Systems Spotlight

Systems SpotlightRichard Ball It’s not just a chipset… Rockwell has full system solution for GSM At CeBIT last week, Rockwell Semiconductor Systems unveiled a chipset for GSM mobile phones. On the face of it, Rockwell’s announcement seems run of the mill, somewhat behind the times even. But delving deeper reveals that the company is providing much more than just the chips for a cellphone. What we have is a full system solution for GSM. We’re not just talking about the chipset, said Alex Katouzian, senior product manager. The company provides the real time operating system, the all important protocol stack software, application programming interface and a man-machine interface design. A hardware reference design is available, but Rockwell will go further still. We can do the entire PCB layout design, system integration, testing and make prototypes, said Katouzian. The company will even assist its customer through operator and type approval. In short, a company with no experience of the mobile phone industry can go from a blank sheet of paper to a product in as little as nine months, claimed Katouzian. The hardware consists of seven chips along with standard flash and RAM memories (see diagram). The baseband portion is split into an analogue and a digital device. We don’t want the digital part to be polluted by analogue, Katouzian said. It also improves the yield of the devices. In the digital chip, control is provided by an ARM7 Thumb processor with the DSP side handled by Rockwell’s own 100MHz processor. Four chips are used in the RF subsystem. The transceiver, low noise amplifier – mixer and power amplifier controller are bipolar, while the power amplifer is gallium arsenide. Rockwell has rounded off the design with a power management chip. This contains eight low dropout voltage regulators, reducing the number of discrete components needed. The chip can recognise and work with both 3 and 5V SIM cards and any battery technology. It makes for a smaller form factor, by removing all discretes, Katouzian said. A reference design has been completed with a 108 x 45mm circuit board. We could fit this in a 100cc phone. By the end of the year we’re targeting 70cc, said Katouzian. Today’s smallest phones, such as the Philips Genie, are around the 100cc mark. To improve integration, the chip count could be reduced further by using multi-chip modules. Rockwell has considerable experience in this area. A design kit with a visual programming tool aims to reduce the development time. Rapid Plus from Emultek is used to prototype the man-machine interface on a computer screen. The keypad and display are drawn in the CAD package and functions are assigned to the buttons. The function of the phone can be simulated and demonstrated to potential network operators. When the design is fixed, the tool automatically generates C-code for the keypad and display. TI core finds winning combination Texas Instruments’ TMS320C27x core architecture is the company’s first to combine DSP and microprocessor capabilities in a single building block. DSPs are good at number crunching whereas microprocessors run C-code control algorithms effectively and make efficient use of programme memory. TI is not alone in combining the characteristics of both into a single core. ARM’s Piccolo and Hitachi’s SH-DSP both combine DSPand microprocessor features. Where they differ is that ARM and Hitachi are adding DSP characteristics to microprocessors. TI has started with a DSP and added microprocessor attributes. Jean-Marc Darchy, TI’s DSP spokesman, claims: C code for the C27x uses ten per cent less programme memory than the ARM7 Thumb and 45 per cent less than the Motorola HC16. If true, this is impressive, as both of these are microprocessors – and the ARM is heavily optimised for code compactness. A major contribution to this compactness comes from the C27x’s read-modify-write instruction set. A single instruction causes the processor to read data from memory, modify it and write it back to memory. Most DSPs and RISC processors use two or three instructions to do this. The first C27x-based chip is a hard disk drive controller, other dedicated products are expected to follow. TI will be offering a full software development suite. C27x features at a glance General 16-bit fixed-point architecture 100 MIPS at 3V, 0.25?m (150Mips at 0.18?m in 1999, 200Mips in 2000) 32-bit on-chip data bus fetches two words in a single cycle Register-based architecture 16- or 32-bit instructions, 16Mbyte address space
DSP-like Separate program and data busses (modified Harvard architecture) Single-cycle multiply and accumulate (MAC) Saturation instructions and modes
MPU-like Configurable in Von Neumann mode (combined bus) Single-cycle read-modify-write operations (logical and arithmetic) Automatic context save and restore for fast interrupt response Fast interrupt response (80ns latency, 160ns for full context switch) HP looks to ease integration problems with logic analyser Hewlett-Packard’s latest plan to ease the hardware and software integration problems of semiconductor designers is a logic analyser incorporating in-circuit emulation capabilities. The trick that HP has done is not so much the combined functionality in the one $30,000 unit, but that it has succeeded in giving interoperability with industry standard chip debugger software. Proprietary development and debugging tools may cause problems for digital designers, already crunched by the pressures of time to market and design complexity,said Pat Byrne, general manager of HP’s Colorado Springs Division. While it is not uncommon for some chip emulators to provide outputs for logic analysers, HP has inevitably approached the problem from the other side adding microprocessor emulation to its existing logic analyser product with validated connections to standard third party debuggers such as Software Development Systems (SDS), Green Hills Software, Microtec and CAD-UL. This is achieved using what HP calls an open-architecture gateway from the logic analyser to the debugg er. It seems likely that the company will promote this as an industry standard debugger interface. The modular 16700Aanalyser provides up to 1000 channels of state/timing analysis with two emulation slots. The analysis tool will also support multiprocessor systems. In a further twist to the story, HPis paying $5m to SDSto finance a sales and marketing programme for its debug tools in Europe, Japan and Asia.

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