[Gta04-owner] [Tinkerphones] Status GTA04A5

Andreas Kemnade andreas at kemnade.info
Thu Mar 16 23:18:20 CET 2017


Hi,

On Thu, 16 Mar 2017 22:31:33 +0100
joerg Reisenweber <joerg at openmoko.org> wrote:

> On Thu 16 March 2017 13:19:25 H. Nikolaus Schaller wrote:
> > Hi Andreas,
> > 
> > > Am 16.03.2017 um 12:20 schrieb Andreas Kemnade <andreas at kemnade.info>:
> > > 
> > > Hallo Nikolaus,
> > > 
> > > On Tue, 14 Mar 2017 21:24:18 +0100
> > > 
> > > H. Nikolaus Schaller <hns at goldelico.com> wrote:
> > >> Hi all,
> > >> you may be wondering how progress is.
> > >> 
> > >> First of all, I have currently 11 GTA04A5 working boards on my
> > >> desk (one did work initially but failed since now) which boot
> > >> fine.
> > >> 
> > >> It turned out that our hw-test script was not testing all
> > >> components as good as possible, so I have worked on it to
> > >> be much better. Now it also tests WLAN, Bluetooth, GPS
> > >> and some other components. In total it was much more effort
> > >> to put into kernel and hw-test to really be able to do
> > >> such an automated test. Reason is that you also have to test
> > >> the tester... And make the kernel and user-space work stable
> > >> for almost all chips and interfaces.
> > > 
> > > What I am wondering about is the backup battery test. I do not think it
> > > is a good idea to test only once. My old semi-broken gta04 gives flaky
> > > values there. So sometimes the voltage might look ok, sometimes wrong.
> > > So the test might miss problems.
> > 
> > Yes. It is very difficult to write tests that have 100% coverage of
> > all potential failures. Especially for rare failures.
> > 
> > Most of the tests are a little primitive and hence incomplete. They
> > mainly test if the PCB has been soldered properly, i.e. if peripheral
> > components can be accessed and respond reasonable to all stimuli.
> > 
> > Sometimes they don't even check this. For example the tvout test does
> > not test hardware (unless a tv set is connected to the headset jack
> > and somebody has a look at the result). So it is not even an automatic
> > test.
> > 
> > The backup test only checks if the supercap is being charged and has
> > reached a reasonable voltage since power-on. If the supercap would be
> > missing or had a bad solder joint it would no charge at all.
> > 
> > It does not even attempt to test the capacity of the supercap and if
> > and how long it maintains RTC during battery switching.
> 
> 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
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