[EMAIL PROTECTED] wrote: > Tilman Baumann wrote: >> [EMAIL PROTECTED] wrote: >>> >>> Are there plans to provide a car adapter for the Neo? >> >> This is a general problem. Where are USB-Power Adator out there. Also >> for cars. >> But most of them just power the 5V line. This is bad with 99% of the >> bad behaving usb gadgets out there. >> But Neo is prolite and asks the host if it could draw it's 500mA and >> if not only takes 100mA out of the bus. >> This is how the usb specs tell you to do it. >> But most devices (like usb microovens and the like) just draw power >> as there would be no tomorrow and don't care how much the host can >> privice. If your usb-powersupply burns out - bummer. :) > Don't know if I understood right. Do you mean, > the Neo asks the power supply how much power it's able to provide? > Why should the Neo do this? Like I described below I guess > the Neo uses the 5V channel only for charging, and so > the 500mA are always okay. Why not use a normal 500mA > power supply then? > The USB specification only guarantees 100ma available to each client-mode device (in theory the Neo can be host or client, though currently only client mode is functional). If a device wants to draw more power it is required to "ask permission" from the host/hub. Many simple [non-compliant] devices skip this step and just assume that they can draw as much power as they want, which leads to problems of overloading the host/hub. The Neo will not draw more than 100ma until it has gotten "permission". There is one exception - the neo can detect its own 'dumb' charger by the presence of 48kOhm resistance between USB pin 5 and ground. In this case the power mgmt unit will allow the full 500ma power draw.
So if you have a decently noise-free 5V USB car charger, it would be fairly simple to solder in a 48k resistor (note that it should be low-tolerance - 1%) and have the neo pull 500mA for fast charging. As for forcing the neo to ignore USB power negotiation, I don't know if this is a kernel driver issue (hackable) or a USB chipset issue (less hackable)... -Rusty >> A button that puts your Neo in the same "i don't care about specs or >> your usb interface asshole" mode other deivces use and just draws >> it's power. (No idea if that would even work. But i think it might) > Does this mean, if we push this button, it's not possible > anymore to use a second USB device at the same time? > > I guess that doesn't change anything because if I understood right, > the 5V channel is used only for charging the Neo, (No power output > for attached devices) what is the reason for why we need those > external powered USB hub. > _______________________________________________ OpenMoko community mailing list [email protected] http://lists.openmoko.org/mailman/listinfo/community
