A Detailed Comparison of SerDes Camera Interfaces: GMSL2 vs. FPDLink III

GMSL2 and FPDLink III are also the modem camera interfaces commonly used in embedded systems with strong backing, high transmission speed, and at long range. This blog discusses their technical variations, benefits, and where they should be used.

The most typical interfaces found in embedded vision and which can provide long range with high bandwidth, are GMSL (Gigabit Multimedia Serial Link) and FPDLink (Flat Panel Display Link). It can be claimed that, out of all the releases in both series, GMSL2 and FPDLink III have gained the most popularity because of their features, performance, and broad compatibility.

Although they are rather comparable in the feature list, GMSL2 and FPDLink III have certain structural and architectural aspect differences. This paper aims to present an end-to-end comparison of the two interfaces that is whether based on feature, architecture, performance, or application.

The technology of GMSL2 and FPDLink III interfaces

The source technology underlying the GMSL2 and FPDLink III interfaces isn't the only technology of its kind with a history of high vertical integration. The non-just-a-cable approach pattern has been expressed in myriad forms over the past several decades.

SerDes-based data transmission techniques are used by both the GMSL2 and FPDLink III. SerDes is an encoding method and is created to boost data speed transfer by distorting the parallel data to a serial stream at the sender side and back to parallel data at the recipient side.

The conversion of the parallel stream into the serial stream is performed with the help of the so-called serializer, whereas its inverse conversion is performed with the help of the so-called deserializer. Therefore, the term SerDes (Serializer/Deserializer).

The major strengths of the SerDes technology encompass:

• It offers minimal latency and great speed (long distance).

• The SerDes interfaces as well as cables are immune to shocks and vibration. Therefore, they can be utilised in industrial rugged conditions.

• They can be applied to other markets like AMRs (Autonomous Mobile Robots) and other autonomous and manual vehicles, albeit of an industrial grade; nevertheless, they are mostly intended to be used in automotives since GMSL and FPDLink are industrial grade.

What are GMSL2 cameras?

Implementations of GMSL 2. In order to transmit camera data to the host, GMSL 2 cameras use the GMSL 2 interface. According to Maxim Integrated (designers of the GMSL interface), the GMSL family of interfaces is as follows:

Gigabit Multimedia Serial Link (GMSL) feature complete, high-speed communication IC SerDes serializers and deserializers are the latest innovation in high-speed communications ICs that provide the bandwidth, complex interconnect, and data integrity that allows support of a variety of multimedia and other devices. Automotive infotainment systems and advanced driver assistance systems (ADAS).

The latest technology in the GMSL series is called GMSL3. Although the latter is more sophisticated, GMSL2 is enough for the majority of contemporary embedded vision applications since it can send data at an FC (Forward Channel) and BC (Backward Channel) bandwidth of 6Gbps and 187Mbps, respectively. This connection is made on a coaxial Shielded Twisted Pair (STP) cable or Shielded Parallel Pair (SPP) cable.

What is the camera's FPDLink III?

Texas Instruments developed the long-haul transmission interface known as FPDLink III. The authors of the interface orient the FPDLink III to ADAS, security & surveillance cameras, industrial, and medical imaging. The maximum data transmission range of FPDLink III cameras is 15 meters, just like that of the GMSL2.

With regard to bandwidth, FPDLink III offers FC & BC bandwidth of 50Mbps and 4.16Gbps, respectively. Moreover, the single-ended coaxial or Shielded Twisted Pair (STP) cable facilitated by the interface is automotive grade and can be applied in a host of vehicles - both automotive and robots, as well as tractors

FPD-Link III cameras vs GMSL2 cameras: A comparison by feature

Having clearer knowledge of what the two interfaces imply, it is time to compare and contrast the technical features and specifications of GMSL2 and FPDLink III on a side-by-side basis.

The same is shown in the table below:

Feature / Parameter	FPDLink III	GMSL2
Control Interface (Backchannel)	Utilizes I²C for configuration and control.	Supports both I²C and UART, enabling more flexible communication options.
Video Interface (Forward Channel)	Uses a 4-lane MIPI CSI-2 output to transmit video.	Offers both MIPI CSI-2 and parallel interface options, increasing design choices.
Form Factor / Chip Size	Compact footprint of 5mm x 5mm—ideal for space-constrained applications.	Slightly larger at 7mm x 7mm—requires more board space.
Operating Temperature Range	Automotive-grade: Performs reliably from –40°C to +125°C.	Also rated for extreme environments with the same temperature range.
Data Bandwidth (Forward / Backward)	Supports 4.16 Gbps for video and 50 Mbps for control.	Higher bandwidth: 6 Gbps for video and 187 Mbps for control.
GPIO Support	Provides up to 4 General-Purpose Input/Output (GPIO) pins.	Offers more flexibility with up to 10 GPIOs.
Audio Support	Capable of transmitting audio data alongside video.	Does not support audio transmission.
Synchronization Features	Supports frame synchronization between multiple camera modules.	Also supports synchronization across multiple sensors.
Maximum Cable Length	Can maintain signal quality up to 15 meters over coax/STP.	Matches the same reach of up to 15 meters.

Which One to Choose: GMSL2 or FPDLink III?

GMSL2 and FPDLink III are both high-performance, robust SerDes camera interfaces that satisfy the performance and evolving requirements of embedded vision systems. Although GMSL2 doubles the bandwidth and provides an increased amount of GPIO and more flexibility in the interface, FPDLink III can support audio transmission and has a smaller footprint, which is good in space-constrained applications.

The last option you choose will be as per limited application requirements, that is, ensuring optimum data throughput, space optimization, or multilevel synchronization. Whichever one is chosen, both interfaces provide the long-haul and high-speed transmission capabilities needed in the modern automotive, industrial, and medical imaging applications.

Final Thoughts

As embedded vision applications continue to demand higher performance, longer range, and greater integration, choosing the right camera interface becomes a critical design decision. Both GMSL2 and FPDLink III offer reliable, high-speed data transmission with automotive-grade robustness, but their nuanced differences make each suitable for specific use cases. Whether you prioritize bandwidth, audio support, interface flexibility, or physical footprint, a careful assessment of your system's needs will guide the optimal choice. Ultimately, both interfaces represent the forefront of SerDes-based imaging solutions—and selecting the right one ensures your system is future-ready, scalable, and built for high-efficiency visual processing.