MIPI CSI-2 D-PHY Protocol Decoder for Sigrok

A sigrok protocol decoder for MIPI Camera Serial Interface 2 (CSI-2) using D-PHY physical layer.

Overview

This decoder implements support for MIPI CSI-2 D-PHY protocol, which is commonly used in camera applications for high-speed serial data transmission. The decoder can parse:

• D-PHY lane signals (clock + data lanes)
• CSI-2 packet structure
• Start/End of Transmission (SoT/EoT) markers
• Short and long packet types
• Lane synchronization
• Various data types (YUV, RGB, RAW, JPEG)

Features

• Multi-lane support: Configurable 1-4 data lanes
• Packet parsing: Short packets (control) and long packets (image data)
• Data type recognition: Common CSI-2 data types
• Virtual channel support: Multiple virtual channels
• Comprehensive annotations: Detailed protocol analysis
• Binary output: Raw packet data export

Installation

Prerequisites

• Python 3.x
• Sigrok (libsigrokdecode)

Setup

1. Clone or copy the mipi_csi2_dphy directory to your sigrok decoders directory:

   cp -r mipi_csi2_dphy /path/to/libsigrokdecode/decoders/

2. Restart your sigrok frontend (PulseView, etc.)

Usage

Channel Configuration

Connect your signals as follows:

• CLK: Clock lane (required)
• DATA0: Data lane 0 (required)
• DATA1: Data lane 1 (optional)
• DATA2: Data lane 2 (optional)
• DATA3: Data lane 3 (optional)

Decoder Options

• Number of data lanes: 1-4 (default: 1)
• Expected bitrate: 500-2500 Mbps (default: 1000)

Annotations

The decoder provides several annotation types:

Markers

• SOT: Start of Transmission
• EOT: End of Transmission
• SYNC: Lane synchronization

Packets

• Short packet: Control packets
• Long packet: Image data packets
• Payload: Packet payload data
• Footer: Packet footer/checksum

Metadata

• Data type: YUV, RGB, RAW, JPEG formats
• Virtual channel: Channel number
• Frame count: Frame identifier
• Line count: Line number
• Pixel count: Pixel count

Errors

• Protocol error: Decoding errors

Protocol Details

MIPI CSI-2 D-PHY

MIPI CSI-2 D-PHY is a high-speed serial interface that uses:

• D-PHY physical layer: Differential signaling
• CSI-2 protocol: Packet-based data transmission
• Multiple lanes: Parallel data transmission for higher bandwidth

Packet Structure

1. SoT (Start of Transmission): 0xB8 marker
2. Packet Header: Data type, virtual channel, metadata
3. Payload: Image or control data
4. EoT (End of Transmission): 0x9C marker

Data Types

Common CSI-2 data types supported:

• YUV formats: YUV420, YUV422 (8-bit, 10-bit)
• RGB formats: RGB444, RGB555, RGB565, RGB666, RGB888
• RAW formats: RAW6, RAW7, RAW8, RAW10, RAW12, RAW14
• JPEG: JPEG compressed data

Testing

Run the test script to verify the decoder structure:

python3 test_decoder_mock.py

This will test:

• Decoder import and instantiation
• Channel configuration
• Annotation definitions
• Method functionality

Development

Project Structure

mipi_csi2_dphy/
├── __init__.py          # Module metadata and imports
├── pd.py               # Main decoder implementation
└── README.md           # This file

Key Components

• Decoder class: Main decoder implementation
• Channel definitions: Signal input configuration
• Annotation system: Protocol analysis output
• Binary output: Raw data export
• State machine: Protocol state tracking

Extending the Decoder

The decoder is designed to be extensible:

1. Add new data types: Extend the DATA_TYPE_NAMES dictionary
2. Enhance packet parsing: Modify the decode methods
3. Add new annotations: Extend the annotations tuple
4. Improve lane handling: Enhance multi-lane support

Limitations

Current implementation includes:

• Basic packet detection framework
• Simplified lane synchronization
• Core CSI-2 data type support

Future enhancements could include:

• Advanced lane synchronization
• Error detection and recovery
• Timing analysis
• Performance optimization

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test thoroughly
5. Submit a pull request

License

This decoder is licensed under GPLv2+ (GNU General Public License v2 or later).

References

• MIPI Alliance CSI-2 Specification
• Sigrok Protocol Decoder HOWTO
• Sigrok Project

TODO

• Implement advanced lane synchronization
• Add error detection and recovery
• Enhance timing analysis
• Add performance optimization
• Create unit tests with real signal data
• Add documentation for advanced features