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Anatomy of a cheap USB-to-Ethernet adapter

279 points| dshankar | 12 years ago |projectgus.com

74 comments

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[+] jrockway|12 years ago|reply
I appreciate the shielding Apple added, especially with two resonators in the HF band. The shielding is, BTW, probably to prevent the device from causing interference, not to prevent other devices from interfering with it. (It's not a radio, after all.)

Note that if you do choose to buy the cheaper one without any shielding, it's your responsibility (in the US) to prevent it from interfering with licensed users of the RF spectrum. (In this case, 25m shortwave broadcasters on 12MHz and government-run time-transfer services, like WWV and WWVH, on 25MHz.)

If your device is particularly annoying to some shortwave listener, expect to get a letter from the FCC telling you to shut the thing off.

(I looked up a few of the letters, and I really appreciate the politeness from the government: http://www.arrl.org/files/file/Part%2015%20Letters/04-06-24-... "There are several simple and inexpensive steps that can be taken to eliminate interference from battery chargers, and we would be glad to send them to you if needed.")

[+] streetnigga|12 years ago|reply
The complainant even provided the fix (Toroid cores, often seen as those lumps on USB cables) for free, installed and everything. In response the emitting neighbor went and...

"You apparently discarded the toroid devices, tossing them in Mr. (deleted) yard. The devices were simple and non-intrusive, and we can envision no reason whatsoever for you not to continue using them, other than a desire to be uncooperative."

Dabbling in RTL-SDR for a bit quickly brought me up against the interference monster, and since the USB sticks are typically powered by bus if no direct power modifications are done one of those sources of interference was hooked right into the receiver. Toroid cores either clipped on or looped were indeed the answer for quieting the cable. This doesn't help much if the interfering device is emitting really badly off the board itself though so manufactures shielding their devices as a standard is rather welcome.

[+] mdisraeli|12 years ago|reply
According to Bunnie's investigation into microSD cards[1], that low serial number probably indicates that the components were produced on a "ghost shift", when a rogue worker comes in at night and runs the plant off the books

[1] http://www.bunniestudios.com/blog/?page_id=1022

[+] selectodude|12 years ago|reply
I'm equally impressed by the Apple adapter. They make expensive stuff, but they legitimately don't cut corners. It's nice to see there's still one consumer electronics company that still does that.
[+] kps|12 years ago|reply
Right. They skimp on strain relief for esthetic rather than financial reasons.
[+] smackfu|12 years ago|reply
They don't cut corners on this kind of thing, but their version still probably costs $5 or less to manufacturer.
[+] fat0wl|12 years ago|reply
I guess it's nice to see that they put some thought into it but it still seems, well... over-engineered. If you are trying to be the monolith that your customers buy EVERYTHING from then you should be a little more realistic... nobody wants to shell out an extra $25 for a fancier chip with a little shielding.

It bugs me that Apple customers seem to get ripped off by their brand for simple things & then they thank them for it. I'm glad a 3rd party market for Apple stuff finally emerged. I remember the dark ages when you couldn't even tell your friend "check ebay I'm sure theres one of those..."

Part of the reason I am still in the PC world vs Mac (I build my own powerhouse desktops for research data-mining & gaming, buy cheap laptops for practical use) is that the multitude of companies making parts means they find the proper price/quality balance much more often.

I'm glad this author gives credit to the off-brand. I'm very impressed with the quality of cheap Chinese electronics, and if it breaks you have 8 or so more tries to get it right before you reach the same amount spent. & plus, let's face it the main problem with this stuff is that you lose it, not that it breaks so I have a tendency to sway way toward the cheaper end with non-essential cabling & components for that reason.

Inside my research PCs is a different story... no expense spared on CPU/GPU/drives/mobo/etc. :D

[+] Vecrios|12 years ago|reply
What do you mean by "[Apple] don't cut corners"? Serious question.
[+] userbinator|12 years ago|reply
The lack of shielding is rarely any problem. Two oscillators is not better than one, since PLLs can generate the required clocks (480MHz = 25 / 5 x 96, 100MHz = 25 x 4, 125MHz = 25 x 5); SMSC has some USB/Ethernet solutions that use the same 25MHz frequency.

> The Windows drivers are the exact same digitally signed ones that Microsoft distributes through Windows Update

AFAIK there is a standard device class for "USB ethernet controllers", so any chipset that conforms to it will work fine with the standard drivers.

As for the unmarked chip - many IC companies are not averse to creating custom designs for a specific customer (and marking it however you want) if you're willing to buy enough. I don't think it's ASIX since they don't have the single 25MHz clock source; more willing to bet on Microchip or SMSC.

[+] angusgr|12 years ago|reply
(Blog author here)

You're spot on about the PLL stage, a few people on Reddit pointed the same thing out when I first posted it. Makes sense, although I still think it's interesting they added it internally to an otherwise (apparently) cloned design.

You're also right that USB CDC does provide the option for a generic USB Ethernet device, however this silicon is ASIX-specific (not just the USB IDs.) ASIX's Windows drivers include their own system driver binaries, and the ASIX Linux driver has a lot of ASIX-specific stuff in it.

I think it's kind of possible ASIX made this themselves as some kind of no-name branded unadvertised market segmentation effort. I can't understand what their rationale would be exactly but hardware companies do unusual things sometimes...

[+] rsynnott|12 years ago|reply
> I don't think it's ASIX since they don't have the single 25MHz clock source; more willing to bet on Microchip or SMSC.

Note that it identifies itself to the system as ASIX, though. Of course, it could be that other companies actually have a license to make ASIX things...

[+] Tomdarkness|12 years ago|reply
I recently purchased a Gigabit ethernet adapter for my rMBP. If you're fine with something a bit larger and are willing to go above "dirt cheap" I'd strongly recommend the Inateck HBU3VL3-4. It's made by a German company so I'm not sure how available it is over in the USA.

It has an ASIX AX88179 which is a USB 3.0 to Gigabit chip and it my tests I was easily able to get around 800-900Mbps. It also has 3x USB 3.0 ports, so not only do you not lose your USB 3.0 port you gain 2 more. I've not dismantled it but it feels solidly built.

Here in the UK I paid the same price as the Apple USB to Ethernet Adapter, which is only 100BASE-T and offers no hub.

[+] rsynnott|12 years ago|reply
Note that Apple also make a Thunderbolt gigabit adaptor for the same price.
[+] gresrun|12 years ago|reply
We have used a similar dongle at our company for a 2nd ethernet adapter on our Foxconn-built boxes and found out that they usually don't have unique MAC addresses. This made our lives very difficult because Cobranet audio network uses level-2 addressing. We eventually found a supplier with real MAC addresses.
[+] userbinator|12 years ago|reply
You know it is usually pretty trivial to assign whatever MAC you want to them.

(I have an unbranded Android phone that assigns a random MAC address every time I turn WiFi on/off. Apparently this happens since they didn't bother to initialise the EEPROM and just left it at all zeroes. But this means being harder to track, so I consider it more a feature than a bug...)

[+] nitrogen|12 years ago|reply
Were you able to get reliable performance sending CobraNet over USB Ethernet adapters? I once wrote a simple audio recording program for the Linux console for diagnosing CobraNet issues, but haven't tried it over a USB adapter.
[+] analog31|12 years ago|reply
An old analog hacker rule of thumb is that if your product is going to emit RF, you'll find spurious RF on input and output terminals (including ground terminals), which you can check with a scope. Such a pre-test is cheaper than getting a field test done and failing.

The scope test might be do-able on a comparison basis between the two designs. It's possible that Apple over-engineered their shielding.

It's not necessarily a cloned design. The cheap part may simply implement standard protocols, and use the name of the Apple part to ensure driver compatibility without too much testing. Still, that seems rather under-handed if it's what it seems.

[+] catch23|12 years ago|reply
Good article. It reminds me of the stories Wozniak would tell about his chip reduction techniques back when microchips were really expensive.
[+] Eduardo3rd|12 years ago|reply
OP isn't alone - I find these parts dissections fascinating as well. Posts like these show you how and why hardware is becoming a comodity. It's going to be a very interesting century.
[+] aroch|12 years ago|reply
>I’d love to learn more about these secretive industries and the engineers who work in them.

Isn't it pretty well known that 1) they aren't secretive and 2) they don't actually design their own hardware. They start off by producing the legitimate item, in the factory that's contracted by the company who designed the product. If the product is successful or easily fits in their existing knockoff fabs, they plans are basically copied over

[+] gbog|12 years ago|reply
They aren't secretive, but they are hungry, and they are foolish.

I'd venture the shanzhai chinese geeks fiddling relentlessly with hardware in Guangzhou are much closer to Steve Jobs' ideal than the average Apple Store clients.

On one side you have rich kids who can afford a $30 dongle, knowing perfectly (after reading this article) that they are giving away $25 to a marketing department and that they are bowing to their own voodooish cargo cult. These guys are simply afraid of the remote possibility of having to spend 5 mn of their precious time checking a connection, and maybe too, something really catastrophic! lose ONE of their 10.000 instagram pizza photos because of a subpar component in their setup.

On the other side you have these ugly hackers who are photocopying hardware components for 1 year old companies named Yunxingdianziguangzhoujituanyouxiangongsi, and their logo is ugly, and these guys are Chinese! I know them: they are hungry, not only hungry for money, but also hungry for knowledge, recognition, they are curious about the world, about the future, and they have no fear for bad taste: a pink iPhone clone with teddy bear shape? check!

[+] wtallis|12 years ago|reply
While that does happen, not all knockoffs are just counterfeits made to the approximate specs of the original. There are a ton of knockoffs that have radically different internals that required significant engineering effort to design.
[+] chockablock|12 years ago|reply
The example in the article is of a functional cloned part that has half as many pins, and needs only 1 external oscillator instead of 2.

Author does not decap the chip, but the implication is that there was indeed some real engineering that went into the design of the clone.

[+] rsynnott|12 years ago|reply
This part pretty clearly isn't a knockoff, though; it's a version made cheap almost to the limits of practicality (or maybe beyond, if you care about producing radio interference) through design changes.
[+] naner|12 years ago|reply
We use a ton of USB adapters where I work and are using them all day long with several different systems. A few months ago we got a batch of cheap adapters and one noticeable difference was the cheap ones get really hot compared to the more expensive name brand adapters. Appear to work OK, though.
[+] chenster|12 years ago|reply
Very interesting study. Somehow in the back of my head, it still whispers "You get what you paid for".
[+] kalleboo|12 years ago|reply
It's just a shame that it looks like your options are paying $3 for a part that cost $2 to make, or $30 for a part that cost $6 to make
[+] rahimnathwani|12 years ago|reply
The taobao link in the original post leads to a listing which does not specify the chipset or support for Mac. This suggests it's a cheaper chipset. The 4-5 best-selling cheap USB-to-Ethernet adapters on taobao use the RD9700 chipset, and can be had for 22RMB including shipping.

The cheapest Asix 88772-based one I can find from a reliable seller is 25RMB including shipping.

It seems like there is another 50 cents that can be cut from the design, although the RD9700 may not have an OSX driver: http://forums.macrumors.com/showthread.php?t=1450026

[+] userbinator|12 years ago|reply
The RD9700 is "USB 2.0" and what they don't tell you is that it's actallly "USB 2.0 (FS)", i.e. the 12Mbps full speed mode.

It also comes in a 32-pin package, and comes from a shady-looking company (http://www.corechip-sz.com/ ) that has parts numbered 6872 and 6873, so the "RD6877" on the PCB of OP's clone suggests it might be a RD6877.

[+] 14113|12 years ago|reply
This is interesting - and more importantly, is there any part of the ethernet standard they don't support? I only ask, as at my university there were a number of networks that students simply couldn't connect to if they used any ethernet adaptors. Oddly enough, thunderbolt adaptors, and ethernet on the motherboard worked fine, just USB adaptors didn't work.
[+] nknighthb|12 years ago|reply
There have been times in the past when I've found almost every USB ethernet adapter available on the market to be of a single chipset. If one very common chip at that time had a poor interaction with your school's switches, boom.

Most of the time, the cheap no-name electronics I've encountered have been pretty feature-complete, or even feature-laden, and any bugs were usually minor annoyances rather than fatal flaws.

But the quality control is a crapshoot, so a good chunk of them tend to be DOA. Of the ones that work fine at the start, many will fail in the following weeks, months, and years at much higher rates than you'd expect.

[+] rhizome|12 years ago|reply
once upon a time there were chipsets that didn't play well with autonegotiated switch ports.
[+] hafflelog|12 years ago|reply
If there is a part of the standard they don't support, it's a bug in the component.
[+] bane|12 years ago|reply
Great writeup.

So I guess the question is, is the one with the fruit on it worth $25 more? It seems like the cheap one is more "Wozniak" in approach.

[+] EpicEng|12 years ago|reply
The problems I have run into with the cheap versions of hardware like this is that they tend to fall apart. For example, my last mini-DVI to HDMI adapter performed just fine... until the glue holding the female end in broke loose. I glued it back, and then the plastic started to crack.

The guts of it (the electrical bits) looked fine, worked properly, etc. It was the mechanical design that gave me problems. Replaced it with a (ridiculously expensive at $29.99) higher end version and that has lasted me quite some time.

[+] rsynnott|12 years ago|reply
Well, note that the cheap one is somewhat slower in the iPerf test (though, for the sorts of things people use ultra-cheap ethernet adaptors for, this would rarely matter). Also, while I'm not sure if it's the case for this one, a lot of ultra-cheap network hardware has the same MAC address for _every device in existence_, which can cause entertaining issues.
[+] noonespecial|12 years ago|reply
The cheap one: looks like we're running without containment, just not enough to cook us.
[+] chrislaco|12 years ago|reply
Anyone done a writeup like this, but for mdp -> dvi adapters... Apple vs Monoprice, etc?
[+] chockablock|12 years ago|reply
Mini DisplayPort -> single-link DVI-D is just a passive cable adapter, so a lot harder to screw up.

(And even less reason for it to cost $29, but that seems to be Apple's default minimum price for an accessory.)

[+] mariuolo|12 years ago|reply
Love that blog, thanks for pointing me at it.