Servo motor control with PWM in Raspberry Pi - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the PWMOutputDevice class from the gpiozero library.

Raspberry Pi

from gpiozero import [1]

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

APWM

BPWMOutputDevice

CServo

DLED

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Servo' instead of 'PWMOutputDevice' because Servo is a different class.

Using 'LED' which is unrelated to PWM control.

The PWMOutputDevice class is used to control pulse width modulation signals on Raspberry Pi GPIO pins.

2fill in blank

medium

Complete the code to create a PWM object on GPIO pin 17.

Raspberry Pi

servo = PWMOutputDevice([1], frequency=50)

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

A18

B27

C22

D17

Attempts:

3 left

💡 Hint

Common Mistakes

Using pin 18 which is often used for PWM but not the one specified here.

Using pin 22 or 27 which are valid GPIO pins but not the correct one.

GPIO pin 17 is commonly used for PWM control of servos on Raspberry Pi.

3fill in blank

hard

Fix the error in setting the servo pulse width to 1.5 milliseconds.

Raspberry Pi

servo.value = [1]

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

A0.075

B1.5

C0.5

D1500

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1.5 directly which is out of range.

Using 1500 which is a pulse width in microseconds, not a fraction.

The servo.value expects a duty cycle value between 0 and 1. At 50Hz (20ms period), 1.5ms pulse width corresponds to 1.5/20 = 0.075.

4fill in blank

hard

Fill both blanks to create a dictionary mapping angles to PWM values for 0 and 90 degrees.

Raspberry Pi

angle_to_pwm = {0: [1], 90: [2]

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

A0.0

B0.075

C0.05

D1.0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0.0 for 0 degrees which gives no pulse.

Using 1.0 for 90 degrees which is maximum duty cycle.

For servo control at 50Hz, 0.05 corresponds to ~1ms pulse (0 degrees) and 0.075 to ~1.5ms pulse (90 degrees) duty cycle.

5fill in blank

hard

Fill all three blanks to complete the code that sets the servo to 45 degrees using the angle_to_pwm dictionary.

Raspberry Pi

angle = 45
pwm_value = (angle_to_pwm[0] + angle_to_pwm[90]) / 2
servo.value = [1]

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

Apwm_value

Bangle

C0.25

Dservo.value

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'angle' which is just the angle, not the PWM value.

Using 'servo.value' which is the property, not a value.

The variable pwm_value holds the PWM value for 45 degrees, so we assign it to servo.value.