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Electronic Scratch Paper

Electronic Scratch Paper Simon Huang Stamford Hwang Ted Wang Agenda Introduction Components Improvements Q&A Purpose Records information anywhere, anytime Reduces the use of paper Acts as a whiteboard Works as a portable device System Components Altera DE2 FPGA Board

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Electronic Scratch Paper

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  1. Electronic Scratch Paper Simon Huang Stamford Hwang Ted Wang

  2. Agenda • Introduction • Components • Improvements • Q&A

  3. Purpose • Records information anywhere, anytime • Reduces the use of paper • Acts as a whiteboard • Works as a portable device

  4. System Components • Altera DE2 FPGA Board • 17.1’’ Touch Screen • 17.1’’ LCD Monitor • Bilateral Switch (CD4016CN) • Microprocessor (PIC16F877A) • A/D Converter (AD573JN)

  5. Block Diagram (Hardware)

  6. Block Diagram (Software)

  7. Agenda • Introduction • Components • Improvements • Q&A

  8. Touch Screen • Each Resistor • 300 Ω • Simple Voltage Divider • Output slightly less than 2.5V • Scratch of length < 20µm is ignored

  9. Touch Screen to A/D • Bilateral Switch (CD4016CN) to automate • “On” resistance 300 Ω

  10. Wiring Obtain Y coordinate Obtain X coordinate

  11. A/D Converter (AD573JN) • A/D Converter to convert analog to 10 bit digital signal

  12. Wiring • All 10 bits desired • Unipolar input • 0V ~ 5 V • Input to Convert • At least > 500ns wide 1 2 3

  13. Tc = Conversion Time (30 – 40 µs) Tcs = Convert Pulse Width (at least 500 ns)

  14. Small Spike

  15. Parallel to Serial Conversion

  16. Protocol of Transmission • Operates at 10 kHZ

  17. State Diagram

  18. Why PS/2? • Complication via USB coding • Successful testing via PS/2 • i.e. make code of E = 24

  19. PS/2 vs. RS-232

  20. PS/2 vs. RS-232 (cont.) • Data • Not Implemented • Ground • Vcc (+5V) • Clock • Not Implemented

  21. LCD Controller • Purpose: To control the display of LCD • Input: • PS/2 serial communication • Makecode of X and Y coordinate • Output: • 640 x 480 resolution 10 bit RGB VGA signal

  22. Block Diagram of LCD controller

  23. Decoder • Purpose: Translate PS/2 Protocol to X and Y • Input: • Makecode of X and Y coordinate • Output: • X position (0 – 640) • Y position (0 – 480)

  24. State Machine • Purpose: CPU to determine functionality • Input: X and Y coordinates • Output: • Clear • Draw • Save • Load • Erase

  25. Memory Unit • Purpose: grid like storage for 640 x 480 pixel info • Input: • operation determined by SM • XY coord of user touch • Current XY coord VGA is drawing • Output: • RGB signal

  26. VGA Driver • Purpose: Calculate correct VGA signals • Input: RGB of pixel • Output: • VGA Signals • XY of next pixel draw

  27. Agenda • Introduction • Components • Improvements • Q&A

  28. Improvements • Include an amplifier to increase the resolution • Utilize NIOS2 to program through USB A/D Converter • Improve the resolutions shown on the monitor • Improve circuitry through other means • Use RAM instead of registers to increase the amount of data stored

  29. Agenda • Introduction • Components • Improvements • Q&A

  30. Q&A

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