Under the Hood: Apple for the living room - Embedded.com

Under the Hood: Apple for the living room


Having conquered the market for portable media players, Apple marches on toward the living room. Apple's computers remain a distant second in market share to the Windows-powered PC (though they've shown some recent strength), but the iPod has won its product category hands down. Now Apple, having stripped “Computer” out of its name, is targeting wireless distribution to the home via the Apple TV (A-TV). The goal is to move digital media from the “lean forward” world of the computer to the “lean back” environment of the home television. The irony is that the Apple uses a pared-down computer to get there.

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Characteristically, Apple's setup instructions for the A-TV are dead simple: “Download, synch, watch.” I haven't yet tried the A-TV, but other experience with the company's goods would suggest that the startup process is as relatively pain-free as promised.

The box itself measures a modest 197 mm x 197 mm x 28 mm, so no major real estate will get consumed in anyone's home theater setup. An I/O panel on the back of the unit sprouts connectors for Ethernet, a hobbled USB interface, a High Definition Multimedia Interface (HDMI), component video, RCA-jack audio and optical audio, while the front panel has only a small window for the infrared remote control. The A-TV adheres to the industrial design aesthetic evident in such other Apple products as Airport Extreme and the Mac Mini.

The platform uses 802.11g or 802.11n wireless to handle the transfer of movie files from the iTunes environment. Of course, it requires that the host computer with iTunes have the same wireless support, though 10/100-Mbit/second Ethernet is available as a wired alternative for connectivity. It's worth noting that the iTunes requirement here does not necessarily mean an Apple computer must be used, since iTunes works with both the Mac and Windows OS.

Unlike some other Apple products, the A-TV was easy enough to open, with corner Torx-head screws tucked underneath the adhesively attached rubber anti-skid bottom surface.

A 40-Gbyte 2.5-inch hard drive is bolted to the floor panel of the A-TV, serving as the mass storage for holding local copies of iTunes content. A Fujitsu MHW2040AT was used in the unit analyzed here, but multisourcing would leave other vendor options available to Apple given the seemingly generic nature of the drive. Indeed, outside of Apple, clever entrepreneurial types have already started offering disk swaps to increase storage capacity, further supporting the notion of a standard hard drive interface.

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The electronics in the A-TV consist of a single “motherboard,” an 802.11a/ b/ g/n plug-in daughtercard and a power supply brick assembly to convert the 120-Vac input to a 5-Vdc (7.2-amp) supply rail. The use of the term motherboard is fitting here because, in many respects, the A-TV is really a connected PC. Despite the A-TV's focus on a media adapter function, the component set is really a scaled-down computer, with a CPU, graphics adapter, I/O controller, memory hub and ports for Ethernet, Wi-Fi and USB.

Intel inside
As for the suppliers of those key “hidden PC” functions, the CPU comes from Intel, in a move consistent with Apple's recent migration to that company's processor elsewhere in its computer lineup. Given the A-TV's use of an OSX operating system derivative, the CPU selection here is of little surprise. While the part number etched on the Intel die (7645A966) does not provide a lead to a specific Intel part number, others have concluded that the component is Intel's Crofton variant of the Pentium-M family, running at 1 GHz. Dedicated hackers (you folks are amazing!) have already devised ways to boot a full-blown OSX and run the A-TV as an ordinary Apple computer, albeit with modest horsepower.

The I/O controller also is provided by Intel, in the form of the PC82801, joining up with the Intel QG82945 graphics/memory hub controller. The GHMC is coupled to four Nanya 64-Mbyte DDR2 memory chips (again almost certainly interchangeable with other manufacturers' chips) for a total of 256 Mbytes of system memory. The Intel I/O chip interfaces with the hard drive, a USB controller from Cypress Semiconductor (the CY7C63823) and a 10/100-Mbit/s Ethernet controller from Realtek (the RTL8100C). While the USB port is nominally restricted to use for diagnostics, the hacker community has devised workarounds to open up the USB port to accept mice, keyboards and other USB peripherals.

Nvidiaprovides the graphics processor: the GeForce 7300, supported by 64 Mbytes of graphics memory in the form of two 32-Mbyte of Graphics DDR3 SDRAMs from Samsung(K4J55323QG). The Nvidia chip handles all of the video processing and scaling between native iTunes video and the 1080i 60/50-Hz, 720p 60/50-Hz, 576p 50-Hz (PAL format) or 480p 60-Hz output options.

While the Nvidia chip handles output to the A-TV's composite video jacks, a separate Silicon Image SiI1930 chip provides interface to the HDMI output option. Audio support comes from a Realtek ALC885 audio codec; that device, with a small amplifier, drives the stereo audio ports.

A clock generator from Cypress (CY28445), an Intel-specific power controller from Intersil (ISL6218) and a small microcontroller from Silicon Storage Technology (SST89V54RD2) join with various smaller-scale power management and memory components to complete the major motherboard component set.

The 802.11 Wi-Fi adapter card is a plug-in module–perhaps a surprising decision, since motherboard-based placement could have allowed a pinch of cost reduction. Technical as well as business issues may have driven the decision to keep the function separate.

Isolating the wireless function potentially allows the wireless card to be multisourced. While saving a connector and a few parts may reduce cost locally, the impact of potential competition can work wonders in improving overall vendor pricing on a much larger scale.

A technical benefit of the Wi-Fi daughtercard is simply the ability to upgrade the wireless functionality independently of the balance of the A-TV design. But this has a business-oriented upside as well, given Apple's penchant for secrecy.

On the fast-moving wireless front, the next big thing can come along in a hurry. If a separate Wi-Fi module is used, only that module needs FCC certification–along with the requisite early visibility in component makeup. Thus, the FCC certification documents would reveal the attributes of the wireless connection only; the Apple TV's full makeup would be known only after launch.

The Wi-Fi module here is based on a two-chip solution from Broadcom in which the BCM4321 baseband/MAC chip joins up with the BCM2055 transceiver. Much of the technical complexity and multiband diversity of the RF front end is hidden within SiGe Semiconductor's SE2545A front end, which uses multichip packaging to bring in two dual-band transmit/receive chains, power amplifiers, power detectors, switches, diplexers and matching.

The A-TV takes an important next step in Apple's desire to become a bigger part of home infotainment. As the analysis here and hacker efforts elsewhere have shown, the Apple TV is essentially another Mac, stepped down in performance to meet the needs of a wireless media adapter.

It's too early to tell whether the intended consumers will embrace the media distribution model on which the A-TV is based. In the meantime, the technologically adventuresome have another toy to play with–provided they're willing to void their warranty.

David Carey is president of Portelligent (www.teardown.com). The Austin, Texas, company produces teardown reports and related industry research on wireless, mobile and personal electronics.

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