[Gta04-owner] Questions

Dr. H. Nikolaus Schaller hns at goldelico.com
Fri Oct 14 09:00:04 CEST 2011


Hi,

Am 14.10.2011 um 05:10 schrieb Wm. D. Clark, III:

> Hello to all,
> 
> Thanks for all the great work. I'm looking forward to the production runs.
> 
> Just a few question (sorry if they have already been covered and I
> missed them);
> 
> 1.) Has the problem of not being able to charge a completely dead
> battery been eliminated?

Not really. For the GTA02 the latest versions (A7) did solve it.

On the GTA04 we use a completely different power management
chip (TPS65950) and the errata denote a problem without known
workaround.

The reason is that the default current flowing from the USB input into the
battery is approx. 70 mA. This charges the battery from completely empty
to approx. 3.2 V. In that moment, the power controller thinks it is
safe to start up and power the CPU (and some peripherals).

But the charging current is not increased, so the voltage breaks
down and everything shuts off after some milliseconds. In the meantime,
the battery has also been discharged a little. Therefore, the system does
not come beyond this point of battery charge.

We have tried to add some code to the bootloader that it enables
real charging current immediately, but that failed. It appears that there
is not enough time for the code to really run. And, we can not disable
the auto-power-on function and wait until the user presses the Power
button.

The same problem makes it impossible to boot with USB power but
without battery. After the device is booted with battery, it is possible
to remove the battery and just power from USB (unless UMTS or WLAN
is enabled - then the device draws more current than USB provides).

We are currently reviewing some ideas for the GTA04A4 board to
reduce the immediate power consumption right after CPU startup,
but we don't know yet if it improves the situation.

> 2.) Has any thought been given to using an OLED display? Hopefully it
> would be daylight readable and extend battery run-time.

Our constraint was to reuse the existing case. Therefore, the display
module had to be exactly the same as for the GTA02. Of course we
want to improve that in the far future, but that requires to be able to
design and produce (cheap!) case parts.

> 3.) What about MeeGo for an OS? It run on the Nokia N900 with the ARM
> Cortex-A8.

Yes, appears absoultely feasible. Our idea is that there will be several
software projects like SHR, QtMoko, hackable:1, Android (e.g. based on
Rowboat), and whatever people like to work on. MeeGo fits into this idea,
but needs some persons to work on it. We just provide a bootloader,
kernel and preconfigured stock Debian/LXDE (for testing - not intended
for operation).

Nikolaus



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