[Gta04-owner] Power in suspend (was Re: New GTA04 installation!)

Dr. H. Nikolaus Schaller hns at goldelico.com
Tue Nov 20 14:18:02 CET 2012

Am 20.11.2012 um 14:01 schrieb Radek Polak:

> On Tuesday, November 20, 2012 11:37:28 AM Dr. H. Nikolaus Schaller wrote:
>> BTW: it is even worse if the modem sees some base stations but they
>> don't receive the answers. I have seen the modem alternate every 30
>> seconds between 3-10 mA and 200 mA.
> Hi Nikolaus,
> have you actually tried to meassure the current drawn by modem or is this 
> number just from the modem specs?

That was collected during one measurement. If I remember correctly it was
on an A3 board connected to a power supply and mA-meter where the
TPS/CPU was completely shut down and the Modem was still trying to
connect to a network. It oscillated between these 3-10 mA and ca. 200 mA.

After removing SIM (i.e. the modem won't ever try to connect to a network)
it was constantly between 3-10 mA.

A similar test with the initial A4 boards did reveal a hardware bug with the
RS232 driver that did not shut down at all. But this has been fixed for all
boards by adding a small copper wire (near the camera connector).

> It would be nice to know that modem is not eating our battery. With 3.5 kernel 
> i have ~30mA in suspend so there must be still something eating those 
> 20..27mAmps then..

Well, the DRAM needs some refresh and some other chips are/may be not
completely be shut down because the 1.8V and 3.3V rails are still active.
Candidates that can draw some mA in idle (not suspend) are compass,
IrDA and RS232 driver. For the latter the new A5 board is planned to have
separate GPIO controls.

And potentially it could also be the display module where I don't know if
the suspend code sends the right commands. And since we have only the
GTA02 code and no data sheet for this part of the module we don't know if
the GTA02 code has been ported correctly.

> Btw do you have idea why A3 users have better the suspend numbers? (i cant 
> check but IIRC someone with A3 reported better numbers, is it true?)

Besides the missing function to send the modem to draw some 10 uA
I am not aware of any differences that can influence the power consumption.

So I would rather assume it is a different setup of base station. But this
is difficult to compare. One would have to make an experiment with
a case glued to some table and swap boards, SIM, SD etc...


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