Acronym · Automotive
GMSL (Gigabit Multimedia Serial Link)
The Maxim, now Analog Devices, automotive SerDes family carrying uncompressed camera and display video with a bidirectional control channel over coax or STP, at 12 Gbit/s forward and 187.5 Mbit/s reverse in GMSL3.
- Also known as
- GMSL2, GMSL3
- Type
- Acronym
- Domain
- Automotive, Camera and display links
- Also relevant to
- Interfaces & SerDes
Notes
Widely used in ADAS camera links; Analog Devices opened the specification through the OpenGMSL Association in 2024.
Overview
GMSL (Gigabit Multimedia Serial Link) is Analog Devices' family of automotive serialiser and deserialiser (SerDes) chips and link technology for carrying high-speed video and data, such as camera and display streams, over a single coaxial or shielded twisted-pair cable inside a vehicle. A serialiser at the camera or display end converts parallel or MIPI CSI-2 video into one fast serial stream, and a deserialiser near the processor converts it back, with a slower reverse channel for control. Since 2025 the OpenGMSL Association has been turning the technology into an open, multi-vendor standard.
How it works
A camera module typically contains an image sensor and a GMSL serialiser; a long cable runs to a deserialiser on the ADAS or infotainment controller, which outputs video to the system-on-chip, for example over MIPI CSI-2. The link is asymmetric. The forward channel carries the video at high speed, while a much slower reverse channel carries configuration and control traffic back to the camera, so the controller can set up the sensor through the same cable. Power can also be delivered to the remote module over the coax, which keeps wiring simple.
GMSL has gone through several generations. GMSL2 uses NRZ signalling, one bit per symbol. GMSL3 switches to PAM4, which carries two bits per symbol, doubling the data rate at the same symbol rate to a fixed 12 Gbit/s on the forward channel, with a 187.5 Mbit/s reverse channel and forward error correction to keep long links robust.
Because the links run over several metres of cable, connectors and inline power circuits, Analog Devices publishes channel specifications that set limits on insertion loss, return loss and crosstalk for the whole path, and test vendors offer physical layer tests for the links. The OpenGMSL v3.0 specification is based on, and backward compatible with, GMSL2 and GMSL3, and the association is developing a compliance test specification for multi-vendor interoperability.
Examples
- A front-facing ADAS camera sending high-resolution video to a central controller over a single coax cable through a GMSL3 serialiser and deserialiser.
- A deserialiser that combines several GMSL camera links into MIPI CSI-2 outputs for an automotive system-on-chip.
- Rohde & Schwarz oscilloscope firmware that runs physical layer tests on GMSL links, developed with Analog Devices.
Why it matters
Modern vehicles carry many cameras and displays, and each needs a reliable, low-latency, uncompressed video link that tolerates the electrical noise and cable lengths of a car. ADAS and camera system architects, automotive SoC teams, SerDes PHY designers, channel and signal integrity engineers and automotive network verification engineers all work with GMSL links.
Related terms
Part of the Automotive glossary, with every term in the topic and the lifecycles, tools and standards that use them.
Where it appears on the Hub
Used on 4 pages of the Hub. In each group, the pages that mention it most come first.
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Last reviewed . Written by The Semiconductor Hub editorial team. The full glossary