GTA02 is now an expensive brick

Henner Zeller h.zeller at
Tue Jan 6 18:33:25 CET 2009

On Tue, Jan 6, 2009 at 2:55 PM, Gothnet <openmoko at> wrote:
> Mike Montour wrote:
>> 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.
> 1. This really ought to be default behaviour, the current way is really
> *really* bad.
> 2. Why stick to 100mA? I thought the USB standard was for ports to support
> 500mA?

USB always allows for 100mA. This is how devices you plug into USB
work in the first place (after all, they need to draw power to even be
able to negotiate, right ?). However, anything _beyond_ 100mA needs to
be negotiated with the host, _up to_ 500mA - but it is not guranteed
that you get it; 100mA is guarenteed.

So I agree: the default should be 100mA initially.

> 3. I'm sure the FR doesn't need to negotiate with its charger.
> 4. How easy is it to make this change?
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