Bringing 8051 microcontrollers to FPGAs as IP platforms

Designers have always faced severe time-to-market pressures when developing products for fast-moving markets such as consumer electronics and automotive. But now, these strict time requirements have shifted to many other areas, including embedded control and industrial design. Undoubtedly
, the most talked-about chip design trend in recent years has been the move to system-on-chip (SoC), which has been achieved through rapid advances in process technology and design methodologies. But SoC development is still slow and very sensitive to market changes. In addition, developing SoCs is inherently a costly and high-risk enterprise. Few companies have sufficient resources to afford the non-recurring engineering expenses (NRE) required to develop SoC products into mass production, and even those that do must carefully consider the opportunity to obtain a return on investment.
The desire to quickly bring products to market is very important in the industry. Every week of delay in product sales will result in lost revenue: for example, if the average selling price of a product is $1,500 and its manufacturer expects sales to rise to 100 units per week, a three-month design delay will result in more than $1 million in losses.
Therefore, designers look to field programmable gate arrays (FPGAs) as a flexible industrial design platform. This trend is even more evident in industrial wireless communication designs. In this application, application-specific standard products (ASSPs) were initially considered, followed by application-specific integrated circuits (ASICs). However, when time to market, implementation flexibility, and future obsolescence were considered, the design team decided to turn to FPGAs for the project implementation.

Moving into the Embedded Market
As might be expected, time-to-market pressures are not the only driver that has led designers to turn to programmable logic devices for value-added functionality in industrial designs. Today’s manufacturing processes are enabling a new generation of programmable logic devices that offer more and faster logic and faster I/O at lower price points. As a result, FPGAs are now available for embedded applications that, in the past, were only possible with ASICs or ASSPs due to performance reasons.
Today’s high-functioning FPGAs are no longer limited to introducing system glue logic, but can also serve as SoC platforms that industrial designers can easily modify to make changes, fix bugs, or create future derivative products as user needs evolve and the market evolves. Designers who previously chose semi-custom ASSPs no longer have to accept a less-than-ideal solution for their application, but can now build custom FPGA-based solutions faster than with ASICs, while adapting to changing market requirements.
Another reason for the increase in FPGA usage is the vastly increased number and range of IP blocks that can be programmed into the device, including standard functions such as the 8051 microcontroller that is widely used in industrial applications. These pre-verified and tested IP modules are optimized for programmable logic applications, allowing designers to quickly build systems and program them into FPGAs. IP cores are usually provided in the form of netlists or RTL resources, so designers can quickly use them without modification or configure them according to design requirements.
For example, Actel's Core8051 IP core is compatible with the 8051 instruction set, allowing designers to take advantage of their experience with existing microcontroller architectures and take advantage of the large amount of existing code and tools to further shorten the development cycle. Usually, these cores have additional features: For example, Core8051 has on-chip debugging capabilities, which can simplify system debugging when the core is deeply embedded, helping designers to launch products to the market faster.
IP platforms come into being
. When the annual production volume is less than 100,000 units, FPGAs can be an excellent platform that can meet the needs of many industrial and embedded control market segments. There are two main factors in the development of microcontroller-based SoCs, namely the number of components or peripherals that need to be integrated, and the integration of application software and dedicated drivers for the selected components. Ideally, designers would of course like to reduce development time by reducing the number of processes and components. In addition, they will also simplify the integration of application software. Using synthesizable or "soft" IP platforms within FPGAs is a modern solution to simplify the design process and shorten time to market. In the flowchart (Figure 1), we compare the key steps of building a microcontroller SoC using a large number of IP cores with the steps required to develop an FPGA design using an IP platform.

Figure 1. Comparison of the process of building an SoC based on IP and developing an FPGA.

The design concept of an IP platform is to integrate multiple components into a dedicated module. These component modules and platforms have been pre-integrated and pre-verified. Of course, the main problem with pre-built IP modules is that users may not want to integrate all the components and features of the platform. The solution to this problem is to make not only the component modules but also the key product features of these component modules configurable.
In fact, Actel's Core8051 is part of such a pre-verified, configurable platform, which is called Platform8051. In addition to the 8-bit Core8051 microcontroller, it also includes five other IP units: Core10/100, CoreSDLC, CoreI2C, CoreSPI, and Core16X50. (See sidebar "IP Core Resources in Platform8051") Designers can specify any configuration of these IP cores to implement a unique SoC design, while the time and expense required to develop an ASIC is only a fraction of the time.
In embedded control applications, the component cores included in Platform8051 are commonly used peripherals because they allow designers to implement key functions such as sensing, control, monitoring and communication. With these pre-verified units, designers can easily reuse IP without spending time repeatedly developing and integrating the same core into the platform. Using Platform8051, design teams can use valuable design and verification time to develop value-added application software and peripherals to make the final product more distinctive. [page]

Development Environment Support
Designers need development tools to create FPGAs and application code for the 8051. Actel's Libero design environment allows designers to simulate and synthesize the complete integrated RTL, then simulate and analyze the design at the netlist level, and perform place-and-route using Actel's Designer software. Finally, the FPGA is programmed using Actel's FlashPRO or Silicon Sculptor programmers.
For microcontroller programming and debugging, Actel has partnered with First Silicon Solutions (FS2) and Keil Software. The FS2 System Analyzer is designed to support in-circuit debugging of application software using the special features and integrated peripherals of Actel's Core8051 microcontrollers. An extension of the FS2 On-Chip Instrumentation (OCI)—a dedicated "silicon hook"—will be integrated into the Core8051 MCU, allowing FS2 to offer advanced and powerful debugging tools. The μVision Integrated Development Environment (IDE) from Keil combines project management, source code editing, and program debugging into a powerful development environment. The μVision debugger is powerful and comprehensive, allowing software developers to fully simulate the target program on a PC.

Figure 2, Platform8051 platform architecture.

In addition to software development tools, Actel also provides the Platform8051 development kit, shown in Figure 2, which enables designers to observe the operation of the Actel core and quickly and efficiently create and simulate derivative designs. This kit can significantly reduce system verification time. It also includes a reprogrammable ProASICPLUS FPGA, the previously mentioned web server design programmed on the device, web server code examples, all corresponding cables, FS2 System Analyzer and Keil μVision evaluation software package, and optional FlashPRO Lite programmer. Influencing designer
decisions
The advantages of FPGAs are obvious through the platform IP approach, such as the recent design of a modular wireless industrial network for high-noise factory environments and manufacturing automation. The design team initially wanted to use discrete ASSPs, but soon found that this approach could not achieve the right combination of functions while meeting size and power requirements.
In other words, designers can only choose between ASICs and FPGAs. A cost analysis study for the project showed that for the projected module volumes, the cost of ASIC and FPGA devices was similar; however, FPGAs did not require any NRE investment. Therefore, the design team decided to use the FPGA solution.
When the design team considered the IP required for the project, they realized that FPGAs had greater advantages in terms of cost and time to market. Since the FPGA vendor already had most of the IP required for the project, the design team only had to develop a small amount of unique IP. Using pre-developed and verified IP can shorten the design cycle by up to six months, allowing the design team to bring products to market faster and in a shorter time. And the shorter time to market has tangible financial results. Because the product has captured a larger market share than expected, sales and profits have increased significantly.
At the same time, the design team can customize the module according to the application and specific needs of larger users, and perform field product upgrades without replacing the entire circuit board, which only requires reprogramming the FPGA. This can reduce the user's total cost of ownership, increase the perceived value of the product, and expand market demand.
The time-to-market pressure faced by industrial designers has never been greater. Whether designing network interfaces, motor controllers, logic controllers, communication systems, or any of the hundreds of industrial applications, FPGAs combined with a wide variety of available IP are becoming the preferred solution for industrial design. FPGAs offer advantages over ASSP and ASIC solutions in terms of time to market, flexibility of implementation, and future product obsolescence. In addition, because many industrial applications never reach high volume, FPGAs often offer significant cost savings over traditional ASIC solutions. The ability to quickly program functions and test them in an application product, then reprogram as functional specifications change, is naturally attractive to industrial engineers. These features, combined with current advances in performance, size, and price, allow industrial designers to quickly bring products to market using familiar standards and maximize product retention and sales revenue.

Sidebar: IP Core Resources in Platform8051
The Core8051 is a full-featured single-cycle 8-bit microcontroller unit that is compatible with the popular ASM51 instruction code and can operate at frequencies above 40 MHz. Figure 2 shows a block diagram illustrating the features of this core. Core10/100 is an Ethernet media access controller that connects to a local area network at a data rate of 10 or 100 Mb/s. It has a media independent interface (MII) for physical connection and can implement the carrier sense multiple access with collision detection (CSMA/CD) algorithm according to the IEEE802.3 standard. These two cores form the network server design used in the Platform8051 development kit.
CoreSDLC is a high-speed synchronous serial data link controller that operates similarly to the Intel 80C152 global serial channel working in SDLC mode under CPU control. This core is used as a custom serial interface for embedded applications.

Figure a, Core8051 block diagram.

CoreI2C is a bus controller that provides a two-wire serial interface and supports 100 kb/s and 400 kb/s data transmission of the Philips I2C standard. This daisy chain bus standard is adopted by many consumer electronics and embedded applications.
CoreSPI is a serial peripheral interface that enables synchronous serial data transmission between 8051 and peripheral devices. SPI is a point-to-point bus standard used in various embedded applications.
The Core16X50 is a Universal Asynchronous Receiver/Transmitter (UART) with or without FIFO support, software compatible with the Texas Instruments 16550 device, and adds additional serial channels to the Core8051. It can also be used as a serial or modem interface.