Some commenters seem to claim theyve used it for Ethernet access but I dont see how unless there are multiple products being shipped from the same SKU.The Apple adapter measured throughput of 94.3Mbps.The cheap adapter measured 87.4Mbps.By comparison, the builtin ethernet on my laptop measured 94.8Mbps (after being set from gigabit to 100Mbps.).
It might even be a brand new ASIC, created from scratch to be compatible. The Apple adapter has two TXC brand oscillators (the shiny silver packages.) These cost around 1.33 each if you buy 15,000 4. This wholesale cost alone is nearly the retail price of the cheap adapter on taobao.com. I checked the reference schematic for ASIXs Demoboard and hes right. Thanks Gerard So the cheapest ones they could be are around 0.40 each ( 12MHz 25MHz ), the cheaper boards single crystal is then closer to 20 of the cost. Without a high speed oscilloscope or a USB 2.0 logic analyser itd be hard to tell how well this goes at meeting the 480MHz -500ppm requirement of the USB High Speed spec. ASIX themselves warn that if their precision 12MHz clock source has an incorrect capacitor it can cause some problem during USB High Speed mode enumeration. ![]() ![]() For the cheap adapter design, every fraction of a cent saved is important. The Apple adapter actually has a space on the PCB for this, but no LED in place (Apples designers presumably nixed it for aesthetic reasons.) Im surprised the manufacturer paid the few cents to add this feature. Rd9700 Usb2.0 To Fast Ethernet Adapter Air Drivers For WindowsThe CD that came with the cheap adapter contains ASIXs own drivers for Windows and OS X. Something the actual device manufacturer surely couldnt have afforded. I ran an eight hour two-way ping flood (assuring plenty of collisions) with zero lost packets. The Apple adapter is protected from an electrically noisy environment by its metal shielding, and extra decoupling capacitors on the board. Its possible the protocols are well engineered enough that youll never notice the difference. So far I havent found any (I tested some of the uncommon features like forcing 10Mbps, forcing half duplex, adjusting MTU.) Id be interested to hear of any, though. Im fascinated that someone is out there redesigning existing silicon to make a knockoff that is smaller, cheaper but otherwise near-equivalent to be used in devices that retail for less than 3. ![]() Not the same oscillators but the same brand, meeting the spec that ASIX requires: 25MHz 12MHz. Of course both Apple and our noname manufacturer would pay less than Digikeys prices, but it gives you some idea. I think the Linux kernel could know the raw USB bit error rate, giving some idea of how precise the timing was, but the kernel doesnt record it anywhere Assuming you can ignore copyright law, and have no qualms about reproducing other companies intellectual property for profit. Shouldnt be any farther off than the crystal is otherwise though jitter might be an issue. There is another set of listings (even cheaper still) advertising ones that only work with Windows 2000,XP Vista.
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