Interrupt vector table in Embedded C - Mini Project: Build & Apply

Interrupt Vector Table Setup in Embedded C

📖 Scenario: You are working on a simple embedded system that uses interrupts to handle events like timers and external signals. To manage these interrupts, you need to create an interrupt vector table that links interrupt numbers to their handler functions.

🎯 Goal: Build a basic interrupt vector table in C that assigns specific interrupt handler functions to interrupt numbers. This will help the microcontroller know which function to run when an interrupt occurs.

📋 What You'll Learn

Create an array called interrupt_vector_table of function pointers

Define three interrupt handler functions: reset_handler, timer_handler, and external_handler

Assign these handlers to the correct positions in the vector table

Print the address of the timer_handler function from the vector table

💡 Why This Matters

🌍 Real World

Microcontrollers use interrupt vector tables to quickly jump to the right code when hardware events happen, like timers or button presses.

💼 Career

Embedded software engineers must understand how to set up and use interrupt vector tables to write efficient and responsive firmware.

1

Define interrupt handler functions

Write three empty interrupt handler functions called reset_handler, timer_handler, and external_handler. Each function should return void and take no parameters.

Embedded C

// Your code here

Need a hint?

Use the syntax void function_name(void) {} to define each handler.

2

Create the interrupt vector table array

Create an array of function pointers called interrupt_vector_table with three elements. Each element should be a pointer to a function returning void and taking no parameters.

Embedded C

void reset_handler(void) {}
void timer_handler(void) {}
void external_handler(void) {}

// Your code here

Need a hint?

Declare interrupt_vector_table as an array of 3 pointers to functions with void return type and no parameters.

3

Assign handlers to the vector table

Assign reset_handler to interrupt_vector_table[0], timer_handler to interrupt_vector_table[1], and external_handler to interrupt_vector_table[2].

Embedded C

void reset_handler(void) {}
void timer_handler(void) {}
void external_handler(void) {}

void (*interrupt_vector_table[3])(void);

// Your code here

Need a hint?

Use the assignment operator = to link each handler function to the correct index in the array.

4

Print the address of the timer handler

Write a printf statement to print the address stored in interrupt_vector_table[1]. Use %p format specifier and cast the function pointer to void *.

Embedded C

void reset_handler(void) {}
void timer_handler(void) {}
void external_handler(void) {}

void (*interrupt_vector_table[3])(void);

interrupt_vector_table[0] = reset_handler;
interrupt_vector_table[1] = timer_handler;
interrupt_vector_table[2] = external_handler;

// Your code here

Need a hint?

Use printf("Timer handler address: %p\n", (void *)interrupt_vector_table[1]); inside main().