Reading a hardware register in Embedded C - Mini Project: Build & Apply

Reading a hardware register

📖 Scenario: You are working on a simple embedded system. You need to read a value from a hardware register to check the status of a device.

🎯 Goal: Learn how to read a hardware register by accessing a memory-mapped register address and print its value.

📋 What You'll Learn

Create a pointer to the hardware register address

Read the value from the hardware register

Store the value in a variable

Print the value using printf

💡 Why This Matters

🌍 Real World

Reading hardware registers is essential in embedded systems to check device status, control peripherals, and interact with hardware components.

💼 Career

Embedded software engineers and firmware developers frequently read and write hardware registers to control microcontrollers and hardware devices.

1

Define the hardware register address

Create a constant pointer called REG_STATUS that points to the hardware register address 0x40021000 as a volatile unsigned 32-bit integer.

Embedded C

// Your code here

Need a hint?

Use volatile unsigned int * to declare the pointer and cast the address 0x40021000.

2

Create a variable to hold the register value

Create an unsigned integer variable called status_value to store the value read from the hardware register.

Embedded C

volatile unsigned int *REG_STATUS = (volatile unsigned int *)0x40021000;
// Your code here

Need a hint?

Declare status_value as an unsigned int variable.

3

Read the value from the hardware register

Assign the value pointed to by REG_STATUS to the variable status_value.

Embedded C

volatile unsigned int *REG_STATUS = (volatile unsigned int *)0x40021000;
unsigned int status_value;
// Your code here

Need a hint?

Use the dereference operator * to read the value from the pointer.

4

Print the register value

Use printf to display the text Status Register Value: followed by the value of status_value in hexadecimal format.

Embedded C

volatile unsigned int *REG_STATUS = (volatile unsigned int *)0x40021000;
unsigned int status_value;
status_value = *REG_STATUS;
// Your code here

Need a hint?

Use printf("Status Register Value: 0x%X\n", status_value); to print the value in hex.