Stepper motor with driver module in Arduino - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Stepper Motor Basic Rotation Output

What will be the output behavior of the stepper motor when running this Arduino code snippet?

Arduino

const int stepPin = 3;
const int dirPin = 4;

void setup() {
  pinMode(stepPin, OUTPUT);
  pinMode(dirPin, OUTPUT);
  digitalWrite(dirPin, HIGH); // Set direction
}

void loop() {
  digitalWrite(stepPin, HIGH);
  delayMicroseconds(1000);
  digitalWrite(stepPin, LOW);
  delayMicroseconds(1000);
}

A The motor rotates back and forth repeatedly.

B The motor rotates continuously in one direction at a steady speed.

C The motor does not rotate because the step pin is never pulsed.

D The motor rotates continuously but changes direction every second.

💡 Hint

Look at how the step pin is pulsed and the direction pin is set once in setup.

The code sets the direction pin HIGH once, so the motor direction is fixed. The step pin is pulsed repeatedly with equal HIGH and LOW durations, causing continuous rotation in one direction.

🧠 Conceptual

intermediate

Understanding Stepper Motor Driver Pins

Which pin on a typical stepper motor driver module controls the rotation direction of the motor?

A Ground pin

B Enable pin

C Step pin

D Direction pin

💡 Hint

Think about which pin tells the motor which way to turn.

The direction pin controls the rotation direction by setting it HIGH or LOW. The step pin controls stepping pulses, enable pin turns the driver on/off, and ground is for electrical reference.

🔧 Debug

advanced

Identify the Error in Stepper Motor Speed Control Code

What error will occur when running this Arduino code to control stepper motor speed?

Arduino

const int stepPin = 3;
const int dirPin = 4;

void setup() {
  pinMode(stepPin, OUTPUT);
  pinMode(dirPin, OUTPUT);
  digitalWrite(dirPin, LOW);
}

void loop() {
  for (int i = 0; i < 200; i++) {
    digitalWrite(stepPin, HIGH);
    delay(1);
    digitalWrite(stepPin, LOW);
    delay(1);
  }
  delay(1000);
  delay(0);
}

A The code runs without error and rotates the motor 200 steps then pauses.

B The delay(0) causes a compile-time error because 0 is invalid.

C The motor will not rotate because the direction pin is never set HIGH.

D The motor rotates but the speed is too fast to control.

💡 Hint

Check if delay(0) is valid and what setting direction LOW means.

delay(0) is valid and just causes no delay. Direction LOW is a valid direction. The loop pulses the step pin 200 times with 1 ms delay each, rotating the motor 200 steps then pauses 1 second.

📝 Syntax

advanced

Find the Syntax Error in Stepper Motor Control Code

Which option contains the correct syntax to set the step pin HIGH and LOW with a 500 microsecond delay between?

A

digitalWrite(stepPin, HIGH);
delayMicroseconds(500);
digitalWrite(stepPin, LOW);
delayMicroseconds(500);

B

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C

digitalWrite(stepPin, HIGH)
delayMicroseconds(500)
digitalWrite(stepPin, LOW)
delayMicroseconds(500)

D

digitalWrite(stepPin HIGH);
delayMicroseconds(500);
digitalWrite(stepPin LOW);
delayMicroseconds(500);

💡 Hint

Check for missing commas, semicolons, and parentheses.

Option A has correct syntax: commas separate arguments in digitalWrite, and semicolons terminate every statement. Option A misses semicolon after last delayMicroseconds(500). Option A misses commas after stepPin. Option A misses semicolons after each statement.

🚀 Application

expert

Calculate Steps for 90 Degree Rotation

A stepper motor has 200 steps per full revolution. Using a driver module, how many step pulses must be sent to rotate the motor shaft exactly 90 degrees?

A 25 steps

B 100 steps

C 50 steps

D 200 steps

💡 Hint

A full revolution is 360 degrees. Calculate the fraction for 90 degrees.

90 degrees is one quarter of 360 degrees. One quarter of 200 steps is 50 steps.

Practice

1. What is the main role of a driver module when controlling a stepper motor with Arduino?

easy

A. To store the motor's position data

B. To increase the speed of the Arduino board

C. To safely provide the correct power and signals to the motor

D. To convert analog signals to digital

Solution

1. Step 1: Understand the function of a driver module

   The driver module acts as a bridge between Arduino and the stepper motor, providing the right voltage and current safely.

2. Step 2: Identify the correct role

   It controls power and signals to the motor, preventing damage and ensuring proper movement.

3. Final Answer:

   To safely provide the correct power and signals to the motor -> Option C

4. Quick Check:

   Driver module = safe power and signals [OK]

Hint: Driver modules protect motor and Arduino by controlling power [OK]

Common Mistakes:

• Thinking driver speeds up Arduino
• Believing driver stores position data
• Confusing driver with signal converter

2. Which Arduino code snippet correctly sets the direction pin to HIGH for a stepper motor driver?

easy

A. digitalWrite(directionPin, low);

B. digitalWrite(directionPin, "HIGH");

C. digitalWrite(directionPin, 0);

D. digitalWrite(directionPin, HIGH);

Solution

1. Step 1: Check correct syntax for digitalWrite

   The function digitalWrite(pin, value) expects the value to be HIGH or LOW without quotes and case-sensitive.

2. Step 2: Identify correct usage

   digitalWrite(directionPin, HIGH); uses digitalWrite(directionPin, HIGH); which is correct syntax and case.

3. Final Answer:

   digitalWrite(directionPin, HIGH); -> Option D

4. Quick Check:

   digitalWrite with HIGH (uppercase, no quotes) [OK]

Hint: Use uppercase HIGH/LOW without quotes in digitalWrite [OK]

Common Mistakes:

• Using lowercase 'low' instead of 'LOW'
• Passing numbers instead of HIGH/LOW constants
• Using quotes around HIGH or LOW

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

const int stepPin = 3;
const int dirPin = 4;

void setup() {
  pinMode(stepPin, OUTPUT);
  pinMode(dirPin, OUTPUT);
  digitalWrite(dirPin, HIGH);
}

void loop() {
  digitalWrite(stepPin, HIGH);
  delay(2);
  digitalWrite(stepPin, LOW);
  delay(2);
}

medium

A. The code will cause a compile error

B. The motor will rotate continuously in one direction at a slow speed

C. The motor will not move because direction is not set

D. The motor will rotate once and stop

Solution

1. Step 1: Analyze pin setup and direction

   Direction pin is set to HIGH once in setup, so motor direction is fixed.

2. Step 2: Analyze loop step pulses

   Loop sends pulses to stepPin with 2ms HIGH and 2ms LOW delays, causing continuous stepping.

3. Final Answer:

   The motor will rotate continuously in one direction at a slow speed -> Option B

4. Quick Check:

   Continuous pulses + fixed direction = continuous rotation [OK]

Hint: Continuous step pulses with fixed direction cause continuous rotation [OK]

Common Mistakes:

• Thinking motor moves once then stops
• Assuming direction not set means no movement
• Expecting compile errors from correct code

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

int stepPin = 5;
int dirPin = 6;

void setup() {
  pinMode(stepPin, OUTPUT);
  pinMode(dirPin, OUTPUT);
  digitalWrite(dirPin, HIGH);
}

void loop() {
  digitalWrite(stepPin, HIGH);
  delay(1);
  digitalWrite(stepPin, HIGH);
  delay(1);
}

medium

A. The stepPin is never set to LOW, so no step pulse is generated

B. The direction pin is not set as input

C. The delay time is too short to move the motor

D. The pinMode calls are missing

Solution

1. Step 1: Check step pulse signal

   Step pulses require a HIGH then LOW transition to trigger a step.

2. Step 2: Identify missing LOW signal

   Code sets stepPin HIGH twice without setting it LOW in between, so no pulse occurs.

3. Final Answer:

   The stepPin is never set to LOW, so no step pulse is generated -> Option A

4. Quick Check:

   Step pulse = HIGH then LOW [OK]

Hint: Step pulse needs HIGH then LOW transition [OK]

Common Mistakes:

• Forgetting to set stepPin LOW after HIGH
• Confusing direction pin mode
• Assuming short delay fixes pulse issue

5. You want to rotate a stepper motor exactly 200 steps clockwise, then 200 steps counterclockwise using a driver module. Which Arduino code snippet correctly achieves this?

hard

A. for(int i=0; i<200; i++) { digitalWrite(dirPin, HIGH); digitalWrite(stepPin, HIGH); delay(1); digitalWrite(stepPin, LOW); delay(1); } for(int i=0; i<200; i++) { digitalWrite(dirPin, LOW); digitalWrite(stepPin, HIGH); delay(1); digitalWrite(stepPin, LOW); delay(1); }

B. digitalWrite(dirPin, HIGH); for(int i=0; i<=200; i++) { digitalWrite(stepPin, HIGH); delay(1); digitalWrite(stepPin, LOW); delay(1); } digitalWrite(dirPin, LOW); for(int i=0; i<=200; i++) { digitalWrite(stepPin, HIGH); delay(1); digitalWrite(stepPin, LOW); delay(1); }

C. for(int i=0; i<200; i++) { digitalWrite(stepPin, HIGH); delay(1); digitalWrite(stepPin, LOW); delay(1); } digitalWrite(dirPin, HIGH); for(int i=0; i<200; i++) { digitalWrite(stepPin, HIGH); delay(1); digitalWrite(stepPin, LOW); delay(1); }

D. digitalWrite(dirPin, HIGH); digitalWrite(stepPin, HIGH); delay(200); digitalWrite(stepPin, LOW); delay(200); digitalWrite(dirPin, LOW); digitalWrite(stepPin, HIGH); delay(200); digitalWrite(stepPin, LOW); delay(200);

Solution

1. Step 1: Set direction before stepping

   Each loop sets direction pin before sending step pulses to control rotation direction.

2. Step 2: Send exact number of step pulses

   Each for loop sends 200 pulses with HIGH then LOW signals and delays for timing.

3. Step 3: Verify code correctness

   for(int i=0; i<200; i++) { digitalWrite(dirPin, HIGH); digitalWrite(stepPin, HIGH); delay(1); digitalWrite(stepPin, LOW); delay(1); } for(int i=0; i<200; i++) { digitalWrite(dirPin, LOW); digitalWrite(stepPin, HIGH); delay(1); digitalWrite(stepPin, LOW); delay(1); } correctly sets direction inside each loop and sends 200 pulses per direction.

4. Final Answer:

   for(int i=0; i<200; i++) { digitalWrite(dirPin, HIGH); digitalWrite(stepPin, HIGH); delay(1); digitalWrite(stepPin, LOW); delay(1); } for(int i=0; i<200; i++) { digitalWrite(dirPin, LOW); digitalWrite(stepPin, HIGH); delay(1); digitalWrite(stepPin, LOW); delay(1); } -> Option A

5. Quick Check:

   Set direction before stepping, send 200 pulses each way [OK]

Hint: Set direction before loop, pulse stepPin HIGH then LOW 200 times [OK]

Common Mistakes:

• Setting direction inside step pulse loop incorrectly
• Using delay as step count instead of pulse count
• Not toggling stepPin LOW after HIGH