Double buffer technique in Embedded C - Mini Project: Build & Apply

Double Buffer Technique in Embedded C

📖 Scenario: You are working on a simple embedded system that controls an LED display. To avoid flickering on the display, you will use the double buffer technique. This means you will prepare the next frame of data in a separate buffer while the current frame is being shown. When the next frame is ready, you swap the buffers to update the display smoothly.

🎯 Goal: Build a program that uses two buffers to hold LED states. You will fill one buffer with new data while the other buffer is being displayed. Then you will swap the buffers to update the display without flicker.

📋 What You'll Learn

Create two buffers to hold LED states

Use a variable to track the active buffer

Write code to fill the inactive buffer with new LED data

Swap the active and inactive buffers

Print the active buffer contents to simulate display output

💡 Why This Matters

🌍 Real World

Double buffering is used in embedded systems to update displays smoothly without flicker by preparing data in a hidden buffer before showing it.

💼 Career

Understanding double buffering is important for embedded developers working on display drivers, real-time systems, and graphics programming.

1

Create two LED buffers

Create two integer arrays called buffer1 and buffer2, each with 5 elements initialized to 0.

Embedded C

# Create two integer arrays called buffer1 and buffer2, each with 5 elements initialized to 0
// Your code here

Need a hint?

Use int buffer1[5] = {0, 0, 0, 0, 0}; and similarly for buffer2.

2

Add a variable to track the active buffer

Create an integer variable called active_buffer and set it to 1 to indicate buffer1 is active.

Embedded C

int buffer1[5] = {0, 0, 0, 0, 0};
int buffer2[5] = {0, 0, 0, 0, 0};
// Create an integer variable active_buffer and set it to 1
// Your code here

Need a hint?

Use int active_buffer = 1; to track which buffer is active.

3

Fill the inactive buffer with new LED data

Write code to fill the inactive buffer with the values 1, 2, 3, 4, 5. Use an integer pointer inactive to point to the inactive buffer based on active_buffer. Use a for loop with variable i to assign values.

Embedded C

int buffer1[5] = {0, 0, 0, 0, 0};
int buffer2[5] = {0, 0, 0, 0, 0};
int active_buffer = 1;
// Create a pointer inactive to point to the inactive buffer
// Use a for loop with i to fill inactive buffer with 1, 2, 3, 4, 5
// Your code here

Need a hint?

Use a pointer inactive to select the buffer not active, then fill it with values 1 to 5 using a for loop.

4

Swap buffers and print active buffer

Swap the value of active_buffer between 1 and 2. Then create a pointer active to point to the active buffer. Use a for loop with variable i to print each element of the active buffer separated by spaces using printf. End with a newline.

Embedded C

int buffer1[5] = {0, 0, 0, 0, 0};
int buffer2[5] = {0, 0, 0, 0, 0};
int active_buffer = 1;

int *inactive = (active_buffer == 1) ? buffer2 : buffer1;
for (int i = 0; i < 5; i++) {
    inactive[i] = i + 1;
}
// Swap active_buffer between 1 and 2
// Create pointer active to point to active buffer
// Print active buffer elements separated by spaces
// Your code here

Need a hint?

Toggle active_buffer between 1 and 2. Use a pointer active to the active buffer. Print each element with printf("%d ", active[i]). Finish with printf("\n").