[Tinkerphones] Status GTA04A5

joerg Reisenweber joerg at openmoko.org
Thu Mar 16 23:40:38 CET 2017


On Thu 16 March 2017 23:18:20 Andreas Kemnade wrote:
> > That's probably a problem here: even an unsoldered polyacene cap would
> > leave  the charger circuit with a - however minimal - capacity vs GND, so
> > it would charge up very quickly and for sure reach nominal voltage. For a
> > way more thorough test, the charger circuit in TWL4030 should get
> > switched off prior to voltage test (if possible, I don't have the TRM at
> > hand, with the register specs) or alternatively RTC get checked if it has
> > a "power failed" flag set, or keeps time, after brief removal of main
> > power supply
> >
> > 
> 
> I don't think so. The charger will oscillate. Here is a measurement
> result of probably such a situation:
> root at gta04:~# for i in 1 2 3 4 5 6 7 8 ; do
> cat /sys/bus/iio/devices/iio\:device1/in_voltage9_input  ; sleep 1 ;
> done 3030 2863
> 3431
> 3466
> 3382
> 2727
> 3316
> 3171
> 
> Regards,
> Andreas

Yes, the TRM suggests that too:
>>
With this configuration, the backup battery starts charging automatically when 
VBAT > 3.2 V and VBAT >
VBACKUP. Backup battery charging automatically stops when VBACKUP reaches the 
specified BBSEL
voltage.
<<
(however neither is in contradiction to what I said above)

could you run a 
  for (( i=0; i<100; i++ )); do 
    cat /sys/bus/iio/devices/iio\:device1/in_voltage9_input
  done
instead? (no sleep)
I'd also be interested in state of BBCHEN and the way in_voltage9_input.get() 
works - note how the TRM also suggests a A/D conversation on ADIN9 needs 
BBCHEN=1 to connect the voltage divider and analog input to the battery, I 
wonder if and how the *.get() does that, if at all.

/j

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