Why gpiozero simplifies hardware in Raspberry Pi - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the gpiozero library.

Raspberry Pi

from gpiozero import [1]

Drag options to blanks, or click blank then click option'

AGPIO

BLED

CPin

DBoard

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'GPIO' which is not a class in gpiozero

Using 'Pin' or 'Board' which are not classes to control LEDs

The LED class is part of gpiozero and is used to control an LED easily.

2fill in blank

medium

Complete the code to create an LED object on GPIO pin 17.

Raspberry Pi

led = LED([1])

Drag options to blanks, or click blank then click option'

A27

B5

C22

D17

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing pin numbers not matching the example

Confusing physical pin numbers with GPIO numbers

GPIO pin 17 is commonly used and matches the example to control the LED.

3fill in blank

hard

Fix the error in the code to turn the LED on.

Raspberry Pi

led.[1]()

Drag options to blanks, or click blank then click option'

Aoff

Benable

Con

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'off' which turns the LED off

Using 'start' or 'enable' which are not gpiozero methods

The on() method turns the LED on in gpiozero.

4fill in blank

hard

Fill both blanks to create a Button on pin 2 and check if it is pressed.

Raspberry Pi

button = Button([1])
if button.[2]:
    print('Pressed!')

Drag options to blanks, or click blank then click option'

A2

B3

Cis_pressed

Dpressed

Attempts:

3 left

💡 Hint

Common Mistakes

Using pin 3 instead of 2

Using 'pressed' which is not a gpiozero property

The Button class uses pin 2 here, and is_pressed is the property to check if the button is pressed.

5fill in blank

hard

Fill all three blanks to create a PWMLED on pin 18, set brightness to 50%, and turn it on.

Raspberry Pi

pwm_led = PWMLED([1])
pwm_led.[2] = [3]
pwm_led.on()

Drag options to blanks, or click blank then click option'

A18

Bbrightness

C0.5

D17

Attempts:

3 left

💡 Hint

Common Mistakes

Using pin 17 instead of 18

Setting brightness to 1 instead of 0.5

Pin 18 is used for PWMLED, brightness controls the light level, and 0.5 sets it to 50% brightness.

Practice

1. What is the main advantage of using gpiozero on a Raspberry Pi?

easy

A. It only works with LEDs and no other devices.

B. It requires writing complex C code for hardware control.

C. It allows easy control of hardware devices with simple Python code.

D. It replaces the need for any physical wiring.

Solution

1. Step 1: Understand gpiozero purpose

   gpiozero is designed to simplify hardware control on Raspberry Pi using Python.

2. Step 2: Compare options

   It allows easy control of hardware devices with simple Python code. correctly states it allows easy control with simple Python code. Other options are incorrect because gpiozero does not require complex C code, supports many devices beyond LEDs, and does not remove the need for wiring.

3. Final Answer:

   It allows easy control of hardware devices with simple Python code. -> Option C

4. Quick Check:

   gpiozero simplifies hardware control = It allows easy control of hardware devices with simple Python code. [OK]

Hint: Remember gpiozero means easy Python hardware control [OK]

Common Mistakes:

• Thinking gpiozero only works with LEDs
• Believing gpiozero replaces wiring
• Assuming it needs complex code

2. Which of the following is the correct way to import the LED class from gpiozero in Python?

easy

A. import gpiozero.LED

B. import LED from gpiozero

C. from gpiozero import led

D. from gpiozero import LED

Solution

1. Step 1: Recall Python import syntax

   The correct syntax to import a class from a module is: from module import ClassName.

2. Step 2: Check options

   from gpiozero import LED matches this syntax exactly with correct capitalization. import gpiozero.LED is invalid syntax, import LED from gpiozero reverses the import order (JavaScript syntax), and from gpiozero import led uses lowercase 'led' which is incorrect.

3. Final Answer:

   from gpiozero import LED -> Option D

4. Quick Check:

   Correct Python import syntax = from gpiozero import LED [OK]

Hint: Use 'from module import Class' for classes [OK]

Common Mistakes:

• Using wrong import syntax
• Incorrect capitalization of class name
• Trying to import with 'import Class from module'

3. What will be the output of this code snippet using gpiozero?

from gpiozero import LED
from time import sleep
led = LED(17)
led.on()
sleep(1)
print(led.is_lit)

medium

A. False

B. True

C. 1

D. None

Solution

1. Step 1: Understand the code actions

   The code imports LED, creates an LED object on pin 17, turns it on, waits 1 second, then prints if the LED is lit.

2. Step 2: Determine the output of led.is_lit

   Since led.on() was called, led.is_lit returns True, so the printed output is True.

3. Final Answer:

   True -> Option B

4. Quick Check:

   LED turned on means is_lit = True [OK]

Hint: led.on() sets is_lit True immediately [OK]

Common Mistakes:

• Expecting False because of sleep
• Thinking is_lit returns 1 or None
• Confusing method names

4. Identify the error in this gpiozero code snippet:

from gpiozero import Button
button = Button(2)
button.pressed = True
print(button.is_pressed)

medium

A. button.pressed is an event, not a property to assign.

B. Button pin number 2 is invalid.

C. print(button.is_pressed) should be print(button.pressed)

D. You cannot assign True to button.pressed; it's a method.

Solution

1. Step 1: Understand gpiozero Button attributes

   In gpiozero, button.pressed is an event handler property, not a boolean you can assign.

2. Step 2: Identify the error

   Assigning True to button.pressed is incorrect; it should be used to assign a function callback. The correct property to check button state is button.is_pressed.

3. Final Answer:

   button.pressed is an event, not a property to assign. -> Option A

4. Quick Check:

   pressed is event handler, not assignable boolean [OK]

Hint: pressed is event, is_pressed is state boolean [OK]

Common Mistakes:

• Assigning boolean to event handler
• Confusing is_pressed and pressed
• Assuming pin 2 is invalid

5. You want to control two LEDs connected to pins 17 and 27 using gpiozero. Which code snippet correctly turns on both LEDs for 2 seconds, then turns them off?

hard

A. from gpiozero import LED
from time import sleep
led1 = LED(17)
led2 = LED(27)
led1.on()
led2.on()
sleep(2)
led1.off()
led2.off()

B. from gpiozero import LED
from time import sleep
led1 = LED(17)
led2 = LED(27)
led1.on()
sleep(2)
led2.on()
led1.off()
led2.off()

C. from gpiozero import LED
from time import sleep
led1 = LED(17)
led2 = LED(27)
led1.off()
led2.off()
sleep(2)
led1.on()
led2.on()

D. from gpiozero import LED
from time import sleep
led1 = LED(17)
led2 = LED(27)
led1.on()
led2.off()
sleep(2)
led1.off()
led2.on()

Solution

1. Step 1: Analyze the goal

   We want both LEDs on at the same time for 2 seconds, then both off.

2. Step 2: Check each option's sequence

   from gpiozero import LED from time import sleep led1 = LED(17) led2 = LED(27) led1.on() led2.on() sleep(2) led1.off() led2.off() turns both LEDs on, waits 2 seconds, then turns both off. from gpiozero import LED from time import sleep led1 = LED(17) led2 = LED(27) led1.on() sleep(2) led2.on() led1.off() led2.off() turns on led1, waits, then led2 on (not simultaneous). from gpiozero import LED from time import sleep led1 = LED(17) led2 = LED(27) led1.off() led2.off() sleep(2) led1.on() led2.on() turns LEDs off first, then on after sleep (wrong order). from gpiozero import LED from time import sleep led1 = LED(17) led2 = LED(27) led1.on() led2.off() sleep(2) led1.off() led2.on() turns one LED on and the other off, then switches after sleep (not both on together).

3. Final Answer:

   Code that turns both LEDs on together, waits, then turns both off. -> Option A

4. Quick Check:

   Both LEDs on simultaneously for 2 seconds = from gpiozero import LED from time import sleep led1 = LED(17) led2 = LED(27) led1.on() led2.on() sleep(2) led1.off() led2.off() [OK]

Hint: Turn both on before sleep, then off after sleep [OK]

Common Mistakes:

• Turning LEDs on/off at different times
• Switching off before turning on
• Not waiting with both LEDs on