PWM ทำอะไรจริง ๆ

A digital pin can only output full voltage or none at all. So how do you get a dim LED instead of just bright or dark? 💡

The answer is PWM: turn the pin on and off so quickly that your eye blends the flickers into one steady, in-between brightness.

PWM means Pulse Width Modulation. You keep flipping the pin, and you change how wide each on-pulse is to control the average power.

The duty cycle is the percent of each cycle the pin stays on. 50% on means roughly half power and a half-bright LED.

A wider pulse means more on-time, so the LED looks brighter or a motor spins faster. Narrow pulses give you dim and slow.

PWM never outputs a true middle voltage. The pin is always fully HIGH or fully LOW, just switching fast enough to feel smooth.

The LED really does flicker, but the switching is so fast that persistence of vision makes it look like one constant level.

The frequency is how many on-off cycles happen each second. Arduino runs PWM around 490 Hz, fast enough to hide the flicker.

Not every pin supports PWM. On an Uno, look for pins marked with a tilde symbol next to numbers like 3, 5, 6, 9, 10, and 11.

PWM powers real effects: dimming an LED, fading lights, controlling motor speed, and even shaping simple tones from a buzzer. 🔊

In code you do not toggle the pin yourself. One built-in analogWrite call sets the duty cycle and the chip pulses for you.

Let's lock in what PWM really controls.

PWM fakes analog output by pulsing a digital pin fast. The duty cycle sets the power, and your eyes blend it into smooth brightness. 🎉