PWM frequency and duty cycle relationship in Raspberry Pi - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the PWM frequency to 1000 Hz.

Raspberry Pi

pwm = GPIO.PWM(pin, [1])

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

A500

B1000

C2000

D50

Attempts:

3 left

💡 Hint

Common Mistakes

Using a frequency too low or too high for the device.

Confusing frequency with duty cycle.

The frequency of PWM is set by the second argument in GPIO.PWM(). Here, 1000 Hz is the correct frequency.

2fill in blank

medium

Complete the code to set the PWM duty cycle to 75%.

Raspberry Pi

pwm.ChangeDutyCycle([1])

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

A50

B100

C25

D75

Attempts:

3 left

💡 Hint

Common Mistakes

Using values outside 0-100 range.

Confusing duty cycle with frequency.

The duty cycle is the percentage of time the signal is ON. 75 means 75% ON time.

3fill in blank

hard

Fix the error in setting the PWM frequency to 0 Hz (which is invalid).

Raspberry Pi

pwm = GPIO.PWM(pin, [1])

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

A100

B-50

C0

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Setting frequency to zero or negative values.

Passing None instead of a number.

Frequency cannot be zero or negative. 100 Hz is a valid frequency.

4fill in blank

hard

Fill both blanks to create a dictionary mapping duty cycle percentages to their ON time in milliseconds for a 1 kHz PWM signal.

Raspberry Pi

on_time_ms = {dc: dc / 100 [1] 1000 / freq for dc in duty_cycles if dc [2] 0}

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

A*

B/

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using division instead of multiplication for ON time.

Including duty cycles less than or equal to zero.

The ON time in milliseconds is calculated as (duty cycle / 100) * 1000 / frequency. We only include duty cycles greater than 0.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps duty cycle percentages to their OFF time in milliseconds for a given frequency.

Raspberry Pi

off_time_ms = {dc: (100 - dc) / 100 [1] 1000 [2] freq [3] 0}

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

A*

B/

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect operators for multiplication or division.

Including duty cycles less than or equal to zero.

The OFF time is calculated as (100 - duty cycle) / 100 * 1000 / frequency. We include only duty cycles greater than 0.