EE Times Under the Hood - June 23, 2008 - (Page U54)

UTH0623COMP_pg42_55.qxd 6/12/08 5:38 PM Page 54 under the hood: w w w. e e t i m e s . c o m C OMPUT ERS & GAM I NG • w w w. t e c h o n l i n e . c o m $100 BOM eludes first OLPC laptop BY DAVID CAREY T he XO-1 is the first shipping design to emerge from the One Laptop per Child project, an interesting initiative blending laudable objectives with an effort to redefine the PC cost structure. The OLPC organization aims to provide the XO laptops to children of developing nations, in an effort to democratize technology for the long-term global good. couldn’t detect anything other than a fairly standard pixel stackup and construction vs. a standard transflectiveLCD construction. The RGB pixel filter arrangement does require some special addressing and dithering, but otherwise, we saw little evidence of a radical approach to the LCD. White LEDs are used for backlighting in transmissive mode. Fluorescent tubes have been the norm in backlighting for cost-sensitive panels of the size used in the OLPC, but perhaps power-efficiency considerations won out over cost here. Power savings a priority Certainly, reduced power consumption for the OLPC drove the reflectivemonochrome viewing mode. The guiding principle is that developing countries would often lack the energy sources to provide for frequent recharge or plugged-in operation. In a further effort to lower power draw, the Himax HX8837 LCD timing and controller chip allows the CPU to sleep without loss of the displayed image, for power savings. An image buffer for this device comes by way of an ESMT M12S16161A 2-Mbyte mobile SDRAM. In full-tilt operation, we observed power consumption of about 6 to 7 watts. The OLPC’s roughly 20-watt-hour LiFePO4 battery would thus supply up to three hours of operation in most-active use. Preliminary reports of real-world battery life peg the 10- to 12-hour runtime claim as far too optimistic, and The XO-1 is designed to be rugged and low in cost, using open-source software (for now) and solid-state memory instead of a traditional hard drive. Nevertheless, the design offers 802.11 wireless connectivity and features a dual-mode display; users can turn off the backlight to attain a sunlight-readable, reflective-monochrome-type screen. A VGA Web camera, internal microphone, dual speakers, Qwerty rubber keyboard, resistive-capacitive touchpad, three USB ports, external microphone and headphone jack are other traditional PC features. Adding cost, but increasing usability, the chassis of the XO is designed with a pivoting, reversible display that may be used in a tablet-PC or e-book format. Made in Taiwan While OLPC drove the design and specification of the box, Taiwanese OEM Quanta Computer is behind its detailed implementation and manufacturing. In final form, the XO-1 places the display and electronics in the swivel upper half, while the battery, keyboard, combo resistive-capacitive touchpad and little else live below. The arrangement runs a bit counter to the mainstream market, which usually places only the LCD panel above. The dual-mode LCD—supplied by AUO—is a curious bit of technology. Despite much talk of fancy diffraction gratings and other trickery to implement a combination color-backlit and monochrome-reflective display, we our data would tend to agree. The compute electronics of the XO are centered on the AMD Geode LX700 and AMD CS5536 companion device for I/O and bridge functions. The low-power chip set and solidstate memory contribute to the system’s ability to operate without the need for a fan. A single 1-Gbyte package of NAND flash—consisting of two SLC NAND dice at 512 Mbytes each from Hynix (the HY27UG088G5M device)—provides the operational equivalent of a hard drive, though it clearly falls well short of the normal expected nonvolatile storage of the traditional PC. Operating memory is provided by Hynix as well, in the form of four single-die packages of 64 Mbytes each (HY5DU121622CTP), for a total of 256 Mbytes—again, a bit thin compared with the mainstream but adequate for the task. The audio features are handled with an Analog Devices audio codec (AD1888) and stereo amplifier (SSM2302). The XO-1 creates its own mesh network. Each machine is a full-time wireless router, such that multiple Wi-Fi-capable OLPCs are made aware of one another and can route information across and through the mesh. Flip-up Wi-Fi antenna “ears” on the display’s edge do double duty as latches, holding the top and bottom halves together. Connectivity is provided by a Marvell solution on its own substrate: a 802.11 transceiver (88W8015) and 802.11 system-on-chip (88W8388), with a 16-kbyte E2PROM from STMicroelectronics (M95128). Marvell also provides the SD memory and camera controller solution. User input is accomplished with a membrane keyboard comprising two PET films and one elastomer keypad. 54 Electronic Engineering Times, TechOnline | June 23, 2008 http://www.eetimes.com http://www.techonline.com

Table of Contents Feed for the Digital Edition of Under the Hood - June 23, 2008

Under the Hood - June 23, 2008 Extreme Design: SuitSat Pushes Desigers' Limits Evolution of the Smart Phone Mature Devices get Rolly Rocking GPS: Garmin Nuvi 750 vs. HP iPaq 310 Inside the Sony OLED TV Multizone Dgital Audio Flip Ultra Camcorder - An Ode to Clean Design Robot Guitar Tunes Itself E-book is a Sight for Sore Eyes Scientific Calculator Boils Down to Two ICs $100 BOM Eludes First OLPC Laptop 45 nm: What Intel Didn't Tell You Next Step in NAND Flash Evolution Surveillance on a Shoestring Hot 3G Phone Owes Debt to Analog SecurID Fob: Single-Chip Safety Net

Under the Hood - June 23, 2008

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