[Gta04-owner] Progress GTA04 and Letux OS

H. Nikolaus Schaller hns at goldelico.com
Tue Dec 19 10:57:48 CET 2017

Hi all,
even if it looks as if nothing is happening, it
is sometimes behind the scenes and we are still alive
and committed to improve the GTA04.

First of all there is a new release of the Letux Kernel:

letux-4.15-rc4: http://projects.goldelico.com/p/gta04-kernel/

Next, Andreas has provided some patches for U-Boot.

The most important one is to fix the "charge auto"
command so that I was able to add it to the boot.scr.

What problem does that solve for you?

The GTA04 had a problem that existed right from the
beginning, but wasn't ever solved well.

If you let the battery drain below 0% the device would
no longer start on battery insertion. Only if you connect
it to a charger, the battery will start charging with
~50-100mA. After a while the battery voltage reaches
3.2V and this will wake up the GTA04.

But then it starts to boot through U-Boot into the full
Linux kernel. This is a situation where the power hungry
OMAP and Display and backlight are all turned on
and draw ~400 mA. This immediately starts to discharge
the still almost empty battery and unless you are lucky,
the system will shut off, before it can start the Linux
charger driver and switch to 500 mA mode.

So in the wort case the device would cycle and try to
start Linux every ca. 10 minutes but never succeeds.
In the best case the battery gets more and more energy
and after several cycles Linux fully boots and you can
charge up to 100%. In the worst case it cycles forever.

The solution is simple: we just have to enable 500mA
charging earlier. E.g. in U-Boot, which means ca. 3
seconds after the system turned on.

What you should do: update your U-Boot in NAND.

To do this, use makesd gta04 / makesd gta04a5 to format
a "production image" SD card (dual partition). Insert
into your GTA04, press the AUX button and insert the
battery. This will flash the new U-Boot into NAND
(red screen) and from that moment on you have this new
feature in your U-Boot and can use the SD card for other

So thanks to Andreas!

Andreas has also prepared drivers for dfu access,
but I have not yet tested and integrated that. Comes

This will allow to reflash NAND through USB so we
might eventually be able to do such updates without
a need for special SD cards.

On the OS (user space) side we still have to find a way
to rebuild and maintain QtMoko2 and Replicant. If someone
is doing experiments, please share! Or if someone wants
to take care of it, please tell. We are a community
which lives from exchange and activity of many individuals.

Regarding the GTA04 accessories like Qi & battery
charger or the FST-1 clone, it still needs some time for
preparing the first prototypes. It is not forgotten, but
takes time since hardware production need 100% perfection.
We can't apt-get upgrade a PCB :)

Finally, there is a new idea for a tool to help repair
the broken GTA04A5 boards, which collect dust. You remember
that the OMAP processor chips had shorts under the BGA
balls and that I have already removed these bad chips a
while ago:


What has to be done next is to mount new ones and this
is where the new idea for a special tool comes in.
Its task is to protect the chips from swimming
away or rotating while melting the BGA solder balls.

I plan to build and test the tool in January - with new
energy :)

So please don't loose spirit and enthusiasm. Tinkerphones
and GTA04 are not dead but alive... And you can help to
make them even more alive by tinkering with your GTA04
or other device :) Please use this mailing list to share
ideas and ask questions and give answers.

Let me close with wishing happy holidays and a good start
into 2018 which will hopefully bring a lot of new (and good)
things to tinker with - and good discussions.


PS: please do not forget to add yourself to this
tableau if you will visit FOSDEM 2018:


PPS: The Pyra Project is very close to arrive at destination:


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