GPIO pin numbering (BCM vs BOARD) in Raspberry Pi - Hands-On Comparison

GPIO Pin Numbering (BCM vs BOARD)

📖 Scenario: You are working on a Raspberry Pi project that controls an LED light. To do this, you need to set up the GPIO pins correctly. Raspberry Pi allows two ways to number pins: BCM (Broadcom chip numbering) and BOARD (physical pin numbering on the header).Understanding the difference helps you connect your hardware and write code that controls the pins properly.

🎯 Goal: Build a simple Python program that sets up the GPIO pins using both BCM and BOARD numbering modes. You will create a dictionary of pins, choose a numbering mode, and then print the pin numbers according to the chosen mode.

📋 What You'll Learn

Create a dictionary with pin names and their BCM and BOARD numbers

Create a variable to store the chosen numbering mode ('BCM' or 'BOARD')

Use a dictionary comprehension to create a new dictionary with pin names and their numbers based on the chosen mode

Print the resulting dictionary of pins with their numbers

💡 Why This Matters

🌍 Real World

When building Raspberry Pi projects, you must know how to refer to pins correctly to connect sensors, buttons, and LEDs safely and effectively.

💼 Career

Understanding GPIO pin numbering is essential for hardware engineers, IoT developers, and anyone working with embedded systems using Raspberry Pi.

1

Create the GPIO pins dictionary

Create a dictionary called gpio_pins with these exact entries: 'LED': {'BCM': 17, 'BOARD': 11}, 'Button': {'BCM': 27, 'BOARD': 13}, and 'Sensor': {'BCM': 22, 'BOARD': 15}.

Raspberry Pi

# Create the gpio_pins dictionary with pin names and their BCM and BOARD numbers
# Your code here

Need a hint?

Think of gpio_pins as a map where each device name points to another map of its BCM and BOARD pin numbers.

2

Set the numbering mode

Create a variable called numbering_mode and set it to the string 'BCM'.

Raspberry Pi

gpio_pins = {
    'LED': {'BCM': 17, 'BOARD': 11},
    'Button': {'BCM': 27, 'BOARD': 13},
    'Sensor': {'BCM': 22, 'BOARD': 15}
}
# Set the numbering_mode variable to 'BCM'
# Your code here

Need a hint?

This variable will decide which pin numbering system your program uses.

3

Create a dictionary with pins using the chosen numbering mode

Use a dictionary comprehension to create a new dictionary called pins that maps each pin name to its number using the numbering_mode. For example, pins = {name: gpio_pins[name][numbering_mode] for name in gpio_pins}.

Raspberry Pi

gpio_pins = {
    'LED': {'BCM': 17, 'BOARD': 11},
    'Button': {'BCM': 27, 'BOARD': 13},
    'Sensor': {'BCM': 22, 'BOARD': 15}
}
numbering_mode = 'BCM'
# Create the pins dictionary using dictionary comprehension and numbering_mode
# Your code here

Need a hint?

Use a dictionary comprehension to pick the right pin number for each device based on the numbering_mode.

4

Print the pins dictionary

Write a print statement to display the pins dictionary.

Raspberry Pi

gpio_pins = {
    'LED': {'BCM': 17, 'BOARD': 11},
    'Button': {'BCM': 27, 'BOARD': 13},
    'Sensor': {'BCM': 22, 'BOARD': 15}
}
numbering_mode = 'BCM'
pins = {name: gpio_pins[name][numbering_mode] for name in gpio_pins}
# Print the pins dictionary
# Your code here

Need a hint?

Use print(pins) to show the final pin numbers.