The proliferation of cameras and displays in modern vehicles has revolutionized the driving experience, facilitating advanced safety features, enhanced navigation systems, and new entertainment options (Fig. 1). However, the growing number of these components poses a significant challenge for car manufacturers: ensuring seamless connectivity and interoperability between the various systems. One of the biggest challenges is managing local connectivity within the vehicle.
Fast, reliable, and over longer distances
MIPI (mobile industry processor interface) protocols on higher layers are commonly used in vehicles to connect sensors and displays with domain control units and other onboard computers. To facilitate communication between cameras, displays, and other onboard systems, data are traditionally transmitted using source-synchronous interfaces like MIPI D-PHY and MIPI C-PHY. While these interfaces are effective for short-range connections, they struggle with data transmission over longer distances within the vehicle.
To address this issue, cabling interfaces like MIPI A-PHY have been adopted for distributing cameras and displays within the vehicle. A-PHY is an asymmetrical data link in a point-to-point topology that enables very fast, unidirectional data transmission with embedded bidirectional control data and optional power supply via a single cable.
The use of A-PHY allows suppliers to achieve efficient transmission over longer distances – cable lengths of up to 15 meters – while ensuring fast, reliable, and efficient communication between various vehicle components. MIPI A-PHY v1.0 supports five speed levels (2, 4, 8, 12, and 16 Gbps), offering greater design flexibility. The latest version, MIPI A-PHY v1.1, doubles the total downlink bandwidth from 16 to 32 Gbps by supporting Star Quad (STQ) cables, which feature two differential wire pairs in a single shielded jacket. This enables the use of two A-PHY ports via a single cable, reducing costs, weight, and complexity compared to using two separate coaxial or shielded twisted pair cables.
Bridge between various interface protocols
However, the introduction of interface standards entails a number of challenges. Different suppliers use proprietary protocols or hardware interfaces, leading to compatibility issues and fragmented ecosystems. To simplify the introduction of interface standards, car manufacturers use programmable FPGA-based interface bridges.
These versatile solutions act as a bridge between different interface protocols and enhance compatibility and flexibility within the vehicle architecture. FPGA-based interface bridges enable the integration of multiple device interfaces, facilitating the aggregation, partitioning, control, and initialization of various components (Fig. 2).
They provide advanced functions such as preprocessing and buffering for real-time processing of camera and display data, for instance. With a latency of under 15 ms, FPGAs offer significantly lower response times compared to SoC-based solutions, which typically have a latency of around 30 ms. They also support compression methods that allow for higher resolution and increased image and data rates via the cable connection. Car manufacturers can thus offer their drivers and passengers a cutting-edge visual experience without sacrificing performance or efficiency.
The use of Gowin FPGAs for controlling LED backlighting in automotive applications provides several key advantages (Fig. 3): They offer cost-effective, customizable logic that facilitates rapid prototyping and precise control of LED brightness and color, enhancing display readability and driver comfort. Moreover, the FPGAs are designed for low power consumption, which is essential for energy efficiency in vehicles. They meet the stringent standards of the automotive industry in terms of reliability and temperature resistance. Their integration capabilities support seamless connection to other vehicle systems and comprehensive control and monitoring on a single chip.
Summary
By employing FPGA-based interface bridges, car manufacturers can address the challenges of camera and display interfaces, ensuring seamless connectivity and standardized communication protocols within their vehicles.
These solutions not only improve the driving experience but also pave the way for innovations in automotive technology. As the industry evolves, FPGA-based interface bridges will be crucial in shaping the future of connected vehicles.
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