In this chapter you will
Learn how to connect numeric keypads to your Arduino
Read values from the keypad in a sketch
Expand on decision systems with the
Create a PIN-controlled lock or switch
As your projects become more involved, you might want to accept numeric input from users when your Arduino isn’t connected to a PC—for example, if you’d like to have the ability to turn something on or off by entering a secret number. One option would be to wire up 10 or more push buttons to various digital input pins (for the numbers 0 through 9); but it’s much easier to use a numeric keypad like the one shown in Figure 9-1.
One of the benefits of using a keypad is ...