Digital output (GPIO.output) in Raspberry Pi - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set GPIO pin 18 as output.

Raspberry Pi

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setup(18, [1])

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

AGPIO.PWM

BGPIO.IN

CGPIO.OUT

DGPIO.SPI

Attempts:

3 left

💡 Hint

Common Mistakes

Using GPIO.IN instead of GPIO.OUT

Confusing pin modes with communication protocols

GPIO.OUT sets the pin as an output pin so you can send signals.

2fill in blank

medium

Complete the code to turn GPIO pin 18 ON (set it HIGH).

Raspberry Pi

GPIO.output(18, [1])

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AGPIO.TRUE

BGPIO.LOW

CGPIO.ON

DGPIO.HIGH

Attempts:

3 left

💡 Hint

Common Mistakes

Using GPIO.LOW to turn the pin ON

Using non-existent constants like GPIO.ON

GPIO.HIGH sets the pin voltage to high, turning it ON.

3fill in blank

hard

Fix the error in the code to turn GPIO pin 23 OFF (set it LOW).

Raspberry Pi

GPIO.output(23, [1])

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AGPIO.LOW

BGPIO.HIGH

CGPIO.TRUE

DGPIO.ON

Attempts:

3 left

💡 Hint

Common Mistakes

Using GPIO.HIGH to turn the pin OFF

Using invalid constants like GPIO.ON

GPIO.LOW sets the pin voltage to low, turning it OFF.

4fill in blank

hard

Fill both blanks to create a dictionary of pin states for pins 17 and 27, setting 17 HIGH and 27 LOW.

Raspberry Pi

pin_states = {17: [1], 27: [2]

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AGPIO.HIGH

BGPIO.LOW

CGPIO.OUT

DGPIO.IN

Attempts:

3 left

💡 Hint

Common Mistakes

Using GPIO.OUT or GPIO.IN as pin states

Mixing up HIGH and LOW values

Pin 17 is set HIGH to turn ON, pin 27 is set LOW to turn OFF.

5fill in blank

hard

Fill all three blanks to set up pin 22 as output, turn it ON, and then clean up GPIO.

Raspberry Pi

GPIO.setup(22, [1])
GPIO.output(22, [2])
GPIO.[3]()

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

AGPIO.IN

BGPIO.HIGH

Ccleanup

DGPIO.OUT

Attempts:

3 left

💡 Hint

Common Mistakes

Using GPIO.IN instead of GPIO.OUT for setup

Forgetting to call cleanup()

Using wrong constants for output

First, set pin 22 as output with GPIO.OUT, then turn it ON with GPIO.HIGH, and finally clean up with GPIO.cleanup().

Practice

1. What does GPIO.output(pin, GPIO.HIGH) do on a Raspberry Pi?

easy

A. It sets the pin mode to input.

B. It turns the specified pin ON by setting it to HIGH voltage.

C. It reads the current value from the specified pin.

D. It resets the Raspberry Pi GPIO pins.

Solution

1. Step 1: Understand GPIO.output function

   The function GPIO.output(pin, value) sets the voltage level of the pin.

2. Step 2: Interpret GPIO.HIGH

   GPIO.HIGH means turning the pin ON by applying a high voltage.

3. Final Answer:

   It turns the specified pin ON by setting it to HIGH voltage. -> Option B

4. Quick Check:

   GPIO.output with GPIO.HIGH = Pin ON [OK]

Hint: HIGH means ON, LOW means OFF for GPIO pins [OK]

Common Mistakes:

• Confusing output with input reading
• Thinking GPIO.HIGH reads pin value
• Assuming it sets pin mode

2. Which of the following is the correct syntax to set GPIO pin 18 as an output pin?

easy

A. GPIO.setup(18, GPIO.INPUT)

B. GPIO.output(18, GPIO.HIGH)

C. GPIO.setup(18, GPIO.OUT)

D. GPIO.output(18, GPIO.OUT)

Solution

1. Step 1: Identify the function to set pin mode

   GPIO.setup(pin, mode) is used to set pin mode.

2. Step 2: Choose correct mode for output

   GPIO.OUT sets the pin as output, so GPIO.setup(18, GPIO.OUT) is correct.

3. Final Answer:

   GPIO.setup(18, GPIO.OUT) -> Option C

4. Quick Check:

   Pin mode output = GPIO.setup(pin, GPIO.OUT) [OK]

Hint: Use GPIO.setup(pin, GPIO.OUT) to set output mode [OK]

Common Mistakes:

• Using GPIO.INPUT instead of GPIO.OUT
• Trying to set output with GPIO.output before setup
• Using GPIO.output to set pin mode

3. What will be the output state of pin 23 after running this code?

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setup(23, GPIO.OUT)
GPIO.output(23, GPIO.LOW)

medium

A. Code will cause a runtime error.

B. Pin 23 will be ON (HIGH voltage).

C. Pin 23 will be set as input.

D. Pin 23 will be OFF (LOW voltage).

Solution

1. Step 1: Analyze pin setup

   Pin 23 is set as output using GPIO.setup(23, GPIO.OUT).

2. Step 2: Check output command

   GPIO.output(23, GPIO.LOW) sets pin 23 to LOW voltage, turning it OFF.

3. Final Answer:

   Pin 23 will be OFF (LOW voltage). -> Option D

4. Quick Check:

   GPIO.output(pin, GPIO.LOW) = Pin OFF [OK]

Hint: LOW means OFF, so pin is off after output LOW [OK]

Common Mistakes:

• Assuming LOW means ON
• Forgetting to set pin as output first
• Confusing pin number with mode

4. Identify the error in this code snippet:

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.output(17, GPIO.HIGH)

medium

A. Pin 17 is not set as output before using GPIO.output.

B. GPIO.HIGH is not a valid value for GPIO.output.

C. GPIO.setmode(GPIO.BCM) is incorrect syntax.

D. Missing import statement for GPIO.

Solution

1. Step 1: Check pin setup before output

   The code calls GPIO.output without first setting pin 17 as output using GPIO.setup(17, GPIO.OUT).

2. Step 2: Confirm other parts are correct

   GPIO.HIGH and GPIO.setmode(GPIO.BCM) are correct, and import is present.

3. Final Answer:

   Pin 17 is not set as output before using GPIO.output. -> Option A

4. Quick Check:

   Must setup pin as output before GPIO.output [OK]

Hint: Always setup pin as output before writing HIGH/LOW [OK]

Common Mistakes:

• Skipping GPIO.setup for output pins
• Confusing GPIO.HIGH with pin mode
• Incorrect setmode usage

5. You want to blink an LED connected to pin 12 five times. Which code snippet correctly turns the LED ON and OFF using GPIO.output inside a loop?

hard

A. for i in range(5):
GPIO.output(12, GPIO.HIGH)
time.sleep(1)
GPIO.output(12, GPIO.LOW)
time.sleep(1)

B. for i in range(5):
GPIO.output(12, GPIO.LOW)
time.sleep(1)
GPIO.output(12, GPIO.HIGH)
time.sleep(1)

C. GPIO.output(12, GPIO.HIGH)
for i in range(5):
time.sleep(1)
GPIO.output(12, GPIO.LOW)
time.sleep(1)

D. for i in range(5):
GPIO.setup(12, GPIO.OUT)
GPIO.output(12, GPIO.HIGH)
GPIO.output(12, GPIO.LOW)

Solution

1. Step 1: Understand blinking logic

   Blinking means turning LED ON (HIGH), waiting, then OFF (LOW), waiting, repeated 5 times.

2. Step 2: Analyze each option

   for i in range(5): GPIO.output(12, GPIO.HIGH) time.sleep(1) GPIO.output(12, GPIO.LOW) time.sleep(1) correctly loops 5 times, sets pin HIGH, waits, sets LOW, waits. for i in range(5): GPIO.output(12, GPIO.LOW) time.sleep(1) GPIO.output(12, GPIO.HIGH) time.sleep(1) reverses ON/OFF order. GPIO.output(12, GPIO.HIGH) for i in range(5): time.sleep(1) GPIO.output(12, GPIO.LOW) time.sleep(1) turns ON once before loop. for i in range(5): GPIO.setup(12, GPIO.OUT) GPIO.output(12, GPIO.HIGH) GPIO.output(12, GPIO.LOW) wrongly calls setup inside loop.

3. Final Answer:

   for i in range(5): GPIO.output(12, GPIO.HIGH) time.sleep(1) GPIO.output(12, GPIO.LOW) time.sleep(1) -> Option A

4. Quick Check:

   Blink = ON + wait + OFF + wait in loop [OK]

Hint: Turn ON then OFF with delays inside loop to blink [OK]

Common Mistakes:

• Calling GPIO.setup inside loop repeatedly
• Reversing ON/OFF order
• Not including delays between ON and OFF