB, Transceivers, Proto-board lay out
Mohamed: PCB, Real time clock, Transceivers, Proto-board lay out
Questions?