Stepper motor basics in Arduino - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a stepper motor?

A stepper motor is a type of motor that moves in small, fixed steps instead of spinning continuously. It allows precise control of position and speed.

beginner

How does a stepper motor move?

It moves by energizing coils in a sequence, causing the motor shaft to rotate in small steps, like climbing stairs one step at a time.

beginner

What is the purpose of a driver in a stepper motor setup?

The driver controls the power to the motor coils, switching them on and off in the right order to make the motor step.

beginner

What does 'steps per revolution' mean in a stepper motor?

It means how many small steps the motor takes to complete one full turn (360 degrees). For example, 200 steps per revolution means each step is 1.8 degrees.

beginner

Why is controlling a stepper motor useful in projects?

Because it lets you move things very precisely, like turning a knob exactly 10 degrees or moving a robot arm to a specific position.

What type of movement does a stepper motor produce?

A Small fixed steps

B Continuous smooth rotation

C Random spinning

D Back and forth swinging

Stepper motors move in small fixed steps, not continuous rotation.

What component controls the power to a stepper motor's coils?

A Switch

B Battery

C Sensor

D Driver

The driver switches power to the coils in the correct order to make the motor step.

If a stepper motor has 200 steps per revolution, how many degrees does one step move?

A 2 degrees

B 0.5 degrees

C 1.8 degrees

D 5 degrees

360 degrees divided by 200 steps equals 1.8 degrees per step.

Why might you choose a stepper motor over a regular motor?

A For quieter operation

B For precise position control

C For less power use

D For faster spinning

Stepper motors are chosen when you need precise control of position.

What happens if you energize the coils of a stepper motor in the wrong order?

A The motor may not move correctly

B The motor spins faster

C The motor reverses direction automatically

D The motor gets damaged immediately

Wrong coil sequence causes incorrect or no movement.

Explain how a stepper motor moves and why it is useful for precise control.

Think about how the motor moves like climbing stairs and why that helps in projects.

Describe the role of a driver in a stepper motor system.

The driver is like the motor's controller or conductor.

Practice

1. What is the main advantage of using a stepper motor in Arduino projects?

easy

A. It moves in precise, small steps for accurate positioning.

B. It runs faster than all other motors.

C. It uses less power than a servo motor.

D. It requires no programming to control.

Solution

1. Step 1: Understand stepper motor movement

   Stepper motors move in small, fixed steps, allowing precise control of position.

2. Step 2: Compare with other motors

   Unlike regular motors, stepper motors do not rotate freely but in exact increments.

3. Final Answer:

   It moves in precise, small steps for accurate positioning. -> Option A

4. Quick Check:

   Stepper motor precision = Accurate small steps [OK]

Hint: Stepper motors move in fixed steps for precision [OK]

Common Mistakes:

• Thinking stepper motors run faster than all motors
• Assuming no programming is needed
• Confusing power usage with motor type

2. Which of the following is the correct way to create a Stepper object in Arduino code?

easy

A. Stepper myStepper = new Stepper(pin1, pin2, pin3, pin4);

B. Stepper myStepper = Stepper(stepsPerRevolution, pin1, pin2);

C. Stepper myStepper(stepsPerRevolution);

D. Stepper myStepper(stepsPerRevolution, pin1, pin2, pin3, pin4);

Solution

1. Step 1: Recall Stepper constructor syntax

   The Stepper library requires the number of steps per revolution and four control pins.

2. Step 2: Match syntax with options

   Stepper myStepper(stepsPerRevolution, pin1, pin2, pin3, pin4); correctly uses Stepper(stepsPerRevolution, pin1, pin2, pin3, pin4) to create the object.

3. Final Answer:

   Stepper myStepper(stepsPerRevolution, pin1, pin2, pin3, pin4); -> Option D

4. Quick Check:

   Stepper constructor needs steps and 4 pins [OK]

Hint: Stepper needs steps and 4 pins in constructor [OK]

Common Mistakes:

• Using only 2 pins instead of 4
• Trying to use 'new' keyword in Arduino
• Omitting steps per revolution

3. What will be the output behavior of this Arduino code snippet controlling a stepper motor?

Stepper myStepper(200, 8, 9, 10, 11);
void setup() {
  myStepper.setSpeed(60);
}
void loop() {
  myStepper.step(100);
  delay(1000);
  myStepper.step(-100);
  delay(1000);
}

medium

A. The motor rotates 100 steps forward, pauses 1 second, then 100 steps backward, pauses 1 second, and repeats.

B. The motor rotates continuously forward without stopping.

C. The motor rotates 100 steps backward only once.

D. The code will cause a compilation error due to missing pinMode setup.

Solution

1. Step 1: Analyze step commands in loop()

   The code commands the motor to move 100 steps forward, then 100 steps backward, each followed by a 1-second delay.

2. Step 2: Understand loop repetition

   Since this is in loop(), the forward and backward steps repeat indefinitely with pauses.

3. Final Answer:

   The motor rotates 100 steps forward, pauses 1 second, then 100 steps backward, pauses 1 second, and repeats. -> Option A

4. Quick Check:

   Stepper steps forward and backward with delay [OK]

Hint: Positive steps move forward; negative steps move backward [OK]

Common Mistakes:

• Thinking motor runs continuously forward
• Assuming missing pinMode causes error
• Ignoring the delay pauses

4. Identify the error in this Arduino code controlling a stepper motor:

Stepper myStepper(200, 8, 9, 10, 11);
void setup() {
  myStepper.setSpeed(60);
}
void loop() {
  myStepper.step(50);
  delay(500);
}

medium

A. The stepper motor pins are not set as outputs using pinMode.

B. There is no error; the code will run correctly.

C. The step() function requires a negative number to move forward.

D. The setSpeed() function is called in setup(), which is incorrect.

Solution

1. Step 1: Check pinMode necessity for Stepper library

   The Stepper library internally handles pin modes, so explicit pinMode calls are not required.

2. Step 2: Verify setSpeed and step usage

   Calling setSpeed() in setup() and step() in loop() is correct usage for controlling speed and movement.

3. Final Answer:

   There is no error; the code will run correctly. -> Option B

4. Quick Check:

   Stepper library manages pins; code is valid [OK]

Hint: Stepper library sets pins automatically; no pinMode needed [OK]

Common Mistakes:

• Adding unnecessary pinMode calls
• Misunderstanding setSpeed() placement
• Confusing step() sign for direction

5. You want to rotate a stepper motor exactly one full revolution at 120 RPM using Arduino's Stepper library. The motor has 200 steps per revolution. Which code snippet correctly achieves this in the loop() function?

hard

A. myStepper.setSpeed(60);
myStepper.step(200);

B. myStepper.setSpeed(120);
myStepper.step(100);

C. myStepper.setSpeed(120);
myStepper.step(200);

D. myStepper.setSpeed(120);
myStepper.step(-200);

Solution

1. Step 1: Calculate steps for one revolution

   The motor requires 200 steps for one full revolution.

2. Step 2: Set speed and steps correctly

   To rotate at 120 RPM, setSpeed(120) is correct, and step(200) moves one full revolution forward.

3. Final Answer:

   myStepper.setSpeed(120); myStepper.step(200); -> Option C

4. Quick Check:

   200 steps = 1 revolution; speed 120 RPM [OK]

Hint: Steps = motor steps/rev; speed = desired RPM [OK]

Common Mistakes:

• Using half the steps (100) for full revolution
• Setting speed lower than desired RPM
• Using negative steps when forward rotation needed