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On Sun, 22 Jul 2012, Grant Phillips-Sewell wrote:
My brother has asked if I could have a look into tiny powered USB hubs and tiny USB WiFi adapters for his RPi - he isn't (yet) much into Linux and would prefer something that *just works* (ie no need to download kernel drivers, firmwares, etc... just plug in and configure). Ordinarily this wouldn't necessarily be a big problem, but with the added ARMness of the RPi, and the disparity between what works on the different architecture's kernels, this could potentially make things a bit more awkward. Add to that the fact that I don't have an RPi to play with! :D Now, I have found one "tiny" USB adapter which works, but requires a bit of messing around (which he's not really happy doing). As far as the powered hubs are concerned, I really haven't a clue. I was under the impression that a powered USB hub was a powered USB hub - I didn't know there was a real difference between them. Anyone got any thoughts or comments?
I've not used Wi-Fi on a Pi, however I've been chatting to many who have...
The USB ports on the Pi are limited to a maximum of 140mA each (via a self-resetting polyfuse) and it's my understanding that a lot of Wi-Fi adapters will require more than this... So, some people have been bypassing the polyfuses on the USB ports and running wires directly from the power in to the USB sockets...
USB hubs - I use one, a LOGIK one with a 2A PSU. It's powering one of my Pi's. I've also powered Pis from my Acer Aspire One laptop, my desktop, and a couple of phone/bluetooth headset chargers. I appear to be lucky as I've had no power issues whatsoever. My LOGIK hub has even powered 2 Pis at once.
One issue with hubs is that USB is only supposed to allow up to 100mA without power negotiation, then up to 500mA - the Pi doesn't have the hardware/software to do power negotiation - neither does my laptop, desktop, nor the powered hub I have... So much for standards.... So it's conceviable that if your powering a Pi off a hub and the hub is actually obeying the standards it won't give the Pi enough juice to boot...
Wi-Fi is of-course tricky to get going at the best of times - hard in console/text mode, but I've not had any issues with Wicd under X on my Laptops...
Gordon -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/listfaq