Raspberry Pi - GPIO Basics with Python
You want to write a program that reads a button connected to GPIO pin 17 (BCM numbering) and turns on an LED on pin 27 when pressed. Which setup code is correct?
You want to write a program that reads a button connected to GPIO pin 17 (BCM numbering) and turns on an LED on pin 27 when pressed. Which setup code is correct?
hard📝 Application Q9 of 15
Step-by-Step Solution
Solution:
Step 1: Understand pin numbering and roles
Button is on GPIO 17 input, LED on GPIO 27 output, both BCM numbering.Step 2: Check mode and setup calls
GPIO.setmode(GPIO.BCM) GPIO.setup(17, GPIO.IN) GPIO.setup(27, GPIO.OUT) sets mode to BCM and configures pin 17 as input and 27 as output correctly.Step 3: Evaluate other options
GPIO.setmode(GPIO.BOARD) GPIO.setup(17, GPIO.IN) GPIO.setup(27, GPIO.OUT) uses BOARD mode but pins 17 and 27 are BCM numbers, so mismatch. GPIO.setmode(GPIO.BCM) GPIO.setup(17, GPIO.OUT) GPIO.setup(27, GPIO.IN) swaps input/output roles. GPIO.setmode(GPIO.BOARD) GPIO.setup(11, GPIO.IN) GPIO.setup(13, GPIO.OUT) uses BOARD pins 11 and 13, unrelated.Final Answer:
GPIO.setmode(GPIO.BCM) GPIO.setup(17, GPIO.IN) GPIO.setup(27, GPIO.OUT) -> Option CQuick Check:
Correct BCM setup for button and LED = B [OK]
Quick Trick: Match pin numbers with mode and roles carefully [OK]
Common Mistakes:
- Mixing BOARD and BCM modes
- Swapping input and output pins
- Using wrong pin numbers for mode
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