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Hexadecimal Keypad

Hexadecimal Keypad. Doug Butterworth Email: epor@psu.edu AIM: Epor55 Phone: 814.217.2466. Hardware Description Internal Organization The Circuit in Action Signal Bouncing. Hardware Description:. 16-Button Numeric Keypad Rugged black plastic

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Hexadecimal Keypad

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  1. Hexadecimal Keypad Doug Butterworth Email: epor@psu.edu AIM: Epor55 Phone: 814.217.2466 • Hardware Description • Internal Organization • The Circuit in Action • Signal Bouncing

  2. Hardware Description: 16-Button Numeric Keypad • Rugged black plastic • 4 x 4 Matrix Type • 8-position solder pad • Contact rating: 24VDC @ 20mA • Contact resistance: 200 Ohms max. • Life test: 1,000,000 life cycles per key • Size: 3.0"L x 2.8"W x 0.6"H • $7.95 from Links: Product Page Technical Documentation(pretty under whelming)

  3. Internal Organization Output organization Output pin #Symbol Pin 1 Row 2 Pin 2 Row 3 Pin 3 Col 1 Pin 4 Row 4 Pin 5 Col 2 Pin 6 Col 3 Pin 7 Col 4 Pin 8 Row 1 When a button is pushed, the associated row and column pin for that button are connected together.

  4. Circuit Diagram Row 1 1 2 3 A

  5. Hex Keypad: The Movie!

  6. Uses • Wired into a keypad encoder. (presentation 19 with Anthony Dotterer) • Xilinx • Use your imagination…

  7. Signal Bouncing Background Theory: • Nearly all mechanical switches generate some bounce. • After switched, they actually open and close several times before settling down to their new position. • Can Last as little as a fraction of a millisecond to as long as 50 ms. • Only very high quality switches generate little or no bounce.

  8. Signal Bouncing (Simulated by touching a wire to a alligator clip)

  9. Signal Bouncing On the Keypad (Wow!)

  10. How to prevent: • Use an RC network to slow either the rising or falling edge of the event. • Buy a really good switch!

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