pinMode와 OUTPUT

Every Arduino pin can either listen or speak. Before you use one, you must tell it which job to do. That setup is the role of pinMode. 🔌

To light an LED, the pin must send current out into the world. You declare that intent by setting the pin to OUTPUT mode.

You configure a pin once, inside setup(). The pinMode function takes a pin number and a mode, and it remembers your choice.

Hard-coded numbers get confusing fast. Give the pin a clear name with a constant so your sketch reads like plain language.

You only need to declare a pin's mode a single time. Put pinMode in setup(), which runs once when the board powers on.

Pin 13 is special: most Arduino boards wire it to a tiny onboard LED. That means you can test output with no extra parts. 💡

You do not have to memorize the number. Arduino gives you the built-in name LED_BUILTIN, which points to that onboard LED for you.

Each pin defaults to listening. Setting OUTPUT flips it so the pin actively drives a voltage instead of just sensing one.

An OUTPUT pin can push out about 5 volts or pull down to 0. That controlled push is how a pin drives an LED on or off.

Skip pinMode and your LED may stay dim or dead. The pin never enters OUTPUT mode, so it cannot push enough current to shine.

Think of setup() as preparing the stage before the show. Declaring your pin's mode here gets everything ready for the loop that follows.

You want a pin to light an LED. What do you call first?

You learned to claim a pin with pinMode and OUTPUT inside setup(). With the pin ready to drive current, you can now make it blink. 🎉