Memory-mapped I/O concept in Embedded C - Mini Project: Build & Apply

Memory-mapped I/O Concept in Embedded C

📖 Scenario: You are working on a simple embedded system where you control an LED connected to a specific memory address. This address is part of the memory-mapped I/O region. Writing to this address turns the LED on or off.

🎯 Goal: You will create a small program that uses memory-mapped I/O to turn an LED on and off by writing to a specific memory address.

📋 What You'll Learn

Create a pointer to the LED control register at address 0x40021018

Create a variable to hold the LED ON value

Write the LED ON value to the memory address using the pointer

Print the value written to the LED control register

💡 Why This Matters

🌍 Real World

Memory-mapped I/O is used in embedded systems to control hardware devices like LEDs, buttons, and sensors by reading and writing to specific memory addresses.

💼 Career

Understanding memory-mapped I/O is essential for embedded software engineers working on microcontrollers, device drivers, and hardware interfacing.

1

Create a pointer to the LED control register

Create a pointer called led_reg that points to the memory address 0x40021018 as a volatile unsigned 32-bit integer.

Embedded C

// Your code here

Need a hint?

Use a pointer with volatile to tell the compiler this memory can change outside the program.

2

Create a variable for LED ON value

Create an unsigned integer variable called LED_ON and set it to 1 to represent turning the LED on.

Embedded C

volatile unsigned int *led_reg = (volatile unsigned int *)0x40021018;
// Your code here

Need a hint?

Use a simple unsigned int variable to hold the value 1.

3

Write the LED ON value to the memory address

Write the value of LED_ON to the memory address pointed to by led_reg using the dereference operator.

Embedded C

volatile unsigned int *led_reg = (volatile unsigned int *)0x40021018;
unsigned int LED_ON = 1;
// Your code here

Need a hint?

Use *led_reg = LED_ON; to write the value to the hardware register.

4

Print the value written to the LED control register

Use printf to display the message "LED register value: %u\n" with the value stored at the memory address pointed to by led_reg.

Embedded C

volatile unsigned int *led_reg = (volatile unsigned int *)0x40021018;
unsigned int LED_ON = 1;
*led_reg = LED_ON;
// Your code here

Need a hint?

Use printf("LED register value: %u\n", *led_reg); to print the value.