The Automotive SerDes Alliance (ASA) is a non-profit industry alliance, founded in 2019, that standardises asymmetric SerDes links for cars. Its specification, ASA Motion Link (ASA-ML), carries high-bandwidth video and sensor data from cameras, radars and displays to ECUs at downstream line rates of 2 to 16 Gbps, with a slower return channel for control. The aim is an open, multi-vendor alternative to the proprietary SerDes links that have dominated camera and display connections.
As vehicles become smarter, more connected and more autonomous, the demand for robust, high-speed data links inside the car keeps growing. From advanced driver-assistance systems (ADAS) to in-vehicle infotainment (IVI) and autonomous driving, modern cars rely on a network of sensors, cameras and displays that need high-bandwidth connectivity. This post looks at the mission, achievements and likely impact of the ASA.
Key takeaways
- ASA-ML is asymmetric: most bandwidth flows one way (sensor to ECU, or ECU to display), so the return channel can be much slower and cheaper.
- Downstream line rates span 2 to 16 Gbps, enough for multi-megapixel cameras and high-resolution displays, with encryption and authentication applied.
- The specification covers physical, data link and transport layers, so parts from different vendors can interoperate.
- A liaison with the MIPI Alliance (announced in 2023) creates a route to carry MIPI CSI-2 camera data natively over the ASA-ML physical layer.
- Work continues on Ethernet integration, security, compliance testing and a second-generation specification.
What is the Automotive SerDes Alliance?
The Automotive SerDes Alliance is a collaborative effort among automotive and technology companies to develop and promote a standardised Serializer/Deserializer (SerDes) technology for the automotive industry. It was founded by companies including BMW, Continental, Broadcom, Fraunhofer IIS and NXP, and had grown to more than 90 member companies by 2024, as reported at the time. Members span car makers (OEMs), Tier-1 suppliers, semiconductor vendors, cable and connector makers, and test tool providers. That mix helps keep the standards aligned with real market needs.
SerDes technology, which converts parallel data into a serial stream and back again, is critical for high-speed, point-to-point links between sensors, displays and electronic control units (ECUs). Unlike proprietary SerDes solutions that lack interoperability, the ASA's goal is an open, standardised framework, the ASA Motion Link (ASA-ML), that supports high-bandwidth, low-latency and secure data transmission in harsh automotive environments.
How an asymmetric automotive SerDes link works
A camera link is a good example. The camera module contains an image sensor and a serializer. The serializer takes the sensor's parallel or CSI-2 output, packs it into frames, adds error protection and sends it as a single high-speed serial stream over one coaxial or shielded twisted-pair cable. At the ECU, a deserializer recovers the clock and data and hands the video to the processor. In the opposite direction, a much slower link carries configuration commands, trigger signals and sometimes power control back to the camera.
Because the two directions have very different needs, an asymmetric design saves cost and power: only one end needs the fast transmitter and only the other end needs the fast receiver.
Worked example: how much bandwidth does a camera need?
The figures below are illustrative, to show the order of magnitude.
| Camera | Pixels | Frame rate | Bits per pixel (raw) | Raw payload |
|---|---|---|---|---|
| 2 MP (1920 x 1080) | 2.07 million | 30 fps | 12 | about 0.75 Gbps |
| 8 MP (3840 x 2160) | 8.29 million | 30 fps | 12 | about 3.0 Gbps |
| 8 MP (3840 x 2160) | 8.29 million | 60 fps | 12 | about 6.0 Gbps |
The calculation is pixels x frame rate x bits per pixel. For the 8 MP, 60 fps case: 8.29 million x 60 x 12 is about 5.97 Gbps. Line coding, packet overhead, forward error correction and security tags add to this, so a link of 8 Gbps or more would be a sensible choice for that camera. This is why a range of 2 to 16 Gbps covers most of today's automotive cameras and displays.
The need for standardisation in automotive SerDes
In earlier vehicle designs, cameras and displays were usually connected to ECUs using proprietary SerDes solutions, which made interoperability and component selection harder. As vehicles evolve into software-defined platforms with more high-resolution cameras and sensors, the lack of a standard protocol creates inefficiencies and limits collaboration between suppliers and OEMs.
The ASA addresses these challenges in four ways:
- Interoperability: by defining specifications for physical, data link and transport layers, the ASA aims to let components from different manufacturers work together. This supports a multi-vendor ecosystem, reducing costs and speeding development.
- High bandwidth: ASA Motion Link supports downstream speeds from 2 Gbps to 16 Gbps, suited to high-resolution cameras and displays, even with encryption and authentication applied.
- Security: with connected and autonomous vehicles, securing data transmission is critical. The ASA-ML specification includes a security framework to protect against unauthorised access and tampering.
- Robustness: ASA links are designed for harsh conditions such as high temperatures, vibration and electromagnetic interference, over the cable lengths found in vehicles.
Key milestones and achievements
Since its inception, the ASA has made steady progress:
- First specification: the ASA introduced the first version of its SerDes standard, defining in-vehicle links with data rates from 2 Gbps to 16 Gbps. Industry reports date the ASA-ML 1.01 transceiver specification to December 2020. It supports asymmetric transmission, ideal for camera and display applications where high downstream bandwidth is needed and the return channel needs less.
- Ethernet integration: a later specification update introduced asymmetrical Ethernet capabilities, to integrate with Automotive Ethernet for simpler vehicle network architectures. This supports the trend of combining SerDes with Ethernet for high-speed communication.
- First PMA Plugfest: held in Hasselt, Belgium, the inaugural ASA Plugfest for the Physical Medium Attachment (PMA) Electrical Compliance Test Specification (CTS) tested and validated the PMA CTS draft and showed interoperability among components.
- MIPI liaison: in August 2023 the ASA and the MIPI Alliance announced a liaison agreement to enable native implementation of MIPI Camera Serial Interface 2 (CSI-2) over the ASA-ML physical layer. This extends the widely used CSI-2 standard in automotive applications and reduces integration work.
- Live demonstrations: at events such as AutoSens and the Automotive Ethernet Congress, ASA members including BMW and VSI have shown ASA-ML technology in live demonstrations. At CES 2024, VSI presented its VS775S single serializer and VS776Q quad deserializer, as reported at the time.
The impact of ASA on the automotive industry
The ASA's work supports a standardised, interoperable ecosystem for next-generation vehicles. Key impacts include:
- Enabling ADAS and autonomous driving: high-speed SerDes is critical for moving large volumes of sensor data to processors in real time, supporting features such as lane-keeping, collision avoidance and autonomous navigation.
- Streamlining vehicle architectures: by integrating with Automotive Ethernet, ASA-ML can simplify network designs, reducing complexity and cost for OEMs. This matters most in zonal architectures, where data from many sensors and displays is aggregated in zone controllers.
- Energy efficiency: ASA-ML is designed to keep link power low, which matters in electric vehicles where every watt affects range.
- Collaboration: with more than 90 members as of 2024, including OEMs such as General Motors and Stellantis and Tier-1 suppliers such as Aptiv (membership as reported at the time), the ASA gives the industry a shared platform so that standards evolve in line with its needs.
ASA-ML compared with other options
| Option | Type | Typical use |
|---|---|---|
| Proprietary SerDes (several vendors) | Closed, vendor-specific | Cameras and displays, widely deployed; serializer and deserializer usually from the same vendor |
| ASA Motion Link | Open alliance specification, asymmetric | Cameras, displays and sensors, multi-vendor |
| MIPI A-PHY | Open MIPI specification, asymmetric | Long-reach camera and display links, also adopted as an IEEE standard |
| Automotive Ethernet (100BASE-T1, 1000BASE-T1, multi-gig) | IEEE 802.3, symmetric | Vehicle backbone and ECU-to-ECU networking |
Recent developments and future outlook
The ASA continues to push automotive connectivity forward. Highlights reported in 2024 include:
- Ecosystem growth: on 17 June 2024, the ASA announced a broad ecosystem for ASA-ML, with support from OEMs, tool providers, and cable and connector suppliers such as TE Connectivity and Würth Elektronik, giving implementers a range of compatible components.
- Industry events: at the Automotive Ethernet Congress 2024, ASA members demonstrated an 8 MP automotive camera using ASA-ML, presented as a sign of readiness for series production.
- Security: the ASA is addressing the need for secure data transmission with features such as encryption and intrusion detection, to protect connected vehicles from cyber threats.
Looking ahead, the ASA stated in 2024 that it aimed to finalise the ASA-ML 2.0 draft specification by the end of 2025, further integrating Ethernet capabilities and expanding support for new automotive applications. Since then the alliance has reported further compliance plugfests and interoperability events, so check the ASA website for the current status of the 2.0 work. As vehicles become more connected and autonomous, a standardised approach should help interoperability, scalability and reliability across the automotive ecosystem.
Common questions engineers ask
Why not just use Automotive Ethernet for cameras?
Ethernet is symmetric and packet-switched. A camera mostly needs a fast one-way stream with low, predictable latency. An asymmetric SerDes puts the cost and power into one direction only, which suits sensors and displays. ASA's Ethernet work aims to let the two coexist in the same architecture.
Does ASA-ML replace MIPI CSI-2?
No. CSI-2 is the camera protocol many image sensors and processors already use. The ASA and MIPI liaison is about carrying CSI-2 over the ASA-ML physical layer, not replacing it.
What does a design team need to check when choosing a link?
Required bandwidth with overheads, cable type and length, power budget, security needs, available silicon from more than one supplier, and compliance test tools.
How to get involved
Membership in the ASA is open to any legal entity committed to advancing automotive SerDes standardisation. Members gain access to specifications, working groups and the chance to shape in-vehicle connectivity.
When this post was first published in October 2024, the listed contacts were the ASA Chair, Christoph Arndt (Christoph.Arndt@continental-corporation.com), and Vice Chair, Claude Gauthier (Claude.Gauthier@nxp.com). Officers change over time, so check the ASA website for current contacts and details.
Conclusion
The Automotive SerDes Alliance is changing in-vehicle connectivity by providing a standardised, high-performance and secure SerDes solution for the automotive industry. Through the ASA Motion Link, partnerships such as the MIPI liaison and a growing ecosystem, it is supporting the next generation of connected and autonomous vehicles.
For more information, visit auto-serdes.org or follow the ASA on LinkedIn for the latest updates.
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