My Gta02s wont charge

Werner Almesberger werner at
Mon Jun 23 03:00:46 CEST 2008

Joerg Reisenweber wrote:
> Yep, you got it. That's what I say with "when we don't obey the specs...".

But which spec would we be violating ? If there's nothing connected,
nothing happens anyway. If there is a USB upstream device or the
adapter, we're allowed to draw 100mA without the need for further

So all we have to do is make sure the power we draw until we're in a
better position to decide on the system's fate doesn't exceed 80mA
(this is what the 100mA limit effectlively translates to, see the
PCF60633 manual, table 91, page 75).

Since our system currently exceeds this 80mA envelope, we do wait for
an indication that we have a power source that can (probably) give us
what we need. It's in u-boot, board/neo1973/gta02/gta02.c, function

Note that this isn't bullet-proof. We could do better by running the
CPU at a lower clock speed. Also, given the excessive current drawn
by the GTA02v5 LEDs, the LED that's being blinked as an indication
in wait_for_power will probably bring down the system by pushing it
over the 80-100mA current limit.

- Werner

More information about the openmoko-kernel mailing list