the root cause of flip-flop charging logic if you insert wall charger

[matt_hsu]

Werner Almesberger wrote:
> Andy Green wrote:
>   
>> | The root cause is the signal from VBUS rasies and drops rapidly when
>> | inserting a wall charger.
>>     
> [...]
>   
>> It sounds like you were already in Linux doing this, so I wonder what is
>> the excuse of the adapter now to drop dead briefly on insertion?
>>     
>
> Is this VBUS coming out of the adapter (i.e., measured on the adapter's
> cable) or VBUS obtained by the system,
I'm not sure of this. I measured it from USB1/USB2 which is connected to 
PMU.
Do you think this elevator-style-signal is caused by system?
>  i.e., subject to contact bounce
> and all that ?
>
> Still, USB detection has a fairly generous debounce time of 62ms, which
> should be sufficient.
>   
Yes. But the USBx ping voltage raises/drops over 62ms, according to the 
following pics.

http://people.openmoko.org/matt_hsu/defect_usbx_signal.jpg
http://people.openmoko.org/matt_hsu/usbx_signal.jpg

The time dimension is 500ms.

Matt
> By the way, Matt, I didn't see your original mail. Could you perhaps
> post it here with the pictures (or, if they're too big, put them on
> sita aka people) ?
>   
> - Werner
>