XOR for toggling bits in Embedded C - Mini Project: Build & Apply

XOR for toggling bits

📖 Scenario: You are working with a simple embedded system that controls an LED light. The LED can be turned ON or OFF by toggling a specific bit in a control register.Using XOR is a common way to toggle bits in embedded programming.

🎯 Goal: Build a small program that toggles the 3rd bit (bit 2, counting from 0) of a byte variable called control_register using XOR.This simulates turning the LED ON or OFF by flipping the bit.

📋 What You'll Learn

Create a variable control_register with initial value 0b00001000 (decimal 8).

Create a variable toggle_mask with value 0b00000100 (decimal 4) to select the 3rd bit.

Use XOR operator to toggle the 3rd bit of control_register.

Print the value of control_register in binary after toggling.

💡 Why This Matters

🌍 Real World

Toggling bits is common in embedded systems to control hardware like LEDs, switches, and sensors efficiently.

💼 Career

Embedded software engineers often use bitwise operations like XOR to manipulate hardware registers for device control.

1

DATA SETUP: Create the control register variable

Create an unsigned 8-bit variable called control_register and set it to 0b00001000 (decimal 8).

Embedded C

// Your code here

Need a hint?

Use uint8_t for an 8-bit unsigned variable and assign the binary value 0b00001000.

2

CONFIGURATION: Create the toggle mask

Create an unsigned 8-bit variable called toggle_mask and set it to 0b00000100 (decimal 4) to select the 3rd bit.

Embedded C

#include 
#include 

uint8_t control_register = 0b00001000;
// Your code here

Need a hint?

The mask selects the bit to toggle. Use 0b00000100 for the 3rd bit.

3

CORE LOGIC: Toggle the bit using XOR

Use the XOR operator ^= with toggle_mask to toggle the 3rd bit of control_register.

Embedded C

#include 
#include 

uint8_t control_register = 0b00001000;
uint8_t toggle_mask = 0b00000100;

// Your code here

Need a hint?

XOR with 1 flips the bit, XOR with 0 leaves it unchanged.

4

OUTPUT: Print the toggled control register in binary

Write a printf statement to print control_register as an 8-bit binary number using this format: "Control register: 0bXXXXXXXX\n" where XXXXXXXX is the binary representation.

Embedded C

#include 
#include 

uint8_t control_register = 0b00001000;
uint8_t toggle_mask = 0b00000100;

control_register ^= toggle_mask;

// Your code here

Need a hint?

Use a loop to print each bit from the highest (7) to lowest (0) by shifting and masking.