matt_hsu at openmoko.org
Thu Feb 14 05:34:30 CET 2008
> I'm not sure I understood the explanation properly yet. How can we get
> 4mA performance by setting low GPIO which "also block[s] GSM [entering]
> into sleep mode"? You mean we get 4mA performance if we do the LOW GPIO
> *and* we turned OFF power to the GSM module?
> But if we stay with the forced low GPIO and leave power on GSM, we get
> crazy behaviour during suspend from the GSM module power consumption?
> We don't need the GSM GPIO to be forced low any more to get lower
> current with GSM *OFF*, Allen will remove the resistor that made the
> reason to force the GSM GPIO low to hide the current flowing.
> Maybe we need to force GPIO for this RTS CTS thing -- is that still
> believed to be a problem?
> > If you don't have GSM related GPIO configuration, then resuming from GSM
> > incoming call works quite well. Unfortunately, the suspend current would
> > becomes 18mA. And the current does not always stay at 18mA, it would up
> > to 30mA periodically.
> What is the path this 18mA travels when it flows? It's inside the GSM
> module that this current is used?
It's our next step. And Allen is checking this now.
> > I try to have GSM related pins as PULLUP configuration. But nothing
> > changes. It seems that we might need HW solution such as a buffer
> > between GSM and CPU.
> PULLUP is really PULLDOWN now I think.
> - -Andy
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