Serializers and deserializers (SerDes) simplify the connection between computer elements such as electronic control units (ECUs), high-bandwidth sensors or displays.

SerDes combine multiple interfaces such as video data, I2C, GPIO, and power over a single coaxial or twisted pair cable. Combining these interfaces on a single cable creates a long-reach, asymmetric, transparent, high-speed link between the sensor or display and the ECU.
  • Long-reach—SerDes links can typically operate over cable lengths that exceed 10 meters. Direct connections between the ECU and the sensor or display typically support much shorter distances.
  • Asymmetric—The link supports high-bandwidth data transmission only in the direction from the serializer to the deserializer. A low-bandwidth backchannel (sometimes called the side-channel or reverse-channel) allows the deserializer to send data to the serializer. Data transmission in both directions happens simultaneously.
  • Transparent—The ECU and sensor or display transmit data to each other as if a direct connection exists between the devices. For example, the same sequence of I2C commands is used to configure an image sensor when directly connected or when connected via a SerDes link.
  • High-speed—SerDes links support bandwidths in excess of 12 Gbps to support the demands of displays and sensors.
    • Figure 9. Generic SerDes Link

    Block diagram showing a generic SerDes link

    Why SerDes Are Used in Vehicle Architectures

    Automotive sensors generate more data than conventional wiring can transmit. A single high‑resolution camera can produce several gigabits per second of raw pixel data. A vehicle might include a dozen or more sensors. Likewise, in-vehicle displays also require large amounts of video bandwidth. Both sensors and displays also require a variety of control signals and power to operate. SerDes address these challenges by:

    • Reducing the cable count and weight: SerDes replaces wide parallel buses with a single conductor or a twisted-pair conductor per sensor. A serial link over coax maintains signal integrity across the lengths typical of automotive routing (up to several meters).
    • Simplifying the power delivery network: Power over Coax (PoC) eliminates the need for a separate power harness for each remote node.
    • Supporting bidirectional control: Bidirectional control embeds a backchannel in the serial link. The backchannel carries I2C commands and GPIO signals from the ECU to the remote sensor without extra wiring.
    • Enabling precise multi-sensor synchronization: The ECU can distribute a reference clock and synchronization trigger to all sensors simultaneously. The trigger ensures that all sensors capture new data at the same instant.
    • Daisychaining: Drives multiple displays from a single serializer through a chain of deserializers, reducing SoC output requirements and cable count.
    • Link aggregation: Combines data streams from multiple sensors into a single serial interface, reducing cable count and SoC input requirements.

    Types of SerDes Used in Vehicle Architectures

    Interface adapter modules are grouped into two categories — Advanced Driver Assistance System (ADAS) SerDes and In-Vehicle Infotainment (IVI) SerDes.

    ADAS SerDes are often referred to as Camera SerDes. IVI SerDes are often referred to as Display SerDes. In this document, the terms ADAS and Camera , as well as IVI and Display, are used interchangeably.

    • ADAS SerDes transfers data between cameras and ECUs.
    • Display SerDes transfers data between ECUs and in-vehicle displays.
    Both ADAS SerDes and Display SerDes support the following features:
    • Video data
    • Backchannel control data, such as I2C (Inter-Integrated Circuit) or SPI (Serial Peripheral Interface)
    • Additional general purpose digital inputs/outputs (GPIO)
    • Power over coax (PoC)
    Display SerDes chipsets offer additional support for these items:
    • Audio data, such as PDM (Pulse-density modulation) or I2S (Inter-IC Sound)
    • Video compression and decompression
    • High-bandwidth digital content protection (HDCP)
    • Wake over coax (WoC)

    Depending on the vendor and type of SerDes, supported features can vary. SerDes devices might also provide features that are not listed here.

    Note SerDes devices are highly configurable and support many features. Understanding how SerDes features are used in different applications and how the carrier module implements support for those features will help you develop your test application.