Experiment 25: PWM Control of LED Brightness

Objective: Use PWM signals to control the brightness of an LED.

Background:

PWM (Pulse Width Modulation) is a technique used to control the amount of power delivered to a load by switching the power on and off at a high frequency. In this experiment, we will use PWM signals to adjust the brightness of an LED by varying the duty cycle of the PWM signal.

Steps:

  1. Setup:
    • Connect the LED to a microcontroller's PWM pin. Use a current-limiting resistor in series to protect the LED.
    • Ensure the PWM pin is configured correctly in the microcontroller's software to output a PWM signal.
  2. Generate PWM Signals:
    • Configure the microcontroller to generate PWM signals with different duty cycles (e.g., 0%, 25%, 50%, 75%, 100%).
    • Use the microcontroller's software to change the duty cycle in real-time or using a potentiometer or another input device.
  3. Observation:
    • Observe the LED’s brightness as the duty cycle of the PWM signal changes.
    • At a 0% duty cycle, the LED will be off, and at a 100% duty cycle, the LED will be fully bright.
    • Intermediate duty cycles will result in varying brightness levels based on the proportion of time the LED is on during each cycle.

Expected Outcome:

Understand how PWM signals work and how varying the duty cycle influences the perceived brightness of an LED. This experiment demonstrates the practical application of PWM for controlling power to electronic devices such as LEDs, motors, and more.