Re: [Gumstix-users] Connex 400 low power ?

[Yuvraj A. <yu...@uc...>]

Hi Dave, 

Thanks for the reply. I am trying to optimize the _idle_ power of the 
gumstix. I was able to put the WiFi chip in Power Save Mode (PSM) which
drastically reduced the idle power of the WiFi Stix. I still get a 
kernel BUG when I try to set the parameter using iwconfig, but it seems 
to work after checking on the Oscilloscope (sets to a 100ms sleep interval
it seems) 

For everyone the command I used to enable PSM was "iwconfig mwlan0 power
on". For some reason the normal way of setting the PSM period using
"iwconfig power period 200ms" doesn't quite work. Anyways - at least the
power of the WiFiStix reduces from about 1W to ~100mW or so level using the
other command.  

I was trying to figure out ways to reduce the power consumption of the base 
Gumstix-connex400. I cant seem to get the processor voltage scaling to work 
even though the 2.6.21-gum kernel has options for allowing it that I have
enabled. Did you get Voltage/Frequency scaling to workh? 

cheers
Yuvraj

-----Original Message-----
From: gum...@li...
[mailto:gum...@li...] On Behalf Of Dave
Hylands
Sent: Monday, October 29, 2007 5:29 AM
To: General mailing list for gumstix users.
Subject: Re: [Gumstix-users] Connex 400 low power ?

HI Yuvraj,

> even considering the 60mA (0.06A) for the connex-400, it should translate
to
> about ~300mW. Unfortunately for my combination (connex400 + thumbstix +
> wifistix) I am measuring almost 1W of power draw! The WiFi part should not
> be consuming more than
> 100mW from what I understand.

No - the wifistix promises not to transmit more than 100 mW of power.
The wifistix actually consumes alot more.

When transmitting, the wifistix draws about 0.5 A, which at 3.3v
translates to 1.65 watts.

It consumes more power than the gumstix when its running full tilt.

> Any thoughts on what can be done to lower the power consumed by the
gumstix
> ?

I don't think that the gumstix is the problem in your case. It's the
wifistix. Wifi devices are notoriously power hungry devices. Switching
to some other wireless communication method is probably the best bet.

-- 
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/

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