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2.19 Keypad

Overview

In this lesson, you will learn to use Keypad. Keypad can be applied into various kinds of devices, including mobile phone, fax machine, microwave oven and so on. It is commonly used in user input.

Components Required

../_images/Part_two_19.png

Fritzing Circuit

In this example, we extend the pins 1~8 of Keypad to connect to the digital pins 2~9.

../_images/image176.png

Schematic Diagram

../_images/image177.png

Code

Note

  • You can open the file 2.19_keypad.ino under the path of sunfounder_vincent_kit_for_arduino\code\2.19_keypad directly.

  • The Keypad library is used here, you can install it from the Library Manager.

    ../_images/lib_keypad.png

After uploading the codes to the Mega2560 board, on the serial monitor, you can see the value of the key currently pressed on the Keypad.

Code Analysis

By calling the Keypad.h library, you can easily use Keypad.

#include <Keypad.h>

Library Functions:

Keypad(char *userKeymap, byte *row, byte *col, byte numRows, byte numCols)

Initializes the internal keymap to be equal to userKeymap.

  • userKeymap: The symbols on the buttons of the keypads.

  • row, col: Pin configuration.

  • numRows, numCols: Keypad sizes.

char getKey()

Returns the key that is pressed, if any. This function is non-blocking.

Phenomenon Picture

../_images/image178.jpeg