[Community] GTA04 - Power management improvements

Dr. H. Nikolaus Schaller hns at goldelico.com
Tue Jan 28 11:27:06 CET 2014


Am 28.01.2014 um 10:28 schrieb Hermann Schwärzler:

> On 01/28/2014 08:58 AM, Dr. H. Nikolaus Schaller wrote:
>> Am 28.01.2014 um 08:50 schrieb Hermann Schwärzler:
> [...]
>>> Hmm. When I measure power-usage by reading the charge-values of the
>>> battery I get the following:
>>> Over night
>>> 1) a switched-off device uses 288.1 mAh over a time of  9:33 hours;
>>>  a switch-off-on cycle uses about 7 mAh so the net usage is 281.1 mAh
>>>  equivalent to an average current of 29.4 mA.
>>> 2) a suspended device uses 195.3 mAh over a time of 9:20 hours
>>>  i.e. an average current of 20.9 mA
>>> This is more or less the 20 mA Radek is seeing.
>>> So both our devices are broken?
>>> Or is my test-setting "broken"?
>> How do you "switch off"?
> [...]
>> The correct way to turn the modem off is a script like this:
>> http://git.goldelico.com/?p=gta04-rootfs.git;a=blob;f=debian/config/root/wwan-off;h=87efafcf5f38a80b4e4fa074b7e5c31c2f7b635a;hb=HEAD
> No I did not use such a script. Just the "poweroff" command of the
> system. Tonight I will power off after running this script and will
> report my findings.


> But there remains the power-usage of a suspended device (that has no
> need to communicate with the base station as it lies on the same place
> all the time and receives neither calls nor text-messages): If
> communcation with the base station draws 100 mA the device would have to
> communicate 19% of the time with the station to get an average current
> of 20.9 mA...

Well, in suspend the CPU is in sleep mode and the DRAM in self-refresh. This
still needs some mA.

And we know that the IrDA receiver may still be turned on (known bug in GTA04A4
hardware). Since I don't know exactly what the Neil-kernel
does in suspend it may even be the RS232 that is not turned off.

So you have to expect ~10mA plus the average of the modem.


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