Renesas Electronics ("Renesas") launched the RZ/A1 Group in June—the first wave of its emerging RZ Family of microprocessors (MPUs), built around the Arm Cortex™-A9 CPU. This initial group shall comprise 15 models, divided into three package types: RZ/A1H, RZ/A1M, and RZ/A1L. Equipped with large-capacity internal RAM, these new MPUs enable DRAM-less solutions characterized by high performance and low system costs. Renesas is already shipping samples of ten models of types RZ/A1H and RZ/A1L, and is targeting sales of 1 million units by June 2015. In this feature we look at the RZ Family's development background and its promise for the future. We also look at the implications for the future of SH microprocessors and microcontrollers, a topic that concerns many of our readers.
A New High-End Family
Today's world is full of MCU and MPU systems that interact with us—in industrial machines, household appliances, medical monitors, office automation equipment, vending machines, audio equipment, and much more. And we are learning to interact in new ways—such as with the touches, flicks, and swipes brought to us by the smartphone and its relatives. For these reasons, the demand for more effective HMIs (human-machine interfaces) is always with us. At the same time, manufacturers are also seeking turnkey solutions that can reduce costs and turn-around times.
The two most important components for meeting these demands are: high-performance MPUs, and good software. While it is true that high-performance customized chips may also be a solution in some cases, MCUs or MPUs are the way to go in markets characterized by relatively small production runs of many different product variations.
This is one of the major reasons for the unfolding of a new Renesas MPU family based on the Arm CPU. This new RZ Family stands at the top of a deep product line that includes the RL78 next-generation 16-bit microcontrollers (MCUs), the 32-bit middle-range RX MCUs, and the new RH850 automotive MCUs.
"When designing and building MCUs and MPUs that offer a combination of control functions, computing power, and connectivity, we find that for some applications our own cores work best, while for other applications we do better with Arm cores. So we make both types of products available to our customers, and I think that's very helpful for them." (Hiroshi Yamamoto)
The RZ Family is intended for use in high-end products requiring strong connectivity, for products utilizing big data or fast data streams, and for other such high-performance applications. These target products also tend to require large software, which in turn must be backed up by a powerful support ecosystem.
With the addition of the new family, Renesas now offers a larger range of core types to choose from. "The most important thing, however, is not the number of core types available; rather, the key issue is in finding the core that best meets the user's needs. After all, changing the core type will not make much difference if you keep the same peripherals. And remember that the development environment, the compiler, and the OS have more impact on development work than the core itself. Customers should rest assured our all of our MCUs and MPUs, regardless of core type, come with deep development support and deliver highly reliable performance." (Yoshio Sato)
About 800 Million Arm-Core Products Shipped Over the Last Decade
The Renesas/Arm collaboration is now in its tenth year. It began in 2003, when the two companied formed a strategic partnership and initiated joint development of an Arm-11 Multichip Processor. The technology emerging from that collaboration is the basis for our current joint development of the Cortex-A9 microprocessor.
About 800 million of the ASICs and ASSPs coming from Renesas over the past decade have contained Arm cores. "We also have a strong background in chips for the mobile market, so people here were pretty open to the idea of tackling the development of the new RZ Family. We were already sharing information with Arm, and Arm-core support teams and design groups were already in place." (Satoshi Chiba)
Readers should not get the impression that Renesas cores and Arm cores are competing in a contest. Renesas simply believes that it can present customers with a wider range of choices by offering both types of cores in its MCU and MPU families. "Some people ask us if we're discontinuing our SH products. The answer is no. We will continue producing our SH line, and our other cores as well." (Hiroshi Yamamoto)
Why did Renesas choose to go with the Cortex-A9, given that the Cortex-M is already in wide use in today's products? "To get the same level of performance as an SH-2A, you need a superscalar design. And the Cortex-A9 also supports NEON technology, making it a more attractive choice for graphics and audio products." (Yoshio Sato) In addition, Renesas already has experience with the Cortex-A9 market, and there is a mature support ecosystem already in place.
"It's true that the Cortex-A9 takes up more space than the SH-2A core. But Renesas has developed powerful mounting technologies, and we felt we could bring to the Cortex-A9 the same type of low-power small-footprint implementations that we have achieved with our SH-2A cores." (Yutaka Oshima)
Large Internal SRAM Solves Many Problems
One of the most significant features of the RZ Family is the presence of up to 10 MB of internal SRAM—more than available from any other MCU or MPU on the market today (as of June 13, 2013, according to research by Renesas). In particular, the RZ/A1H and RZ/A1L come with 10 MB and 3 MB respectively (samples of both are already shipping), while the RZ/A1M will have 5 MB. "In recent years, customers have told us that they were seeking solutions to various issues caused by use of external DRAM. So we directed our development work accordingly." (Yoshio Sato)
The increasing use of external DRAM is associated with numerous issues that drive the costs up—higher power use, more noise, more difficulties in board design, the need to secure sufficient bandwidth for the bus to external RAM, and the need for dedicated power. In addition, the general-purpose, mid-speed, mid-capacity DRAM that is most suited to embedded systems is also the type of DRAM most subject to price fluctuations and supply shortages.
"Large users have the power to negotiate with memory manufacturers, but smaller users must always worry about interruptions in supply. The instability of the supply adversely impacts these users' production processes, and can put the survival of their business at risk." (Yoshio Sato) Because memory devices are a crucial part of every system, a reliable supply is extremely important to most users. "After considering how best to help user achieve anxiety-free production development, we set our sights on MPUs with very large RAM capacities. Many single-chip MCUs or MPUs come with only about 512 KB of internal RAM, whereas external DDR products typically have 1 GB or more. For many products, an internal RAM of around 3 MB to 5 MB would be about right—but this is more than you could find on a single-chip MCU or MPU." (Yoshio Sato)
"After considering how best to help user achieve anxiety-free production development, we set our sights on MPUs with very large RAM capacities. Many single-chip MCUs or MPUs come with only about 512 KB of internal RAM, whereas external DDR products typically have 1 GB or more. For many products, an internal RAM of around 3 MB to 5 MB would be about right—but this is more than you could find on a single-chip MCU or MPU." (Yoshio Sato)
A Treasury of Peripheral Assets
The RZ/A1H and /A1M include the Renesas OpenVG graphics engine. "These RZ MPUs deliver between 2 and 10 times the performance of the SH7269, which also includes this engine." (Yoshio Sato) With the SH7269, you need sufficient bus width to access external memory—and this impedes the performance. In contrast, the RZ Family uses a multilayer/multibank AXI bus structure, eliminating all worries about bus bandwidth. Reports indicate that this approach boosts performance—relative to external-RAM designs—by a factor of 1.5 or higher. So while the RZ/A1 actually runs at 400 MHz, it delivers the performance you'd expect from a 600-MHz MPU.
But changing to a different processor core won't make a great difference if you keep using the same peripherals. "Renesas has a large number of peripheral assets. When designing the RZ Family, we chose peripherals that were most suited to the design. We also listened carefully to our top customers, and to our sales force." (Yutaka Oshima) Top customers included manufacturers of car audio systems, car panels and displays, door phones, and arcade games.
RZ evaluation boards are already available, and additional models are forthcoming. "The evaluation boards we produce here at Renesas are full-featured, but we are expecting that our partners will also produce less ornate, more economical versions." (Yoshio Sato) Prices for these third-party boards are expected to range from under 10,000 yen up to perhaps 40,000 or 50,000 yen. There is also some thought about producing boards based on the concept of the Arm-based Raspberry Pi single-board computer.
CMSIS-RTOS RTS: Originally for Cortex-M, Now Also for Cortex-A9
Real-time operating systems occupy an important place in embedded-systems design. "When we asked around about RTOS use, a number of different RTOS names came up, and we also noticed that there was some regional variation in the responses." (Yoshio Sato)
But overall, Renesas developers seem to share a high opinion of the CMSIS-RTOS RTX approach toward realizing a common API. "We worked out the CMSIS-RTOS RTX specifications with Arm, and then evaluated the ported code." (Yasu Kutsuma)
Readers should note that the CMSIS-RTOS RTX is a royalty-free (BSD-licensed) real-time OS, provided as source code. It comes bundled with the Arm Development Studio (DS-5™) reference-software development suite, together with the DS-5 Starter Kit for the RZ/A1.
The CMSIS-RTOS RTX was originally designed for Cortex-M cores. Now adapted for use with the RZ Family and its Cortex-A9 core, it offers a new solution for users unable to get the performance they need from the Cortex-M.
The development ecosystem is already up and running, with 41 partners participating. "Renesas has been associated with these partners for many years, and they're a vital asset for us." (Yoshi Sato) Support activities have already started, and the number of partners is expected to grow. Renesas is planning a strong joint marketing approach, which will include exhibiting our products at partners' events, and inviting partners to seminars we hold for our marketing agents.
Renesas Solutions, the company in charge of supporting practical applications, "is working together with partners and tool vendors to achieve true software solutions." (Yasu Kutsuma) The company is currently working with customers to build software platforms for car audio, graphics, and communication applications. "We manage software worldwide, in collaboration with our partners, in a way that helps reduce their product-development turn-around time. We are very responsive to our partners' needs." (Yasu Kutsuma)
The RZ Family is intended for applications that use anywhere from 512 KB to 10 MB of RAM. A 10 MB model, for example, could be used to build an HMI system with a WXGA display (1280×768), with no need for external DRAM. "The RZ/A1H can pack a frame buffer, real-time OS, and middleware. It can process and store all of the data for the HMI display—in accordance with runtime command codes, 2D graphics processes, and so on—without any need for external memory." (Yoshio Sato)
The RZ Family MPUs also supports implementation of security cameras, 2D barcode readers, and other such camera applications. And of course they are suitable for implementing smart-meter gateways and data communications modules, and in general for a wide range of applications that can run within the 10 MB memory limit, regardless of whether or not imaging and display features are involved. "The RZ/A1 models include a standard interface, so they can easily be used as simple, general-purpose MPUs." (Yoshio Sato)
Because Renesas already leads the industry in the area of high-speed flash MCUs, it is reasonable to ask about the relationship, if any, between those MCUs and the new RZ Family. "Renesas has a high share of the market for MCUs that run at about 200 MHz and utilize high-speed flash memory processes. But there are many cases where the user wants a powerful HMI that simply cannot be implemented at 200 MHz. At present, these users often turn to SoC implementations to get the HMI they need. These are the users who we developed the RZ Family for; we used leading-edge processes to develop a RAM-based MPU family that could implement these HMIs internally." (Hiroshi Yamamoto)
The RZ Family is an addition to the Renesas lineup, not a replacement. Production of flash MCUs will continue without change.
The Cortex-A9 as an Everyday Product
Thanks to the widespread use of Arm cores, the barriers to production of MCU-based systems have largely disappeared. As a result, most semiconductor vendors are now offering MCU products. "Renesas has a high share of the MCU market, and we sell a wide range of products. But at the high end, our SH4 and MIPS cores are typically used in ASSPs and SoCs, rather than in more general-purpose products. The new Arm-based RZ Family should serve a wide group of potential customers looking to use high-performance MPUs for a wide range of product types." (Satoshi Chiba)
The new family now makes it easy to build systems that incorporate the power of the high-performance Cortex-A9. "At present, there are no generalized MCU or MPU products that make use of the Cortex-A9. The RZ Family presents the Cortex-A9 in the form of an MPU chip that can be easily used to implement everyday systems." (Yoshio Sato)
Mr. Sato concludes the interview with the following words. "We plan to make these products widely available—so that they can be readily purchased even by walk-in shoppers in the Akihabara district, for example. These products will be available to both low-volume and high-volume users, and application notes will be available for download from our website. Even students and hobbyists will be able to use these chips, by taking advantage of low-cost evaluation and development boards that will become available. We're even thinking of having collaboration projects with hobbyist magazines."
So we can now foresee that the emerging RZ Family will be the first microprocessors to make Cortex-A9 capabilities available for generalized day-to-day use. We sense that this new approach has the potential to deliver a paradigm shift. It may change the way we think about and use the embedded systems that are all around us.