GPIO pin numbering (BCM vs BOARD) in Raspberry Pi - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

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

Raspberry Pi

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.[1])

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

ABOARD

BNUM

CPIN

DBCM

Attempts:

3 left

💡 Hint

Common Mistakes

Using BOARD instead of BCM for BCM numbering.

BCM mode uses the Broadcom chip's pin numbers.

2fill in blank

medium

Complete the code to set up pin 18 as an output using BCM numbering.

Raspberry Pi

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

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

A18

B12

C7

D22

Attempts:

3 left

💡 Hint

Common Mistakes

Using physical pin numbers instead of BCM numbers.

Pin 18 is a common GPIO pin in BCM mode.

3fill in blank

hard

Fix the error in the code to set the GPIO mode to BOARD numbering.

Raspberry Pi

GPIO.setmode(GPIO.[1])

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

APIN

BBOARD

CBCM

DNUM

Attempts:

3 left

💡 Hint

Common Mistakes

Using BCM instead of BOARD for physical pin numbering.

BOARD mode uses the physical pin numbers on the Raspberry Pi header.

4fill in blank

hard

Fill both blanks to create a dictionary mapping physical pins to BCM pins for pins 7 and 11.

Raspberry Pi

pin_map = {7: [1], 11: [2]

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A4

B17

C27

D22

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up physical and BCM pin numbers.

Physical pin 7 maps to BCM 4, and physical pin 11 maps to BCM 17.

5fill in blank

hard

Fill all three blanks to set up physical pin 12 as output, set it high, and then clean up.

Raspberry Pi

GPIO.setmode(GPIO.[1])
GPIO.setup([2], GPIO.OUT)
GPIO.output([3], GPIO.HIGH)
GPIO.cleanup()

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

ABOARD

B12

DBCM

Attempts:

3 left

💡 Hint

Common Mistakes

Using BCM mode but physical pin numbers.

Use BOARD mode for physical pin numbering, set up pin 12 as output, then set it high.

Practice

1. Which GPIO pin numbering mode uses the physical pin numbers on the Raspberry Pi header?

easy

A. BOARD numbering mode

B. BCM numbering mode

C. WIRING numbering mode

D. PIN numbering mode

Solution

1. Step 1: Understand GPIO numbering modes

   GPIO pins can be numbered by their physical location (BOARD) or by the Broadcom chip numbering (BCM).

2. Step 2: Identify physical pin numbering

   BOARD mode refers to the physical pin numbers on the Raspberry Pi header.

3. Final Answer:

   BOARD numbering mode -> Option A

4. Quick Check:

   Physical pins = BOARD [OK]

Hint: BOARD mode matches physical pin numbers on the header [OK]

Common Mistakes:

• Confusing BCM with physical pin numbers
• Thinking BCM is the physical numbering
• Assuming WIRING or PIN modes exist

2. Which of the following is the correct way to set GPIO pin numbering to BCM mode in Python?

easy

A. GPIO.setmode(GPIO.BOARD)

B. GPIO.setupmode(GPIO.BCM)

C. GPIO.mode(GPIO.BCM)

D. GPIO.setmode(GPIO.BCM)

Solution

1. Step 1: Recall the correct function to set GPIO mode

   The function to set numbering mode is GPIO.setmode().

2. Step 2: Use the correct constant for BCM mode

   GPIO.BCM is the constant for BCM numbering mode.

3. Final Answer:

   GPIO.setmode(GPIO.BCM) -> Option D

4. Quick Check:

   Use setmode with BCM constant [OK]

Hint: Use GPIO.setmode(GPIO.BCM) to select BCM numbering [OK]

Common Mistakes:

• Using GPIO.mode instead of GPIO.setmode
• Using BOARD instead of BCM constant
• Calling GPIO.setupmode which doesn't exist

3. Given the code snippet:

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
GPIO.setup(7, GPIO.OUT)
GPIO.output(7, GPIO.HIGH)

Which physical pin is set HIGH?

medium

A. Pin 11 on the physical header

B. GPIO pin number 7 on the Broadcom chip

C. Pin 7 on the physical header

D. GPIO pin number 11 on the Broadcom chip

Solution

1. Step 1: Identify the numbering mode used

   The code uses GPIO.setmode(GPIO.BOARD), so pin numbers refer to physical header pins.

2. Step 2: Check which pin is set HIGH

   GPIO.setup(7, GPIO.OUT) and GPIO.output(7, GPIO.HIGH) set physical pin 7 HIGH.

3. Final Answer:

   Pin 7 on the physical header -> Option C

4. Quick Check:

   BOARD mode pin 7 = physical pin 7 [OK]

Hint: BOARD mode means pin number is physical header pin [OK]

Common Mistakes:

• Confusing BOARD pin 7 with BCM GPIO 7
• Assuming pin 7 means BCM numbering
• Mixing physical pin numbers with BCM numbers

4. What is wrong with this code snippet?

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setup(10, GPIO.OUT)
GPIO.output(10, GPIO.HIGH)

Assuming the LED is wired to physical pin 10 on the header.

medium

A. Pin 10 in BCM does not match physical pin 10 wiring

B. GPIO.setmode(GPIO.BOARD) should be used instead

C. GPIO.output() requires pin number as string

D. GPIO.setup() cannot use BCM numbering

Solution

1. Step 1: Understand numbering mismatch

   GPIO.setmode(GPIO.BCM) means pin numbers refer to Broadcom chip pins, not physical pins.

2. Step 2: Check wiring vs numbering

   Physical pin 10 corresponds to BCM GPIO 15. The code uses BCM pin 10 (physical pin 19), so it does not control the wired physical pin 10.

3. Final Answer:

   Pin 10 in BCM does not match physical pin 10 wiring -> Option A

4. Quick Check:

   BCM 10 controls physical 19 ≠ pin 10 [OK]

Hint: Match numbering mode to wiring to avoid pin mismatch [OK]

Common Mistakes:

• Assuming physical pin numbers work with BCM mode
• Using string instead of int for pin number
• Thinking GPIO.setup can't use BCM numbering

5. You want to control an LED connected to physical pin 12 on the Raspberry Pi header. Which code snippet correctly sets the pin HIGH using BCM numbering?

hard

A. GPIO.setmode(GPIO.BOARD)
GPIO.setup(12, GPIO.OUT)
GPIO.output(12, GPIO.HIGH)

B. GPIO.setmode(GPIO.BCM)
GPIO.setup(18, GPIO.OUT)
GPIO.output(18, GPIO.HIGH)

C. GPIO.setmode(GPIO.BCM)
GPIO.setup(12, GPIO.OUT)
GPIO.output(12, GPIO.HIGH)

D. GPIO.setmode(GPIO.BOARD)
GPIO.setup(18, GPIO.OUT)
GPIO.output(18, GPIO.HIGH)

Solution

1. Step 1: Identify physical pin 12's BCM number

   Physical pin 12 corresponds to BCM GPIO 18 on Raspberry Pi.

2. Step 2: Use BCM numbering mode and correct pin

   Set mode to GPIO.BCM and use pin 18 in setup and output.

3. Final Answer:

   GPIO.setmode(GPIO.BCM) GPIO.setup(18, GPIO.OUT) GPIO.output(18, GPIO.HIGH) -> Option B

4. Quick Check:

   Physical pin 12 = BCM 18, use BCM mode [OK]

Hint: Convert physical pin to BCM before coding [OK]

Common Mistakes:

• Using physical pin number with BCM mode
• Using BCM pin number with BOARD mode
• Mixing pin numbers without conversion