The Differences Between MIPI CSI and MIPI DSI

High performance associated with the MIPI CSI and DSI interfaces comes from the ability of these interfaces to transmit data at a very fast rate. Hence, a significant volume of data that exceeds standard minimal frame rate requirements can be transferred. This means that MIPI interfaces can be utilized for high-speed applications like video with high resolution and great color rendering. The Mobile Industry Processor Interface (MIPI) Alliance has created both the Camera Serial Interface (CSI) specification and the Display Serial Interface (DSI).

CSI describes the interaction between a host CPU and a camera. CSI-2 v3.0, CSI-3 v1.1, and CCS v1.0, which were released in 2019, 2014, and 2017, respectively, are the most recent active interface specifications. CSI is used for ADAS, imaging, biometric recognition, context awareness, surveillance, machine vision, and in-vehicle entertainment.

The MIPI DSI interface standard decreases the number of pins to simplify the design while maintaining vendor compatibility. MIPI DSI has two communication levels. The interface layer handles low-level communication, while the packet layer handles high-level communication. Both can operate in high-speed or low-speed modes at the interface level. The MIPI DSI interface is utilized by smartphones, tablets, smartwatches, and other embedded display applications. The advantages of both MIPI DSI and CSI include low EMI, great performance, and low power consumption.

There are three MIPI Camera Serial Interface versions, CSI-1, CSI-2, and CSI-3. The first MIPI interface for cameras was called CSI-1. It was created as an architecture to specify how a camera would connect to a host processor. It was replaced by the still-evolving MIPI CSI-2 and MIPI CSI-3 standards. CSI-2 was released in 2005 and had a few layers: Pixel to Byte, Conversion Layer, Application Layer, Physical Layer (C-PHY/D-PHY), Lane Merger Layer, and Low-Level Protocol Layers. The CSI-2 v2.0 standard was made public in April 2017. Support for RAW-16 and RAW-20 color depth was added in CSI-2 version 2.0, along with an increase in virtual channels from 4 to 32, Latency Reduction and Transport Efficiency (LRTE), Differential Pulse-Code Modulation (DPCM) compression, and scrambling to lower Power Spectral Density. Finally, in a multi-layered, peer-to-peer, UniPro-based M-PHY device network, MIPI CSI-3 is a high-speed, bidirectional protocol principally designed for image and video transmission between cameras and hosts. It was first released in 2012 and then again in 2014 as version 1.1.

The DSI communications protocol describes two sets of instructions. The first specifies the structure of the Display Command Set (DCS), a collection of standard commands for managing the display device. It describes the addresses of registers as well as how they function. Basic commands like sleep, enable, and reverse display are included. A second, device-specific command space, the Maker Command Set (MCS), is defined by the device manufacturer. It frequently contains instructions needed to do tasks not covered by the DSI standard, such as setting certain device registers (such as gamma correction) or programming non-volatile memory.

MIPI CSI is a widely adopted, high-speed protocol for the transmission of still and video images from image sensors to application processors, whereas DSI is a high-speed interface that is scalable and forward-looking and defines the high-bandwidth connection between host CPUs and displays. Both standards are crucial to understanding when it comes to designing modern devices that will be capturing or displaying video with associated quality hardware available at FocusLCDs.