About GSM modem

ALLEN_CHANG at fic.com.tw ALLEN_CHANG at fic.com.tw
Fri Feb 22 02:50:28 CET 2008

Hi Andy:

> > TX_MODEM : 2.9V
> OK did we remove the pullup on TX_MODEM on this board?
Yes, I did.

> > RX_MODEM: 0 V
> One of these should float since it is an input?
Yes, this is an input.

> > CTS= 0v
> >
> > RTS= 0v
> One of these should float since it is an input?
Yes, I think CTS is float. 

> > INT0: Floating
> >
> > INT0=2.9V
> I didn't get why INT0 shows floating AND 2.9V here.
> > I think maybe some wrong settings make our GSM_MODEM can’t enter sleep
> mode.

Sorry, I type wrong. 
INT0: floating, (this pin is use to interrupt GSM_MODEM)
IO1: 2.9V(When GTA02 has the incoming call,IO1 will wake up S3C2442)
> If I understood it, you are in a good sleep mode if we only pull 4-5mA
> with GSM modem "on"?
> > Do you have any idea?
> What is the level for Vbat at this time?  2.9 sounds like a diode-ish
> drop away from maybe 3.3V.  Is Vbat really still ~3.6V?

Yes, I set the VBAT to 4.0V.
I will check the GSM_MODEM's datasheet. Why is the 2.9V?

  Best Wishes~


Allen Chang ( 張 吉 隆 )

First International Computer Inc.
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Email:allen_chang at fic.com.tw

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