[Gta04-owner] charging log
Dr. H. Nikolaus Schaller
hns at goldelico.com
Sun Sep 8 19:26:55 CEST 2013
Am 08.09.2013 um 19:00 schrieb Radek Polak:
> attached is shell script and log from my GTA04. I just left GTA04 on USB of my
> computer. Expected result is that it should keep charging/discharging. Actual
> result is that it discharged to 0. Does the log help somehow? Otherwise i was
> quite busy but i plan to test the changes suggested by Neil.
You could use this script which does the same but a little more elaborated:
There you can also see the influence of VBUS.
But it is already clear what happens from these lines:
Thu Sep 5 17:45:32 CEST 2013
Thu Sep 5 17:46:32 CEST 2013
Essentially it shows that your USB charging voltage is too low. It should
be ~5V. Maybe you are drawing too much current from the charger or
the cable is weak.
There is a comparator in the TWL-usb-chager hardware set at fixed
4.5V that turns off the charger if VBUS goes below.
Software only turns on the charger if you manually unplug USB and replug
because only then, you get an MUSB event that enables charging.
There have been heavy discussions last year that this behaviour is right,
i.e. that you battery drains even if connected to USB and that we can't
The main argument is that this is a safety comparator detecting USB
unplugging even if the CPU isn't. And if the CPU would override that
(which is easily done - I had discussed and tested a patch), there is a
risk of overcharging the battery.
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