The media memory box (Media Storage Box, MSB) promotes the opportunity, acts according to the numeric move multimedia equipment which present stage PMP (media player) product development’s limit, the application shortcoming and the marketing difficulty suggested. Only this kind of function’s commercialization mobile equipment may the conformity technology be all kinds, the development and the localization also have the very big change space. Take the MSB product as the example, initially designed the conception namely to get unhooked with the PMP marketing localization, but own locates in the PMP substitution derivative commodity, namely so-called “the multimedia hard disk external connection box” sells. But speaking of the MSB product function and the specification, nearly is the PMP design reprint, may also say that is PMP, individual video frequency product and so on player (PVP) or MP4 player pretage technological development platforms, this is promotes the MSB this kind of hard disk mobile equipment most important technology challenge and the ponder basis.
PR818S development platform and related important component
The reason that MSB designation xi Ma special company (Sigmatel) single chip processor (SoC)PR818S, lies in its formidable technical superiority:
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Chart 1:a. A side is the main body three states of matter way. b. Is the main body way mutually. c. power source cut way. d. isolates the two using the switch buffer. |
1. Formidable operational capability
PR818S is 380LTFBGA (small external dimensions fine spacing ball grid array) the packing, the seal size is 16.5mil(W)×16.5mil(L), the ball grid spacing is 0.65mil, uses 0.13 micron CMOS craft, built-in ARM922T 220MHz processor. The video frequency arranges the decoding to contain MPEG-1, MPEG-2, MPEG-4 to use hardware construction (hardwired), therefore when purely for video frequency utilization, the ARM922T processor still had 90% operational capability earnings. But this operational capability meets the general embedded product demand, like the V2oIP telephone (the visible IP telephone), the media gateway, IP Cam and so on, front the comparison state, MSB visibly for this kind of embedded product development platform. The PR818S main coordination’s operating system is Blue Cat Embedded 4.0 tool which Linux Works Corporation provides, its Linux the Code essence is Ver.2.4.18.
2. Superior video quality
PR818S uses MPEG4 ASP the compress technique, its video quality oneself close H.264 quality. The resolution may support D1, NTSC 720×480, PAL 720×576 to 30fps (frame each second). Simultaneously has the entire double merit synchronization decoding/code capacity, this ability regarding realizes the appointment video recording (when removes can) really indispensable, can support JPEG is also PR818S another characteristic, may take the image head end to the 16M picture element resolution the input.
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Chart 2:PR818S chip level system structure function diagram. |
3. Low power loss
The PR818S core operation voltage is 1.2V, the input/output is 3.3V, the chip itself power loss only then the 350mW, MSB system power loss is also lower than 1W, for portable embedded product development important element.
4. Many Yuan external connection functions
The I2S connection - uses for to connect the audio frequency then decoder. Here audio frequency then decoder is Wolfson Corporation’s WM8978, built-in PLL and can produce the audio frequency clock to PR818S.
The CCIR656/601 connection - uses for to connect the video frequency decoder and the video frequency encoder, here uses TI Corporation’s TVP5150 and ADI Corporation’s ADV7179 separately, the two are the low power loss designs, the ADI7179 interior supports 3 DAC, may take 3 kind of different signal outputs.
The IDE connection - uses for to connect the built-in hard disk, its 2.5 inches compatibilities test good on PR818S.
The MCU connection - uses for to link the ethernet, here ethernet control chip is ASIX Corporation’s AX88796L, links besides USB, seeks in the network the storage application (Network Attached Storage).
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Figure 3: Based on PR818S MSB function diagram. |
SD the connection - SD memory stick is uses for the digital camera content to download to PR818S.
The USB2.0 connection - uses for to link the PC main engine, here use creates only company (Gensys) GL811E. GL811E is high speed USB2.0 to the IDE control chip, it has suitable city occupying rate and 2.5 inch hard disk compatible abilities.
Hardware design concept and design breakthrough
Speaking of the MSB entire hardware design, mainly has two big bottlenecks to consider carefully:
1. IDE line design
Creates the GL811E chip and PR818S each is only the independent individual, moreover the same time can only have one to be possible to work, the two speaking of HDD are mutually and the company, therefore has four ways generally in the application: Take a side as the main body three states of matter way, gets down pulls another side the reset signal to force it to be unable to visit HDD (chart 1a); Is the main body mutually, a side work pulls another side at present the reset signal (chart 1b); By the power source way cut method, causes when its side has the power source, another side non-power supply (chart 1c); (Switch buffer) isolates the two using the switch buffer (chart 1d
Generally in the market condition uses major part for the first kind of pattern, but this MSB the hardware selects the third method, but says hardware engineer by the technical application to be glad to use the fourth kind. In short, has its good and bad points respectively.
2. Line layout aspect
How is the entire circuit wafer most difficult to lie in the loop line goes out PR818S in outside PR818S, the primary cause lies in PR818S the ball spacing (0.65mil) too small, and biggest line width 5mil the hole must in four ball dead centers, therefore topological design engineer nobody goes to PR818S with the 5mil line the loop line, when after wired pulls, all were very easy.
MSB system’s specification
Since MSB the localization is the PMP derivative commodity, its design ideal is looks like PMP to be able to provide “Video-To-Go” equally, but cannot let the consumer “anytime and anywhere” the appreciation movie, but reprints the movie from PVR or in the PC network, from the computer, the monitoring device or the television screen (vehicle carries screen and so on) on to broadcast the movie, not only but it the broadcast movie, as mentioned above it also has the hard disk external connection box (the U plate), the photograph browser and the videocorder function:).
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Chart 4:MSB circuit wafer layout. |
Hard disk capacity: 2.5 inches capacities reach as high as 120G
Transmission connection: High speed USB2.0×1
High speed ethernet ×1
Movie broadcast support: MPEG1 (. Dat), MPEG2 (.MPG, .VOB), MPEG4 (.AVI, Divx).
Movie control: The broadcast, the suspension, the stop, enter quickly, enter quickly with the sound size adjustment
Movie video recording form: MPEG4 ASP
Phantom file support: JPEG
Music broadcast support: MP3 WAV
External connection output: AV out/in/enters the movie output to PAL or the NTSC television system
Three languages: Simplified Chinese/traditional Chinese/English
Power source: External power supply supply
Size: 13cm(L)×7cm(W)
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Chart 5:PCBA diagram. |
Whether the MSB product can accept very quickly for the market, the price certainly is a big key. At least, it has solved PMP “four vary does not have” the problem, namely the power is insufficient, is possibly refers to the battery endurance insufficient, various types solution compression possible strenuous, the LCD response is not smooth, MSB does not have this question very obviously; The picture is not clear, will be refers to the hand-held size kneading board, the picture nature, the resolution to be limited, watches will constrain somewhat with the sad feeling, obviously MSB will not also have this question; The insufficient small advantage, HDD PMP frequently 300 US dollars press up to PDA at present, but sale of the MSB is the retail market, the hard disk belongs to the post-sale market; Insufficient “intelligent”, is refers to the video frequency format conversion difficultly (e.g. DV-MPEG4), only the minority expert or plays the family to edit the use on the computer, but MSB has the code function, can (for example DV/VCD/VHS) the direct video recording compressed encoding into suit the broadcast from the simulation video the file and stores up; And not enough facilitates the movie content, is refers to suits the light-sized broadcast the phantom preparation and the arrangement is not easy generally, but MSB, since supports many kinds of video frequency forms, the resolution easy to reach as high as D1, enriched the content origin to support the dynamic phantom function naturally.
Next generation system specification consideration
As for the next generation MSB design development aspect, toward the direction which dexterous easy to carry pondered, if 2.5 inch HDD alters to 1.8 inch HDD, the power source changes built-, the LCD type and the size are the different people have different views, but should not be affects the selling price the key aspect.
In the MSB function has the simulated video “the direct video recording”, even enters the step to the high-end aircraft type “the appointment video recording”, in addition the television tuner function is a above the price in value! In addition, since the power source built-in has promoted the USB equipment to the OTG(On-The-Go) function, facilitates reads the memory stick (either the U plate) or the connection digit camera, how could it not be matching makes the database and the picture browser even more is an ultra function moves the companion equipment, this is fore-mentioned conformity technology all kinds of reason.
