[Gta04-owner] GTA04 power management.

Rainer Dorsch rdorsch at web.de
Sat Dec 24 11:39:25 CET 2011


Neil,

thanks for the code and sharing the data of your experiments.

can we do a bottom-up calculation? I.e. build up a spreadsheet like document, 
which contains the power consumption of every component/subsystem in each of 
its power mode (if there are more than on and off).

Can you give a pointer to the OPTION GSM module and why it drains battery 
although the device is off?

Not sure if it helps you with your problem directly, but it would certainly 
give me (and maybe others are interested too) much better overview of how the 
power is consumed by the GTA04 (and probably similar numbers hold for other 
platforms...).

Thanks,
Rainer

Am Samstag, 24. Dezember 2011 schrieb NeilBrown:
> Hi,
>  I've been playing with power management and have not achieved the results
> I had hoped for yet and am running out of ideas.  So I thought I would
> summarise were I am at in the hope that someone can say something helpful.
> 
>  I'm particularly looking at suspend-mode.  While runtime power management
>  (turning the CPU on/off dynamically as needed and adjusting voltage) is
>  attractive it can never save more power than full suspend, so suspend mode
>  will show us the minimum power usage without turning the device off
>  completely.
> 
>  I'm current measuring about 8%/hour battery discharge while in suspend
> mode which corresponds to approximately 100mA current drain.  When the
> device is off I lose about  1%/hour which is around 10mA (the precision of
> these measurements isn't great so there is a lot of rounding here) which
> is presumably attributed to the OPTION GSM module (and matches what HNS
> said it would be).
> 
>  So that suggests around 90mA still being used by something else.
> 
>  I've turned off the power supplies for WIFI, BT, GPS antenna, sensors.
>  I've turned off VDD1 and VDD2 to the CPU, and the various power supplies
> for USB and the battery charger (VINTANA, VINTDIG).  All the leds are off.
> 
>  All that should be left on are VDDIO aka 1V8, and REGEN aka 3v3.  It seems
>  that these need to be on by design.
> 
>  With the GPS off (it is, I checked) and the LEDs off and none of the
>  other peripherals enabled, 3V3 shouldn't be providing much current as
>  discussed previously.  The only things of any significance I can see
> driven 1V8 are:
> 
>   - The 26MHz clock.  This seems to be on all the time where I (naively)
>     would have expected it to be enabled by the CLKEN output from the
> TWL4030. I assume there is a reason for that?  How much current does it
> use?
> 
>   - Some power to the CPU.  If I read it correctly it is only supplying
>     - DDS - the display subsystem
>     - POP-DDR and POP_FLASH - the Package on Package memory.
> 
>     I would expect the DDS to be off (not sure how to check yet) and the
>     memory to be in self-refresh mode.
> 
>  Any guesses were that 90mA is going?  I would understand a 10mA draw, but
>  90mA seems a bit steep for a sleeping device.
> 
> 
>  BTW, only slightly related: it looks like it might be possible to get the
>  power management chip to turn 1v8 and 3v3 off and back on again in
> response to warm-reset.  So possibly I could use that to get the GPS into
> a known state if I really need to.
> 
> NeilBrown


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Rainer Dorsch
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