Endianness (big-endian vs little-endian) in Embedded C - Hands-On Comparison

Understanding Endianness in Embedded C

📖 Scenario: You are working on a small embedded system that communicates with other devices. Different devices may use different ways to store multi-byte numbers in memory. This is called endianness.Understanding how to check and handle endianness is important to make sure data is interpreted correctly.

🎯 Goal: You will write a simple C program to detect if your system is using big-endian or little-endian format.This knowledge helps you write code that works correctly on different hardware.

📋 What You'll Learn

Create a 16-bit integer variable with a known value

Create a pointer to access the bytes of the integer

Write logic to check the first byte to determine endianness

Print the detected endianness as a string

💡 Why This Matters

🌍 Real World

Embedded systems often communicate with other devices that may use different byte orders. Detecting and handling endianness ensures data is interpreted correctly.

💼 Career

Understanding endianness is important for embedded developers, firmware engineers, and anyone working with low-level data communication or hardware interfaces.

1

DATA SETUP: Create a 16-bit integer variable

Create a 16-bit unsigned integer variable called num and set it to 0x1234.

Embedded C

# Create a 16-bit unsigned integer variable called num and set it to 0x1234
// Your code here

Need a hint?

Use uint16_t from stdint.h to create a 16-bit unsigned integer.

2

CONFIGURATION: Create a byte pointer to the integer

Create a pointer called ptr of type uint8_t * and set it to point to num.

Embedded C

#include 
#include 

uint16_t num = 0x1234;

// Create a uint8_t pointer called ptr pointing to num
// Your code here

Need a hint?

Cast the address of num to uint8_t * to access individual bytes.

3

CORE LOGIC: Check the first byte to detect endianness

Write an if statement that checks if the first byte pointed by ptr is 0x12. If yes, set a char pointer endian to "Big-endian", else set it to "Little-endian".

Embedded C

#include 
#include 

uint16_t num = 0x1234;
uint8_t *ptr = (uint8_t *)#

// Declare a char pointer called endian
// Use if statement to check *ptr and assign endian
// Your code here

Need a hint?

The first byte of num will be 0x12 if big-endian, else 0x34 if little-endian.

4

OUTPUT: Print the detected endianness

Write a printf statement to print the text "System is: " followed by the value of endian.

Embedded C

#include 
#include 

uint16_t num = 0x1234;
uint8_t *ptr = (uint8_t *)#

char *endian;
if (*ptr == 0x12) {
    endian = "Big-endian";
} else {
    endian = "Little-endian";
}

// Print the detected endianness
// Your code here

Need a hint?

Use printf("System is: %s\n", endian); inside main() to show the result.