by September 17, 2003 0 comments



PDAs are getting smaller, faster and more powerful. Some have GPRS-enabled Web browsing, others have Wi-Fi built-in. Most come with IR and Bluetooth communication, and have some form of expandable memory.

All this is made possible not just by the software, but also by the underlying hardware, mainly the processor. We’ll talk about the widely used series of processors from Intel, based on the XScale technology, which makes all this happen. Besides PDAs, the processor has also been used in mobile phones, multi-service switches, VoIP media gateways, set-top boxes, and smart displays to name a few.

Around the year 2000, Intel announced its initiative in the mobile processor area. It was based on Strong ARM technology that it licensed from ARM technologies. It was named XScale because of the ability of the technology to grow multifold. The first XScale architecture-based processors came out in 2002, and were adopted by major PDA manufacturers like Toshiba, Fujitsu and HP. Today, the same processors (now called PCA, or Personal Internet Client Architecture) have advanced to speeds of 400 MHz and support up to 256 MB of stacked memory. Another feature they offer is low power and turbo modes of operation, which can be
customised.

We look at the PXA26x family of processors, built on the XScale architecture, and available in speeds of 200, 300, and 400 MHz. These are the first family of mobile processors from Intel and have a stacked, multi-chip kind of architecture. The processor is bundled with up to 256 MB of Intel StrataFlash memory, which is Intel’s proprietary flash memory technology.

Besides the main CPU unit, the processor also contains controllers for controlling other devices. Some of these are for IrDA, Bluetooth, an integrated color or B/W LCD controller with its own DMA, and support for SD/MMC/CF cards. Plus, it also has an AC97 audio controller and a USB controller. The processor also provides Universal Asynchronous Receive and Transmit (UART), and Synchronous Serial Port (SSP) functions, which are used for synchronizing and communicating with other devices.

This multi-chip architecture with all the controllers is as small as 13x13x1.4 mm. The compact footprint helps save space when designing handhelds, and even reduces power consumption. All the features, size, performance and low power consumption of these processors have already made them favorites of the major PDA and smart phone vendors. Most PDA manufacturers have high-end models of their offerings based on these processors.

Geetaj Channana

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