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Handheld computer from within

Evgenie Rudometov

www.rudometov.com

Wide functionality of pocket personal computers is defined not only a package, but also the internal architecture and applied electronic parts

Modern handheld computers step-by-step became the multimedia arrangements possessing considerable functionality. The given arrangements in some cases are capable to substitute more difficult and large colleagues. However, despite a functional saturation of these arrangements, there is one circumstance not always arranging potential users.

Certainly, first of all it is a question of the price. Really, at the appearance reminding usual inexpensive calculators, many models of a handheld computer in many cases do not concede under the price to desktop computers and notebooks.

It is possible to tell very long about possibilities of models, proving a price level, but sometimes it is useful to show the internal arrangement simply. It allows to be convinced of a high saturation of a handheld computer by various electronic parts. The quantity of these components, as well as complexity of the main chips, can make a worthy competition to appropriate sets of traditional systems.

Costs of marketing

Estimating possibilities of pocket personal computers, a considerable part of potential users quite often state doubts in validity of the prices on which the given arrangements are offered by numerous corporations-manufacturers.

Really, on dimensions and design many (if not all) handheld computer variants remind calculators. The price of some models of these supercompact computers in some cases corresponds to the elementary notebooks — to products more known to general public, and accordingly and popular in the consumer market.

Besides, parsing perspectivity of those or other models of a handheld computer, the future users should consider growth of functionality of mobile phones also. These bystrorazvivajushchiesja products by means of the built in hardware-software resources are already capable to perform in many cases rather uneasy operation on processing of audio and video of data. Moreover, the received results can be handled on high-frequency radio channels of standard cellular networks (after processing or even in real-time mode) at saving, of course, traditional functions of a voice communication.

The certain turmoil in the environment of potential users of transportable computers is brought also by marketing services of the corporations making processors for a handheld computer. Testing fair pride of perfection of design and functionality of processors, heads and employees of these corporations often appear with appropriate presentations. During these presentations they tell about possibilities of the products and the reached results on perfection of solid-state technologies and an inner pattern of units. In the numerous performances they quite often underline presence of the high-powered processors built in structure created for the market of a handheld computer, the big number of specialised controllers, and in more perfect developments also memory cells of rather big informational size.

As consequence of the given marketing pressure, many potential users of a handheld computer have a number of illusions. Among these illusions, perhaps, greatest distribution has found that practically all possibilities of the given computers are defined by exclusively used processors. These processors as it is already known to many potential users of computer products, have banked in themselves sets of the most complicated chains, capable to fulfil a considerable quantity of multimedia functions.

As a result, many consider, that handheld computer construction is reduced basically to support of correct input/output of signals of the used processor. Logical result is erratic representation about the internal arrangement as about very simple system consisting of the display, several switches and external plugs, well, still, maybe, several additional units, for example, the speaker, a microphone, aerial Wi-Fi. As to a high difference between cost of a finite product and by the processor, reaching several hundreds dollars (and it means price rise in some tens times) the given injustice lays exclusively on conscience of the computer corporations making and realising similar compact computers.

Giving due creative to successes of implementators of processors for a handheld computer, it is necessary to underline an inaccuracy of similar opinions. As the proof it will be served by the analysis of units and structure of one of the handheld computer models, resulted more low.

Processor XScale

The processors used as a part of a handheld computer, on the architecture and the command system essentially differ from the high colleagues. Really, traditional solutions realise ideas x86. And here supercompact transportable computer products which handheld computers concern, are incarnation of the whole series of developments of company ARM.

These developments at a certain stage of their development have been licensed by Intel corporation. Thanks to efforts of its engineers the architecture and command system ARM have received further development in a series of special processors. These processors on Intel plan have been oriented for a number of years basically to the market of network controllers and a handheld computer (before transmission of developments of company Marvell).

Kernel XScale

Processors of the given group, whose refreshed architecture, has received name IntelXScale, are as a matter of fact system-on-chip. As a part of this system fulfilled on a uniform chip and placed in the common tank of the processor, the considerable quantity of controllers is realised. A basis of such system is the kernel presented in a Fig. 1.

Fig. 1. Structure of kernel IntelXScale

This kernel became a basis of some Intel processors, among which representatives of bars 250, 255, 270 and others.

On their basis different handheld computers are created. These arrangements differ from each other accessories and design, and also the system software. But besides, handheld computer models differ also electronic parts used together with processors. These units substantially define the internal architecture and functionality of products. Knowing all features it is possible not only to estimate really a band of possibilities, productivity limits, energopotreblenie and even to predict compatibility of accessories.

As an example, as the object of research of the internal arrangement of a handheld computer model Pocket LOOX of 420 Fujitsu Siemens Computers corporations (Fujitsu Siemens) has been selected. This handheld computer can be considered as an example of standard model of the handheld computer created on the processor of Intel PXA255 with a kernel of microarchitecture IntelXScale. This processor has inherited the best features of the predecessors and has put in pawn bases for the descendants.

The architecture and processor parametres

The processor of Intel PXA255 is created on the basis of the predecessor of Intel PXA250. The new processor has inherited the majority of its architectural features. The main difference is usage of more efficient internal bus, whose clock rate has been increased twice — 200 MHz (at clock rate of a kernel of 400 MHz) against 100 MHz for the same bus of its prototype. It has provided substantial increase of speed of operation of the processor and appropriate increase in productivity of the computer systems created with usage of Intel PXA255.

The command system is compatible with ARM versions 5TE ISA (ARM Thumb Instruction Support, ARM DSP Enhanced Instructions).

Kernel XScale of the processor of Intel PXA255 possesses following characteristics:

                   32 Kbytes a cache memory of commands,

                   32 Kbytes a cache memory of given,

                   2 Kbytes mini a cache memory of given,

                   2 Kbytes mini a cache memory of commands,

                   40 bits the secondary generator and the expanded 16 bit arrangement of multiplication for processing of the multimedia information,

                   controls for memory of instructions and data, etc.

Together with kernel XScale (Fig. 2) are integrated into processor structure following means:

                   the controller of memory,

                   the clock rate and power controller,

                   controller DMA,

                   controller LCD,

                   USB Client,

                   AC ’ 97,

                   I2S,

                   MultiMediaCard,

                   FIR Communication,

                   Syinchronous Serial Protocol Port,

                   I2C,

                   General Purpose I/O,

                   Full Function UART,

                   Standard UART),

                   Bluetooth UART (standard consecutive 960 Kbit UART the interface to the send-receive unit),

                   Real-Time Clock,

                   OS Timers,

                   Pulse Width Modulation,

                   the controller of interruptions.

 

Platform

In a Fig. 2 the generalised structure of one of variants of the architecture of a handheld computer is presented. In it subsystems of a wireless communication of different type are provided.

Fig. 2. Structure of a handheld computer with several subsystems of a wireless communication

Truncating or adding sites, and also varying sets of units, it is possible to receive models of a handheld computer of different functionality.

It is necessary to mark, that many tens corporations, among which not few known corporations are engaged in development, production and handheld computer implementation.

The main technical parametres

Before consideration of features of the internal arrangement of handheld computer PocketLOOX of 420 FujitsuSiemens corporations it is expedient to result its main technical parametres. These parametres are resulted in Table 1.

Table 1. Key parametres of handheld computer Pocket LOOX of 420 Fujitsu Siemens corporations

Units and characteristics

Parametres

The processor

Intel PXA255 of XScale architecture with clock rate of 400 MHz

Memory

32 Mb of ROM / 64 Mb RAM

The screen

The liquid crystal touch panel, the permission 240x320, 64 To colours

Audio

The built in microphone and the speaker, the plug for ear-phones.

The secondary generator

1100 мАh Li-Ion (main) + NiMH (backup)

External plugs and interfaces

IrDa, USB, the power supply plug, Bluetooth, Wi-Fi (IEEE802.11b)

Overgrowth of possibilities

The plug for maps SD/MMCard, hooking up of additional units through this (SDIO plug is possible

Weight

125 gramme

Dimensions

113,1 x 70,6 x 14,1 mm

The operating system

Microsoft Pocket PC 2003 (Version 4.20.0)

The software

Pocket Outlook, Pocket Word, Pocket Excel, the Calculator, MSN Messenger, Windows Media Player, Transcriber, Pocket Internet Explorer, Microsoft Reader 2.2.3, voice recorder, Microsoft Active Sync 3.7.1, etc.

The additional software

The russification program, dictionaries, etc. from PARAGON corporation, applications of indirect manufacturers.

Applied in a handheld computer lithium-ionic (Lithium-Ion) the accumulator battery is substituted. It is allocated under a removable lower cover of a handheld computer. Its size makes 1100 mach.

Additional charge is possible both through kredl, and at direct hooking up of a handheld computer to an external power supply unit.

Estimating possibilities of the secondary generator of a handheld computer traditional lithium-ionic, it is necessary to mark, that except the substituted battery, as a part of a handheld computer is available additional NiMH the secondary generator of small size. It provides safety hranimyh in memory of data for the period of changeover (till 30 minutes) the main battery on the spare secondary generator.

Other units are considered more low.

Handheld computer dismantling

To get access to the internal arrangement of a handheld computer and its components it is necessary to open tank. However dismantling of so difficult arrangement is the operation potentially dangerous to a handheld computer. It is linked by that errors in dismantling and in the subsequent assemblage are fraught with a non-reciprocal malfunction.

For this reason behind the help it has been decided to access to professionals of CPS corporation - Technical Centre (www.cpstc.ru) which experts have helped to disassemble and gather described below handheld computer model, and also have assisted in preconditioning of photos of internal sites.

The internal arrangement of a handheld computer

In a Fig. 3-5 photofragments of a construction of pocket personal computer FujitsuSiemens Pocket LOOX 420 are presented.

In a Fig. 3 it is presented a handheld computer without a back cover of tank and without the secondary generator. Absence of a cover allows to see units of the internal arrangement.

Fig. 3. Handheld computer Fujitsu Siemens Pocket LOOX 420 with the removed lower cover

On the resulted photo in the right end face of a handheld computer the multifunctional plug is allocated. Through it in a handheld computer energy from the external power supply unit working from a network of an alternate current by power of 100-220 d the same plug moves uses for handheld computer hooking up to a notebook or the desktop computer for the purpose of transmission of programs and data. Informational link is carried out on interface USB.

From the combined plug USB/power supply in a handheld computer is in the opposite end the slit type plug SDIO (slot). It together with units environing it uses for hooking up of cards of flash-memory SD/MMC or miniature maps of the extension.

Near to SDIO there is a stereo the plug of headphones.

All these units are allocated on the motherboard excepted from tank and presented in a Fig. 4.

Fig. 4. The card with the main electronic parts

By the way, in the tank deprived of the motherboard remain a number of units among which the bright green disk of the additional secondary generator is selected.

And now purely about the motherboard and the main electronic units allocated on it.

About contact electrodes of the plug combining USB and power supplies, on the card chip ST3243 is allocated. This chip realising consecutive data transfer, often uses as a part of units of the interface of input/output.

Near to these units one more plug is allocated. It is allocated under a corner on narrow to edge of the card and joints the electronic circuit to the components allocated in tank out of the host board.

At centre of the given card the black storage plug with the spring, gilt contact electrodes is allocated.

Near to the storage plug on the card the plug of white colour is placed. Through this plug link of the electronic circuit of a handheld computer with display LCD allocated in tank is provided.

Near to display and storage the chip selected among environing units in the sizes is plugs on the brink of the card. It is company TexasInstruments chip BBADS7846N. It is the touch-sensitive display controller (Touch-Screen Controller) from Sony.

Near to SDIO plug under the metal screen the unit of wireless radio communication Bluetooth is allocated. This unit is environed with electronic units of different complexity.

The considerable quantity of units is allocated on other side of the card of a handheld computer. Appearance of this side of the card is presented in a Fig. 5.

Fig. 5. The Underside of the card with the electronic parts allocated on it

The number of the electronic parts allocated on an underside of the card, is rather great, and their description is beyond given article. However the main chips substantially defining the architecture of the specified handheld computer, deserve a personal mention and appropriate consideration.

The main chip traditionally is the processor of Intel PXA255 realising microarchitecture XScale. This the major the component as fairly it is considered, is a handheld computer basis, and it substantially defines the arrangement architecture. It is a component it is in detail described in the beginning of given article in separate section.

Except the processor, the major chips are memory chips, controllers of interfaces, etc .

Handheld computer dynamic storage is presented by two chips SDRAM. Their total amount makes 64 Mb (2 h 256 Mbit). In a Fig. 5 these chips are allocated above the processor. They store programs and data but only until in secondary generators it is enough for this purpose energy. Besides, chips participate in data processing processes.

The handheld computer Flash-memory is presented by one big chip. This chip is released by Intel company. Its denotation - Intel 4000LOZBQO, and in a Fig. 5 it is allocated to the right of the processor. The chip provides a non-volatile information storage and is intended basically for storage of the system information presented by programs and data of the manufacturer of a handheld computer.

To the right of the flash-memory chip chip HTC 30H88028-00 is allocated . This chip is the so-called chip-partner of the processor of Intel PXA255. It contains controllers of interfaces GPIO (General Purpose Input/Output) and SD/MMC. It means, that through HTC 30H88028-00 transmission of a considerable stream of the information between the processor and other accessories is carried out.

One more large chip is the controller of wireless radio interface Wi-Fi. This controller is realised on the basis of chip Texas Instruments TNETW1100BGHH and controls the unit of the radio interface hidden under the metal screen. The given unit is created on the basis of chip MAXIM MAX2820 (2.4 GHz 802.11b Zero-IF Transceivers). The specified chip fulfilled in tank THIN QFN (7 x 7 x 0.8 mm, 48 pin), supports standard IEEE802.11b (to 11 Mbit/with CCK and to 22 Mbit/with PBCC). Unipolar power supply uses: from +2,7 In to 3,6 V.Iz of other characteristics of the given chip it is necessary to mark sensitivity parametres:-97 dBm Rx Sensitivity at 1 Mbps,-87 dBm Rx Sensitivity at 11 Mbps. Data transfer is carried out in a band of 2,4-2,5 GHz.

It is necessary to mark, that mentioned radio interfaces Bluetooth and Wi-Fi are not unique wireless interfaces of considered model of a handheld computer. To them it is necessary to add the traditional infra-red (IR) interface realised by means of appropriate units, the handheld computers integrated into structure.

By the way, marking possibility of operation of a handheld computer with external audio and videounits, it is necessary to remind, that PocketLOOX 420 itself possesses quite good multimedia possibilities. Sound possibilities of the given model of a handheld computer are supported by a number of the units entering into its architecture. Among them, first of all, it is necessary to mark chip Philips 380HN (UDA1380HN). In a Fig. 5 it is allocated to the left of the processor of Intel PXA255. Given chip Philips 380HN contains in the structure 24-bit analogue-digital (ADC, Analog-to-Digital Converter) and digital-to-analogue (DAC, Digital-to-Analog) converters. According to implementators of specified chip Philips 380HN, it provides low coefficient of deformations and the high dynamic range reaching of level 97 db on limiting values of frequency semplirovanija for processed signals .

It is necessary to mark, that operation of hardware of handheld computer Fujitsu Siemens Pocket LOOX 420 is supported by appropriate system and applied program components of Microsoft, and also other indirect software producers.

Handheld computer clones

In conditions of development of the modern market the mention of the companies which make products under another's brands is not news. Here at once it is necessary to mark, that speech does not go about a piracy. Simply powerful manufacturers offer industrial, and is frequent also research potential to other companies. The companies to which such services (OEM) are oriented, select, order, pay and realise the products created for them. Further they carry out technical support, warranty service, repair, and is frequent also the subsequent recycling of released production.

Examples such not seldom international integration can find much. And pocket personal computers here are not any exception. The numerous models of a handheld computer created by the large companies, carry on themselves prints powerful research and work collectives. It allows with confidence concerns similar arrangements. The big circulation of the platforms released for a handheld computer allows not only to debug finite products, but also it is essential to lower their cost price. And it in turn allows to lower a price level of arrangements on counters of numerous shops.

However, OEM production generates existence of a considerable quantity of the clones differing in main external by the design both the firm system and applied software.

So, for example, handheld computer Fujitsu Siemens Pocket LOOX 420 have "brother-twin" - handheld computer HP iPAQ h4150.

The model iPAQ h4150 was released for HP by the known company HTC which is OEM the manufacturer for many corporations. The same company has made model and for Fujitsu Siemens. And let nobody is fooled by distinctions in external design. The platforms underlying given models, are practically identical. It is possible to be convinced of it easily, considering the illustration resulted more low (a Fig. 6).

By the way, a consequence of identity of models is interchangeability of secondary generators for HP iPAQ h4150 and Fujitsu Siemens Pocket LOOX 420.

As one more object it is possible to result handheld computer Fujitsu Siemens Pocket LOOX N520. External similarity to earlier released prototypes which cards are presented in a Fig. 6, obviously specifies in one OEM the manufacturer. The company all the same HTC became these OEM the manufacturer of all resulted models of a handheld computer.

Fig. 6. A handheld computer iPAQ h4150, Pocket LOOX 420, Pocket LOOX N520 and their motherboards

So, HTC has created specified and many other things products what remains to the companies-customers? On their share, as well as it was marked above, drop out difficult and hlopotnye problems. It, first of all, a choice of parametres and design of the future model. And still there are marketing and advertising problems. Besides, the task of implementation lays down on shoulders of the companies with reception of comprehensible profit, and also questions of technical support, warranty service, repair and many other things. And all is necessary for carrying out it in the conditions of enough strong saturation of the market, competing with other companies. Certainly, it is completely not simple, and is not cheap.

The conclusion

Certainly, by consideration of design features of the transportable computer by the enumerated computer units all set used in the arrangement is not settled. However the resulted representatives make an architecture basis. Other electronic units which hundreds resistors, capacitors, and also the chips of rather low complexity realising converters of power supply, bus shapers, various electronic soglasovateli concern, amplifiers, etc., have not got to the presented description. It is linked by that they play auxiliary though also a necessary role for functioning of the specified compact transportable computer system.

Estimating the internal arrangement of a handheld computer, it is necessary to recognise, that similar incarnations of computer processing techniques by quantity of used units and complexity of the architecture in many respects do not concede to larger clones. As well as desktop systems, together with notebooks, a handheld computer consist of a considerable quantity of units, that, generally speaking, and explains their rather considerable price and the big functional potential at modest size and weight. Also it will be a pity. If this class of computers fades out under the pressure of products competing to them.

The author thanks CPS corporation - Technical Centre (www.cpstc.ru) for the rendered help in dismantling and the subsequent assemblage of a handheld computer



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