Bug #1024 (oscillating re-camping), the latest news.

Dieter Spaar spaar at openmoko.org
Wed May 6 17:48:49 CEST 2009


I spent quite a lot of time to modify and patch
various settings in the GSM firmware trying to change
the behavior of the two phones which show the extreme
"Deep Sleep" problems (immediate PCH reception error
if the phone enters "Deep Sleep").

Those modifications did not remove the problems and
also did not cause any problems for the working
phones I have. So till now it seems that there is
no software workaround which can solve this problem.

However on one phone I was able to solve the problem
by replacing a capacitor which buffers one of the
power supply lines of the Calypso chip (the power
comes from an LDO in one of the other GSM chips).
This capacitor is supposed to be 10uF, however
I measured 7.6uF. I don't have SMD parts here so
I replaced it with a standard 10uF electrolytic
capacitor (I measured 10uF). After this
modification the "Deep Sleep" problems are gone
and the phone works as good as the other good ones.

Its still too early to conclude anything from
the above. I have ordered a few SMD capacitors
and will try the same with the other problematic
phone. Additionally its necessary to test if this
modification just moves the problem to lower
temperatures (remember, the problems also go
away if I warm up the phones by a few degree).

Best regards,

More information about the hardware mailing list