[Solved] What will be the output behavior of this code snippet controlling an LED and button on... What will be the output behavior of this code snippet controlling an LED and button on Raspberry Pi? | Raspberry Pi

Raspberry Pi - LED and Button Projects

What will be the output behavior of this code snippet controlling an LED and button on Raspberry Pi? import RPi.GPIO as GPIO import time GPIO.setmode(GPIO.BCM) GPIO.setup(21, GPIO.OUT) GPIO.setup(20, GPIO.IN, pull_up_down=GPIO.PUD_UP) while True: if GPIO.input(20) == GPIO.LOW: GPIO.output(21, not GPIO.input(21)) time.sleep(0.3)

ALED stays ON permanently after first press

BLED toggles ON and OFF each time button is pressed

CLED never turns ON

DCode causes runtime error due to wrong GPIO input

Step-by-Step Solution

Solution:

Step 1: Analyze button input and LED output setup
Button is input with pull-up resistor; LED is output on pin 21.
Step 2: Understand the toggle logic inside the loop
When button pressed (input LOW), LED output is set to opposite of current state, toggling it.
Final Answer:
LED toggles ON and OFF each time button is pressed -> Option B
Quick Check:
Button press toggles LED = B [OK]

Quick Trick: Toggle LED by setting output to opposite of current state [OK]

Common Mistakes:

Assuming LED stays ON
Thinking LED never turns ON
Believing code causes error

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More Raspberry Pi Quizzes

What will be the output behavior of this code snippet controlling an LED and button on Raspberry Pi?

Step 1: Analyze button input and LED output setup

Step 2: Understand the toggle logic inside the loop

Final Answer:

Quick Check:

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