Power leakage: save 40mW by turning GSM on
werner at openmoko.org
Sat Jan 17 02:09:06 CET 2009
I'm continuing this thread on the more appropriate hardware list.
Background: I'm trying to get the system into a very low-power
state (and very low power variation state) so that I can measure
the effect of the various WLAN power saving options. This yielded
a few surprises. Instead of a few mW, I ended up with suspend
power in the order of up to 0.4W :-(
I found one more funny today: activating GSM saves about 40mW.
min avg max stddev
drain, power cycle, pull USB 242.40mA 243.17mA 243.59mA 0.370mA
suspend 81.90mA 82.96mA 85.91mA 1.043mA
resume 240.53mA 243.16mA 248.99mA 2.867mA
suspend 79.49mA 79.94mA 80.52mA 0.339mA
resume 241.32mA 241.80mA 242.48mA 0.376mA
echo 1 >/sys/bus/platform/devices/neo1973-pm-gsm.0/power_on
229.18mA 230.48mA 233.02mA 1.343mA
suspend 67.31mA 69.08mA 71.82mA 1.553mA
resume 227.32mA 228.56mA 232.24mA 1.429mA
suspend 66.87mA 68.46mA 70.53mA 1.343mA
(This is "battery" current, voltage is 4.0V, each measurements
consists of ten samples within 4-5s, integration period for each
sample is 200ms. GSM introduces some noise, so when I hit a "busy"
period, I rejected the result and retried.)
This run is without all the other power cutting I did yesterday.
So things like BT and GPS are up and running.
My best-case suspend power is still about 80mW, so I haven't found
the black hole yet.
More information about the hardware