What is a MIPI Camera? How does MIPI Camera Work?

Embedded vision is increasingly gaining traction in AI, the Internet of Things (IoT), and other new technology-based applications. As a result, more businesses are attempting to integrate imaging capabilities into their goods at a low cost. Mobile Industry CPU Interface (MIPI) is one of the most popular and convenient means of interfacing cameras with the host processor for many of these devices and applications.

 

Evolution of the MIPI interface

 

CSI-1

 

CSI-1 interface design was the first official MIPI interface architecture, and it defined the connection between a camera and a host processor.

 

CSI-2

Released in 2005, the first version of MIPI CSI-2 came with a protocol divided into layers, such as:

 

• Physical Layer
• Lane Merger Layer
• Low-Level Protocol Layer
• Pixel to Byte Conversion Layer
• Application Layer

 

The second version of MIPI CSI-2 was published later in 2017, and it included support for RAW-16 and RAW-20 colour depths. It could also boost virtual channels from 4 to 32, as well as minimise latency and improve transport efficiency (LRTE).

 

The third version of MIPI CSI-2 was released in 2019 and came with support for RAW-24 color depth.

 

CSI-3

The first version of MIPI CSI-3 was released in 2012, while the second edition was released in 2014. It featured a bidirectional, high-speed image and video communication protocol between cameras and hosts.

MIPI CSI-2 is the most widely used interface among the three types in mobile and remote applications such as autonomous driving, drones, smart cities, medical imaging, computer vision, and so on.

 

More about MIPI CSI-2

 

We looked at how the MIPI interface has changed over time in the previous section. Let's have a look at the MIPI CSI-2 interface in more depth now.

 

MIPI CSI-2 is a camera interface that connects an image sensor to an integrated board to control and process image data. It's commonly used in embedded vision systems. This allows the sensor and embedded board to work together to capture images as a camera system. A MIPI CSI-2 interface is used to connect an embedded camera board to an image sensor.

 

The MIPI CSI-2 interface makes integration easier and future-proofed. MIPI camera modules can be interfaced with processors such as NXP i.MX8, i.MX7, i.MX6, NVIDIA’s Jetson Nano™, Jetson Xavier™ NX, Jetson AGX Xavier™, Jetson™ TX2, and Jetson™ TX2 NX, and other Linux/Windows/Android-based systems .

 

 

MIPI CSI-2 performance highlights

The MIPI CSI-2 interface's important performance highlights are shown below.

 

Its RAW-16 or 24 colour depth increases High Dynamic Range (HDR) and Signal to Noise Ratio (SNR), providing superior vision capabilities to autonomous vehicles.

 

It supports up to 32 virtual channels, allowing it to incorporate image sensors with a variety of data sources. For Advanced Driver Assistance Systems, this enables multi-exposure and multi-range sensor fusion (ADAS).

 

Latency Reduction and Transport Efficiency (LRTE) improves real-time perception while also reducing the number of wires and energy consumption.

 

For vision applications, Differential Pulse Code Modulation (DPCM) compression reduces bandwidth while producing SNR images free of compression artifacts.