PWM with Raspberry Pi4 LED Brightness Control (Pulse Width Modulation) 

In this lesson, we'll explore Pulse Width Modulation(PWM) with Raspberry Pi4. It's very powerful feature which will let us control the duty cycle of clock which in result can be use to control the brightness of an LED. The PWM signal generated in this lesson uses Software PWM feature of Raspberry Pi4. The process of generating Software PWM is easy as compared to Hardware PWM. The Raspberry Pi4 has two hardware PWM Channels PWM0 & PWM1, available on GPIO12, GPIO18, GPIO13, GPIO19 Pins.
PWM Pins on Raspberry Pi are shared with audio subsystem, so we can have either PWM output or Audio output. In the next lesson, we’ll generate PWM Signal on GPIO Pin of Raspberry Pi. We’ll use GPIO21 Pin to change brightness of LED. We’ll generate varying duty cycle, which in result control the brightness of an LED.