Printf debugging over UART in Embedded C - Mini Project: Build & Apply

Printf debugging over UART

📖 Scenario: You are working on a small embedded device that communicates with a computer using UART (serial communication). You want to see messages from your device on the computer screen to help find and fix problems in your code. This is called printf debugging.UART sends text messages one character at a time. To use printf debugging, you need to set up UART and then send messages using printf.

🎯 Goal: Set up UART communication and use printf to send debugging messages over UART. You will create a simple program that initializes UART, sends a message, and prints a variable value to help you understand what your device is doing.

📋 What You'll Learn

Create a UART initialization function called UART_Init.

Create a function called UART_SendChar to send one character over UART.

Redirect printf output to use UART_SendChar.

Send a debugging message using printf that shows a variable value.

💡 Why This Matters

🌍 Real World

Printf debugging over UART is a common way to see what an embedded device is doing without needing complex debugging tools. It helps developers find bugs and understand program flow.

💼 Career

Embedded software engineers often use UART debugging to test and troubleshoot firmware on microcontrollers in devices like sensors, IoT gadgets, and consumer electronics.

1

Set up UART initialization

Write a function called UART_Init that sets up UART registers for 9600 baud rate. For this example, just create an empty function void UART_Init(void) {} as a placeholder.

Embedded C

# Write the UART_Init function below
// Your code here

Need a hint?

Start by writing the function header and empty body for UART_Init.

2

Create UART_SendChar function

Write a function called UART_SendChar that takes a char parameter named c and sends it over UART. For this example, just create an empty function void UART_SendChar(char c) {} as a placeholder.

Embedded C

void UART_Init(void) {
    // UART initialization code here (empty for now)
}

// Write the UART_SendChar function below
// Your code here

Need a hint?

Write the function header and empty body for UART_SendChar.

3

Redirect printf to UART_SendChar

Write a function called int fputc(int ch, FILE *f) that calls UART_SendChar with ch cast to char and returns ch. This will redirect printf output to UART.

Embedded C

void UART_Init(void) {
    // UART initialization code here (empty for now)
}

void UART_SendChar(char c) {
    // UART send character code here (empty for now)
}

// Redirect printf output to UART_SendChar
// Your code here

Need a hint?

Implement fputc to send each character using UART_SendChar.

4

Send debugging message with printf

In the main function, call UART_Init() first. Then create an integer variable value with value 42. Use printf to send the message "Debug: value = %d\n" with value.

Embedded C

void UART_Init(void) {
    // UART initialization code here (empty for now)
}

void UART_SendChar(char c) {
    // UART send character code here (empty for now)
}

int fputc(int ch, FILE *f) {
    UART_SendChar((char)ch);
    return ch;
}

int main(void) {
    // Your code here
}

Need a hint?

Initialize UART, create value, and print the debug message using printf.