Semiconductor giant ARM yesterday unveiled the Cortex-A76AE, a microarchitecture CPU designed for use in autonomous vehicles. The UK-based Softbank subsidiary hailed the new chip as the world’s first autonomous-class processor with integrated safety features.
The A76AE follows on the Cortex-A76, which was released three months ago to succeed ARM’s Cortex-A73 and A75 10nm processors. The A76 processors are built on a 7nm transistor scale with a clock speed of 3GHz — the cutting edge of semiconductor design.
There’s irony hidden in the premise of autonomous cars, according to Lakshmi Mandyam, VP of the Automotive Embedded & Automotive Line of Business at ARM. On one hand, self-driving cars are supposed to significantly reduce, or perhaps even altogether eliminate, crashes and auto accidents due to driver error. But on the flip side, the SoCs and software systems behind self-driving vehicles may not themselves be safe enough to handle autonomy on real roads—particularly at Level 5, where vehicles require no steering wheel or driver intervention.
Arm’s proposed solution to this is the new Cortex-A76AE processor, an autonomous-class processor with integrated features targeted at ensuring that the systems inside autonomous vehicles perform safely and efficiently. For example, it includes systematic flows and development in support of the ISO 26262 and IEC 61508 standards.
“We believe that the challenge that the entire automotive ecosystem faces in terms of security needs to be addressed,” Mandyam said on a media call discussing ARM’s strategy around the A76AE (the AE stands for “Automotive Enhanced”). “And so we’re doing this to prioritize and simplify safety without compromising security performance and power efficiency—both for general purpose automotive applications and autonomous cars processing.”
ARM’s Performance and Safety
The key to the A76AE’s performance, according to Arm, is the integration of Split-Lock technology, which allows the processor to be booted into either a twin performance mode or a dual-redundant mode. Split-Lock itself is not new; Arm included the technology in its Cortex R5 processor released back in 2011. But Mandyam explained that this is the first time Split-Lock has appeared in an application processor.
“We have developed a product that allows you to dynamically decide if you’re deploying cores that are locked or split for performance at boot up,” she said. “…We like to think of [Split-Lock] as being split for performance and locked for safety. And again, this could be on a single SoC.”
She explained that in vehicle infotainment systems, for example, there is a need for many processor cores running many different applications with many different operating systems—all having to do so at a high-performance level. “For these kinds of applications, ASIL-B capability is typically enough. But when you look at more safety critical applications, like an autonomous vehicle controller as an example, you need to have processors that are locked together to be able to achieve higher levels of safety,” Mandyam said.
The Split-Lock feature enables that sort of flexibility for engineers. When in locked mode, two cores can be running the same instructions and each operation is checked, resulting in a high level of safety without additional software complexity. “So this is important not just for automotive, but for industrial, robotics, aerospace—any application where safety is paramount and you need to be sure of how the machine is going to behave for safety conditions,” Mandyam added.
ARM’s Other Autonomous Vehicle Chips
ARM has incorporated autonomous-class features into its other chip designs. Two years ago the company introduced Cortex-R52, a chip optimized for hard real-time and safety-critical applications. Cortex-R52 delivers up to 35 percent higher single core performance and 14 times faster context switching over its predecessor. The chip’s Armv8-R architecture also supports safety critical code independence, so changes to one module do not require wholesale recertification for all the software, thus saving time and effort.
Last year Arm announced its Mali-C71 Image Signal Processor (ISP) series, designed for the Advanced Driver Assistance Systems (ADAS) in vehicles. Mali-C71 was developed with Apical, the UK computer vision and imaging processor company Arm acquired in 2016.
Softbank’s Autonomous Vehicle Ambitions
Arm parent company Softbank has been digging into the autonomous vehicle field for years. After its 2016 acquisition of Arm for £24 billion (US$31 billion), the Japanese tech giant pumped billions of dollars into autonomous vehicle startups, including intelligent camera provider Nauto, Israeli LiDar manufacturer InnoViz, mapping platform Mapbox, and autonomous vehicle company GM Cruise.
Softbank is also expanding its presence in the ride-hailing industry with investments into Uber, Didi Chuxing, and Grab — industry leaders in Silicon Valley, China and Southeast Asia respectively. Softbank also took a US$4 billion stake in GPU & AI chip manufacturer Nvidia, the US chip company dominating the autonomous vehicle computing market with products like its Drive PX2 supercomputer and autonomous car development platform.