A push button will complete a circuit when the button is pressed. What that means is that a current will not flow across the button until it is pressed. When it is released, the circuit will be broken.
Firstly, haave a look at the following GPIO diagram. You'll be using a single ground pin (marked GND) and several GPIO pins (marked GPIO):
| 3V3 | 5V |
| GPIO2 | 5V |
| GPIO3 | GND |
| GPIO4 | GPIO14 |
| GND | GPIO15 |
| GPIO17 | GPIO18 |
| GPIO27 | GND |
| GPIO22 | GPIO23 |
| 3V3 | GPIO24 |
| GPIO10 | GND |
| GPIO9 | GPIO25 |
| GPIO11 | GPIO8 |
| GND | GPIO7 |
| DNC | DNC |
| GPIO5 | GND |
| GPIO6 | GPIO12 |
| GPIO13 | GND |
| GPIO19 | GPIO16 |
| GPIO26 | GPIO20 |
| GND | GPIO21 |
Note that if you have an older Raspberry Pi model you'll only have 26 pins but they have the same layout, starting at the top row (3V3 and 5V and ending at GND and GPIO7).
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Find a ground pin (marked
GND) on the diagram of the Raspberry Pi's pin layout above. -
Attach a wire to a ground pin on the Raspberry Pi and connect it to the ground rail on your breadboard like so:
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Place the button on the breadboard and connect one of its feet to the ground rail.
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Connect the button's other foot (on the same side) to GPIO pin 2 like so:
If you're using a mini breadboard without a designated ground rail, you'll have to use one of the rows as the ground rail. Connect a row to a ground pin and the other points in that row will be connected to ground like so:
