What is a Ring Buffer

A circular buffer, also known as a ring buffer, is a fixed-size data structure that wraps around when it reaches the end. Unlike a linear buffer, it uses two pointers — head and tail — to manage data efficiently without shifting elements.

It’s ideal for scenarios where data is continuously produced and consumed, such as in embedded systems dealing with real-time data streams.

Real-World Use Case

In embedded systems, UART (Universal Asynchronous Receiver/Transmitter) communication often uses circular buffers to store incoming or outgoing bytes.

Example

• RX Buffer: Stores received bytes until the CPU reads them.
• TX Buffer: Holds bytes to be transmitted when the UART is ready.

This ensures smooth data flow without losing bytes or blocking the CPU.

Advantages Over Linear Buffers

• No shifting of data — efficient memory usage
• Constant time enqueue/dequeue
• Ideal for real-time systems
• Prevents buffer overflows with proper checks

Common Pitfalls

• Buffer Overflow: If enqueue is done without checking is_full(), data may overwrite unread bytes.
• Incorrect Wrap-around Logic: Mismanaging head/tail pointers can corrupt data.
• Size Misconfiguration: Choosing a buffer size too small for the data rate can lead to frequent overflows.

Conclusion

Circular buffers are a foundational concept in embedded systems, especially for handling asynchronous data like UART. Understanding their implementation and limitations helps build robust, real-time applications.