Motor direction with H-Bridge (L293D/L298N) in Arduino - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the motor direction pin as output.

Arduino

pinMode([1], OUTPUT);

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

AmotorPin1

BmotorPin2

CmotorSpeed

DanalogPin

Attempts:

3 left

💡 Hint

Common Mistakes

Using the speed pin instead of direction pin.

Forgetting to set the pin mode.

We use pinMode to set the motor direction pin as an output pin so we can control it.

2fill in blank

medium

Complete the code to turn the motor forward by setting motorPin1 HIGH.

Arduino

digitalWrite(motorPin1, [1]);

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

ALOW

BHIGH

CINPUT

DOUTPUT

Attempts:

3 left

💡 Hint

Common Mistakes

Using LOW instead of HIGH.

Confusing pin modes with pin states.

Setting motorPin1 to HIGH makes the motor spin forward.

3fill in blank

hard

Fix the error in the code to stop the motor by setting both direction pins LOW.

Arduino

digitalWrite(motorPin1, [1]);
digitalWrite(motorPin2, [1]);

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

AOUTPUT

BINPUT

CHIGH

DLOW

Attempts:

3 left

💡 Hint

Common Mistakes

Setting one pin HIGH and the other LOW.

Using pin modes instead of pin states.

Setting both direction pins to LOW stops the motor.

4fill in blank

hard

Fill both blanks to reverse the motor direction by setting motorPin1 LOW and motorPin2 HIGH.

Arduino

digitalWrite(motorPin1, [1]);
digitalWrite(motorPin2, [2]);

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

ALOW

BHIGH

CINPUT

DOUTPUT

Attempts:

3 left

💡 Hint

Common Mistakes

Setting both pins HIGH or both LOW.

Mixing up which pin is HIGH or LOW.

To reverse the motor, set motorPin1 to LOW and motorPin2 to HIGH.

5fill in blank

hard

Fill all three blanks to create a 2D array that maps motor states to pin values: forward (motorPin1 HIGH, motorPin2 LOW), reverse (motorPin1 LOW, motorPin2 HIGH), stop (both LOW).

Arduino

int motorStates[3][2] = {
  [1],  // forward
  [2],  // reverse
  [3]   // stop
};

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

A{HIGH, LOW}

B{LOW, HIGH}

C{LOW, LOW}

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the HIGH/LOW order for forward and reverse.

Using HIGH for stop state.

This 2D array maps the motor states to their corresponding pin settings. For example, index 0 ("forward") maps to {HIGH, LOW} for motorPin1 and motorPin2.

Practice

1. Which of the following correctly describes how to make a motor spin forward using an H-Bridge (L293D/L298N) with two Arduino pins pinA and pinB?

easy

A. Set both pinA and pinB HIGH

B. Set pinA LOW and pinB HIGH

C. Set both pinA and pinB LOW

D. Set pinA HIGH and pinB LOW

Solution

1. Step 1: Understand motor direction control

   To spin the motor forward, one pin must be HIGH and the other LOW to create current flow in one direction.

2. Step 2: Apply pin states for forward spin

   Setting pinA HIGH and pinB LOW makes the motor spin forward.

3. Final Answer:

   Set pinA HIGH and pinB LOW -> Option D

4. Quick Check:

   Forward spin = pinA HIGH, pinB LOW [OK]

Hint: Forward spin means one pin HIGH, other LOW [OK]

Common Mistakes:

• Setting both pins HIGH or LOW thinking motor spins
• Confusing which pin should be HIGH for forward
• Assuming both pins LOW spins motor forward

2. Which Arduino code snippet correctly sets pin1 HIGH and pin2 LOW to spin a motor forward using an H-Bridge?

easy

A. digitalWrite(pin1, LOW); digitalWrite(pin2, HIGH);

B. digitalWrite(pin1, HIGH); digitalWrite(pin2, LOW);

C. digitalWrite(pin1, HIGH); digitalWrite(pin2, HIGH);

D. digitalWrite(pin1, LOW); digitalWrite(pin2, LOW);

Solution

1. Step 1: Recall correct pin states for forward

   Forward spin requires first pin HIGH and second pin LOW.

2. Step 2: Match code to pin states

   Code in digitalWrite(pin1, HIGH); digitalWrite(pin2, LOW); sets pin1 HIGH and pin2 LOW correctly.

3. Final Answer:

   digitalWrite(pin1, HIGH); digitalWrite(pin2, LOW); -> Option B

4. Quick Check:

   Pin1 HIGH, Pin2 LOW = forward spin [OK]

Hint: HIGH then LOW means forward spin [OK]

Common Mistakes:

• Swapping HIGH and LOW values
• Setting both pins HIGH or LOW
• Using analogWrite instead of digitalWrite

3. What will be the motor behavior when the following Arduino code runs?

digitalWrite(3, LOW);
digitalWrite(4, HIGH);

medium

A. Motor spins backward

B. Motor spins forward

C. Motor stops

D. Motor speed changes but direction stays same

Solution

1. Step 1: Identify pin states and their meaning

   Pin 3 is LOW and pin 4 is HIGH, which reverses the current flow compared to forward spin.

2. Step 2: Determine motor direction

   This pin combination makes the motor spin backward.

3. Final Answer:

   Motor spins backward -> Option A

4. Quick Check:

   LOW then HIGH = backward spin [OK]

Hint: LOW then HIGH means backward spin [OK]

Common Mistakes:

• Assuming LOW then HIGH is forward spin
• Thinking motor stops when pins differ
• Confusing speed control with direction

4. The following code is intended to stop the motor, but it does not. What is the error?

digitalWrite(5, HIGH);
digitalWrite(6, HIGH);

medium

A. Pins must be set to LOW and HIGH to stop

B. Pins should be set to INPUT to stop motor

C. Both pins HIGH causes motor to brake, not stop

D. digitalWrite cannot be used to stop motor

Solution

1. Step 1: Understand stopping motor with H-Bridge

   To stop the motor, both pins should be LOW to cut power and stop current flow.

2. Step 2: Analyze given pin states

   Both pins are set HIGH, which causes the motor to brake but not coast to a stop.

3. Final Answer:

   Both pins HIGH causes motor to brake, not stop -> Option C

4. Quick Check:

   Stop motor = both pins LOW, not HIGH [OK]

Hint: Stop motor by setting both pins LOW [OK]

Common Mistakes:

• Setting both pins HIGH thinking motor stops
• Using INPUT mode instead of LOW
• Confusing brake with stop

5. You want to write Arduino code to spin a motor forward for 3 seconds, then stop for 2 seconds, then spin backward for 3 seconds using pins 7 and 8 with an L298N. Which code snippet correctly implements this?

hard

A. digitalWrite(7, HIGH); digitalWrite(8, LOW); delay(3000); digitalWrite(7, LOW); digitalWrite(8, LOW); delay(2000); digitalWrite(7, LOW); digitalWrite(8, HIGH); delay(3000);

B. digitalWrite(7, LOW); digitalWrite(8, HIGH); delay(3000); digitalWrite(7, LOW); digitalWrite(8, LOW); delay(2000); digitalWrite(7, HIGH); digitalWrite(8, LOW); delay(3000);

C. digitalWrite(7, HIGH); digitalWrite(8, HIGH); delay(3000); digitalWrite(7, LOW); digitalWrite(8, LOW); delay(2000); digitalWrite(7, LOW); digitalWrite(8, LOW); delay(3000);

D. digitalWrite(7, LOW); digitalWrite(8, LOW); delay(3000); digitalWrite(7, HIGH); digitalWrite(8, LOW); delay(2000); digitalWrite(7, LOW); digitalWrite(8, HIGH); delay(3000);

Solution

1. Step 1: Set pins for forward spin and delay

   Forward spin requires pin 7 HIGH and pin 8 LOW, then delay 3000 ms (3 seconds).

2. Step 2: Stop motor by setting both pins LOW and delay

   Both pins LOW stops motor, delay 2000 ms (2 seconds).

3. Step 3: Set pins for backward spin and delay

   Backward spin requires pin 7 LOW and pin 8 HIGH, delay 3000 ms.

4. Final Answer:

   digitalWrite(7, HIGH); digitalWrite(8, LOW); delay(3000); digitalWrite(7, LOW); digitalWrite(8, LOW); delay(2000); digitalWrite(7, LOW); digitalWrite(8, HIGH); delay(3000); -> Option A

5. Quick Check:

   Forward, stop, backward with correct pins and delays [OK]

Hint: Forward=HIGH-LOW, Stop=LOW-LOW, Backward=LOW-HIGH [OK]

Common Mistakes:

• Swapping forward and backward pin states
• Not stopping motor between directions
• Using HIGH-HIGH which brakes but doesn't stop