Watching register values in Embedded C - Mini Project: Build & Apply

Watching Register Values

📖 Scenario: You are working with a simple embedded system that has a few hardware registers controlling LEDs and buttons. You want to watch the values of these registers to understand how they change when you update them.

🎯 Goal: Build a small program that sets up register variables, updates them, and prints their values to watch how they change step-by-step.

📋 What You'll Learn

Create variables representing hardware registers with exact initial values

Add a configuration variable to control which register to update

Write code to update the selected register value

Print the register values to watch their current state

💡 Why This Matters

🌍 Real World

Embedded developers often need to watch and update hardware registers to control devices like LEDs, buttons, and sensors.

💼 Career

Understanding how to read and write register values is essential for embedded systems programming and debugging hardware behavior.

1

Create register variables

Create three unsigned int variables called LED_REG, BUTTON_REG, and STATUS_REG with initial values 0x01, 0x00, and 0xFF respectively.

Embedded C

# Create the register variables with initial values
// Your code here

Need a hint?

Use unsigned int to represent registers and assign the exact hex values given.

2

Add a config variable to select register

Add an unsigned int variable called selected_register and set it to 2 to select the STATUS_REG for update.

Embedded C

unsigned int LED_REG = 0x01;
unsigned int BUTTON_REG = 0x00;
unsigned int STATUS_REG = 0xFF;

// Add selected_register variable here
// Your code here

Need a hint?

This variable will help decide which register to update later.

3

Update the selected register

Write an if statement that checks if selected_register equals 0, then set LED_REG to 0x0F. Else if selected_register equals 1, set BUTTON_REG to 0x1F. Else if selected_register equals 2, set STATUS_REG to 0xAA.

Embedded C

unsigned int LED_REG = 0x01;
unsigned int BUTTON_REG = 0x00;
unsigned int STATUS_REG = 0xFF;

unsigned int selected_register = 2;

// Update the selected register value
// Your code here

Need a hint?

Use if, else if statements to update the correct register based on selected_register.

4

Print the register values

Write printf statements to print the values of LED_REG, BUTTON_REG, and STATUS_REG in hexadecimal format with labels.

Embedded C

unsigned int LED_REG = 0x01;
unsigned int BUTTON_REG = 0x00;
unsigned int STATUS_REG = 0xFF;

unsigned int selected_register = 2;

if (selected_register == 0) {
    LED_REG = 0x0F;
} else if (selected_register == 1) {
    BUTTON_REG = 0x1F;
} else if (selected_register == 2) {
    STATUS_REG = 0xAA;
}

// Print the register values
// Your code here

Need a hint?

Use printf with 0x%02X format to print hexadecimal values with leading zeros.