Ring buffer for UART receive in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare the ring buffer size.

Embedded C

volatile char uart_buffer[[1]];

Drag options to blanks, or click blank then click option'

A64

B256

C512

D128

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing too large a buffer wastes memory.

Choosing too small a buffer may cause overflow.

The ring buffer size is set to 64 bytes to balance memory and performance.

2fill in blank

medium

Complete the code to increment the head index in the ring buffer.

Embedded C

head = (head + [1]) % BUFFER_SIZE;

Drag options to blanks, or click blank then click option'

A0

B2

C1

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 does not move the head.

Using -1 causes underflow.

Incrementing by 1 moves the head to the next position in the buffer.

3fill in blank

hard

Fix the error in the condition to check if the buffer is full.

Embedded C

if (((head + 1) % BUFFER_SIZE) == [1]) { /* buffer full */ }

Drag options to blanks, or click blank then click option'

A0

Bhead

CBUFFER_SIZE

Dtail

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing to head causes wrong condition.

Comparing to BUFFER_SIZE is invalid index.

The buffer is full when the next head position equals the tail.

4fill in blank

hard

Fill both blanks to read a byte from the buffer and update the tail index.

Embedded C

char data = uart_buffer[[1]];
tail = (tail [2] 1) % BUFFER_SIZE;

Drag options to blanks, or click blank then click option'

Atail

B+

C-

Dhead

Attempts:

3 left

💡 Hint

Common Mistakes

Using head instead of tail to read data.

Decrementing tail causes errors.

Read data at tail, then increment tail by 1 wrapping around.

5fill in blank

hard

Fill all three blanks to write a byte to the buffer and update the head index safely.

Embedded C

if (((head + 1) % BUFFER_SIZE) != [1]) {
    uart_buffer[[2]] = data;
    head = (head [3] 1) % BUFFER_SIZE;
}

Drag options to blanks, or click blank then click option'

Atail

Bhead

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Writing data at tail instead of head.

Using '-' instead of '+' to increment head.

Check buffer not full by comparing next head to tail, write data at head, then increment head.