From: Joe B. <jb...@ne...> - 2005-10-03 03:03:24
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Well, agreed we certainly don't want shiny flames :) But I guess the question that remains for me is that even if we use the USB jack for both charging and connection to a PC, can't there be separate modes for the two scenarios? In other words, if the N3 connects to a PC, it knows to demand no more than 500mA (and thus hopefully avoid the shiny flames). If on the other hand, the N3 connects to a wall adapter, it can know it's a wall adapter and thus draw 1A (or whatever is appropriate for the wall adapter). Since we're supplying both the N3 and the wall adapter can't we do that? Now I recognize that this partially reduces the desirability of the solution since the RZR wall adapter won't allow rapid charging, but it's still ok in a pinch and allows the two other advantages. Am I off base here? Joe -----Original Message----- From: neu...@li... [mailto:neu...@li...] On Behalf Of Steven Robertson Sent: Sunday, October 02, 2005 6:35 PM To: neu...@li... Subject: Re: [Neuros 442 Linux Main] USB jack as power plug for N3 and 442-320? > There are also some tricks that may be necessary to play in order to=20 > convince the hub to give you the full 500 mA. I need to study the spec > a little bit. The question is if full power is readily available from=20 > the USB connector or if we need to establish protocol and enumerate=20 > before the hub give us power. Does anybody know this part of the spec? IIRC, you do need to establish a connection to grab the full 500 mA,=20 *technically*. The USB spec requires a device to register and be=20 accepted as high-power before the bus will allow draw, so that it can=20 keep software control over maximum power draw, etc. On the other=20 hand, low current power (20mA? 50mA?) is available as soon as the=20 cable mates, but the thing being plugged in is still required to=20 report its usage per specs. However, I remember somewhere some USB coder grumbling about how=20 nobody ever actually does this, and that the whole software control=20 thing is pointless. So if spec compliance isn't an issue, then you=20 should be able to draw as much as you want without blowing the USB=20 host. Though that'd be kind of bad to do for the customers; I=20 imagine "i plugged in my neuros and my computer caught fire" would=20 rank pretty much above a color screen in terms of influence over=20 buying patterns. Although some end-users do seem rather neanderthal=20 in their approach to technology, the "ooh shiny" approach would=20 likely backfire if they burned themselves on the shiny flames. Steve ------------------------------------------------------- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl _______________________________________________ Neuros442linux-main mailing list Neu...@li... https://lists.sourceforge.net/lists/listinfo/neuros442linux-main ------------------------------------------------------------ Mail was checked for spam by the Freeware Edition of No Spam Today! The Freeware Edition is free for personal and non-commercial use. You can remove this notice by purchasing a full license! To order or to find out more please visit: http://www.no-spam-today.com |