Hardware IP vendors, such as ARM, and silicon providers that provide turnkey ASIC solutions, such as Open-Silicon, are collaborating on IoT SoC design. The result is SoC solutions that meet the performance, power, price and time-to-market constraints of the quickly evolving IoT Edge, Cloud and Gateway markets.
By Pradeep Sukumaran, Open-Silicon Inc.
The Internet of Things (IoT) means different things to different people and it becomes a hotly debated topic when it comes to definitions, scope and how it impacts the future of almost everything. The semiconductor ecosystem, however, has a much simpler view, which is to categorize the many types of IoT SoCs into three simple segments, Edge SoCs, Gateway SoCs and Cloud SoCs. Through such SoC categorization, semiconductor companies can more easily devise strategies and offerings to address new markets and customers. Aiding this are two key players in the ecosystem, the hardware IP vendors who are now moving up the value chain, and the silicon providers who develop turnkey solutions. Both of these players have started to collaborate on critical aspects of SoC design and are helping make custom SoCs mainstream for IoT designs As a result, IoT SoCs are adapting nicely to performance, power, price and, most importantly, time-to-market demands.
Figure 1: SoC classifications in IoT, as seen by the semiconductor ecosystem.
Edge and Gateway SoCs are used in IoT edge nodes and gateway devices respectively, whereas Cloud SoCs are used in networking, telecommunications, storage and computing hardware. Examples on cloud side include, among many others, LTE base stations, satellite modems, enterprise storage devices, networking switches and HPCs. Turnkey ASIC vendors have been doing design and silicon manufacturing for cloud customers for more than a decade. Over the last 4 years, these companies are also seeing traction in the custom Edge SoC market driven by the proliferation of edge devices.
For custom SoCs, be it either edge, gateway or cloud SoCs, a key ingredient is mature and silicon-proven HW IPs. ARM’s IP portfolio, for example, covers a huge spectrum of applications with its CPUs, GPUs, media processing engines, interface IPs, system IPs and even a Bluetooth radio IP. IPs such as these are predominantly used in microprocessor and microcontroller-based edge and gateway devices. However, they are now gaining popularity in cloud SoCs used in storage, networking and the newer micro-server market.
In the increasingly tighter time-to-market scenario, IP vendors are moving up the value chain by providing IP subsystems and even a standard or reference for SoC architecture. IP subsystems and reference design specification help ease SoC design and verification. It abstracts few complexities during integration, allowing developers to reduce time to tape-out, by at least a few weeks.
A good example of a reference design specification is ARM’s Server Base System Architecture (SBSA). The target markets include private and public clouds, web serving, web caching, web search and a few commercial HPC loads. SBSA is a platform specification for ARMv8-A based 64-bit servers that helps standardize the hardware and software elements and, at the same time, spurs rapid innovation by allowing companies to focus on the differentiating IPs. Cloud technology is also being democratized by collaborations like the Facebook-initiated Open Compute Project, reference specifications like SBSA, and industry consortiums like CCIX, which is working on a specification for cache coherent interconnect for processors and accelerators. These could make the cloud side an interesting and growing market for more custom SoCs.
IP subsystems from ARM include CPU subsystems (ex: big.LITTLE technology for smartphones, IoT Subsystem), TrustZone Cryptocell, Cordio Radio IP etc. The IoT subsystem includes a Cortex-M CPU, AHB bus, and a few peripherals – all of them pre-integrated and verified, but still allowing for expansions on the AHB/APB bus. The TrustZone Cryptocell is a security subsystem that wraps key crypto blocks with a simple to use interface. The Cordio Radio IP is a Bluetooth 4.2 IP subsystem that includes a controller, PHY and RF along with BT software.
Enabling consolidation of critical features, like security within the CPU, the recently announced ARMv8-M architecture is a good step forward in IoT edge device designs. Combined with the AMBA 5 AHB5 interconnect and TrustZone CryptoCell subsystem, the next generation Cortex-M CPUs will further reduce the complexity of designing secure embedded solutions.
With these advances from IP vendors, it is important that the rest of the ecosystem reciprocates by also moving up the value chain and offering more to customers. Turnkey SoC providers can offer SoC platforms that further lower risk and reduce time-to-market. An example of an IoT Edge SoC platform that does this is one developed by Open-Silicon. The platform, employing ARM IP, is implemented on an FPGA and integrates the ARM Cortex-M4 subsystem with TrustZone Cryptocell and Cordio BT IP. ARM’s mbed OS is the operating system used, and this allows easy integration of IoT-specific protocols. Such IP subsystems help to jumpstart and create SoC platforms, which in turn enables faster silicon tape-out.
Figure 2: Open-Silicon’s IoT SoC platform, which gives custom SoC designs for edge devices a jumpstart.
In the application class of CPUs, ARM Cortex-A9 is a workhorse and is widely used in a variety of designs, starting with smartphone SoCs a few years ago, to set-top boxes, modems etc. It is also a good choice as an application CPU for gateway SoCs. An SoC with multi-core Cortex-A9 processors, special packet processing accelerators and high and low speed interfaces can be an ideal choice as the main SoC in an IoT gateway product. Open-Silicon has designed such an SoC in a TSMC 40nm LP process with quad Cortex-A9, running up to 1 GHz, which is one of its kind in the market. This SoC is currently in mass production and comes with a reference design based on Linux LTS OS and support for appropriate wireless communication modules like Zigbee, wireless-HART, Bluetooth, and LPWAN technologies like LoRa.
Figure 3: Open-Silicon’s IoT Gateway SoC Block Diagram and HW Reference Board with Linux OS.
Open-Silicon’s work on ARM-based SoCs are done as part of its ARM Technology Center of Excellence (TCoE), a focused initiative aimed at keeping in step with ARM’s growing IP portfolio and identifying new areas of collaboration. It covers all key aspects of SoC design, including logic and physical architecture, design and verification, FPGA prototyping, CPU hardening and embedded software. As a part of the ARM TCoE, Open-Silicon has completed several custom SoCs for cloud customers and has successfully developed IoT Gateway SoC, including complete reference software. With new initiatives like the ARM Approved Design Partner Program, partners like Open-Silicon can be a turnkey solution provider for custom SoCs for IoT edge devices.
Figure 4: Technology Center of Excellence at Open-Silicon, which focusses on ARM technology. This has been successfully leveraged across multiple SoC designs.
About the author:
Pradeep Sukumaran is a Senior Solutions Architect at Open-Silicon. He has over 15 years of experience in engineering and management in the embedded hardware and software space. He specializes in technical solutions and serves on the company’s strategy team where he works closely with customers and others in the IoT SoC ecosystem.