PWMLED for brightness in Raspberry Pi - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does PWM stand for in PWMLED?

PWM stands for Pulse Width Modulation. It is a technique to control the brightness of an LED by switching it on and off very quickly with varying durations.

beginner

How does PWM control LED brightness?

PWM controls brightness by changing the ratio of ON time to OFF time in each cycle. More ON time means brighter LED; less ON time means dimmer LED.

beginner

In Raspberry Pi, which library is commonly used to control PWMLED?

The gpiozero library is commonly used in Raspberry Pi to control PWMLED easily with simple commands.

beginner

What is the range of brightness values you can set for PWMLED in gpiozero?

Brightness values range from 0 (LED off) to 1 (LED fully on). You can set any decimal value in between for different brightness levels.

beginner

Write a simple Python code snippet to set a PWMLED on GPIO pin 17 to half brightness.

from gpiozero import PWMLED
led = PWMLED(17)
led.value = 0.5  # Sets brightness to 50%

What does PWM control in an LED?

A Brightness by changing ON/OFF time ratio

B Color of the LED

C Temperature of the LED

D Voltage supplied to the LED

PWM controls brightness by adjusting how long the LED is ON versus OFF in each cycle.

Which Python library is used to control PWMLED on Raspberry Pi?

A numpy

B matplotlib

C gpiozero

D pandas

gpiozero is designed for easy control of Raspberry Pi hardware including PWMLED.

What value sets the PWMLED to full brightness?

A 1

B 0.5

C 0

D 255

A value of 1 means the LED is fully on at 100% brightness.

If you want the LED to be off using PWMLED, what value should you set?

A -1

B 1

C 0.5

D 0

Setting the value to 0 turns the LED off completely.

What does a PWM cycle consist of?

A Only ON time

B ON time and OFF time

C Only OFF time

D Voltage and current

A PWM cycle has both ON and OFF times that determine brightness.

Explain how PWM controls the brightness of an LED on a Raspberry Pi.

Think about how fast switching affects how bright the LED looks.

Write a short Python code example to set an LED connected to GPIO 17 to 75% brightness using PWMLED.

Use the gpiozero PWMLED class and set the value property.