Backup battery discharged -> GTA01 and GTA02 dead
Werner Almesberger
werner at openmoko.org
Mon Jul 21 11:58:47 CEST 2008
Rod Whitby wrote:
> but never as a result of the normal NOR boot sequence.
Has it ever booted from NOR (before it started to act strangely) ?
> *Never* have I been able to get it to boot twice in a row.
That sounds bad :-( I've seen systems behaves like yours, but they
were usually afflicted with some hardware problem. Normally, it's
the VB_SYS cap Andy mentioned.
Just to check: is this GTA02 a mass-production device or a preview
model ? Could you please mail the serial number ?
> I'm monitoring the nRESET line at various points in the sequence above,
> and I've never seen it go above 0V.
That would be consistent with the capacitor problem. (But could be
a number of other things as well.) I guess you don't have an
oscilloscope you could attach to watch it continuously for you ?
> Knowing that the batteries and usb charger are fine, and that nRESET is
> still low, what's the next level of debugging I can try - how do I work
> back from the nRESET test point to the PMU pins to find out what's going
> wrong?
Hmm, that's the point where I'd start watching voltage levels with
a scope, and maybe have look the the capacitors under the shield ...
- Werner
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