[Gta04-owner] News: CPUs have arrived - Vibrator motor control - Audio

Dr. H. Nikolaus Schaller hns at goldelico.com
Wed Jun 1 11:11:03 CEST 2011

Dear all,

=== CPUs finally arrived ===

Finally, the DM3730CBP CPU chips have arrived [1]!

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This was the most important missing component to
start building the GTA04A3 Early Adopter boards.

So we see an end of the waiting phase and start of

=== Vibrator motor control ===

We have added some code and command to our
U-Boot that allows to switch the Vibracall motor
H-bridge of the TPS65950 into PWM-mode. This
allows to determine rotation direction and speed
of the motor. And, it works on the GTA04A2 board.

If you study the data sheets of the TPS65950 you
will find that the PWM can also be driven by the
Audio codec (PCM) so it will become possible to
make the vibrator generate noise and music...

Since this requires some music file to be played
we leave this to the ALSA sound drivers in the
Linux kernels that we will have to implement.

There may already be some code e.g. from
the N900 or Palm Pre which share the same
chipset family.

=== Audio ===

For audio we also have added some test code
to U-Boot but were not completely successful.
We only find sound in the right channel, but
the earpiece amplifier is connected to the
left channel subsystem. This needs further study
and may be simply a bug in setting up the
McBSP2 or even Pinmuxing.

=== General availability ===

Let me write a little about general availability of the
GTA04 board since we receive more and more
inquiries (which is very good!).

There are two issues until we can ramp up
production for all of you.

One is about component availability. This changes
daily and every now and then we find out that
one or another component becomes end-of-life.
Then, we can check if we find a replacement or
simply buy some thousands and build our own
stock. This has already happened for 3 components.

A similar problem can be delivery time. Even
if we check weekly it can happen that we find
enough components at the distributors to build
e.g. 100 GTA04 boards. Then, as soon as we
really want to start production and order them,
we find that someone else did buy a big bunch of
let's say Bluetooth antenna chips. And the estimated
restocking date of the distributor is 12 weeks in
the future.  Now, should we simply wait 12 weeks
until we can start production or can we find a
replacement? Or should we build boards without
and then ask everyone to ship the unit back to retrofit
the part?

For the Bluetooth antenna chips we happily
could find an older version of the antenna that only
differs in the maximum power parameter - and price :(

This is a general problem for any open hardware
project (and even for closed hardware if you read between
the lines of product announcements) and I don't see
a simple solution...

Now, the other topic why we can't announce
general availability yet is certification. We need
to do the CE and R&TTE measurements before
we can say that the design is ok and we can sell
the boards.

And to do this we need some more complete units
than the single GTA04A2 board we have... I.e. we
need more boards first, then make them work in all
CE relevant aspects (i.e. all radio transmitters must
work in normal operation mode) do the qualification
and then can announce availability.

But generally we have already done most of the walk.

Thanks for staying tuned,



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