Motor direction with H-Bridge (L293D/L298N) in Arduino - Step-by-Step Execution

Concept Flow - Motor direction with H-Bridge (L293D/L298N)

Set pin modes

↓

Write HIGH/LOW to pins

↓

Motor spins forward

↓

Delay

↓

Write reversed HIGH/LOW

↓

Motor spins backward

↓

Delay

↓

Repeat or stop

The program sets motor control pins, then writes signals to spin the motor forward or backward by controlling the H-Bridge inputs.

Execution Sample

Arduino

const int motorPin1 = 3;
const int motorPin2 = 4;

void setup() {
  pinMode(motorPin1, OUTPUT);
  pinMode(motorPin2, OUTPUT);
}

void loop() {
  digitalWrite(motorPin1, HIGH);
  digitalWrite(motorPin2, LOW);
  delay(2000);
  digitalWrite(motorPin1, LOW);
  digitalWrite(motorPin2, HIGH);
  delay(2000);
}

This code spins the motor forward for 2 seconds, then backward for 2 seconds repeatedly.

Execution Table

Step	Action	motorPin1	motorPin2	Motor Direction	Delay (ms)
1	Set motorPin1 HIGH, motorPin2 LOW	HIGH	LOW	Forward	2000
2	Wait for 2000 ms	HIGH	LOW	Forward	2000
3	Set motorPin1 LOW, motorPin2 HIGH	LOW	HIGH	Backward	2000
4	Wait for 2000 ms	LOW	HIGH	Backward	2000
5	Loop repeats from step 1	HIGH	LOW	Forward	2000

💡 Loop runs indefinitely, alternating motor direction every 2 seconds.

Variable Tracker

Variable	Start	After Step 1	After Step 3	After Step 5 (Loop)
motorPin1	LOW (default)	HIGH	LOW	HIGH
motorPin2	LOW (default)	LOW	HIGH	LOW
Motor Direction	Stopped	Forward	Backward	Forward

Key Moments - 3 Insights

Why does setting motorPin1 HIGH and motorPin2 LOW make the motor spin forward?

Because the H-Bridge uses these pin signals to control current flow direction through the motor, making it spin forward as shown in execution_table step 1.

What happens if both motorPin1 and motorPin2 are set HIGH or LOW at the same time?

The motor will stop or brake because no voltage difference is applied; this is not shown in the current execution but is important to avoid damage.

Why do we use delay after setting the pins?

Delay keeps the motor spinning in one direction for a set time before changing direction, as seen in execution_table steps 2 and 4.

Visual Quiz - 3 Questions

Look at the execution table, what is the state of motorPin2 at step 3?

A LOW

B HIGH

C INPUT

D Not set

💡 Hint

Check the 'motorPin2' column in execution_table row for step 3.

At which step does the motor spin backward?

A Step 1

B Step 2

C Step 3

D Step 5

💡 Hint

Look at the 'Motor Direction' column in execution_table.

If delay(2000) is changed to delay(1000), how does the execution_table change?

A Delay column values become 1000 instead of 2000

B Motor direction changes to stop

C Pin states change to LOW

D No change

💡 Hint

Focus on the 'Delay (ms)' column in execution_table.

Concept Snapshot

Motor direction with H-Bridge:
- Use two pins to control motor direction
- Set one pin HIGH, other LOW for forward
- Reverse pins for backward
- Use delay to keep motor spinning
- Loop to alternate direction

Full Transcript

This example shows how to control a motor's direction using an H-Bridge like L293D or L298N with Arduino. We set two pins as outputs. Writing HIGH to one pin and LOW to the other makes the motor spin forward. Reversing these signals makes it spin backward. Delays keep the motor spinning in each direction for 2 seconds. The loop repeats this forever. The execution table tracks pin states and motor direction step-by-step. Key points include how pin signals control current flow and why delays are needed. The quiz checks understanding of pin states and timing.