Checking if a bit is set in Embedded C - Mini Project: Build & Apply

Checking if a bit is set

📖 Scenario: You are working with a microcontroller and need to check if a specific bit in a status register is set. This is common when reading hardware flags.

🎯 Goal: Build a small program that checks if the 3rd bit (bit number 2, counting from 0) in a byte variable called status_register is set (1) or not (0).

📋 What You'll Learn

Create a variable status_register with the exact value 0b00001100.

Create a variable bit_to_check with the exact value 2.

Use a bitwise operation to check if the bit at position bit_to_check in status_register is set.

Print "Bit is set" if the bit is 1, otherwise print "Bit is not set".

💡 Why This Matters

🌍 Real World

Checking bits in registers is essential in embedded systems to read hardware status flags, control bits, or error indicators.

💼 Career

Embedded software engineers often need to manipulate and check bits directly to interface with hardware devices.

1

Create the status register variable

Create an unsigned char variable called status_register and set it to the binary value 0b00001100.

Embedded C

# Create the status_register variable
// Your code here

Need a hint?

Use unsigned char status_register = 0b00001100; to create the variable.

2

Create the bit position variable

Create an int variable called bit_to_check and set it to 2.

Embedded C

unsigned char status_register = 0b00001100;
// Create the bit_to_check variable
// Your code here

Need a hint?

Use int bit_to_check = 2; to create the variable.

3

Check if the bit is set

Create an int variable called bit_is_set that stores the result of checking if the bit at position bit_to_check in status_register is set. Use the bitwise AND operator and a left shift.

Embedded C

unsigned char status_register = 0b00001100;
int bit_to_check = 2;
// Check if the bit is set and store in bit_is_set
// Your code here

Need a hint?

Use bit_is_set = status_register & (1 << bit_to_check); to check the bit.

4

Print the result

Write an if statement that prints "Bit is set" if bit_is_set is not zero, otherwise print "Bit is not set".

Embedded C

unsigned char status_register = 0b00001100;
int bit_to_check = 2;
int bit_is_set = status_register & (1 << bit_to_check);
// Print if the bit is set or not
// Your code here

Need a hint?

Use if (bit_is_set) { printf("Bit is set\n"); } else { printf("Bit is not set\n"); }