Friday, 17 August 2012

Instant wifi - just add "Edimax EW-7811UN"

Archimedes could use one of these with a pivot
Ah, the 3Com OfficeConnect 3CRUSB10075. I remember it well...

About five years ago this would have been sold as a USB wifi adaptor, though its actual purpose was more to test the structural integrity of laptop USB ports. Extending no less than three inches, it was also cleverly more than an inch wide - providing the added bonus of preventing laptops with vertical USB ports from sitting flat.

Slightly larger than the average car's indicator controls, and also slightly easier to hit, it was close to guaranteed that at some point *something* would strike the OfficeConnect a lateral blow, resulting in  two goodly sized pieces of grey plastic, one still securely connected to the USB port.

Of course the unlucky would find themselves with one very large piece of plastic, still securely connected to your USB port, and a usb sized hole in the side of the laptop.

For mild amusement, I plugged it into my Thinkpad (after turning the laptop on its opposing side, then using both hands and alignment rails to guide it into place) and NetBSD's dmesg blurted out:
zyd0 at uhub3 port 1
zyd0: 3COM 3CRUSB10075, rev 2.00/43.30, addr 2
zyd0: HMAC ZD1211, FW 46.05, RF RFMD, PA 0, address 00:0f:cb:c0:8c:d6
zyd0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
zyd0: 11g rates: 1Mbps 2Mbps 5.5Mbps 11Mbps 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
If I recall it even came with a cap - which itself was around three times the size of the other USB wifi adaptor in the picture - an Edimax EW-7811UN.
For the princely sum of GBP8.95 delivered this diminutive device provides wifi connectivity without significantly adjusting your machine's centre of gravity:
urtwn0: Realtek 802.11n WLAN Adapter, rev 2.00/2.00, addr 2
urtwn0: MAC/BB RTL8188CUS, RF 6052 1T1R, address 80:1f:02:61:13:b0
urtwn0: 1 rx pipe, 2 tx pipes
urtwn0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
urtwn0: 11g rates: 1Mbps 2Mbps 5.5Mbps 11Mbps 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
I had hoped to provide some benchmarks between the two USB devices and my Thinkpad's built in Intel PRO/Wireless 5100 AGN:
iwn0 at pci3 dev 0 function 0: vendor 0x8086 product 0x4237 (rev. 0x00)
iwn0: interrupting at ioapic0 pin 17
iwn0: MIMO 1T2R, MoW, address 00:16:ea:c5:bb:10
iwn0: 11a rates: 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
iwn0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
iwn0: 11g rates: 1Mbps 2Mbps 5.5Mbps 11Mbps 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
... but unfortunately the OfficeConnect appears to no longer be able to associate with my WPA2 network. Possibly some of its valves have worn out, or maybe a small family of mice have set up residence inside - I would shake it to see if it rattles but I fear I might put my back out...

For reference the PRO/Wireless 5100 reported ttcp rates of 17.2 Mbit/sec send and 16.9 Mbit/sec receive, while the Edimax managed 12.7 Mbit/sec and 12.2 Mbit/sec.

Not earth shattering, but not too bad either.

So what prompted this trip down "USB wifi adaptors the size of vinyl records" memory lane? Someone on a mailing list was running NetBSD on a macbook and it wasn't recognising the wifi. I suggested trying a nano USB wifi dongle, but I wanted to recommend one that worked - so I bought one to see it work.

In the process I found out that while NetBSD-current included the urtwn driver and the firmware, NetBSD-6 BETA2 only had the driver and required a manual download of the firmware, so I submitted a pullup request to get the firmware into the NetBSD-6 release - its always nice to have stuff work Out Of the Box :)

About the only thing bad I could have to say about the Edimax is its use of one of those violently blue LEDs - you know the one's suitable for landing aircraft in heavy fog or signalling direct to the Curiosity rover on Mars. It doesn't have any gaps or transparency in the case - the LED just shines directly through the black plastic (and I suspect the metal USB plug if it was far enough out of the machine).

(some time elapses, as it does)

Now *that* is interesting... in a "random profanity and threatening of inanimate objects" sort of way...

Presumably the OfficeConnect did not appreciate my less than glowing comments about it - that, or possibly because I forgot to use the correct guide rails and block-and-tackle to remove it from the machine - when I unplugged it my laptop hung for a moment and then rebooted.

More deserving of the profanity however, on reboot the laptop hung when probing the CPU. Repeated. Powered off, leaving for a minute and back on and it *still* hung on probing the CPU. Eventually I removed the battery and power cable, held the power button down for 30 seconds, then reassembled and successfully booted.

So it appears the OfficeConnect is capable of deranging the USB hardware on a Thinkpad sufficiently well to require a complete disconnection and draining of all power. Handy... if you like the sensation (albeit briefly) of all blood draining from your face as you consider the prospect of your laptop having just been completely fried.

Things you would prefer not to fall out of your battery
As an added bonus, when I removed the battery I found myself in possession of a small spring and broken black plastic tag, which appear to have fallen out of the battery.

It could be a subtle suggestion that its time to replace the battery, or a somewhat less subtle hint that I really should drop the Thinkpad less..

Anyway, that concludes today's "Fun With WiFi And NetBSD" - and today's top hints are:
  • Edimax make a cheap and usable tiny wifi adaptor
  • If you have an old wifi adaptor large enough use as furniture, just carefully dispose of it
  • While repeatedly dropping a Thinkpad may make it gradually lighter over time, its not a good idea

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