Circular buffer DMA mode in Embedded C - Mini Project: Build & Apply

Circular Buffer DMA Mode

📖 Scenario: You are working on an embedded system that receives data continuously from a sensor. To handle this data efficiently without losing any bytes, you will use a circular buffer with DMA (Direct Memory Access) mode. This setup allows the system to store incoming data in a buffer that wraps around when it reaches the end, so the data can be processed smoothly.

🎯 Goal: Build a simple circular buffer in C that works with DMA mode. You will create the buffer, set its size, write data into it using DMA simulation, and then print the buffer content to verify the circular behavior.

📋 What You'll Learn

Create a buffer array with a fixed size

Define a variable for the buffer size

Simulate writing data into the buffer using circular indexing

Print the buffer content after writing

💡 Why This Matters

🌍 Real World

Circular buffers with DMA are used in embedded systems to handle continuous data streams like sensor readings or communication data without losing information.

💼 Career

Understanding circular buffers and DMA is important for embedded software engineers working on real-time systems, IoT devices, or hardware interfacing.

1

Create the circular buffer array

Create a character array called buffer with size 8 to hold incoming data.

Embedded C

char buffer[8]; // Your code here

Need a hint?

Think of buffer as a row of 8 boxes to store data bytes.

2

Define the buffer size variable

Create an integer variable called buffer_size and set it to 8 to represent the size of the buffer.

Embedded C

char buffer[8];
int buffer_size = 0; // Your code here

Need a hint?

This variable helps us know how many bytes the buffer can hold.

3

Simulate writing data with circular indexing

Create a for loop with variable i from 0 to 11. Inside the loop, write the character 'A' + i into buffer[i % buffer_size] to simulate DMA writing data circularly.

Embedded C

char buffer[8];
int buffer_size = 8;

// Your code here

Need a hint?

Use the modulo operator % to wrap the index back to 0 when it reaches the buffer size.

4

Print the buffer content

Use a for loop with variable j from 0 to buffer_size - 1 to print each character in buffer[j] without spaces or newlines.

Embedded C

char buffer[8];
int buffer_size = 8;

for (int i = 0; i < 12; i++) {
    buffer[i % buffer_size] = 'A' + i;
}

// Your code here

Need a hint?

Printing the buffer shows the last 8 characters written, demonstrating the circular buffer behavior.