1Electrical and Computer EngineeringElectrical and Computer Engineering

Cameron ProctorRamsey KhudairiThomas Gilbert

Chad Young

MDR PresentationTekBand

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Overview

MDR Goals and PDR Concerns Development Approach System Overview Component Implementations CDR Goals and Final Demo Questions

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The TekBand

Bluetooth enabled wristband

Alerts wearer when receiving a phone call

• Vibration• LED display

Wireless storage

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MDR Goals & PDR Concerns

MDR Goals: Read/write between MicroSD and microcontroller Select and test battery Create and test sample band with clasp Pair with Bluetooth module

• Pair and send information to both cell phone and PC

PDR Concerns: Power constraints Transmitting data via Bluetooth Communicating with MicroSD card

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Development Approach

Team roles• Division of work• Assisted each other when stuck and worked together

Met together regularly• Discussed, analyzed and resolved any problems

High level of communication• Email• Dropbox• Portable computers

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System Overview

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The Band

Selected silicone-rubber & neodymium magnets• 1:1 ratio• Used to make mold and band• Strongest available magnets

Design Tasks• Make mold and test band• Test strength of material• Test clasp

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Casting Mold and Band

Mold• Poured silicone-rubber around wooden “band”

Band• Applied rubber-to-rubber release to mold• Mixed and poured rubber in mold

Magnetic clasp• Weak• Waiting on larger magnets

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Stress Testing

Instron Machine• Stretches material• Measures force and displacement

Stress = Force/Area• Material constant• Cross-section: 5mm x 13mm• Max stress: 0.43 Mpa

• Can handle 6.4 lbs. force

• Bigger band can handle more force

Hardware failure first

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Analysis of Results

0 5 10 15 20 25 30 35 40 450

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Stress vs. Displacement

Displacement (mm)

Str

ess (

MP

a)

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Bluetooth - Profiles

Serial Port Profile• Created to replace RS-232• Transmits and receives data via

UART• Most Bluetooth modules

support it

Hands-free Profile• Most modern phones have it• We were able to display caller

ID information onto our computer

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Our Bluetooth Module

We Selected the KC-21• UART• SPI port• High Speed of 3Mbps

Currently has the Serial Port Profile• Makes communication for wireless

storage easy

We are able to power and pair with the module

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Transmitting data via Bluetooth

**WILL BE ADDED**

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Microcontrollers

We Selected the PIC16F1827 (Microchip)• UART• 2 SPI ports• Low power

Design Tasks• Design PCB Demo Board• Solder fine pitch component• Program Microcontroller to verify PCB• Read and Write to MicroSD

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PCB Demo Board Design

Need to access pins, yet too small to solder to directly• Breakout General I/O Pins• Breakout SPI and UART Pins• Provide connection for Programming

Designed using PCB Artist, ordered through Advanced Circuits

Challenge: Hand soldering fine pitch (8 mils) 28 pin UQFN package

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Programming the Microcontroller

Initial Goal: Verify circuitry• Solution: simple program programm that blinks an LED

• Verifies that programming circuitry is correct• Verifies I/O breakouts are correct• Blinking frequency verifies internal oscillator

/* Blink LED connected to RA0 *///PORTA = 0x00;bits_off(PORTA, 0b00000001);

__delay_ms(500);//PORTA = 0x01;bits_on(PORTA, 0b00000001);

__delay_ms(500);

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Programming the Microcontroller (Cont.)

With PCB verified, the goal is to read and write to the MicroSD

MicroSD Read and Write Overview• All read and write operations done in 512 byte blocks as

per SD spec.• First send read or write command to the MicroSD• Then transmit the block address for the SD memory• Finally send or receive 512 bytes of data

Byte transmission is handled via the SPI

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Demo Program

Goal: Demonstrate reading and writing capability with MicroSD card

Write a number sequence to the MicroSD card• Store 0, 1, 2, 3, …, 15 on the MicroSD

Access the correct memory location, read number sequence and store in an array• Array now contains what was read from the card

Display contents of array sequentially in binary using 4 LEDs connected to the general purpose IO

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CDR Goals & Demo Day

CDR Goals: All components fully functional (outside of band) Completed prototype of band including clasp and display

design

Demo Day: One fully functional wristband:

• Can store data from PC to band via Bluetooth• Will vibrate and light up specific LED when receiving a

phone call

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Questions?