Flexible, scalable car network

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In the past decade, the vehicle network architecture has become more complicated. Although the number of in-vehicle network protocols has decreased, the number of networks actually in use has increased significantly. This raises the scalability issues of network architectures and requires optimization of semiconductor devices to meet the practical needs of various applications and networks.

FPGAs were once considered a development-only solution, and today's price drop has solved many problems, so they have been put into production at a lower overall system cost than traditional ASIC or ASSP solutions. Now, all major FPGA vendors for the automotive market have passed ISO-TS16949 certification, which has made programmable logic devices the mainstream technology in the automotive market.

Vehicle network electrical architecture

Over the past decade, network protocols for many specialized automotive OEMs have given way to more standardized global agreements such as CAN, MOST and FlexRay. As a result, semiconductor suppliers are carefully crafting devices that comply with these protocols, which has made the first-tier component suppliers more competitive and have cut prices, while also facilitating module interoperability between automotive OEMs. However, there are still many problems in today's automotive electrical architecture that plague automotive OEMs and Tier 1 accessories suppliers.

Engineers can divide and develop network strategies in several different ways. High-end cars can run up to seven different network buses simultaneously. For example, a car can have a LIN loop for the rearview mirror, a 500 Kbps low-speed CAN loop for low-end functions such as seat or door control, a 1 Mbps high-speed CAN loop for body control, and another high-speed The CAN loop is used for the driver information system, a 10 Mbps FlexRay loop is used to provide real-time driver assistance data, and a 25 Mbps MOST loop is used for transmission within or between multiple infotainment systems, such as navigation or rear seat entertainment. Control and media streaming.

On the other hand, a low-end car can have only one LIN or CAN loop, making all other modules work independently with virtually no interaction. Each automotive OEM has handled inter-module communication and automotive network topologies in different ways, and each vehicle platform is different, making it difficult for Tier 1 suppliers to develop a modular architecture that has both the correct interface and reusability. The uncertainty of the final architecture of the housing module is where FPGAs come into play.

ASICs, ASSPs, and microcontrollers have a fixed hardware architecture that often leaves resources unnecessarily redundant and inflexible. The programmability (and reprogrammability) of the FPGA facilitates the addition and subtraction of on-chip channels (such as CAN channels) and allows for the reuse of IP. With this flexibility, solutions that optimize the number and type of network interfaces can be quickly crafted into modules.

Semiconductor implementation of network protocol

The strength of FPGAs is not only the scalability of the number and type of interfaces. In the case of ASSPs, ASICs, and microcontrollers, their peripheral macros are implemented in hardware, which makes them naturally less flexible. In an FPGA environment, the network interface IP itself can be optimized for the IP used.

For example, using Xilinx® LogiCORETM CAN or FlexRay Network IP, users can flexibly set the number of transmit and receive buffers along with the number of filters. In traditional hardware solutions, engineers using CAN controllers typically have only three configuration choices of 16, 32, and 64 message buffers. Depending on the level of system functionality and the processing available outside the FPGA, Xilinx's scalable MOST network interface solution includes network controller IP that can be configured for active or slave operation, as well as asynchronous sample rate converter (ASRC), data router or replication. Protect a large number of IPs such as encryption engines.

This IP allows for optimization, from low-density devices for low-end solutions to higher-density devices for high-end solutions, and its package often occupies the same area on the target board of the module. In addition, middleware stacks and drivers for complete solutions have been developed for each major protocol. This scalability and versatility of FPGA solutions is simply not possible in traditional automotive hardware solutions.

All major FPGA vendors use soft microprocessors that can be effectively implemented in the architecture of control functions and run at speeds comparable to those embedded in some hardware. Another big advantage of the FPGA architecture is the ability to offload microprocessors and partitions by using parallel DSP processing in a multiplier or on-chip hard MAC to improve overall performance and throughput.

We have made great progress

Programmable logic devices have made great strides and are gradually becoming the mainstream technology in the automotive market. A variety of programmable logic devices are indistinguishable in terms of reliability, while FPGA technology enables flexible, scalable integration that is not possible in traditional ASIC, ASSP, or microcontroller architectures. The shortened development cycle, the use of advanced process technology by programmable logic device vendors, and the inevitable economies of scale of programmable devices all contribute to lower overall production system costs.

As key IP and solutions for in-vehicle networks mature and the performance potential of FPGA architectures increases, programmable logic devices will become the protagonists, helping to overcome some of the engineering challenges inherent in the development of automotive electrical architectures.
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