Over the past decade, in-vehicle network architectures have become increasingly complex. While the number of in-vehicle networking protocols has decreased, there has been a significant increase in the number of networks actually deployed. This raises the question of scalability of network architectures and requires semiconductor devices to be optimized to meet the actual needs of various applications and networks.
Once considered a development-only solution, FPGAs have fallen in price so rapidly that many of these problems can be solved and even put into production at a lower overall system cost than traditional ASIC or ASSP solutions. Now, all major FPGA suppliers facing the automotive market have passed ISO-TS16949 certification, making programmable logic devices gradually become the mainstream technology in the automotive market.
In-vehicle network electrical architecture
Over the past decade, many dedicated OEM automakers’ network protocols have given way to more standardized global protocols such as CAN, MOST and FlexRay. As a result, semiconductor suppliers can focus on making devices compliant with these protocols, increasing competition and price cuts among Tier 1 accessory suppliers, and facilitating module interoperability among automotive OEMs. However, there are still many issues in today’s automotive electrical architecture that plague automotive OEMs and Tier 1 parts suppliers.
Engineers can divide and develop network policies in several different ways. High-end cars can have up to seven different network buses running simultaneously. For example, a car can have a LIN loop for the rearview mirror, a 500Kbps low-speed CAN loop for low-end functions like seat or door control, a 1Mbps high-speed CAN loop for body control, and another high-speed CAN loop For driver information systems, a 10Mbps FlexRay loop for real-time driver assistance data, and a 25Mbps MOST loop for control and media streaming within or between various infotainment systems such as navigation or rear seat entertainment .
On the other hand, low-end cars can have only one LIN or CAN loop, leaving all the other modules to work independently with almost no interaction. Inter-module communications and vehicle network topologies are handled differently by different OEM automakers, and each vehicle platform is different, making it difficult for Tier 1 accessory suppliers to develop a reusable module architecture with the correct interface. Uncertainty about the final architecture that houses the modules is where FPGAs come in.
ASICs, ASSPs, and microcontrollers have a fixed hardware architecture, and their resources are often either lacking or oversupplying, and there is no flexibility to speak of. The programmability (and reprogrammability) of FPGAs makes it easy to add or remove on-chip channels (such as CAN channels), and it allows IP to be reused. With this flexibility, solutions optimized for the number and type of network interfaces can be quickly modularized.
Semiconductor Implementation of Network Protocols
The strength of FPGAs is not only scalability in the number and type of interfaces. For ASSPs, ASICs and microcontrollers, the peripheral macros are implemented in hardware and thus inherently lack flexibility. In an FPGA environment, the network interface IP itself can be optimized according to the IP used.
For example, with Xilinx LogiCORE CAN or FlexRay network IP, the user has the flexibility to set the number of transmit and receive buffers and the number of filters. In traditional hardware solutions, engineers using CAN controllers typically only have three configuration options of 16, 32 and 64 message buffers. Depending on the level of system functionality and the processing power available outside the FPGA, Xilinx’s scalable MOST network interface solutions include network controller IP that can be configured as master or slave as well as asynchronous sample rate converters (ASRCs), data routers, or replicas Protects a large number of IPs with encryption engines, etc.
This IP allows optimization to fit both lower-density devices in low-end solutions and higher-density devices in high-end solutions, often using the same package outline on the target board of the module. Additionally, for each major protocol, the industry has developed middleware stacks and drivers that complete the solution. This scalability and versatility of FPGA solutions is simply not possible with traditional automotive hardware solutions.
The major FPGA vendors have soft microprocessors that can be efficiently implemented in the architecture of the control function and that can run at speeds comparable to those embedded in some hardware. Another great advantage of the FPGA architecture is the ability to improve overall performance and throughput by offloading processing tasks on the microprocessor and partitions by using multipliers or parallel DSP processing in the on-chip hard MAC.
Programmable logic devices have come a long way
Programmable logic devices have come a long way and are gradually becoming a mainstream technology in the automotive market. Programmable logic devices of all kinds are indistinguishable in terms of reliability, and FPGA technology enables scalable and flexible integration that is not possible with traditional ASIC, ASSP or microcontroller architectures. Shorter development cycles, the adoption of advanced process technology by programmable logic device suppliers, and the economies of scale that programmable devices inevitably bring, all contribute to lower overall production system costs.
As key IP and solutions for in-vehicle networking mature and the performance potential of FPGA architectures increases, programmable logic devices will play an important role in overcoming some of the engineering challenges inherent in the development of in-vehicle electrical architectures.
Author: Kevin Tanaka
Global Automotive Marketing and Product Planning Manager
Email: [email protected]