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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 l.jpg
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 l.jpg
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)


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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.


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Circuit Diagram

Row 1

1

2

3

A



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Uses

  • Wired into a keypad encoder.

    (presentation 19 with Anthony Dotterer)

  • Xilinx

  • Use your imagination…


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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.


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Signal Bouncing

(Simulated by touching a wire to a alligator clip)



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How to prevent:

  • Use an RC network to slow either the rising or falling edge of the event.

  • Buy a really good switch!