[Gta04-owner] charging log

Dr. H. Nikolaus Schaller hns at goldelico.com
Fri Sep 13 16:31:03 CEST 2013


Hi Radek,

Am 13.09.2013 um 16:05 schrieb Radek Polak:

> On Friday, September 13, 2013 02:40:10 PM Dr. H. Nikolaus Schaller wrote:
> 
>> Nice work, but I am not sure what is going on.
>> 
>> I have tested at least 8 different GTA04 and none did have below 4.5V. A
>> very typical value is like Neil did report (4.8 - 5.0V).
>> 
>> Did you check the cable or your power supply?
> 
> The power supply is USB port of my PC (core i7 - no cheap shit...). The cable 
> is the same cable that works perfectly with my Freerunner and every other mini 
> USB port device i have tried. Since others report the same problem i'd not 
> blame cables and chargers...

Yes, we can blame TI for setting the 4.5V hardware charger disable function without
having some auto-enable. Or using a lower threshold or just limit the charging current
instead of hard switching off.

Or the kernel for not correctly fixing this bug in the PMIC.

But for all the devices, chargers and cables I have seen it never has been a practical
problem, because it did not occur. I have been charging quite some GTA04 devices
with at least 5 different sources and cables and did never see this problem.

With one exception. The Letux7004 prototype. That one is very special because
it also has to power the 1.5 Watt backlight of the LCD and that really draws too much
current from the USB port. Even from a 2 A rated USB charger. There the VBUS
did go down to 4.3V as soon as the backlight switched on. And that shuts off
the charger immediately.

So I wonder if that is really a widespread issue (there haven't been many reports)
or just some small thing that is nice to have.

Nevertheless it is good to have your improvements - even if they are not necessary
in most standard cases.

BR,
Nikolaus

PS: I am still working to reproduce/analyse the reenumeration issue - but have no
definitive answers yet.


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