GSENSOR_3V3 voltage drop

Christoph Mair ml at
Sun Aug 23 20:38:19 CEST 2009

> 2009/8/23 Christoph Mair <ml at>:
> > The voltage is now between 3.32V and 3.44V which seems to be ok,
> Nice.
> > but after
> > suspending it still drops to 2.44V Vmax and 1.78V Vmin (when the compass 
> > starts a measurement).
> Just to make sure I got you right: You enable the "g-sensor" and get about 
> then you suspend and _while suspended_ you get 2.4V and 1.8V respectively?
> What happens when you resume? Do you get back 3.3V? If this is the case you
> probably don't set GPD12/13 (CS), GPG7 (CLK), GPG6 (MOSI) to 0 and GPG5 
> to pulldown during suspend and leak the voltage from the CPU. Can you please
> make sure you set those pins during suspend!
I switch my Neo on, and the line goes immediately to 3.3V (I'm using Qi, if 
that matters). After SHR started (but with andy-tracking-kernel) I take the 
first measurement which results in 3.3V. I never explicitely enabled the g-
sensor. Then I suspend the device which results in the voltage drop down to  
2.4 (normally) or 1.8 (only if my chip draws some current, I think 1mA max, 
but I did not check this yet).
Right after resuming the voltage rises to 3.3V again.
I never touch the other pins since the compass chip has a I²C interface. I 
just use GSENSOR_3V3 as power supply, because it is easily accessible at 


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