DC Motor: PWM Speed & Driver Basics

Why it’s here

Set a PWM duty cycle for a conceptual motor driver.

How it works

The PWM value represents a command to a driver stage. Real speed depends on load and supply, so this animation is not an RPM prediction. Never power a motor directly from an I/O pin.

Try it

1. Open this experiment
2. Run at PWM 64, then 192. Compare the rotation and duty cycle; treat the displayed speed as a teaching illustration.

Connections

• D9 ~ — Driver / transistor input
• External supply — Motor power stage
• GND — Common signal reference

Example sketch

// Pin 9 drives a transistor stage, not a motor directly.

void setup() {
  pinMode(9, OUTPUT);
}

void loop() {
  analogWrite(9, 150);
}

Check your understanding

Can the illustrated RPM predict a real motor’s speed?