What is Serial Framing (COBS/SLIP)?
Serial Framing encodes and decodes data using COBS (Consistent Overhead Byte Stuffing) and SLIP (Serial Line Internet Protocol), two framing protocols used to delimit messages on serial communication lines. When sending binary data over UART, RS-232, or similar byte-stream interfaces, you need a way to mark where one message ends and another begins. COBS and SLIP solve this by encoding the data to eliminate delimiter bytes, then adding delimiters between frames.
COBS eliminates zero bytes from the payload with a fixed overhead of one byte per 254 data bytes, making it efficient and predictable. SLIP escapes the END byte (0xC0) and ESC byte (0xDB) using escape sequences. Both are widely used in embedded systems, microcontroller firmware, and IoT device communication.
How to Use Serial Framing Tool
Paste hex-encoded data into the input area. Select COBS or SLIP as the framing protocol. Choose Encode to wrap raw data in a frame or Decode to extract the original payload from a framed message.
The output shows the encoded or decoded bytes in hex, along with a detailed breakdown of how each byte was transformed. For COBS, the breakdown shows the overhead bytes and the original zero byte positions. For SLIP, it shows where escape sequences replaced delimiter and escape bytes.
Common Use Cases
- UART debugging: Decode captured UART data to extract individual message payloads from a stream of COBS or SLIP framed bytes.
- Firmware development: Verify that your microcontroller’s COBS or SLIP implementation correctly encodes and decodes test payloads.
- Protocol testing: Manually encode test messages to send to embedded devices over serial connections for integration testing.
- IoT device debugging: Decode serial log captures from IoT devices that use framing protocols to multiplex data and debug channels.
- Embedded systems education: Understand how COBS and SLIP transform data by examining the byte-level encoding breakdown step by step.