TI's TMS320C27x Architecture Redefines DSP for the Storage World, Enabling Future-Ready System-on-a-Chip Development for Mass Storage Electronics
By integrating a fully efficient C language engine for interface control with world leading DSP capability for servo/spindle control, the new 'C27x DSP architecture provides high performance yet affordable disk drive uniprocessor solutions.
Texas Instruments (TI) today extends its legacy of digital signal processor (DSP) innovation with a single-processor solution for the mass storage industry with the introduction of the TMS320C27x. Having adopted TI's first-to-market DSP solutions for the mobile hard disk drive (HDD) market (1994) and 3.5" mainstream desktop market (1996), designers of all hard disk drives and other high density storage products such as digital video disk (DVD) and high-density floppy can now realize the dream of creating no-compromise uniprocessor solutions for drive electronics. Such devices will meet ever increasing needs for higher performance while taking advantage of advances in integration and lower costs offered by continually improving semiconductor processes.
The challenge of designing such an all-platform uniprocessor is threefold in that it must address three separate processing needs inherent within a drive architecture. First, the single-chip solution must provide the highly efficient C language compiling, linear address space and the real-time control capabilities of an advanced microcontroller, along with easy programming. To be economically feasible, the solution must also permit development and reuse of a range of standard cells for specialized microcontroller peripherals, including code blocks of efficient buffer management or serial-to-parallel conversion, or even complete macro functions like SCSI, ATAPI, or IEEE 1394 interface, servo control logic and read channels.
Second, the processor must accommodate the use of advanced DSP calculating engines to position the recording heads ever more accurately on the surface of the recording media. At the same time, the processor must control ever more precisely the speed of media rotation. And with the advent of new enabling technologies such as microactuators, these new high performance engines are absolutely essential.
Finally, the processor must accommodate the enhanced partial response, maximum likelihood (EPRML) signal processing techniques employed in today's read channels to complete the integration path.
The new TMS320C27x DSP core is the first available on the market to address all aspects of the storage system architecture requirements for integrated uniprocessor design.
DSP Redefined
"Our new 'C27x core provides world-class DSP performance with 100 MIPS performance and a well defined growth path beyond to keep the drive designer ahead of the curve in the tracks-per-inch race," said Briant Regan, mass storage marketing manager for DSP at TI. "It also offers the power of an advanced RISC microcontroller optimized for real-time control and data processing in storage applications - an ideal computing engine for advanced controller development."
"With all these capabilities, the new 'C27x DSP core actually redefines the meaning of DSP in the storage world," Regan noted. "Not only is it a calculation engine, it is truly an optimized data storage processor."
The 'C27x core will be implemented using TI's 0.25-micron CMOS process, providing 100 MIPS of calculating power at 100 MHz, better than 100 percent more capability than the most advanced DSPs currently in use for servo/spindle control. This will easily accommodate future servo/spindle control requirements brought on by new technologies in development, like microactuators, very high speed motors and 6x or greater DVD. TI has already produced working silicon and is engaged with selected customers on custom storage control devices. Full product release of the 'C27x core in 0.25 micron is planned for the second quarter of 1998. TI plans to migrate the 'C27x to 0.18-micron TImeline™ technology in 1999.
"This strategy provides customers with a real density leadership today at a reasonable cost and guarantees a low cost development path in the servo/spindle area for years to come," Regan noted. "In addition, increasing the processing bandwidth to well beyond 100 MIPS will yield nearly a decade of potential improvement for the drive industry. That's enough to take them through half a dozen or more product cycles without major reinvestment in firmware."
Speeding Controller Firmware Development
Preservation of drive engineering investment from product generation to generation also plays a significant role in the design of the RISC microcontroller (MCU) aspects of the 'C27x core. First of all, the most common high level language in use -C - was adopted. In fact, the optimized C compiler provided with the core is one of the most efficient available, producing up to 30 percent better code density than typical MCU compilers for common mass storage algorithms, significantly reducing system costs. Time-consuming assembly programming can be virtually eliminated.
In addition, existing firmware code for all major drive manufacturers was closely examined, and virtually all of the most commonly used instructions were implemented as part of the final instruction set. This means that drive designers will be able to continue to work the way they have with previous generations of less capable MCU on the 'C27x core processor. It also facilitated the development of a family of tools to port existing legacy code to this new platform to reduce ongoing development time and costs. C++ language support for the new processor family is also planned.
Unique, Industry-Leading Real-Time Emulation and Debug
To speed code development and testing for the 'C27x DSP core, a complete suite of real-time emulation and debugging tools are provided. Of particular importance in the storage world, a JTAG-based visibility port and TI's exclusive Real-Time Data Exchange (RTDX™) technology are provided. These capabilities permit the designer to monitor, analyze and modify code executing at speed without impacting results. Using this window during servo seek, for example, one could modify registers and instructions, stream key data variables or set and execute hardware breakpoints without impacting drive operations. This facility would allow the designer to more quickly isolate firmware bugs and also produce higher quality code in a shorter time. In addition, this windowing capability can actually be used to tune a drive during the manufacturing process to optimize the performance of the 'C27x core for specific head/media combinations.
World Class Intellectual Property from Storage Experts
A wide range of peripherals are scheduled to be released to assist the drive designer up the integration ladder. Initially, these will include a range of embedded memory types for use as buffers, including read only memory (ROM), static random access memory (RAM) and flash. A number of storage-specific macro cells will also be available to speed controller design, including serial-to-parallel and parallel-to-serial converters, buffer managers and standard interface regimens including ATAPI, SCSI and IEEE 1394. Future macro cells will include high-speed EPRML read channels.
Even more importantly, TI is making a major commitment to shortening time to market for its 'C27x core customers by undertaking the development of more complete solutions called integration platforms. These will include a collection of macro cells required to meet a popular configuration, complete with fully tested firmware for both servo/spindle and controller operations. For example, an integration platform might include a 'C27x core with servo positioning control, servo demodulation and sensorless spindle speed control firmware combined with static RAM and ATAPI interface standard cells and completely tested and debugged firmware. Use of such an integration platform would greatly shorten the overall development process, allowing the drive design team to concentrate on developing custom features to differentiate their products. Further platform development details are scheduled to be released in the second quarter of 1998.
Highly-focused field and factory technical support is critical in the development of customized embedded processor solutions. TI offers customers a mass storage dedicated firmware and hardware technical staff, with extensive experience in storage processor solutions.
Target Customers and Costs
In the storage market, most uniprocessor solutions using the 'C27x core will be customized devices, with final prices depending on the size of the final die and the TI intellectual property employed. TI expects a uniprocessor with integrated controller and read channel to cost less than $15 in high volumes (one million plus).
Texas Instruments Storage Products Group
Texas Instruments has formed the Storage Products Group, which is comprised of TI's DSP, application specific integrated circuit (ASIC) and Mixed Signal units for mass storage applications, the group also leverages the acquisitions of Silicon Systems, Inc. and Intersect Technologies, Inc. It provides advanced semiconductors for high performance, desktop, mobile and removable drives. The TI Storage Products Group supplies innovative read channels, servo/spindle controllers, interface controllers, preamps, DSP and ASIC solutions designed and manufactured for hard disk drives, tape drives, high density floppy disk drives optical disk drives and DVD.
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