SENSORS TURN REAL-WORLD measurements into electronic signals that we can then use on our Arduino boards. The projects in this chapter are all about using light and temperature.
We also look at how to interface with keypads and rotary encoders.
This project would not be out of place in the lair of any Evil Genius worth their salt. A secret code must be entered on the keypad, and if it is correct, a green LED will light; otherwise, a red LED will stay lit. In Project 27 we will revisit this project and show how it cannot just show the appropriate light but also control a door lock.
COMPONENTS AND EQUIPMENT
Unfortunately, keypads do not usually have pins attached, so we will have to attach ...