[Tinyos-devel] current draw in deep sleep for telosb

Prabal Dutta prabal at cs.berkeley.edu
Sat Jun 30 15:12:54 PDT 2007


The line's probably floating and you're probably acting like an
antenna and picking up 60 Hz AC.  This might be causing the input
pin's FET to cycle, drawing power as the gate capacitance charges and
discharges.  The solution is usually to either make it an output or
pull it up or down.

- Prabal

On 6/30/07, Razvan Musaloiu-E. <razvanm at cs.jhu.edu> wrote:
> Hi!
>
> On Sat, 30 Jun 2007, Vlado Handziski wrote:
>
> > I suspect a HW problem on your testing node. Have you tried with another
> > one?
>
> I tried with several of the tmote skys I have around. The effect is most
> visible (and persistent) on the ones which have the 10-pin connector
> populated with pins. When I touch the I2C Clock pin the current changes.
>
> I was able to replicate the problem also on a mote without pins by
> touching with my finger the 10-pin connector on the area of the I2C Clock
> hole. The increase in this case was only temporary though. :P
>
> I just checked and the problem is also reproducible in XubunTOS using the
> T2 version 2.0.1.
>
> > The content of MotePlatformC has been stable for a long time and Null
> > consumes ~ 7-8uA on a sensor populated node without any modifications to
> the
> > code.
>
> I think it looks stable because on a mote without pins on the 10-pin
> connector the situation is stable unless you start touching it.
>
> > In general, when not used, the pins on the msp430 are put in input to
> > reduce the leakage currents.
>
> My hardware knowledge is limited so I cannot really argue why puling that
> pin to zero helps. I just experimentally noticed that it does. :-)
>
> --
> Razvan ME
>
> > On 6/30/07, Razvan Musaloiu-E. <razvanm at cs.jhu.edu> wrote:
> >>
> >> Hi!
> >>
> >> I'm running the latest CVS and today I noticed that the Null application
> on
> >> telosb draws an unusually high (and variable) amount current (around
> >> 0.5-0.8mA). The problem seems to be in in Init.init function from
> >> MotePlatformC.nc from tos/platforms/telosb/. At the end of it the
> >> TOSH_FLASH_M25P_DP function the clock pin is put on input. By making it
> >> output on zero the current stabilized to the normal low values (7-8uA). I
> >> attached the patch with the changes. It can be aplied by running the
> >> following commands:
> >>         cd $TOSROOT
> >>         patch -p0 < telosb-current.diff
> >>
> >> Can somebody confirm the problem and test this solution?
> >>
> >> Thank you!
> >> Razvan ME
> >> _______________________________________________
> >> Tinyos-devel mailing list
> >> Tinyos-devel at Millennium.Berkeley.EDU
> >>
> https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-devel
> >>
> >>
> >>
> >
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