From mboxrd@z Thu Jan 1 00:00:00 1970 To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> In-reply-to: Your message of "Fri, 28 Feb 2014 09:45:42 EST." References: <199A32F6-9C38-45B8-B191-CAE2B1972408@orthanc.ca> Date: Fri, 28 Feb 2014 08:24:49 -0800 From: Bakul Shah Message-Id: <20140228162449.BB1BFB827@mail.bitblocks.com> Subject: Re: [9fans] Raspberry Pi: won't recognize the USB mouse Topicbox-Message-UUID: bf7ba96c-ead8-11e9-9d60-3106f5b1d025 On Fri, 28 Feb 2014 09:45:42 EST Anthony Sorace 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!