Other primary ICs that also inhabit that same side of the digital PCB include a Wolfson Microelectronics audio codec (the same one as in the iPod nano, according to SEMIconductor Insights) above the ARM CPU, power-management ICs from Linear Technology (below the ARM CPU) and NXP (the Apple-labeled IC in the bottom left corner of the PCB, according to Portelligent), a National Semiconductor Mobile Pixel Link transmitter between the CPU and NAND-flash Chip, and a Texas Instruments LCD boost converter between the accelerometer and MPL transmitter. The digital board's other side is dominated by the SIM Card connector, but it also houses a diminutive 1-Mbyte parallel-interface SST flash memory, which probably acts as the ARM CPU's boot device.
The iPhone's RF board is similarly jam-PACked with ICs, this time concentrated on one side of the PCB (albeit with discrete components scattered across both sides). Chips you'll find on it include an Infineon GSM/EDGE RF transceiver on the right side of the PCB, a companion Skyworks power amplifier (lower-right corner), an Epcos transmit/receive duplexer (lower left corner), a Marvell 802.11b/g Wi-Fi transceiver on the left side of the PCB, a Bluetooth transceiver from Cambridge SILicon Radio just above the Skyworks IC, an Infineon cellular-baseband processor in the PCB's upper left corner, and an Intel-labeled single-package, two-die memory stack in the upper right corner of the PCB. This final device contains volatile memory and 32 Mbits of NOR flash memory. Ah yes, there's that "volatile memory" term again. As before, Semiconductor Insights says that it's SRAM, whereas Portelligent insists that it's DRAM, specifically PSRAM (self-refresh, low-power DRAM with an SRAM-like system interface).
For completeness, I'll wrap up by showing you some of the other images Portelligent provided (they don't have much semiconductor content, but they'll likely still be of interest to at least some of you):
* The front and back sides of the docking connector assembly wiring harness
* The front and back sides of the wiring harness containing the iPhone 's ambient light and proximity sensors; the former controls the LCD backlight and the latter dISAbles the display and touchscreen when you place the iPhone close to your ear.
* The front and back sides of the wiring harness containing controls for power on/off, volume up/down, and ringer mute, along with a headphone/mICrophone jack and the vibration unit.
Three aspects of the iPhone's design are particularly intriguing to me, aside from my general admiration of its elegance and high degree of integration:
* The NAND-versus-NOR memory- ARC hitecture argument has b
een a long one, waged in public forums and private customer meeting rooms alike. Apple's stance on the debate, at least as exemplified on this device, is "both." As with a PC's HDD, NAND-flash memory stores the majority of the Mac OS X operating system code (which Apple has recompiLED and otherwise adapted to run on ARM ; if there's any doubt in your mind, this link will likely dash your disbelief), along with music tracks, video clips, and other nonvolatile stored data. System-boot code, as with a PC's BIOS Chip, resides on NOR-flash memory. In fact, the iPhone has two distinct NOR-flash devices, one each on the digital and RF boards, respectively feeding the ARM applications processor and the Infineon baseband processor.
* Speaking of ARM, its presence in the iPhone is quite impressive. Count the number of ARM processors in the device, both standalone (two) and integrated as cores within other chips; the 802.11 transceiver, perhaps, or the Infineon baseband processor. And what of the Bluetooth transceiver? See here for more ARM-everywhere system architecture thoughts from EDN's Ron Wilson.
* And speaking of multiple processors per system, here's an area where the iPhone is very unlike a PC (at least until recently, with the emergence of the GPU as a credible general-purpose coprocessor). Multiple CPU cores in the iPhone subdivide the total task and tackle different roles. The system CAN selectively slow-cLOCk them or even power them off when not in use, to save power. Contrast this system architecture approach with Intel's past ARM-based XScale efforts, wherein the company (unsuCCessfully, by and large) adVOCated a single fast CPU core for all system functions. More generally, note that whereas the ARM cores do contain hardware-acceleration logic blocks (for Java processing, for example, which the iPhone doesn't currently support…hmmm) the iPhone is fundamentally a SOFtware-fueled machine. Apple's engineers seem to have made the conscious choice not to generally rely on hardwired circuits, which arguably deliver higher performance at lower power consumption than their software-based counterparts, but at the critical tradeoff of greatly diminished current (and future) function flexibility.
I'll wrap up with one final reference, which in answering a critical question (to at least one kitchen-eQUIPment manufacturer and its potential customers, I guess), also serves as perhaps the ultimate Prying Eyes exercise. Before proceeding, I'll warn those of you with fiscally squeamish constitutions that you may not want to click on the link. That's right, folks, Will It Blend?
上一篇：IPTV承载网解决方案探讨
