Joerg Reisenweber schrieb: > [Nils Faerber Di 13. April 2010]: >> I am preparing for a vacation and want to avoid carrying too many >> accessories. >> So I took my universal USB charger (which is just a USB plug carrying >> the +5V) plugged in the Nokia micro-USB cable and connected to the N900. >> >> Well, it does not charge - in contrast to almost any other device. > > Probably it does, just it charges at 100mA only, and it doesn't signal it's > charging. Well, pitily it does not - I just checked with a "USB charger" which has a dual color LED turning red on current flow. When I connect the N900 via the normal USB cable there it does not change in any way. Just connecting the charging adapter change the LED from green to green plus a little red which mean current flow (just from the regulator). So I think we can safely assume that a blank USB cable will not in any way charge, even not at 100mA. >> This is I think also perfectly valid since there is no host at the other >> end to negotiate the charging current. > > No, according to USB specs any source of VBUS 5Volt USB has to deliver 100mA. > And the charger chip enables charging @ 100mA when detecting external 5V on > USB - completely compliant with these specs. Yes, sure. What I meant is, if the charger is designed in a way to only properly work when sucking more than 100mA it would be valid to refuse charging. If it could handle a 100mA slow charge but it apparently does not do that I would see this as a bug. >> So assuming I know what I am doing is there a way to enforce the N900 to >> start charging even if there is no host connected? This must work >> somehow since the power adapter presumably does not contain a USB host ;) > > Exactly. The charger shorts D+ and D- data lines of USB port. > This should enable fast charging Ah! I will try that - press thumbs that it works ;) >> Some fiddling with /sys/... or DBus would be fine with me... > > Alas we got no sysfs nodes (yet ;-D ) to control the BQ24150 USB charger chip > directly. BME does all the 'magic' for now, and afaik there's no API to tell > BME to switch to a different charging mode. Umpf... too bad. The D+/D- trick sounds promising, many thanks! > cheers > jOERG Cheers nils -- kernel concepts GbR Tel: +49-271-771091-12 Sieghuetter Hauptweg 48 Fax: +49-271-771091-19 D-57072 Siegen Mob: +49-176-21024535 http://www.kernelconcepts.de _______________________________________________ maemo-users mailing list maemo-users@xxxxxxxxx https://lists.maemo.org/mailman/listinfo/maemo-users
