Daktronics Touchpad Testing Device

1
Daktronics Touchpad Testing Device

• SD0801
• Sarthak Ahuja
• Michael Benson
• Kalana Maldeniya

2
Introduction

• Client Daktronics inc.
• Client Representative Kurt Kaski
• Faculty Advisor Dr. Chao You

3
Introduction

• Daktronics swimming timing system uses a
  touchpad to indicate when the swimmer has
  finished each lap.
• Our objective is to develop a handheld, battery
  powered tester for verifying the operation of the
  touchpad.

4
Hardware Requirements

• In its simplest form the tester will give a
  visual (LED) and audible (buzzer) indication of
  when the touchpad is closed.
• A connection to a submersible pressure
  measurement device for measuring actuation force.
• An LCD for displaying the measured force.
• A female DB9 serial port for connection to a
  computer for the purpose of updating firmware,
  etc.
• The battery power supply should be a switcher for
  maximum battery life.
• Decoupling caps on the ICs

5
Software Requirements

• The tester will display the force measurement, as
  well as a latched value indicating the actuation
  force.
• Turn off the LCD and sleep the micro until an
  input is detected from the touchpad input.

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SENSING CIRCUIT
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VISUAL AND AUDIBLE INDICATION
When a touch is sensed ? White LED for
visual indication ? A 4 KHz piezo buzzer
driven by Pulse width Modulation through
the microcontroller
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LOAD CELL

• Used in measurements involving displacement of a
  stressed, linearly elastic member
• Used a compact button style load cell to measure
  applied force
• Applied force is then calculated and displayed
  on the LCD screen
• Displayed reading is accurate to /- .25 lbs.
  and is logged about 20 microseconds after the
  touch is sensed

• .

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Submersible Force Probe

• Uses the load cell to measure the amount of
  force necessary to actuate the touchpad

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Final circuit
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Software
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SLEEPING MODE

• A sleep timer is initialized to 0 whenever a
  touch is sensed
• If is incremented by 1 in every cycle if no touch
  is sensed
• When it reaches 1500 (10 seconds), the LCD is
  turned off, and the PIC enters sleep mode

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Power Supply
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Block diagram of the entire system
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Final Product


16
Setbacks

• Method of testing
• Decoupling Caps
• Sleeping Mode
• Creating the submersible probe
• Troubleshooting
• 1. DC/DC conv.
• 2. Noise

17
Lessons Learned

• Time Management
• More Research
• Priorities
• Parts Ordering
• Debugging

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Timeline
Task Description Duration Start Date End Date
Functional Block Diagram 5 days 1/29/2007 2/2/2007
Gather Components Lists (ALL) 18 days 2/3/2007 2/27/2007
Design Ideas (All) 44 days 2/27/2007 4/26/2007
Rough Schematic (All) 20 days 4/1/2007 4/26/2007
Gather Components (All) 8 days 4/27/2007 5/8/2007
Test Components (All) 23 days 5/9/2007 6/8/2007
Summer Break 74 days 5/14/2007 8/25/2007
Make pcb Board (Kalana) 31 days 9/28/2007 11/9/2007
Test Prototype Board (Kalana and Mike) 18 days 9/17/2007 10/10/2007
Software for PIC (Mike and Sarthak) 18 days 9/17/2007 10/10/2007
Submersible pressure probe (Mike) 21 days 10/5/2007 11/2/2007
Test Software (Mike and Sarthak) 12 days 11/5/2007 11/20/2007
Test Hardware (Kalana and Mike) 14 days 11/23/2007 12/11/2007
Revisions/Modifications (ALL) 18 days 11/28/2007 12/11/2007
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Budget
Local Expenses Local Expenses Local Expenses Local Expenses Local Expenses Local Expenses Local Expenses
Part Description Part Retail Cost Acquired Cost Notes Units/Board Price/Board
OP AMPS MCP602 4.83 -   1 4.83
Microcontroller 16F876 7.44 -   1 7.44
Lcd Display CFAH2004A-NYG 21.89 21.89   1 21.89
Load Cell FC22 55.00 55.00   1 55.00
Switching Regulator R-785.0-0.5 10.57 10.57   1 10.57
Serial port Db9 9.00 - 1 9.00
Transceiver MAX231CPE 4.70 -   1 4.70
Buzzer CEP-1116 1.95 1.95   1 1.95
Resistors R 2.70 -   8 2.70
Capacitors C 2.73 -   1 2.73
Cristal 20MHz 0.70 - - 1 0.70
Enclosure   19.00 19.00   1 19.00
Fabrication   15.00 15.00 Subject to change 1 15.00
    Total Price/Board Total Price/Board Total Price/Board Total Price/Board 155.51
    of Boards of Boards of Boards of Boards 1
    Total Price Total Price Total Price Total Price 155.51
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Future Work

• Further testing to improve reliability
• Develop a permanent enclosure for the submersible
  probe
• Add the ability to test other components of the
  timing system

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Summary

• Designed a handheld tester that meets the
  clients design requirements
• Learned that design is only a small part of the
  development timeline, while debugging is much
  more time consuming

22
Acknowledgements

• Daktronics inc.
• ECE Department
• Dr. Chao You
• Dr. Mark Schroeder
• West Fargo Flyers Swim Team
• West Fargo High School
• Bart Kent

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• Questions?