1. Buttons

2. Overview Any device used to break or complete a circuit
The design engineer decides which device should be used for each specific circumstance
A switch is a type of “latching” button

3. Arduino
The goal of the button is to alter the voltage entering the digital pins
A microcontroller sees CHANGES in voltage
If the pin normally has 0V, then pressing a button should connect it to 5v

4. Arduino Button Pins opposite each other are always connected
Pressing the button connects to 2 pins on the left to the 2 pins on the right

5. Circuit

6. Circuits – Normally LOW
D2 is normally connected to ground through the unpressed button

7. Circuits – Normally LOW
When the button is pressed, the 5V side of the button connects to D2
The resistor prevents a short circuit between 5V and ground when the button is pressed

8. Coding

9. Coding
Or more simply

10. Complete the Button lab in the book