delay() และจังหวะการกะพริบ

Switching a pin on and off happens in microseconds, far too fast to see. To make a real blink, you tell the board to wait with delay. ⏱️

The delay function pauses your sketch for a number of milliseconds. One second is 1000 of them, so delay(1000) waits one full second.

Turn the LED HIGH, then call delay. The board sits still and the LED stays lit for the whole pause before doing anything else.

Now drive the pin LOW and delay again. The LED stays dark for that pause, giving the off half of your blink its own visible moment.

Stack those four lines inside loop() and you get a steady blink: on, wait, off, wait, repeat. That is the classic Blink sketch.

Change the number to change the rhythm. A smaller value like delay(200) makes a quick flash, while a larger one slows the blink right down.

The two delays do not have to match. A long on-time and short off-time gives a steady glow with a brief wink between pulses.

Here is the catch: during a delay the board does nothing else. It cannot read a button or sensor, because delay blocks the whole sketch.

For a simple blink, blocking is fine. Later you will meet millis, a way to time events without freezing the rest of your program.

delay handles milliseconds, but for very short pauses there is delayMicroseconds. You will need it later for precise sensor timing.

You never write a repeat command. Because loop() runs again automatically, your on-off-wait pattern repeats forever on its own.

You want the LED to stay on for exactly two seconds.

You used delay to pace your blink, learned it counts milliseconds, and saw that it blocks everything else. Next you will wire a real LED. 🎉