Python on Raspberry Pi - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Raspberry Pi?

Raspberry Pi is a small, affordable computer that you can use to learn programming and build projects.

beginner

How do you run a Python program on Raspberry Pi?

You can run a Python program by opening the terminal and typing python3 filename.py.

intermediate

What is GPIO on Raspberry Pi?

GPIO stands for General Purpose Input Output. It lets you connect and control electronic parts like LEDs and sensors using Python.

intermediate

Which Python library is commonly used to control GPIO pins on Raspberry Pi?

The RPi.GPIO library is commonly used to control GPIO pins with Python on Raspberry Pi.

beginner

How can you install a Python library on Raspberry Pi?

You can install a Python library using the terminal command pip3 install library_name.

What command runs a Python 3 script named blink.py on Raspberry Pi?

A python3 blink.py

B run blink.py

C execute blink.py

D start blink.py

The correct command is python3 blink.py to run a Python 3 script.

What does GPIO stand for?

A General Program Input Output

B General Purpose Input Output

C General Purpose Internal Output

D General Program Internal Output

GPIO means General Purpose Input Output, used for connecting hardware parts.

Which Python library is used to control Raspberry Pi GPIO pins?

A RPi.GPIO

B gpiozero

C pyserial

D numpy

RPi.GPIO is the common library for GPIO control, though gpiozero is also popular.

How do you install a Python package on Raspberry Pi?

A python3 package_name

B install package_name

C pip3 install package_name

D run package_name

Use pip3 install package_name to install Python packages.

What is the main use of Raspberry Pi?

A Playing video games only

B Replacing smartphones

C Only for web browsing

D Learning programming and building projects

Raspberry Pi is mainly used to learn programming and create projects.

Explain how you would run a Python program on Raspberry Pi and what you need to do first.

Think about the steps from opening the terminal to running the script.

Describe what GPIO pins are and how Python can interact with them on Raspberry Pi.

Imagine controlling lights or sensors with code.

Practice

1. What is the main purpose of using Python on a Raspberry Pi?

easy

A. To control hardware like LEDs and sensors easily

B. To create websites only

C. To run Windows applications

D. To edit videos

Solution

1. Step 1: Understand Raspberry Pi's use with Python

   Python on Raspberry Pi is mainly used to control hardware components like LEDs and sensors.

2. Step 2: Compare options with this purpose

   The options describing website creation only, running Windows applications, and video editing do not relate to hardware control, so they are incorrect.

3. Final Answer:

   To control hardware like LEDs and sensors easily -> Option A

4. Quick Check:

   Python on Raspberry Pi = hardware control [OK]

Hint: Think about what Raspberry Pi projects usually do [OK]

Common Mistakes:

• Confusing Raspberry Pi with a general computer
• Thinking Python on Pi is only for web development
• Assuming it runs Windows apps natively

2. Which of the following is the correct way to import the GPIO library in Python on Raspberry Pi?

easy

A. import GPIO.RPi

B. import RPi.GPIO as GPIO

C. from GPIO import RPi

D. import raspberry.GPIO

Solution

1. Step 1: Recall the standard import syntax for GPIO

   The correct import statement is import RPi.GPIO as GPIO to use GPIO functions easily.

2. Step 2: Check other options for syntax errors

   The other options ('import GPIO.RPi', 'from GPIO import RPi', 'import raspberry.GPIO') do not follow Python import syntax or correct module names.

3. Final Answer:

   import RPi.GPIO as GPIO -> Option B

4. Quick Check:

   Standard GPIO import = import RPi.GPIO as GPIO [OK]

Hint: Remember the exact module name: RPi.GPIO [OK]

Common Mistakes:

• Swapping module and package names incorrectly
• Using wrong import syntax
• Assuming 'GPIO' alone is a module

3. What will be the output of this Python code on Raspberry Pi?

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setup(18, GPIO.OUT)
GPIO.output(18, GPIO.HIGH)
print(GPIO.input(18))

medium

A. 0

B. HIGH

C. 1

D. Error

Solution

1. Step 1: Understand GPIO setup and output

   Pin 18 is set as output and then set to HIGH, which means voltage is ON (1).

2. Step 2: Check GPIO.input(18) after setting HIGH

   Reading the pin returns 1 because it was set HIGH.

3. Final Answer:

   1 -> Option C

4. Quick Check:

   GPIO.output HIGH means input reads 1 [OK]

Hint: HIGH means 1, LOW means 0 in GPIO [OK]

Common Mistakes:

• Confusing HIGH with string 'HIGH'
• Expecting 0 instead of 1 after setting HIGH
• Thinking GPIO.input returns string values

4. Identify the error in this Raspberry Pi Python code snippet:

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
GPIO.setup(12, GPIO.OUT)
GPIO.output(12, HIGH)

medium

A. Missing GPIO prefix before HIGH

B. Wrong pin number for BOARD mode

C. GPIO.setmode should be BCM

D. GPIO.setup should be input, not output

Solution

1. Step 1: Check usage of HIGH constant

   HIGH must be referenced as GPIO.HIGH, not just HIGH alone.

2. Step 2: Verify other code parts

   Pin 12 is valid in BOARD mode, setmode can be BOARD, and output pin can be output.

3. Final Answer:

   Missing GPIO prefix before HIGH -> Option A

4. Quick Check:

   Use GPIO.HIGH, not just HIGH [OK]

Hint: Always prefix constants with GPIO. [OK]

Common Mistakes:

• Using HIGH without GPIO prefix
• Confusing BOARD and BCM pin numbering
• Setting output pin as input by mistake

5. You want to blink an LED connected to pin 17 on Raspberry Pi using Python. Which code snippet correctly blinks the LED once with a 1-second delay?

hard

A. import RPi.GPIO as GPIO
import time
GPIO.setmode(GPIO.BCM)
GPIO.setup(17, GPIO.IN)
GPIO.output(17, GPIO.HIGH)
time.sleep(1)
GPIO.output(17, GPIO.LOW)

B. import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setup(17, GPIO.OUT)
GPIO.output(17, 1)
time.sleep(1)
GPIO.output(17, 0)

C. import RPi.GPIO as GPIO
import time
GPIO.setmode(GPIO.BOARD)
GPIO.setup(17, GPIO.OUT)
GPIO.output(17, GPIO.HIGH)
time.sleep(1)
GPIO.output(17, GPIO.LOW)

D. import RPi.GPIO as GPIO
import time
GPIO.setmode(GPIO.BCM)
GPIO.setup(17, GPIO.OUT)
GPIO.output(17, GPIO.HIGH)
time.sleep(1)
GPIO.output(17, GPIO.LOW)

Solution

1. Step 1: Check pin numbering and setup

   BCM mode, import time, GPIO.setup(17, GPIO.OUT) are all correct.

2. Step 2: Verify output and delay

   GPIO.output(17, GPIO.HIGH), time.sleep(1), GPIO.output(17, GPIO.LOW) blinks once (on for 1s then off).

3. Step 3: Identify errors in other options

   One lacks import time (NameError on sleep); another uses BOARD mode (pin 17 ≠ BCM pin 17 physically); another sets GPIO.IN (should be OUT).

4. Final Answer:

   import RPi.GPIO as GPIO import time GPIO.setmode(GPIO.BCM) GPIO.setup(17, GPIO.OUT) GPIO.output(17, GPIO.HIGH) time.sleep(1) GPIO.output(17, GPIO.LOW) -> Option D

5. Quick Check:

   Use BCM mode, output pin, and time.sleep for blinking [OK]

Hint: Use GPIO.HIGH/LOW with time.sleep for blinking [OK]

Common Mistakes:

• Mixing BOARD and BCM pin numbers
• Setting pin as input instead of output
• Forgetting to import time module