Re: [9fans] Raspberry Pi: won't recognize the USB mouse

[Bakul Shah <bakul@bitblocks.com>]

On Fri, 28 Feb 2014 09:45:42 EST Anthony Sorace <a@9srv.net> wrote:
>
> Based on my own experience with USB weirdness with the Pi, I still suspec
> power issues. How are you powering the Pi itself? Using a 1 amp supply yielded
> problems, regardless of the sort of hub I had, which all went away when I
> switched to a 2 amp supply. I'm told the second generation of these boards are
> a bit better on that regard, but I don't have any to test.

The RasPi FAQ suggest 1.2A or more. In rev 2 they replaced two
current limiting polyfuses with shunts so you can use a a
powered hub or connect periphs requiring > 100mA.

The RasPi wastes a lot of power. Its processor require 1.8V
and only the USB requires 5V.  For battery powered use people
have tried a number of tricks to reduce power use: replace the
onboard linear reg. with a switcher or two, tie 5V + 3.3V
together and only use a USB periphs that runs on 3.3V & use
model A Raspi -- the ethernet chip on model B draws a lot of
power even when idle and you don't need it for wifi.
Apparently Ralink RT5370 basedt cheapo wifi dongles can run on
3.3V.

For robotics use we need a usb wifi driver!