GMSL Camera Interface – Features and Applications?

GMSL interface

This article deals with the features and applications of GMSL camera interface.

High bandwidth, long-range support, data integrity, improved performance, and camera reliability will continue to be critical requirements for embedded vision applications in automotive, robotics, and smart cities. MIPI CSI-2, USB 3.0, and GigE are some of the most popular camera interfaces used in such applications. They are, however, incapable of meeting the growing demands of many new-age applications.

Other interfaces, such as Ethernet and CAN, are widely used in automobiles and automotive applications. They are, however, too slow to transmit large amounts of high-resolution digital video data. This is where the Serializer/Deserializer (SerDes) technique shines. Because it provides high data rates, long-distance support, and improved performance, the SerDes technique is widely used in telecom, datacom, industrial, and cable interconnect applications.

This serial link technology also performs consistently in harsh industrial and outdoor environments, delivering data quickly and with low latency. A SerDes technique is primarily used to provide data transmission over a single coaxial cable or differential pair cables (STP, SPP, etc.) to reduce the number of Input/Output pins and interconnects.

Gigabit Multimedia Serial Link (GMSL) cameras use SerDes technology (GMSL and GMSL2) to transmit high-speed video, bidirectional control data, and power over a single coaxial cable.

What is a GMSL camera interface?

The Gigabit Multimedia Serial Link (GMSL) serial interface is a high-speed serial interface invented by Maxim Integrated that would be primarily utilized in automotive video applications including infotainment and advanced driver assistance systems (ADAS). Additionally, it is employed in a variety of robotic and intelligent traffic applications.

The GMSL camera interface consists of serializer and deserializer families with a variety of interfaces, including HDMI, CSI-2, DSI, asymmetric DSI, eDP, oLDI, and single, dual, and quad GMSL1/GMSL2 at the input or output across a single cable up to 15 meters long with coax or shielded twisted pair. Data is transformed into a serial stream on the transmitting side by a serializer, and into a parallel word for processing on the receiving side by a deserializer.

Before we get into the differences between GMSL and MIPI interfaces, let’s first define a GMSL interface.

Features of GMSL Camera

GMSL cameras are widely used in industrial applications requiring high data rates and long-distance support.

The camera’s ability to send data instantly, even in harsh industrial conditions, and to do so with zero latency is yet another competitive differentiator.

Additionally, the features of GMSL cameras also come with, virtual camera support, backward compatibility, automatic repeat request feature, and compatibility with ARM platforms.

Transmission distance

With the help of the GMSL SerDes technology, transmission across long distances of up to 15m is possible. An adaptive line equalizer can also be used in GMSL to account for increasing cable attenuation at higher frequencies. With 12 levels of adjustment, this cable equalization can handle cables up to 15m STP and 30m coax in length.

Performance of EMI/EMC

Due to the performance degradation, electromagnetic interference (EMI) is still a significant issue in cameras, caused by the nearby cable, connector, PCB, and electronic equipment.

The serializer and deserializer ICs from GMSL provide customizable output-spread spectrum functionality to enhance safety-based camera applications. Without requiring an external spread-spectrum clock, it improves the performance of the link’s EMI.

Video Duplication

The GMSL Splitter mode is designed for usage with display applications. A single serializer and two deserializers make up this type. In splitter mode, it is necessary to mask the output of every video pipe to every GMSL PHY. This is referred to as video duplication.

Applications of GMSL in Embedded Vision

In this section, we will examine some of the most widespread camera-based applications where GMSL is preferred over other interfaces.

Vehicle Infotainment Systems

With features such as passenger entertainment, display of vehicle and environmental information, navigation, and connectivity, automotive infotainment systems provide an immersive experience for drivers and passengers. Such systems frequently necessitate the placement of a camera at a significant distance from the host processor (as in the case of a surround-view system). As a result, GMSL is preferred over MIPI or USB.

GMSL cameras can also be used in inspection cameras and street lighting cameras, in addition to the applications listed above.

Advanced Driver Assistance Systems (ADAS)

ADAS systems contribute to safer roadways. They also improve the driving experience by providing features such as lane positioning, parking assistance, and collision avoidance. The GMSL SerDes technology meets the essential needs of an ADAS system, such as high reliability and flexibility for uncompressed camera feed transmission, due to the benefits discussed in this article.

Robotics

Autonomous mobile robots (AMR) are used for a variety of automated tasks in industries such as warehousing, automotive manufacturing, logistics, e-commerce, and healthcare. Cameras in AMR and robotics systems serve a variety of imaging purposes. Cameras are required in AMR for navigation, object detection, and object identification. Fast frame rates and short exposure times are important considerations when choosing a camera for robotic applications. Because of their fast frame rates and low exposure time capabilities, GMSL cameras provide the best solution. As previously stated, it can transmit data up to a distance of 15m from the host for remote robotics.

Intelligent Transportation Systems

Using sensors, cameras, routers, and other technologies, a smart traffic system improves traffic management and increases safety. This application necessitates the transmission of captured image and video data over long distances. As a result, the GMSL interface with a 15 m cable and multiple camera capture capabilities is used to reliably transmit data to the host platform.

Fleet administration

Multiple cameras are required in a fleet management system to cover large vehicles such as trucks and forklifts. One of the most difficult challenges in such vehicles is recurring accidents caused by blind spots. A common solution to this problem is to use a surround-view system, which provides the driver with 360° awareness by eliminating blind spots. A surround-view system consists of a multi-camera system with cameras placed at a great distance from the host processor. This necessitates the use of an interface such as GMSL, which can reliably transmit data over long distances.

Wrapping Up

Vadzo provides top-notch cameras that employ GMSL technology. Over a single coaxial cable, they may deliver bidirectional control data and power as well as high-speed video transmission. With assured lower latency and greater frame rate, our GMSL cameras can be bound to 15-meter distance from the host processor.

Additionally, we can offer special camera solutions. Moreover, we provide ISP optimization for many different sensors, Processor cores, and use cases.

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