Isn't Wifi supposed to be off by default?

Werner Almesberger werner at
Fri Jan 16 01:40:14 CET 2009

I wrote:
> Let's hope so :-) Anything else would be hard to track down ...

Hmm, things stay somewhat mysterious. I cleaned up the module (the
connector on the WLAN module seems rather sensitive even to
microscopic spots of tin on its legs) and put it back. Now current
consumption looks much better. (All this is with Vbat = 4.0V.)

# hard reset
# cut USB power
					233.57mA 234.28mA 234.72mA  0.395mA
# screen blanker
					158.62mA 159.08mA 159.79mA  0.337mA
# LDO1: accel
					159.92mA 160.27mA 160.86mA  0.321mA
# LDO2: codec
					160.99mA 161.52mA 162.22mA  0.355mA
# LDO4: BT
					153.15mA 153.48mA 154.29mA  0.330mA
# LDO5: RF (GPS)
					109.09mA 109.17mA 109.21mA  0.034mA
					 96.25mA  96.79mA  97.07mA  0.226mA
# Glamo
					 96.48mA  96.78mA  97.55mA  0.308mA
# WLAN reset
					 96.82mA  97.12mA  97.58mA  0.231mA
# force SDIO clock low
gpio e5 e5=0
					 96.64mA  97.06mA  97.85mA  0.318mA
# GSM reset
					 96.86mA  97.07mA  97.52mA  0.174mA
# suspend
					 34.38mA  34.43mA  34.48mA  0.030mA

The figures are almost identical to what I got with the module removed.

So something happened, but I'm not sure what :-( Could be that there
was a bad contact that messed up things without affecting functionality.

Or there is some state, either in the WLAN module or somewhere else in
the system, that doesn't get cleared by hard reset and reboot, and that
state makes WLAN waste power.

I hate those bugs that just teleport away when you're moving in for the
kill :-(

- Werner

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