Improving data bandwidth using 32-bit processors in embedded applications Casper Chang Field Applications Engineer IDT Asia Ltd.

Abstract To make a right decision on 32-bit processor, you have to, first and foremost, look for a manufacturer which is able to offer a wide range of software-compatible, price/performance choices. Its product lines should include high-performance microprocessors, complementary system controllers and integrated controllers to give you a one-stop shop solution. After all they must be able to use in an assortment of embedded communications applications, including internetworking, multimedia, datacom and telecom products. Today’s microprocessors should be based on the MIPS instruction-set, which deliver better price/performance. A comprehensive tools support for the microprocessors is also of great importance. Remember, a well-established manufacturer is, more likely, able to offer a wider range of choices to system designers, giving them extra flexibility in system design. Today’s 133-MHz processors should be able to provide 175Dhrystone MIPS performance and 67 million multiply-accumulate operations per second (MACs/sec). Other key elements to look for include its capability of implementing a large cache memory and a flexible 64-bit-compatible memory management unit (MMU) with a full, 32-page translation lookaside buffer (TLB) for fast virtual-to-physical address decoding. Also go for the one with the bus interface that is programmable for 8-, 16- and 32-bit-wide Memory and I/O regions. Where a support device is concern, a 32-bit RISC-based microprocessor is an obvious choice, such as IDT’s RISController. For instance, its RC32134 provides a glueless interface from the RC32364 to local DRAM, boot ROM and I/ O devices. Users should also consider if they need to expand the I/O capabilities of its system. If yes, go for a system controller that serves a 32-bit, 33-MHz PCI bridge. The last but no the least, check if your most commonly used peripherals, such as a UART, DMA channels, timers and an interrupt controller.

Introduction To make a right decision on 32-bit processor to be able to be used in an assortment of embedded communication applications, including internetworking, multimedia, datacom and telecom products. You have to, first and foremost, look for a

manufacturer which is able to offer a wide range of softwarecompatible, price/performance choices. Its product lines should include High-performance Microprocessors, complementary System Controllers and Integrated Controllers to give you a one-stop shop solution. You can choose a microprocessor from blew directions:

1. Compatible Architecture It is a displeasure experience in spending more time to study different microprocessors’ architecture and learning how to use development tool while features of used processor can’t reach the requirements what you need in upcoming project. It’s is also a challenge to engineers to design broad, flexible and costsensitive products in shorter time to satiate requirement of timeto-market. So, engineers need a microprocessor of lower entry barrier and Compatible Architecture. Lower entry barrier architecture(friendly architecture) gives engineers need not to spend much more time in processors’ studying of hardware and software. Compatible Architecture is an idea which you have much better choices from regular to powerful processors are on the basis of similar architecture to implement your application. You need not to suffer impacts of changing processor. For instance, well-known processor of MIPS’ architecture, normally is a standardized, open and friendly architecture of featuring Integer CPU Core, Coprocessor, Instruction Cache, Data Cache and Bus interface(Fig.1). Engineers will be familiar in MIPS’ processor in a shorter time. Also, MIPS processor ISA(Instruction Set Architecture) has been extended in a backward compatible fashion(Fig.2), each new architecture level(or version) includes the former levels. The practical result is that a processor implement MIPS IV is also able to run MIPS I, MIPS II, or MIPS III user-mode binary programs without change. Vice versa, it’s not difficult to migrate program ran on MIPS I to MIPS II with minor modify. Further, it means that you will have two ways to improve or upgrade performance and feature on your systems/products. One is linear improvement of frequency, the other is non-linear performance enhancement of migrating to upgraded processor of compatible architecture of providing DSP instructions, fast interrupts and bandwidth management...and so on. Compatible architecture processor is

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easy for designers to migrate both their hardware and software from platform to platform with minimal effort and little impact, enabling designers to focus their time to effort on their own application.

performance processor with low cost. Lower price/performance ratio means that you buy a high-performance(powerful) processor with inexpensive cost. You will take an advantage of using processor with lower price/performance ratio to get more cost-sensitive business socket.

5. One-Stop Solutions

Figure 1: MIPS Architecture Microprocessor

Supplier of processors should be able to supply one-stop shop solutions to offer a wide range of choices for system designers, giving them extra flexibility in system design, including: 5.1 High-performance Microprocessor (Fig.1) Stand-alone microprocessor of software-compatible family with high-performance, but low-cost, is suitable to implement a common platform for series applications from regular to high-end systems/products. 5.2 System Controller(Fig.3) Support chip for microprocessor which consists of glueless interface to boot ROM, SRAM, DRAM, commonly used peripherals such as UART, DMA channels, timers, interrupt controller and PCI bridge to expand the I/O capabilities of system. 5.3 Integrated Processor(Fig.4)

Figure 2: MIPS Backward Compatible

2. Support Broad RTOS(Real Time Operation System) High-performance core, a large cache memory, a flexible memory management unit(MMU) with a full, large page translation lookaside buffer(TLB) for fast virtual-to-physical address decoding are major requirements of processors for efficient running of broad RTOS(e.g. WinCE of Microsoft, pSOS of ISI, VxWorks of Wind River, Nucleus of ATI....). Also, it will accelerate RTOS porting to your target board if supplier of processors could provide BSP(Board Support Package which supports hardware initialization on power-up and RTOS access to hardware drivers..) to designer.

Figure 3: System Controller

3. Comprehensive Tool Support Supplier of processors should offer simple, or low-cost incircuit debugging interface for designers such as logic analyzer interface of implementing additional reporting signals to simplify the task of system debugging when using a logic analyzer, or EJTAG(Enhanced JTAG) interface which allowing a lowcost in-circuit emulator to inter-operate with programs executing on processor. Also, supplier of processors should be supported by top vendors in each class of comprehensive tools, including compilers, ICE(In-Circuit Emulators), application software and reference designs...and so on to aid engineers during designing and debugging phase.

4. Lower Price/Performance Ratio In past time, normally, high-performance processor with expensive cost, but it is the main trend in the world which high-

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Figure 4: Integrated Processor

Integrating High-performance Microprocessor and System Controller for application-specific products, especially on cost-sensitive and space-limited products. Again, remember, a well-established supplier of microprocessor should be, more likely, able to offer wider range of choices and comprehensive tool support for system designers, giving them extra flexibility in system design to develop superior systems or products. Author's contact details

Casper Chang Field Applications Engineer IDT Asia Ltd. 10F-1, 508, Sec. 5 Chung-Hsiao E. Road, Taipei, Taiwan Phone: 886 2 2726 7255 Fax: 886 2 2726 7275 Email: [email protected]

Presentation Materials

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