1Electrical and Computer EngineeringElectrical and Computer Engineering

Cam ProctorRamsey Khudairi

Tom GilbertChad Young

Project OrionTekBand

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Outline

Motivation Design Band & Mold Microcontroller Bluetooth Battery Memory Q&A

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Motivation – Cellular Phone Interface

Call, Text, & Emergency Notification• Uses:

• During Meetings• In Class• On the Road

• Will lead to: • Safer Driving• Less Interruptions

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Motivation – Wireless Storage

Wireless Data Storage• Uses:

• On the run• During group projects

• Will lead to: • Protection from Identity Theft• Fewer lost files• Greater Convenience

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Design

Goals:• Interface with Cell Phone to alert user of calls and

messages• Interface with PC to program the band• Interface with PC as wireless storage device• Maintain Fashion & Style

Our wristband will contain:• Microcontroller• Bluetooth module• MicroSD card• Lithium ion battery

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Durability Elasticity Degradation Cost

Urethane Rubber high low none second least expensive

Latex Rubber low high rots from long exposure to

sweat

least expensive

Silicone Rubber high high none most expensive

The Band-Materials

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The Band-Construction

• Target Size: 200mm x 5mm x 22mm• Two-Part Silicone Rubber

– 1:1 Ratio – Pour in mold– Cure time of a few hours

• Can be bought at any local craft store• ~$20/lb.

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The Mold

• Silicone– Rubber-To-Rubber mold release

• Master mold – Mold poured around wooden band

• Other options– Putty– www.amazingmoldputty.com

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The Clasp

Neodymium

Rod Magnets

~$10-$20

Trials

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Microcontroller Considerations

Form factor• Must be small enough to fit inside band

Low power• Running continuously

Interface with peripherals• I/O for user control• Interface with Bluetooth

module• Read/Write to storage

media

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Microcontroller Capabilities

I/O• 3 pins to drive single tri-color LED• Possible analog inputs for gyro, microphone, etc.

SPI (Serial Peripheral Interface)• Read/Write MicroSD card• Communicate with Bluetooth module (KC-21)

UART (Universal asynchronous receiver/transmitter)• Data transfer from Bluetooth module (KC-21, BTM-182)

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Microcontroller SolutionsPIC16F1827 (Microchip)

PIC16F1824 (Microchip)

PIC16F1938 (Microchip)

C8051F531A-IM (Silicon Laboratories)

ATTINY2313-20MU-ND (Atmel)

SPI 2 1 1 1 1

USART 1 1 1 1 1

I/O Pins 16 (18 pin) 12 (14 pin) 25 (28 pin) 16 (20 pin) 18 (20 pin)

ADC 10 bit 10 bit 10 bit 12 bit n/a

Program Memory

7kB, flash 7kB, flash 28kB, flash 8kB, flash 2kB, flash

Size 4x4mm 3x3mm 4x4mm 4x4mm 4x4mm

Power 30nA standby, 100μA @1MHz

20nA standby typical, 600nA operational

60nAStandby, 150μA @1MHz

.1mA operational

<.1μA standby, 230μA @ 1MHz

Cost $1.75 $1.40 $2.25 $2.55 $2.65

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Best Candidates

PIC16F1827 (Microchip)• Good middle ground• 2 SPI ports• Low power• Small size, multiple chips…

PIC16F1938 (Microchip)• Large program memory• Small form factor• Higher cost• Greater power consumption, critical

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PIC16F1827 (Microchip)• Appears to be the ideal candidate

• Low power and cost• Small size, possibility for >1 chip in bracelet• 2 SPI ports and USART

• Start with this chip, others as fallback• Middle of the road – good starting point

Selecting a Microcontroller

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Selecting a Bluetooth

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Bluetooth modules

Module Dimensions Power Transmit Rate Range CostLMX9830* 9x6x.86mm 65mA 0.704Mbps 10m 17.15

WRL-09913 1.4x2.5cm 58mA 0.704Mbps 10m 18.95

KC-21 27x15x2.5mm 90mA 3Mbps 20m 36.00

CSR1000** 5x5x0.6mm 60mA 24Mbps 50m NA

* Does not come with an antenna** Not yet available on the market

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Battery Considerations

Form factor• Small enough to fit inside band (< 20mm wide x 2mm thick)

Capacity: 100mAh• Approx. 100mA during read/write to MicroSD• Approx. 90mA during Bluetooth transmit

Must be rechargeable• Wireless Charging

Strategy: Multiple Small Batteries

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Battery Options

Coin Cell:

Thin Film Surface Mount:

Module Voltage Capacity Dimensions Cost

ML-2020/F1AN 3.0V 45mAh 20mm diam x 2mm thick $2.68

ML 1220/F1AN 3.0V 17mAh 12.5mm diam x 2mm thick $2.38

MS920SE-FL27E 3.1V 11mAh 9.5mm diam x 2mm thick $2.05

MS621FE 3.0V 5mAh 6.8mm diam x 1.5mm thick $0.94

Module Voltage Capacity Dimensions Cost

CBC050-M8C-TR1 3.8V 50uAh 8mm x 8mm ultrathin $3.82

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Battery Form Factor Considerations

50mm(1/4 of total band length)

ML6216.8mm5mAh

MS920SE9.5mm11mAh

MS920SE12mm17mAh

CBC0508mm50uAh

ML202020mm45mAh

20mm

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4GB Memory – Possible Add-on

MicroSD• Small – 11mm X 15mm X 1mm• Voltage Range: 2.7 – 3.6V• Clock Rate: 0 – 25MHz• Supports Serial Peripheral Interface (SPI)• Assuming 25MHz clock, Read/Write time: 40s/Gb• Power:

• Sleep – 150uA max• Read – 100mA max• Write – 100mA max

• Cost: $3 - $5• Performance: -25oC to 85oC

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MicroSD Communication

Serial Peripheral Interface (SPI) protocol• Data clocked with clock signal (SCK)• Clock signal controls when data is changed and read• SPI is Sychronous

• Data rate will change to accommodate changing clock rate

• SSP or MSSP module in PICmicro device allows SPI

Pin # Name Type Description

1 RSV Disconnected

2 CS Input Chip Select

3 DI Input Data In

4 Vdd Supply Supply Voltage

5 SCLK Input Clock

6 Vss Supply Supply Ground

7 DO Output Data Out

8 RSV Disconnected

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TimelineOct 17-23 Oct 24 - 30 Oct 31 - 6 Nov 7 - 13 Nov 14 - 20 Nov 21 - 27 Nov 28 - 4

Battery - Tom

Purchase

Test & Reconsider Components

Integrate

Microcontroller - Cam

Purchase

Test & Reconsider Components

Integrate

Bluetooth - Chad

Purchase

Test & Reconsider Components

Integrate

Band Construction - Ramsey

Purchase Supplies

Build Protype Band

Test & Evaluate

Construct Prototype Mold

Memory - Tom & Ramsey

Purchase Card

Test Power Consumption

Integrage or Eval Other Options

MDR

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Budget

Band Construction• Supplies for 10 Bands & Mold: $60• Rubber to rubber mold release: $10• 100 Magnets: $20• Total: $90

Bluetooth• Module: $40• Development Kit: $100-$150 (depending on module)• Total: $140-$190

Microcontroller• Module: $1.20• Breakout Board & Dev Kit: $165

MicroSD• Module: $3-$5

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Conclusion

Our wristband will contain:• Microcontroller• Bluetooth module• microSD card

The final product will:• Interface with Cell Phone to alert user of calls and messages• Interface with PC to program alert preferences• Possible Addition: Interface with PC as wireless storage device

Key constraints: Power and Size

Deliverables by MDR:• Prototype of electronics working on board• Prototype wristband w/o HW