Motor speed control with PWM in Arduino - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does PWM stand for in motor speed control?

PWM stands for Pulse Width Modulation. It controls motor speed by changing the amount of time the power is ON versus OFF.

beginner

How does PWM control the speed of a DC motor?

PWM changes the motor's speed by adjusting the duty cycle, which is the percentage of time the signal is HIGH in each cycle. More HIGH time means faster motor speed.

beginner

Which Arduino function is used to generate a PWM signal?

The Arduino function analogWrite(pin, value) generates a PWM signal on the specified pin. The value ranges from 0 (always OFF) to 255 (always ON).

intermediate

Why can't we use analogWrite to get a true analog voltage?

Because analogWrite creates a digital PWM signal that switches ON and OFF rapidly. The motor or device averages this to behave like an analog voltage.

beginner

What is the typical range of PWM values for controlling motor speed on Arduino?

PWM values range from 0 to 255. 0 means motor is stopped, 255 means motor runs at full speed, and values in between control speed proportionally.

What does a PWM duty cycle of 50% mean for motor speed?

A Motor runs at full speed

B Motor runs at double speed

C Motor is stopped

D Motor runs at half speed

A 50% duty cycle means the power is ON half the time, so the motor runs roughly at half speed.

Which Arduino function is used to send a PWM signal to a motor?

A digitalWrite()

B analogWrite()

C pinMode()

D delay()

analogWrite() sends a PWM signal by varying the duty cycle.

What happens if you set PWM value to 0 on Arduino motor control?

A Motor runs at full speed

B Motor runs at half speed

C Motor stops

D Motor reverses direction

PWM value 0 means the signal is always OFF, so the motor stops.

Why is PWM preferred over a simple resistor to control motor speed?

A PWM provides efficient speed control without heat loss

B PWM wastes more power

C Resistors are cheaper

D PWM is slower to respond

PWM controls speed efficiently by switching power ON and OFF rapidly, reducing heat loss compared to resistors.

What is the maximum PWM value you can use with Arduino's analogWrite()?

A 255

B 1023

C 100

D 500

Arduino's analogWrite() uses values from 0 to 255 for PWM duty cycle.

Explain how PWM controls the speed of a DC motor using Arduino.

Think about how changing the time the motor gets power affects its speed.

Describe why PWM is more efficient than using a resistor to control motor speed.

Consider what happens to energy when power is switched ON and OFF quickly.