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Asian vendor moves Linux PDA design forward

Posted: 01 Jul 2002 ?? ?Print Version ?Bookmark and Share

Keywords:pda? ip? embedded network? strongarm? pcmcia?

The world's first Chinese Linux PDA operating with Intel's StrongARM released in the Computex Conference Taipei last month by Linpus Technologies Inc., a Taiwanese embedded apps company, has been drawing attention from a wide section of consumers interested in portable electronic devices. The PDAs OS supports up to 64K-color display and includes more than 30 applications and wireless features.

The Linux PDA consists of a 500KB Kernel and a 600KB graphics engine. The Kernel natively inherits the benefit of Linux, such as high performance, stability, multi-tasking and shared library features. In addition, this Linux PDA OS is still able to leverage the benefit from the open source communities. For example, any device drivers and protocols available in Linux for X86 PC can directly be applied to the PDA OS, simply through cross compiling. The compact size is also one of its major advantages with only 8MB flash memory required for its OS.

The 500KB Kernel makes the booting much faster. It takes only 6 seconds from power on to getting the graphics system ready. It supports standard protocols and peripherals, such as TCP/IP, PPP, IrDA, RS-232, USB, CF, PCMCIA, RTC and so on.

Wireless, multimedia considerations

Wireless features are important and are supported by this Linux PDA OS, in which both GPRS and 802.11b technologies have been implemented. In addition, CDMA is greatly considered and will be addressed later on as the system develops. Inside the OS, there exists a Java Virtual Machine (JVM), based on J2ME, which is compact enough for handheld devices.

The system's graphics engine is well modularized and is also able for re-composition. The total size of this engine ranges from 200KB to 1.4MB, depending on the feature requirements. The engine consists of five major modules, including a character processing module, a graphic processing module, an audio processing module, a multimedia module and optional add-on modules. The add-on modules include the API designed for special applications, such as GPS, and database applications, which may not be common and are not included by default. The engine provides basic API for graphic application development, such as radio button, scroll bar, text box, button, message box and so on. In addition, significant multimedia functions are provided too, such as JPEG decompression, GIF display, MP3 playback, MPEG 1/4 playback and so on. Most of the major languages have been supported in the character processing module, such as Traditional Chinese, Simplified Chinese, English, Japanese and Korean. Finally, for the handwriting recognition, Linpus is working with PenPower, a vendor in this field. The recognition engine supports a wide range of the Oriental and the Western characters, even including Hong Kong characters, which are kind of Chinese characters but are used only in Hong Kong. Of course, this handwriting recognition engine supports all of the above languages.

Regarding the font display, this engine supports the bitmap font display and the true type font (TTF) display as well, the latter of which is optional due to its size requirement and more computing power demand. For example, a TTF character set of Traditional Chinese, supporting around 9,000 characters, typically occupying 3MB to 5MB. Apparently, the TTF support is too luxurious for a PDA with only 8MB or 16MB.

In order to verify the maturity and the quality of our graphics engine, Linpus developed its own proprietary applications. More than 30 applications have been done for this matter. For example, the audio setting application is developed to make sure that the scroll bar function and the button function work well. Tetrix is designed to verify the feature of the customized graphics buttons. Last year, Linpus started working on SDK, a beta version released to third parties for add-on applications. Now, most of the applications are developed based on the SDK. In fact, the maturity of this OS is accomplished through many back-and-forth processes among third parties, application engineers, API engineers and project managers. The following indicates the list of major applications released for SDK:

System applications: This includes screen alignment, LCD backlight alignment, clock/time setting, audio settings, power management, hand writing recognition, SW keyboard, task manager and live update.

Multimedia applications: This includes MP3 player, audio recorder, MPEG1/VCD player and MPEG 4 streaming.

Additionally, personal applications are included, which features owner info display, personal secretary functions, e-mail reader, drawer, notepad, entertainment/calculator apps and English-Chinese Dictionary functions.

Foresight assessment

This PDA software is providing the turnkey for future device apps running on the same path. As a result, different SoC designers and hardware manufacturers along with Linpus have made many engineering changes to further improve system design and functionality. Unlike Win CE, which is positioned in the top segment of handheld device markets in terms of price, the Linux PDA is accepted primarily due to non-exclusivity (i.e., open source), easy customization and lower cost. In order to make PDA products more cost effective, Linpus is requested to provide a Linux PDA OS with 256-color support for 8MB PDA, while normally 16MB or even more is required for these kinds of products. In addition, more and more customers prefer NAND flash memory and discard the traditional NOR flash memory. The former is cheaper but cannot support Execution In Place (XIP), while the latter easily does, but costs 40 percent higher. In order to support PDA with NAND flash memory, Linpus is changing their design approach so that the Linux Kernel is decompressed initially from Flash memory to SRAM so that the kernel can execute the operations in RAM.

? Stephen Lin

Linpus Technologies Inc.

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