New Developments Set To Accelerate MIPI CSI-2 Adoption In Automotive

Increased flexibility for handling data from the ever-growing number of sensors inside cars.


As Advanced Driver-Assistance Systems (ADAS) become more sophisticated, cars are equipped with an increasing number of cameras and sensors. To support features like automated parking, adaptive cruise control, and enhanced night vision, sensors source multiple wavelengths and deploy cameras with higher quality data formats, higher frame and refresh rates. ADAS systems are all powered by data sourced from lidar, radar, and global shutter cameras and integrated together to form a constantly updated real-time digital representation of the car’s environment. As you can imagine, the amount of high-quality data being acquired, communicated and processed will not slow down any time soon as each new generation of cars becomes increasingly automated.

Managing such a vast amount of sensor data inside a car demands high bandwidth. The MIPI Camera Serial Interface 2 (MIPI CSI-2) efficiently handles this data transfer. MIPI CSI-2 can support sensors with a broad range of different image resolutions, video frame rates, and color depths. This makes it ideal for handling data from the ever-growing number of sensors inside cars, each with their own function and each handling a different type of data, regardless of the application’s tolerance for video gaps or not.

CSI-2 v4.0, released in February 2022, added several new capabilities that can bring additional advantages and flexibility to designers architecting ADAS applications. These include Always-On Sentinel Conduit (AOSC) capabilities where ultra-low-power image sensors and video signal processors (VSPs) continuously monitor their surrounding environments and then wake their CPUs only when something significant happens, as well as RAW28 pixel encoding for high-dynamic-range automotive image sensors. With 4.5 Gbit/s D-PHY lane rate and 6.0 Gsym/s C-PHY trio rates, ADAS system architectures can also start to consider leveraging CSI-2 virtual channels to effectively manage multiple sensor data streams with a single physical link.

There have recently been some new developments that will support even greater adoption of CSI-2 in the automotive market. The MIPI Alliance and the Automotive SerDes Alliance (ASA) announced an agreement in August 2023 that will pave the way for MIPI CSI-2 controllers to connect directly with ASA Motion Link (ASA-ML) PHYs. Supporting specifications, such as MIPI Camera Service Extensions (MIPI CSE) providing protocol-layer security and additional functional safety support, will be available too.

As part of this agreement, ASA will introduce an Application Stream Encapsulation Protocol (ASEP) for seamless CSI-2 transfer via the ASA-ML PHY. Once MIPI approves ASEP, ASA will make CSI-2 ASEP the sole recommended camera protocol interface in its next specification release. There is also ongoing dialogue between the two organizations about future areas of collaboration such as MIPI Display Serial Interface 2 (MIPI DSI-2) and security-related specifications. For automotive chip and system manufacturers, this new agreement between MIPI and ASA offers a broader technology palette and reduces costs by eliminating the need for a MIPI-compatible bridge chip.

Rambus has been a provider of MIPI CSI-2 and DSI-2 controller IP for over a decade with a demonstrated track record of over 250 ASIC and FPGA MIPI designs. For those designing a chip for the ADAS market, we provide automotive-specific MIPI CSI-2 solutions with expert technical support, a full suite of automotive-focused features, including automotive RTL safety insertions, Safety Manual, Failure Mode, Effects and Diagnostic Analysis (FMEDA), Design Failure Mode & Effects Analysis (DFMEA) and PHY integration services.

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