Real-time sensor dashboard in Raspberry Pi - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the library needed to read sensor data.

Raspberry Pi

import [1]

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

Agpiozero

Btime

Cos

Dsys

Attempts:

3 left

💡 Hint

Common Mistakes

Importing unrelated libraries like os or sys.

Forgetting to import gpiozero for sensor control.

The gpiozero library is used to interact with sensors on Raspberry Pi.

2fill in blank

medium

Complete the code to create a temperature sensor object on GPIO pin 4.

Raspberry Pi

sensor = gpiozero.TemperatureSensor([1])

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

A17

B4

C22

D27

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong pin numbers that don't match the hardware setup.

Confusing pin numbers with sensor types.

GPIO pin 4 is commonly used for temperature sensors in examples.

3fill in blank

hard

Fix the error in the code to read the current temperature value.

Raspberry Pi

current_temp = sensor.[1]

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

Avalue

Btemperature()

Cget()

Dread()

Attempts:

3 left

💡 Hint

Common Mistakes

Calling a method that does not exist like read() or get().

Using parentheses with a property.

The value property gives the current sensor reading directly.

4fill in blank

hard

Fill both blanks to create a dictionary with sensor name and its current value.

Raspberry Pi

sensor_data = [1]: [2]

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

A'temperature'

Bsensor.value

C'humidity'

Dsensor.read

Attempts:

3 left

💡 Hint

Common Mistakes

Using method calls instead of properties for sensor value.

Not using quotes around the dictionary key.

The dictionary key is the sensor name as a string, and the value is the current reading from sensor.value.

5fill in blank

hard

Fill all three blanks to create a dashboard update function that prints sensor data with a label.

Raspberry Pi

def update_dashboard():
    print(f"[1]: [2] °C")
    return [3]

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

A'Temperature'

Bsensor.value

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Using method calls instead of properties for sensor value.

Returning the sensor value instead of None.

The function prints the label 'Temperature' and the current sensor value, then returns None as it only outputs data.

Practice

1. What is the main purpose of a real-time sensor dashboard on a Raspberry Pi?

easy

A. To run heavy data processing tasks offline

B. To store sensor data for long-term analysis only

C. To display live sensor data instantly for monitoring

D. To control the Raspberry Pi remotely

Solution

1. Step 1: Understand the dashboard function

   A real-time sensor dashboard shows live data as it changes, helping users monitor conditions instantly.

2. Step 2: Compare options to purpose

   Only To display live sensor data instantly for monitoring describes displaying live sensor data instantly, which matches the dashboard's main goal.

3. Final Answer:

   To display live sensor data instantly for monitoring -> Option C

4. Quick Check:

   Real-time dashboard = live data display [OK]

Hint: Real-time means showing data as it happens [OK]

Common Mistakes:

• Confusing storage with live display
• Thinking dashboard controls the device
• Assuming heavy processing is done on dashboard

2. Which Python code snippet correctly reads a sensor value on Raspberry Pi for real-time updates?

easy

A. sensor_value = sensor.read()

B. sensor_value == sensor.read()

C. sensor.read = sensor_value()

D. sensor_value := sensor.read

Solution

1. Step 1: Identify correct assignment syntax

   In Python, to assign a value from a function call, use single equals: variable = function().

2. Step 2: Check each option

   sensor_value = sensor.read() uses correct assignment and function call syntax. Options B and C misuse operators or assignment. sensor_value := sensor.read uses walrus operator incorrectly without parentheses.

3. Final Answer:

   sensor_value = sensor.read() -> Option A

4. Quick Check:

   Assignment uses =, not == or := alone [OK]

Hint: Use single = to assign function output to variable [OK]

Common Mistakes:

• Using == instead of = for assignment
• Trying to assign function call incorrectly
• Misusing walrus operator without parentheses

3. Given this Python code snippet for updating a dashboard:

import time
sensor_value = 0
for _ in range(3):
    sensor_value += 5
    print(sensor_value)
    time.sleep(1)

What will be the printed output?

medium

A. 5\n10\n15

B. 0\n5\n10

C. 5\n5\n5

D. 0\n0\n0

Solution

1. Step 1: Analyze the loop increments

   Initially, sensor_value = 0. Each loop adds 5, so values become 5, then 10, then 15.

2. Step 2: Confirm printed values

   Each iteration prints the updated sensor_value, so output lines are 5, 10, and 15.

3. Final Answer:

   5\n10\n15 -> Option A

4. Quick Check:

   Increment by 5 each loop = 5,10,15 [OK]

Hint: Add increments stepwise and print each [OK]

Common Mistakes:

• Printing before incrementing
• Resetting sensor_value inside loop
• Ignoring loop iterations count

4. You wrote this code to update a sensor dashboard:

while True:
    sensor_value = sensor.read
    print(sensor_value)
    time.sleep(1)

Why does the dashboard not show updated sensor values?

medium

A. Because time.sleep(1) pauses too long

B. Because sensor.read is missing parentheses to call the function

C. Because print() does not display values

D. Because while True causes an infinite loop

Solution

1. Step 1: Identify function call syntax error

   sensor.read is a function and must be called with parentheses: sensor.read()

2. Step 2: Understand impact on sensor_value

   Without parentheses, sensor_value stores the function object, not the sensor data, so printed values don't update.

3. Final Answer:

   Because sensor.read is missing parentheses to call the function -> Option B

4. Quick Check:

   Function call needs () to get value [OK]

Hint: Always add () to call functions [OK]

Common Mistakes:

• Ignoring missing parentheses on function calls
• Blaming sleep for no updates
• Thinking print() doesn't show output

5. You want to build a real-time dashboard on Raspberry Pi that updates sensor data every second and shows the average of last 5 readings. Which approach is best?

hard

A. Calculate average once at start, then display static value

B. Store all readings forever and calculate average of all data each second

C. Update dashboard only when sensor value changes, ignoring average

D. Store last 5 readings in a list, update every second, calculate average, then update dashboard

Solution

1. Step 1: Understand real-time averaging requirement

   To show average of last 5 readings updated every second, you must keep a rolling list of last 5 values.

2. Step 2: Evaluate options for efficiency and accuracy

   Store last 5 readings in a list, update every second, calculate average, then update dashboard correctly stores last 5 readings, updates average each second, and refreshes dashboard. Calculate average once at start, then display static value is static, C ignores averaging, D is inefficient and grows data indefinitely.

3. Final Answer:

   Store last 5 readings in a list, update every second, calculate average, then update dashboard -> Option D

4. Quick Check:

   Rolling average needs recent 5 values updated regularly [OK]

Hint: Keep fixed-size list for rolling average updates [OK]

Common Mistakes:

• Calculating average only once
• Ignoring rolling window for average
• Storing unlimited data causing slowdowns