Reaction time game in Raspberry Pi - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the module needed to measure time.

Raspberry Pi

import [1]

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

Atime

Brandom

Cgpiozero

Dsys

Attempts:

3 left

💡 Hint

Common Mistakes

Importing the wrong module like random or gpiozero instead of time.

The time module lets us measure time intervals, which is important for a reaction time game.

2fill in blank

medium

Complete the code to wait for a random time between 1 and 3 seconds before starting the reaction timer.

Raspberry Pi

import random
import time

wait_time = random.[1](1, 3)
time.sleep(wait_time)

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

Achoice

Buniform

Crandom

Drandint

Attempts:

3 left

💡 Hint

Common Mistakes

Using random.choice which picks from a list, not a range.

Using random.uniform which picks a float, not an integer.

random.randint(1, 3) picks a whole number between 1 and 3 seconds to wait.

3fill in blank

hard

Fix the error in the code that measures the reaction time by capturing start and end times.

Raspberry Pi

start = time.[1]()
# wait for user input here
end = time.perf_counter()
reaction_time = end - start

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

Asleep

Btime

Cperf_counter

Dprocess_time

Attempts:

3 left

💡 Hint

Common Mistakes

Using time.sleep which pauses the program.

Using time.time which is less precise for short intervals.

time.perf_counter() gives a precise timer for measuring short durations like reaction time.

4fill in blank

hard

Fill both blanks to create a dictionary that stores reaction times for each player if their time is less than 2 seconds.

Raspberry Pi

reaction_times = {player: [1] for player, [2] in results.items() if [1] < 2}

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

Atime

Bscore

Creaction

Dresult

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same variable name for player and time.

Using undefined variable names.

The dictionary comprehension uses time as the value and time as the variable for the reaction time in the loop.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that stores uppercase player names as keys and their scores if scores are above 0.

Raspberry Pi

high_scores = { [1]: [2] for [3], [2] in scores.items() if [2] > 0}

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

Aplayer.upper()

Bscore

Cplayer

Dpoints

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up variable names or using undefined variables.

Not using the upper() method for keys.

The keys are uppercase player names using player.upper(), values are score, and the loop variables are player and score.

Practice

1. What is the main purpose of a reaction time game on a Raspberry Pi?

easy

A. To measure how quickly a player presses a button after an LED lights up

B. To count how many times a button is pressed in a minute

C. To display random colors on an LED strip

D. To control the brightness of an LED using a sensor

Solution

1. Step 1: Understand the game goal

   The reaction time game tests how fast a player reacts to a signal, usually an LED lighting up.

2. Step 2: Identify the key action

   The player must press a button as soon as the LED lights up to measure reaction speed.

3. Final Answer:

   To measure how quickly a player presses a button after an LED lights up -> Option A

4. Quick Check:

   Reaction time = button press speed after LED [OK]

Hint: Focus on measuring speed after LED signal [OK]

Common Mistakes:

• Confusing reaction time with counting presses
• Thinking the game controls LED brightness
• Assuming it displays colors randomly

2. Which Python code snippet correctly sets up GPIO pin 17 as an input for a button on Raspberry Pi?

easy

A. GPIO.setup(17, GPIO.OUT)

B. GPIO.setup(17, GPIO.IN)

C. GPIO.input(17, GPIO.IN)

D. GPIO.output(17, GPIO.IN)

Solution

1. Step 1: Recall GPIO setup syntax

   To set a pin as input, use GPIO.setup(pin_number, GPIO.IN).

2. Step 2: Match the correct option

   GPIO.setup(17, GPIO.IN) uses GPIO.setup(17, GPIO.IN), which is correct for input pin setup.

3. Final Answer:

   GPIO.setup(17, GPIO.IN) -> Option B

4. Quick Check:

   GPIO.setup(pin, GPIO.IN) sets input pin [OK]

Hint: Use GPIO.setup with GPIO.IN for input pins [OK]

Common Mistakes:

• Using GPIO.OUT instead of GPIO.IN for input
• Confusing GPIO.input() with GPIO.setup()
• Trying to use GPIO.output() on input pins

3. What will be the output of this code snippet in a reaction time game?

import time
start = time.time()
# LED lights up here
input('Press Enter as fast as you can!')
end = time.time()
print(f'Reaction time: {end - start:.2f} seconds')

medium

A. No output because input() is not called

B. Reaction time: 0.00 seconds

C. SyntaxError due to missing parentheses

D. Reaction time: time taken between prompt and Enter press

Solution

1. Step 1: Understand timing with time.time()

   The code records time before and after waiting for user input.

2. Step 2: Calculate reaction time

   The difference end - start measures how long the user took to press Enter after the prompt.

3. Final Answer:

   Reaction time: time taken between prompt and Enter press -> Option D

4. Quick Check:

   Reaction time = end - start after input [OK]

Hint: time.time() difference measures reaction delay [OK]

Common Mistakes:

• Assuming reaction time is always zero
• Confusing syntax errors with correct code
• Thinking input() is not called

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

GPIO.setup(18, GPIO.OUT)
GPIO.setup(23, GPIO.IN)
GPIO.output(23, GPIO.HIGH)
# Wait for button press on pin 23

medium

A. Pin 23 should be set as GPIO.OUT

B. GPIO.setup() missing for pin 18

C. GPIO.output() used on input pin 23, which is incorrect

D. No error, code is correct

Solution

1. Step 1: Check pin setup

   Pin 23 is set as input with GPIO.setup(23, GPIO.IN).

2. Step 2: Identify incorrect usage

   GPIO.output() cannot be used on input pins; it is only for output pins.

3. Final Answer:

   GPIO.output() used on input pin 23, which is incorrect -> Option C

4. Quick Check:

   GPIO.output() only for output pins [OK]

Hint: Use GPIO.output only on output pins [OK]

Common Mistakes:

• Trying to write output on input pins
• Forgetting to setup pins before use
• Assuming no error when pin modes mismatch

5. You want to improve your Raspberry Pi reaction time game by adding a random delay before lighting the LED. Which code snippet correctly adds a random delay between 1 and 5 seconds before turning on the LED on pin 18?

hard

A. import random
import time
wait = random.randint(1, 5)
time.sleep(wait)
GPIO.output(18, GPIO.HIGH)

B. import random
wait = random.random(1, 5)
time.sleep(wait)
GPIO.output(18, GPIO.HIGH)

C. import random
wait = random.randint(1, 5)
GPIO.output(18, GPIO.HIGH)
time.sleep(wait)

D. import time
wait = random.randint(1, 5)
time.sleep(wait)
GPIO.output(18, GPIO.HIGH)

Solution

1. Step 1: Use random.randint for integer delay

   random.randint(1, 5) returns an integer between 1 and 5 seconds.

2. Step 2: Sleep before turning LED on

   time.sleep(wait) pauses the program before GPIO.output(18, GPIO.HIGH) lights the LED.

3. Final Answer:

   import random import time wait = random.randint(1, 5) time.sleep(wait) GPIO.output(18, GPIO.HIGH) -> Option A

4. Quick Check:

   random.randint + sleep before LED ON [OK]

Hint: Sleep before LED ON using random.randint delay [OK]

Common Mistakes:

• Using random.random with arguments (invalid)
• Sleeping after turning LED on
• Not importing random module