Backup battery discharged -> GTA01 and GTA02 dead

Werner Almesberger werner at
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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