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

[Werner Almesberger]

matt_hsu wrote:
>    Wall charger

Okay, so let me double-check: this is

- wall charger connected to the Neo's USB port, then
- plug wall charger into mains

Correct ? In this case, some instability as the wall charger gets
started seems quite normal. Good, nothing sinister is going on :-)

So yes, it seems checking MBCS1.usbpres, like Andy suggested, is
the right thing to do:

- get and clear interrupt status
- read MBCS1.usbpres and act on it
- if USB has changed between reading the interrupt status and
  reading usbpres, we'll get a new interrupt and repeat the
  procedure with the same result

- Werner