Printf redirect to UART in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to redirect printf output to UART by defining the correct function name.

Embedded C

int [1](char ch, FILE *f) {
    // UART transmit code here
    return ch;
}

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Afputc

Bprintf

Cuart_send

Dputchar

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'printf' or 'putchar' instead of 'fputc' for redirection.

The fputc function is used to redirect characters output by printf to UART.

2fill in blank

medium

Complete the code to send a character over UART inside the fputc function.

Embedded C

int fputc(char ch, FILE *f) {
    while (![1]()); // Wait until UART ready
    UART_DR = ch; // Send character
    return ch;
}

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Auart_error

Buart_rx_ready

Cuart_tx_ready

Duart_busy

Attempts:

3 left

💡 Hint

Common Mistakes

Using receive ready or busy flags instead of transmit ready.

The function uart_tx_ready() checks if UART is ready to transmit a new character.

3fill in blank

hard

Fix the error in the UART initialization code to enable UART transmit interrupt.

Embedded C

void uart_init() {
    UART_CR = 0x00;
    UART_BRR = 9600;
    UART_CR |= [1]; // Enable UART
    UART_CR |= [2]; // Enable TX interrupt
}

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AUART_CR_RXNEIE

BUART_CR_RE

CUART_CR_TXEIE

DUART_CR_TE

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing receiver enable with transmitter enable.

To enable UART transmitter, set UART_CR_TE. To enable TX interrupt, set UART_CR_TXEIE.

4fill in blank

hard

Fill both blanks to complete the UART transmit function that waits for transmit buffer empty and sends a character.

Embedded C

void uart_send_char(char ch) {
    while (![1]());
    [2] = ch;
}

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Auart_tx_ready

BUART_DR

Cuart_rx_ready

DUART_SR

Attempts:

3 left

💡 Hint

Common Mistakes

Using receive ready flag or status register incorrectly.

Wait for uart_tx_ready() to confirm UART is ready, then write character to UART_DR data register.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps characters to their ASCII codes if code is greater than 64.

Embedded C

ascii_map = [1]: ord([2]) for [3] in 'ABCDEF' if ord([2]) > 64}

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Ach

Dchar

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently.

The variable ch is used as key and in ord() to get ASCII code for each character.