RPi.GPIO library setup in Raspberry Pi - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the RPi.GPIO library with the common alias.

Raspberry Pi

import [1] as GPIO

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

ARPi.GPIO

Bgpiozero

CGPIO

Draspberry_gpio

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'gpiozero' instead of 'RPi.GPIO' which is a different library.

Trying to import 'GPIO' directly without the full library name.

The RPi.GPIO library is imported using import RPi.GPIO as GPIO to allow easy access with the alias GPIO.

2fill in blank

medium

Complete the code to set the GPIO numbering mode to BCM.

Raspberry Pi

GPIO.setmode([1])

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

AGPIO.BCM

BGPIO.BOARD

CGPIO.OUT

DGPIO.IN

Attempts:

3 left

💡 Hint

Common Mistakes

Using BOARD mode when BCM mode is required.

Passing direction constants like OUT or IN instead of mode.

Setting the mode to GPIO.BCM tells the library to use the Broadcom chip's pin numbering.

3fill in blank

hard

Fix the error in the code to clean up GPIO settings at the end.

Raspberry Pi

GPIO.[1]()

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

Aclose

Bclear

Ccleanup

Dreset

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'clear' or 'reset' which are not valid methods.

Forgetting to call cleanup causing warnings on next run.

The correct method to reset GPIO pins is GPIO.cleanup(). Other options do not exist or cause errors.

4fill in blank

hard

Fill both blanks to set up a GPIO pin 18 as an output.

Raspberry Pi

GPIO.setup([1], [2])

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

A18

BGPIO.OUT

CGPIO.IN

D17

Attempts:

3 left

💡 Hint

Common Mistakes

Using pin 17 instead of 18.

Setting pin as input instead of output.

Pin 18 is set as an output using GPIO.setup(18, GPIO.OUT).

5fill in blank

hard

Fill all three blanks to set pin 23 as input with a pull-up resistor.

Raspberry Pi

GPIO.setup([1], [2], pull_up_down=GPIO.[3])

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

A23

BGPIO.IN

CPUD_UP

DGPIO.OUT

Attempts:

3 left

💡 Hint

Common Mistakes

Using GPIO.OUT instead of GPIO.IN for input pin.

Using PUD_DOWN instead of PUD_UP for pull-up resistor.

Pin 23 is set as input with a pull-up resistor using GPIO.setup(23, GPIO.IN, pull_up_down=GPIO.PUD_UP).

Practice

1. What is the purpose of the GPIO.setmode() function in the RPi.GPIO library?

easy

A. It sets the pin numbering system to use (BOARD or BCM).

B. It cleans up all GPIO pins after use.

C. It sets the direction of a specific pin (input or output).

D. It reads the current value of a GPIO pin.

Solution

1. Step 1: Understand the role of GPIO.setmode()

   This function tells the Raspberry Pi how to number the pins, either by physical board numbers (BOARD) or by Broadcom chip numbers (BCM).

2. Step 2: Differentiate from other functions

   Cleaning pins is done by GPIO.cleanup(), setting pin direction is GPIO.setup(), and reading pin value is done by GPIO.input().

3. Final Answer:

   It sets the pin numbering system to use (BOARD or BCM). -> Option A

4. Quick Check:

   GPIO.setmode() = sets pin numbering [OK]

Hint: Remember: setmode chooses pin numbering style [OK]

Common Mistakes:

• Confusing setmode() with cleanup()
• Thinking setmode() sets pin direction
• Mixing up setmode() with reading pin values

2. Which of the following is the correct way to import the RPi.GPIO library and set the pin numbering mode to BCM?

easy

A. import RPi.GPIO as GPIO\nGPIO.setmode(GPIO.BCM)

B. import RPi.GPIO as GPIO\nGPIO.setmode(GPIO.BOARD)

C. import GPIO\nGPIO.setmode(GPIO.BCM)

D. import RPi.GPIO\nGPIO.setmode(GPIO.BCM)

Solution

1. Step 1: Check the correct import syntax

   The standard way is to import RPi.GPIO as GPIO to use GPIO functions easily.

2. Step 2: Verify the setmode argument

   To set pin numbering to BCM, use GPIO.setmode(GPIO.BCM). import RPi.GPIO as GPIO\nGPIO.setmode(GPIO.BCM) matches both correct import and setmode usage.

3. Final Answer:

   import RPi.GPIO as GPIO\nGPIO.setmode(GPIO.BCM) -> Option A

4. Quick Check:

   Import as GPIO + setmode BCM = import RPi.GPIO as GPIO\nGPIO.setmode(GPIO.BCM) [OK]

Hint: Import as GPIO and use GPIO.BCM for BCM mode [OK]

Common Mistakes:

• Forgetting 'as GPIO' in import
• Using BOARD instead of BCM when BCM is asked
• Importing just GPIO without RPi

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

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
GPIO.setup(7, GPIO.OUT)
print(GPIO.gpio_function(7))

Assuming pin 7 is set as output.

medium

A. 0

B. 3

C. 2

D. 1

Solution

1. Step 1: Understand GPIO.gpio_function()

   This function returns a number representing the pin's current function. For output pins, it returns 1.

2. Step 2: Check pin setup

   Pin 7 is set as GPIO.OUT, so gpio_function(7) returns 1.

3. Final Answer:

   1 -> Option D

4. Quick Check:

   Output pin function code = 1 [OK]

Hint: Output pins return 1 from gpio_function() [OK]

Common Mistakes:

• Assuming gpio_function returns pin number
• Confusing output code with input code
• Not setting pin mode before calling gpio_function

4. Identify the error in this code snippet:

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
GPIO.setup(11, "OUT")
GPIO.output(11, True)
GPIO.cleanup()

medium

A. Calling GPIO.cleanup() before output.

B. Using string "OUT" instead of GPIO.OUT in setup.

C. Missing GPIO.setwarnings(False) before setup.

D. Not importing time module for delays.

Solution

1. Step 1: Check GPIO.setup() syntax

   The direction argument must be GPIO.OUT or GPIO.IN, not a string like "OUT".

2. Step 2: Verify other lines

   GPIO.setwarnings() is optional, cleanup is correctly called last, and time module is not needed here.

3. Final Answer:

   Using string "OUT" instead of GPIO.OUT in setup. -> Option B

4. Quick Check:

   Pin direction must be GPIO.OUT, not "OUT" [OK]

Hint: Use GPIO.OUT constant, not string "OUT" [OK]

Common Mistakes:

• Passing pin direction as string
• Calling cleanup too early
• Forgetting to import GPIO properly

5. You want to control an LED connected to pin 12 using BCM numbering. Which sequence of commands correctly sets up the pin and turns the LED on, then cleans up properly?

hard

A. GPIO.setmode(GPIO.BCM)\nGPIO.setup(18, GPIO.OUT)\nGPIO.output(18, True)\nGPIO.cleanup()

B. GPIO.setmode(GPIO.BOARD)\nGPIO.setup(12, GPIO.OUT)\nGPIO.output(12, True)\nGPIO.cleanup()

C. GPIO.setmode(GPIO.BCM)\nGPIO.setup(12, GPIO.OUT)\nGPIO.output(12, True)\nGPIO.cleanup()

D. GPIO.setmode(GPIO.BOARD)\nGPIO.setup(18, GPIO.OUT)\nGPIO.output(18, True)\nGPIO.cleanup()

Solution

1. Step 1: Match numbering mode with pin number

   Pin 12 in BCM mode corresponds to GPIO12, so setmode(GPIO.BCM) and setup(12) is correct.

2. Step 2: Confirm output setup and cleanup

   Pin is set as output, turned on with True, and cleanup is called last to reset pins.

3. Final Answer:

   GPIO.setmode(GPIO.BCM)\nGPIO.setup(12, GPIO.OUT)\nGPIO.output(12, True)\nGPIO.cleanup() -> Option C

4. Quick Check:

   BCM mode + pin 12 + output + cleanup = GPIO.setmode(GPIO.BCM)\nGPIO.setup(12, GPIO.OUT)\nGPIO.output(12, True)\nGPIO.cleanup() [OK]

Hint: Match setmode with pin number system [OK]

Common Mistakes:

• Mixing BOARD and BCM numbering
• Using wrong pin number for chosen mode
• Forgetting to call cleanup()