Re: [Gumstix-users] Re: 100% cpu utilization issues with 400mhz c onnex-xm

[Craig g. <cra...@gm...>]

This sounds very symptomatic of a heat problem-- Random hangs/reboots
at high CPU utilization.  I've noticed that the etherstix gets quite
hot.  One could try not connecting the etherstix to see if that fixes
the problem as well.

Craig


On 6/5/05, Holly Gates <hg...@ei...> wrote:
> Exactly what I had in mind too; dropout regulator gets too hot and
> starts cutting out -> gumstix hangs or reboots. The factors which would
> make this behavior worse are higher input voltage (like Dave says, the
> more you put in over ~4V, the more heat that will be generated) and
> increasing current draw. Higher CPU utilization will draw more current,
> resulting in more heat from the dropout regulator.
>=20
> Just last week I was having a similar problem with an FPGA board running
> from a dropout regulator. It was fine if running intermittently, or at
> full speed for about 30 minutes. But if I ran it full speed for a long
> time it would end up hanging. Putting a massive heat sink on it solved
> the problem, but that isn't really an option for the gumstix. Someone
> could try running the 100% test with their rig in the fridge or freezer
> to see if lower ambient temp eliminates the hanging.
>=20
> -Holly
>=20
> Dave Hylands wrote:
>=20
> > Hi Alan,
> >
> > > But if I change it use the 4.2V setting, it doesn't
> > > lock up anymore; at least it's been running for the
> > > last 20 minutes and I think it should work 'forever'
> > > now.
> > >
> > > Using a voltmeter (not terribly accurate analog
> > > voltmeter), the power adaptor from gumstix is 5V as
> > > printed, and the 5V on the universal is also 5V, and
> > > the 4.2V setting is about 4.2V.
> > >
> > > Does anyone have any thoughts on this?
> >
> > It sounds like a power problem with the voltage regulator on the
> > gumstix. I'm not sure what exactly is being used, but most modern
> > voltage regulators have a thermal shutdown mode.
> >
> > Running the CPU at 100% will draw the most amount of current. The
> > difference between the voltage being provided (5v) and that being
> > consumed (3.3v) is wasted as heat in the voltage regulator. Dropping
> > the voltage to 4.2v will reduce the thermal energy being dissipated.
> >
> > That's my hypothesis.
> >
> > --
> > Dave Hylands
> > Vancouver, BC, Canada
> > http://www.DaveHylands.com/
> >
> >
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>=20
>=20
>=20
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