[Solved] Find the bug in this code that prevents LED brightness control:import RPi.GPIO as GPIO GPIO.setmode(GPIO.BCM) GPIO.setup(21, GPIO.IN) pwm = GPIO.PWM(21, 1000) pwm.start(50) | Raspberry Pi

Raspberry Pi - PWM Output

Find the bug in this code that prevents LED brightness control:

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setup(21, GPIO.IN)
pwm = GPIO.PWM(21, 1000)
pwm.start(50)

AGPIO pin 21 is set as input instead of output

BPWM frequency 1000 is too high

CMissing pwm.ChangeDutyCycle call

DGPIO.setmode should be BOARD, not BCM

Step-by-Step Solution

Solution:

Step 1: Check GPIO pin mode
Pin 21 is set as input, but PWM requires output mode.
Step 2: Confirm other code correctness
Frequency 1000 Hz is valid; ChangeDutyCycle is optional after start; setmode BCM is acceptable.
Final Answer:
GPIO pin 21 is set as input instead of output -> Option A
Quick Check:
GPIO pin mode must be output for PWM [OK]

Quick Trick: Set GPIO pin as output for PWM [OK]

Common Mistakes:

Master "PWM Output" in Raspberry Pi

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Find the bug in this code that prevents LED brightness control: