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PWM (Pulse Width Modulation)

PWM is a technique used to generate analog-like behavior from a digital pin. By switching a pin ON and OFF very rapidly, you can control the average power delivered to a component.

1. Duty Cycle & Frequency

There are two primary parameters that define a PWM signal:

Frequency (Hz)

How many times per second the pin switches. For LED dimming, 1kHz (1000Hz) is standard to prevent flickering.

Duty Cycle (%)

The percentage of time the pin is HIGH during one cycle. A 50% duty cycle means the pin is ON half the time, resulting in half-brightness.

2. Implementation (LED Dimming)

In this example, we’ll set an LED to 25% brightness using a 1kHz frequency.

import { PWM } from 'intarva';

const led = new PWM('GP25');
led.freq(1000);    // Set frequency to 1kHz
led.duty(0.25);    // Set duty cycle to 25% (0.0 to 1.0)
                    
from machine import Pin, PWM

led = PWM(Pin(25))
led.freq(1000)     # Set frequency to 1kHz
led.duty_u16(16384) # 25% of 65535

3. Use Cases

  • LED Dimming: Controlling perceived brightness.
  • Servo Control: Positioning motor arms (typically requires 50Hz frequency).
  • Audio Generation: Creating simple “beeps” by varying the frequency.
  • Motor Speed: Controlling DC motor velocity via a motor driver.