[Tech]Exploring the Versatility of GMSL Cameras

#GMSL #Autonomous #Vision #AI #ADAS #Robot #SerDes #Jetson #nvidia #MIPI #TELROP

Telelian, engaged in productization and service provision related to the NVIDIA Jetson platform, naturally received requests for video processing due to its engineering resources being strong in video and streaming. This led to the necessity for cameras alongside systems for AI recognition, resulting in the provision of vehicle AI/ADAS cameras with strengths in LFM (Light Field Management) and HDR (High Dynamic Range) processing. Telelian has gone further to provide a software pipeline for vision processing that is designed, driven, tuned, and optimized.

The application of the GMSL interface began due to requests from various robot manufacturers and for vehicle vision processing, experiencing its advantages, utility, and engineering approaches.

What is GMSL?

GMSL (Gigabit Multimedia Serial Link) is a high-speed serial interface used in automotive vision systems and robotics, featuring Serializer/Deserializer (SerDes) technology that enables long-distance transmission. Below is a block diagram of an embedded vision system using the GMSL interface.

What is MIPI?

Looking at the camera block diagram, one can see the MIPI (Mobile Industry Processor Interface) interface output from the image sensor side. MIPI is a high-speed protocol for transmitting video and image data between the camera and host processor. One of the MIPI interface variants, MIPI CSI-2, provides a bandwidth of up to 6Gb per second, with an achievable bandwidth of about 5Gb per second. MIPI CSI-2 connects the image sensor to the embedded board for image data control and processing. The maximum cable length for standard MIPI CSI-2 camera connections is 30cm.

GMSL and MIPI Interfaces in Embedded Vision

Compared to the MIPI interface, which is easy to implement for relatively short direct connections, the GMSL interface is widely used in embedded systems for its advantages in transmission distance and EMI/EMC performance aspects.

Although the cost of the GMSL interface is relatively high, making it generally unused, it is effective for long-distance transmission needs in driver assistance systems (ADAS), robotics, and traffic systems.

From a technical perspective, configuring a GMSL interface involves more than just image sensors and ISPs; it allows for a variety of configurations, including Serializer & Deserializer. Therefore, setting up a GMSL camera and application system requires additional work on image quality tuning, Device Tree, and driver work, compared to interfaces like MIPI or USB.


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