UART interrupt-driven communication in Embedded C - Mini Project: Build & Apply

UART Interrupt-Driven Communication

📖 Scenario: You are working on a small embedded system that communicates with a sensor using UART (Universal Asynchronous Receiver/Transmitter). To efficiently receive data without constantly checking the UART status, you will use interrupt-driven communication.This means the microcontroller will automatically call a special function (interrupt handler) when new data arrives, so your program can respond immediately.

🎯 Goal: Build a simple UART interrupt-driven communication program that receives characters from the sensor and stores them in a buffer.You will create the UART data buffer, configure the interrupt flag, write the interrupt handler to read incoming data, and finally print the received data.

📋 What You'll Learn

Create a character array buffer called uart_buffer with size 10

Create an integer variable buffer_index to track the buffer position

Create a variable uart_interrupt_flag to simulate the UART interrupt flag

Write an interrupt handler function UART_ISR that reads a character from uart_data_register and stores it in uart_buffer at buffer_index, then increments buffer_index

Reset uart_interrupt_flag inside the interrupt handler

Simulate receiving 3 characters by setting uart_data_register and uart_interrupt_flag, then calling UART_ISR each time

Print the contents of uart_buffer after receiving the characters

💡 Why This Matters

🌍 Real World

UART interrupt-driven communication is used in embedded devices like sensors, GPS modules, and serial communication between microcontrollers to efficiently receive data without wasting CPU time.

💼 Career

Understanding UART interrupts is essential for embedded systems engineers and firmware developers working on real-time communication and device drivers.

1

Create UART buffer and index

Create a character array called uart_buffer with size 10 and an integer variable called buffer_index initialized to 0.

Embedded C

# Create uart_buffer array and buffer_index variable
# Your code here

Need a hint?

Think of uart_buffer as a small box to hold characters, and buffer_index as a marker showing where to put the next character.

2

Create UART interrupt flag and data register

Create an integer variable called uart_interrupt_flag initialized to 0 and a character variable called uart_data_register to simulate incoming UART data.

Embedded C

char uart_buffer[10];
int buffer_index = 0;

// Create uart_interrupt_flag and uart_data_register
// Your code here

Need a hint?

The uart_interrupt_flag tells us when new data arrives. The uart_data_register holds the incoming character.

3

Write UART interrupt service routine

Write a function called UART_ISR that checks if uart_interrupt_flag is 1. If yes, it stores uart_data_register into uart_buffer at buffer_index, increments buffer_index, and resets uart_interrupt_flag to 0.

Embedded C

char uart_buffer[10];
int buffer_index = 0;

int uart_interrupt_flag = 0;
char uart_data_register;

// Write UART_ISR function
// Your code here

Need a hint?

This function acts like a helper that runs automatically when data arrives. It saves the data and clears the flag.

4

Simulate receiving data and print buffer

Simulate receiving characters 'A', 'B', and 'C' by setting uart_data_register to each character, setting uart_interrupt_flag to 1, and calling UART_ISR() each time. Then print the contents of uart_buffer as a string.

Embedded C

char uart_buffer[10];
int buffer_index = 0;

int uart_interrupt_flag = 0;
char uart_data_register;

void UART_ISR() {
    if (uart_interrupt_flag == 1) {
        uart_buffer[buffer_index] = uart_data_register;
        buffer_index++;
        uart_interrupt_flag = 0;
    }
}

// Simulate receiving 'A', 'B', 'C' and print uart_buffer
// Your code here

Need a hint?

Think of this as the sensor sending three letters one by one. Each time, the interrupt handler saves the letter. Finally, we print all saved letters.