USB Powered Speakers

[Programmer In Training]

On 04/09/10 15:24, Warren Block wrote:
> On Fri, 9 Apr 2010, Programmer In Training wrote:
> 
>> On 04/09/10 10:15, Brodey Dover wrote:
>>> "Apr  8 22:30:16 heaven kernel: usb_alloc_device:1624: getting device
>>> descriptor at addr 3 failed, USB_ERR_IOERROR!"
>>>
>>> exactly! That is what is causing the issues. From what I can see, it
>>> is like it was explained before. The OS has chosen to play nice and
>>> request that the speakers are disabled.
>>>
>>> The power requirements will not affect the system until the speakers
>>> are producing sound. In other words, the system will only draw UP to
>>> the power input rating while in operation. At idle, I'd wager they may
>>> only use 1/10 of its power rating for the idle ICs and a power LED.
> 
> Just to add:
> 
> When you plug in a USB device, it is a "low power" device (single unit
> load, 100 mA) by default.
> 
> If that device wants to draw more power, it has to request high power (5
> unit loads) from the hub.  The hub can provide that power, or shut down
> the port.

I never knew that about USB ports.

>> Only it's not the speakers that have their operation interrupted, JUST
>> the keyboard (not even the mouse is affected).
> 
> Guesses:
> 
> Total power budget (but FIFO?).

I don't get that. Do you mean total power allocated to USB?

> Speaker/keyboard USB ports are on the same internal hub.

I'm not sure what you mean here. I've put the speakers on the internal,
builtin USB ports (1.x) and they work fine except keyboard starts
flaking out. I put them on the USB expansion card (which mouse and
keyboard are on because they were starting to flake out on the builtins)
with the same exact behavior.

> High-power OLED keyboard (my eyes!).

Keyboard label (if it is to be believed) is +5V 100mA. It's just a
standard keyboard with some extra multimedia keys that aren't active (a
pity, too).

> Speakers labelled 500 mA but really only a low-power USB device.

Than they shouldn't be messing with the keyboard, right?

It usually takes about an hour or so for the keyboard to settle down to
a usable state (until then, I'm doing a lot of mousing as the keyboard
is near useless).

I really don't know where to look for this. I've never even heard of USB
powered speakers until I got these (no, I don't pay much attention to
what's available unless I have a great need for it). I'm thinking I'm
just going to wait until Tuesday and get a brand new pair of
wall-powered speakers. This hassle is NOT worth it (they put out decent
sound).

-- 
Yours In Christ,

PIT
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