I ment to send this to the whole list earlier but accidentally only sent it to one person.

Has the idea come up yet of having a single plug, on the N3 with two wires coming out of it, one would plug into USB, the other into a wall socket?  I realize that this might seem annoying as a concept, but I do have a couple of smaller devices that do this.  Notably, my Sony Clie.  This should use less space on the neuros than having two plugs and would not require the USB to pump out a full 500mA.  This would also allow the neuros to charge without the computer being on and even be able to charge without a computer at all without an additional power adapter.

-Nate

On 10/5/05, Joe Born <jborn@neurosaudio.com> wrote:
Definitely a valid concern.  Ultimately, you can't really count on a PC or hub for anything more than a trickle charge, but in practice, it seems pretty rare that it won't provide at least enough juice to run a 2.5" external harddrive.  I know that from experience with the vDrive, I haven't yet come across a computer that wouldn't power it (and it has no battery so there's no cheating).
 
Joe
-----Original Message-----
From: Dragon Wisard [mailto:dragonwisard@gmail.com]
Sent: Wednesday, October 05, 2005 9:13 PM
To: Joe Born
Subject: Re: [Neuros 442 Linux Main] USB jack as power plug for N3 and 442-320?

Does each device get a full 500mA or is that for the entire bus? I've had power issues with USB devices when I have two USB-powered devices on the same unpowered hub or, on some computers, if they are plug in next to each other in the back. And some usb dongles don't work on the front of some comptuers because apparently not all PCs provide enough power to the front USB ports. Does any of this sound like a reasonable concern?


On 10/5/05, Joe Born <jborn@neurosaudio.com> wrote:
well, that's good, but what about draining more from a special wall wart that we design (or buy or whatever)?  In other words, if it's a hub or PC, we request 500mA and we take whatever it provides.  If it's a wall wart, we get 1A or whatever.  Can we do that?
 
Joe
-----Original Message-----
From: neuros442linux-main-admin@lists.sourceforge.net [mailto:neuros442linux-main-admin@lists.sourceforge.net] On Behalf Of Bob Faskos
Sent: Wednesday, October 05, 2005 8:00 PM
To: Steven Robertson
Cc: neuros442linux-main@lists.sourceforge.net
Subject: Re: [Neuros 442 Linux Main] USB jack as power plug for N3 and 442-320?

Steve,

Thank you.
I asked someone who designed USB hubs before about usual hub power policies.
He said that there are some USB hubs (1.1) out on the market that will completelly shut down power to any peripheral that attempts to drain more than 100mA of power without declaring it first. This is a "short-circuit" protection mechanism to protect the client.
He says that these tend to be higher-end models and cost more, so it is quite unlikely that you will find them in real life.
He also told me that ports on PCs tend to be switched and protected, but not restricted.

I think that this pretty much clears us to drain up to 500 mA without any pains in the conscience.

Bob



Steven Robertson wrote:
On Wednesday 05 October 2005 01:33, Bob Faskos wrote:
 Steven,

Thank you for the explanation.
I do remember seen some flashlights and "personal fans" that are
USB powered...

Anyway, if we cap power drain at 500mA I doubt that we will ever

get a computer (or any other host) on fire, simply because they are
designed to supply that amount of power. My concerns are the
reverse: how many actual host ports would deny power if we don't
enumerate? This would appear to the average user as "my N3 (or 443)

does not work with my computer". What do you think?

Bob
I'll google it further, but I don't believe the USB host actually has 
the ability to regulate current. My understanding is that the only

control the host has is to deny the high-power's software request, at
which point the client (or whatever) "officially" must not power up.
I've never seen a host controller that actually can selectively deny

power to a port, or limit current, that's not on a mobile device
(i.e. the digicam-to-Neuros thing we hawked for a while (and of
course the N3/442-320)). Certanily not any of the standard
south-bridge chips in modern desktops or even laptops. We should be

safe.

IANA USB engineer, nor have I read the spec myself, so I don't know
for sure. I'll hunt around, though.

Steve


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