Current Bootchart / GSM power
andy at openmoko.com
Fri Jul 11 12:02:26 CEST 2008
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Somebody in the thread at some point said:
| My commentary is not about the small amount of power used by devices in
| the "off" state, rather it is about the fact that the GSM on the GTA01
| and GTA02 is left in a fully-operational, completely up-and-running
| state, even when you have shut down the Linux kernel and the PCF606xx
| PMU chip has otherwise shut down the power to all other components in
| the phone.
| The troubles this might make for the unaware user range from the trivial
| and very probable draining of the battery when the phone is supposedly
| off, to the improbable and not-so-trivial.
On GTA01 IIRC and certainly 02 there is a) what claims to be some kind
of logical on / off switch in the form of an NPN transistor that goes
into the GSM chipset, and b) the GSM logic side has switched power
itself that can be on and off.
The RF power amp is connected directly to battery because of the high
current it wants, the enable for it should be always disabled when GSM
logic side is unpowered... I seem to recall Allen has checked this.
GSM side is a bit funny because it has pretty direct access to battery
but if logic gets both told to be "off" and then depowered on shutdown
as it presumably should then it should be OK AFAIK.
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