AT%SLEEP=n power consumption
Joerg Reisenweber
joerg at openmoko.org
Mon Oct 20 11:48:21 CEST 2008
Am Mo 20. Oktober 2008 schrieb Alastair Johnson:
> Werner Almesberger wrote:
> > I order to evaluate the impact of the AT%SLEEP=2 work-around, Joerg
> > asked me to measure how the sleep mode affects the current drawn by
> > the system.
> >
> > Test setup:
> >
> > - device is idle but (for convenience) not suspended
> > - GSM is active and has registered with the network (AT+CFUN=1,
> > AT+COPS=0)
> > - the test setup does not suffer from #1024
> > - power is supplied to the battery terminals from a lab power supply
> > set to 4.0V
> > - USB is not connected
> >
> > Battery current of the whole system in mA. Values are from measurements
> > averaged over about 15 minutes each:
> >
> > at%sleep= avg min max samples
> > 4 96.0 91.6 198.0 20006
> > 3 98.4 91.6 214.6 21432
> > 2 102.2 97.6 209.3 21428
> > 1 104.0 101.9 197.2 21352
> > 0 120.3 118.8 213.0 21452
> >
> > Integration period is one power line cycle (20ms). There are transients
> > much faster than 50Hz. E.g., sampling at 2.5kHz finds more noise but
> > does not change the difference in the averaged value:
> >
> > at%sleep= avg min max samples
> > 4 95.1 63.1 242.5 210207
> > 3 97.1 62.8 242.9 215460
> > 2 101.4 68.7 243.4 208230
> >
> > Note that this is an idle but not suspended system, hence the large
> > minimum current.
> >
> > So the difference between sleep=2 and sleep=4 is about 6mA. Joerg
> > mentioned that the idle current of the GSM subsystem should be 4mA,
> > so this would be an increase to 250%.
> >
> > Andy, you once measured the power consumption when the overall system
> > is perfectly suspended. Do you still remember how much it was ?
> >
> > - Werner
>
> Can you repeat the test on a handset that is suffering from #1024? I
> suspect that the frequent reregisters increase power consumption, but I
> don't have the equipment available to make the measurements. It
> certainly produces more instances of GSM interference on my PC speakers
> which suggests more transmit operations. If this is the case then for
> those wth #1024 SLEEP=2 may be no worse, or possibly better, than SLEEP=4.
that's the idea behind Mickey's recent bandaid, switching to SLEEP=2 on
detecting #1024 behaviour
/j
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 194 bytes
Desc: This is a digitally signed message part.
Url : http://lists.openmoko.org/pipermail/hardware/attachments/20081020/7458b227/attachment.pgp
More information about the hardware
mailing list