According to Renesas, these SoCs are expected to play a crucial role in defining the next-generation electrical/electronic (E/E) architecture in automotive systems.
SoCs for automotive gateways need to be able to provide both high levels of performance to implement new applications such as cloud services, and low power consumption when they are not in use. They also need to deliver fast CAN response to support instant start-up.
In addition, these SoCs need to provide power-efficient communication technology that enables network functions as a gateway using limited power and security technology to enable safe communication outside the vehicle.
To address these requirements, Renesas has developed an architecture that: dynamically changes the circuit operation timing to match the vehicle conditions with optimised performance and power consumption, provides fast start-up technology by partitioning and powering essential programmes only, delivers a network accelerator that achieves a power efficiency of 10 gigabits per second/watt (Gbps/W), and includes security technology that is able to prevent communication interference by recognising and protecting vital in-vehicle communication related to vehicle control.
These various achievements were announced at the International Solid-State Circuits Conference 2023 (ISSCC 2023), currently being held in San Francisco, California.
Further details
Communication gateway SoCs need to deliver processing performance exceeding 30,000 Dhrystone million instructions per second (DMIPS) when running, while also keeping standby power consumption to 2 mW or less in order to maintain battery life.
Typically, high-performance SoCs also have high power consumption in standby mode, while low-power SoCs with small standby power consumption have performance issues.
To resolve this trade-off, Renesas has combined in a single chip with a high-performance application system and a control system that’s optimised for ultralow standby power consumption. The new architecture controls the power supplies of these two subsystems and changes the timing of circuit operation to achieve an optimal balance between performance and power efficiency. This results in higher performance during operation and lower power consumption during standby.
Because communication gateway SoCs manage processing of critical functions related to vehicle control, they must be able to respond to CAN within 50 milliseconds (msec.) of start-up. However, if the SoC uses a process that does not support embedded flash memory, the start-up programme must be encrypted and stored in external flash memory.
This means that it takes additional time to load programme data and decrypt it.
To solve this, Renesas has developed technology that splits the programme into sections and initially loads and decrypts only an essential portion for start-up, while continuing to load the rest of the programme in parallel. This enables a fast response to CAN (50ms or less), even when using external flash memory.
To allow air cooling and heat dissipation for electronic control units (ECUs), communication gateway SoCs must keep power consumption to 7W or less. Since computing processing performance of 30,000 DMIPS or higher requires approximately 6W of power, only around 1W can be used for network processing. This presents a challenge as the total communication of 10 Gbps must be achieved using 1W of power, with a processing efficiency of only around 3Gbps/W when processed by the CPU.
To work around this issue, Renesas offloaded processing from the CPU to a custom network accelerator, achieving higher efficiency at 9.4 Gbps/W. Additionally, Renesas boosted efficiency to 11.5 Gbps/W by switching the routing method from a conventional TCAM approach to a hash table in SRAM.
Finally, a communication gateway SoC performs a mixed set of tasks such as data processing related to vehicle control that requires a high level of reliability, and large amounts of random data communication with cloud services and others.
Since vehicle control is essential to ensuring safety, protecting and separating mission-critical data is important. However, despite the differences in data types, all data is transmitted through the same in-vehicle network, leading to physical intersections and raising security issues.
To address this challenge, Renesas has developed security technology that analyses incoming packets to the SoC. It determines whether or not they contain essential data and then assigns them to different pathways and control functions within the network accelerator. This prevents interference with data that requires high reliability and safeguards in-vehicle data communication from a variety of security threats.
These four technologies have been incorporated into Renesas’ R-Car S4 vehicle communication gateway SoC.
With the latest R-Car S4, developers will be able to accelerate advances in E/E architectures, implement secure connection with cloud services, and ensure safe and reliable vehicle control at the same time.
