GTA02 is now an expensive brick
raijinsetsu at gmail.com
Tue Jan 6 14:40:44 CET 2009
From: Mike Montour <mail at mmontour.net>
> I still find it amazing that the FR doesn't charge when off and empty.
> phone (and every other portable device) I've ever owned does this. It's
> even a software thing - there ought to be some direct hardware way to
> the battery from totally dead without the need to even start booting.
The FR's power-management chip (PCF50633) can be configured to do this,
but it's not as simple as you might think. One source of complexity is
the USB standard, which requires devices to negotiate their power
consumption with the host computer. Another complication is a brownout
problem on some phones which prevents them from booting the CPU unless a
battery is present.
If you program the PCF50633 as:
- charger enabled
- 100mA current limit
- do not wake on USB insertion (avoids the brownout issue)
then it will have the behaviour that you want - even with a
completely-dead battery, you can plug it in and it will slow-charge the
battery in hardware. I think it still technically violates one of the
USB standards by drawing current without talking to the host, but IMHO
it's unlikely to cause any real-world problems.
This, to me, would seem like the best solution to this issue. In fact, I'm
suprised this isn't the default behavior of the power management chip. Is
this something we can do?
PS - Someone from OpenMoko was kind enough to work with me on the battery
issue, but I'd like to prevent it in the future.
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