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Current revision as of 13:17, 29 November 2007
Hardware Design Process
Designing hardware is much more constrained than software; while you may sometimes have great influence on the design of a chip many months in advance of availablility, you can only actually use chips which you can get in the volumes required at prices that you can afford. Even a single missing component, or component not available in the quantities you need, may cripple your production. Many in the software community, who are used to more fluid ability to modify design and produce in unlimited copies, find this a foreign concept.
Designing hardware is similar to making sausage: you may be able to grow new ingredients starting long in advance if you are friendly with farmers (chip designers). You can only make your sausage, however, with the ingredients required by your recipe that you can actually buy in the volume you need to manufacture. Sometimes you can substitute ingredients without spoiling the general recipe, and sometimes the result would be inedible. In this case, we have a single chip that Mark Foster is specifying, that sits between the CPU and the display, and over which we have detailed control.
If you'd like some insight into this process, you can look at older versions of this page in the wiki.
High-Volume Design and Manufacturing
Furthermore, production of high-volume hardware is now a very specialized business, and is now often joint between the organization/company that specifies what the hardware should do—often to the point of selection of major and minor components—and an ODM (original device manufacturer), which specializes in very high-volume design and production. The ODM generally does the detailed design for production; e.g., exact part selection if there are variants, schematics, layout, board routing, mechanical design, testing, debugging for production, logistics, and production of the finished goods.
In OLPC's case, the ODM is Quanta, as announced in mid December. There is a good chance that your laptop was manufactured by Quanta, headed by Barry Lam, which is possibly the largest company few people have heard of. Quanta manufactures more laptops than any other company in the world (almost 1/3rd of the total made), whether branded HP or Apple or others. Detailed design of the first production OLPC design is just starting, though OLPC has investigated (and continues to investigate) the possible components and other design tradeoffs.
Note that CPU chip manufacturers generally provide sample designs, development boards, and application notes, that are often complete and usable by themselves, though often include interfaces or hardware you might not choose in volume production. These clarify how their products might be "designed in" to actual products. Our prototype machine seen at Tunis was using one of the AMD "Rumba" boards. It approximated much of the first OLPC hardware, though used a conventional disk rather than NAND flash, and has components we will not use (e.g. ethernet), and that conceptual (but working) model lacked the much cheaper flat panel that is under development.
Detailed schematics and layouts of such sample AMD designs are generally available in the chip manufacturer's developer programs. If you are interested in exact design details of hardware you can get for immediate experimentation, we direct your attention to these programs, which generally include the ability to buy such sample hardware. Most of the information required to program devices, however, is completely freely available at the manufacturer's web sites in fully public specifications.
In concert with ODMs, such sample designs are generally customized to fit the exact product needs and engineered for high-volume-production tooling and techniques that are not applicable to low-volume development-board runs. OLPC has just entered in partnership with Quanta on this engineering-for-production phase of the project .
Detailed schematics and board layouts of these high-volume designs are often considered proprietary to the ODM's, or jointly owned by both parties involved. They represent the competitive advantage one ODM may have with its rivals (who may have access to the same components as they do). Those design schematics are sometimes available to programmers after production starts under NDA agreements; for example, schematics of many of the iPAQ handhelds were made available to programmers in the open-source community under NDA, when insufficient written programming information was available. OLPC will try to document our designs sufficiently to avoid NDAs; we expect this will be less effort than the logistics of requiring NDAs in such a large and diverse community.
Currently we can foresee three generations of machines: a first one to ship in mid 2007.
Subsequent OLPC designs may use components that have not yet been shipped by their manufacturer, and we often will arrange a program whereby the open source community can get early access to specifications of those components for driver development.
We also can anticipate future display technologies such as E-Ink, though such displays are still cloudy in the crystal ball.
We will try to keep this specification up to date as more and more details of the first design (and subsequent designs) are nailed down, provide links to specifications for the chosen components, and provide information required to program them (e.g. address space assignments).
The first generation design uses already available components, with the (major) exception of the new flat panel and the chip that drives it, and we expect a novel bi-modal touch pad, and a ASIC to interface NAND flash, SD and a camera.
The electrical interface to the flat panel and the LCD panel itself is now in detailed engineering. A family of flat panels all based on a common LCD panel, but differing on their use of color filters, what kinds of backlights or temporal color, which have different properties (power consumption, resolution, gamut) and risks will be built in the future, the initial display panel uses color filters and works extremely well, and does not require TFT process changes for manufacturing.
Several other designs are higher risk, but better performance, either on effective resolution or power consumption. It we will initially use this low risk panel and may phase in one of the alternatives to manufacturing later in 2007 or 2008. 3M is building specialized plastic optical components being used in the design of these displays.