Electronic Design

Digital ICs: Microcontrollers & Microprocessors

Embedded Processors Mean Variety
This year, more new processor variants than ever will be released. But don't expect any really new processor architectures, except AMD's (www.amd.com) 64-bit alternative to Intel's (www.intel.com) very-long-instruction-word-based Itanium. Processor variety is primarily due to the plethora of embedded applications with a wide range of power, performance, and feature requirements.

At the high end, processors like the Pentium 4, Athlon, Sparc, and Itanium will continue their innumerable refinements with performance as their ultimate goal. The remaining spectrum is split between 32-bit designs that can support sophisticated operating systems and 8- to 16-bit microcontrollers surrounded by an ever-increasing number of peripheral controllers. Java accelerators will become more prevalent in 32-bit processors this year.


Higher levels of integration are coming. The complexity of processors in system-on-a-chip (SoC) designs will continue to increase as process technologies continue to add more transistors on ever-decreasing dies. Improved software design tools make high integration and low turnaround time practical. Soft processor architectures will let designers tightly integrate new instructions and registers with on-chip peripherals for more efficient operation.


Microcontrollers rock. The 8- and 16-bit microcontrollers will continue to make up a major percentage of processor shipments. Their low price, ease of development, and variety of custom interfaces from analog to CAN let them be more cost-effective solutions than 32-bit embedded processors. Watch out for multichip solutions. Look for microcontrollers in network and Internet applications. TCP/IP support for almost every microcontroller is available off the shelf. Also watch out for multichip solutions. A pair of microcontrollers can often run rings around a single 32-bit processor for many applications.


VLIW is here to stay. VLIW processors will hit highs and lows, and Intel's Itanium family will continue its push into the enterprise. Ongoing software migration and optimizing compilers will make IA-32 compatibility less important. Expect stiff competition from Sun's (www.sun.com) UltraSparc III line. The UltraSparc IIIi fills in the low end where Itanium dares not go. RISC and CISC will not be displaced by VLIW.

Look for a lot of action in specialized VLIW processors, especially multimedia and communications support. VLIW may displace or be incorporated into DSP architectures for many applications.


The 32-bit embedded processor will be the platform of choice for most embedded designs. SoC technology allows developers to bring more processing power to bear. The 32-bit processors also support a wide range of sophisticated operating systems like Linux. This is important as more designs take advantage of memory management units and large memories. Shrinking die sizes and lower costs will put pressure on 16-bit microcontrollers, especially where software development costs are more of an issue than processor cost or performance.

See associated timeline.

The Pentium, Athlon, MIPS, UltraSparc III, and PowerPC have all reached the 1-GHz bar. The Itanium will reach the bar this year. Desktop and enterprise platforms will push clock speeds to their limits, which is well above a gigahertz this year. Look to other embedded processors to push this mark too, as process technologies permit higher performance while keeping power and heat low.


Chips to cores: processor architectures will keep their march from standalone devices to SoC-integrated cores. Most of these will be for desktop PCs and servers. Few processor architectures will remain as standalone chips. Even fewer will be used in embedded applications as standard and custom SoCs are employed in more applications.


The trend toward sophisticated processor designs will continue. Implementation techniques like superscalar, superpipelining, and out-of-order execution will be added to embedded processors to meet more demanding performance requirements. RISC and CISC architectures will need these features to keep ahead of VLIW processors. Luckily, higher chip densities will support the additional hardware needed for these implementations.


Look for lower voltages and better power conservation. Transmeta's (www.transmeta.com) Crusoe lit a fire under the competition. Software-based power management is more critical than ever and not limited to battery-operated environments. Designers will continue dropping operating voltages to keep chips from turning into heating elements. The demand for server racks full of processors as well as portable devices will push power-conservative processor design.


Asymmetric multiprocessor solutions will continue to gain ground in the embedded space. DSP/CPU combinations provide analog and process control designers with a one-two punch, permitting parts of applications to be hosted by the most appropriate subsystem. Network processors will have more processors on-chip, minimizing interprocessor communication delays and improving system performance.


Pure Java processors fill a niche. But watch for most embedded processors to have a Java accelerator option as Java applications become even more important in the embedded space. Almost every embedded processor architecture has one or more Java accelerator options already.

Java is becoming more important in the cell phone, PDA, and gateway space were Java acceleration can be a key feature. The real-time Java specification will also spur the growth of Java-enabled processors.

See associated timeline.

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