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Fake Analog Output (PWM) | NexaLearn IoT Lab | NexaLearn

Analog I/O20 دقيقة

Fake Analog Output (PWM)

Arduino can't output 3 volts — only 0 or 5. So how do we gradually control LED brightness?

Lesson Content

Pulse Width Modulation (PWM) is an optical trick. Arduino turns 5V on and off at an extremely fast rate (hundreds of times per second). If it's on half the time and off half the time, the eye perceives the LED as glowing at half power (an average of 2.5V). Pins that support this trick have a tilde (~) symbol next to them.

Components Needed

Arduino UnoLEDمقاومة 220 أوم

Wiring Notes

Connect the LED to pin 9 (or 3, 5, 6, 10, 11) through a resistor.

Code Example

void setup() {
  pinMode(9, OUTPUT);
}
void loop() {
  // تدرج الإضاءة من 0 (مطفأ) إلى 255 (أقصى إضاءة)
  for(int i = 0; i <= 255; i++) {
    analogWrite(9, i);
    delay(10);
  }
}

Common Mistakes

Using analogWrite() on a pin without the (~) symbol — the LED won't dim gradually but will suddenly turn on and off.

Next Lesson

Analog Input: The Variable Resistor (Potentiometer)