Dr. H. Nikolaus Schaller
hns at goldelico.com
Fri Jan 21 09:57:01 CET 2011
welcome to this new list where we want to give all Early Adopters a forum to
exchange ideas, requests, status, questions etc. with the developing
Christoph, David, myself and others from the core development team will try to
answer your questions.
1. Component Sourcing
We have ordered the first GTM601W modules and 25 units will arrive
in approx. 10 days. So UMTS is secured.
For the OMAP processors it is not difficult to get them. Either DigiKey,
Mouser, EBV/Avnet have them in stock.
A minor issue is finding the best price. There are different options:
* OMAP3503DCBB (w/o DSM and Graphics engine) is the cheapest
* OMAP3530DCBB (600 MHz variant)
* OMAP3530DCBB72 (720 MHz variant)
* DM3730CBB1000 (1GHz)
They are are drop-in replacements and there is only one very small
difference between OMAP35xx and DM3730 (replace a R with a C).
The price is not exactly clear. From my research it appears that
the DM3730 is cheaper than the OMAP3530DCBB72 - i.e. more
MIPS/€. But this has to be verified before we order.
A major issue is sourcing of the PoP Memory chips. We need quite
special devices since they must match the OMAP processor.
Micron is the main supplier and has two different types:
a) MT29C - combined LPDDR/NAND flash
b) MT46H - LPDDR only
If you want to help us with search please check for a VFBGA168
package (there are many different packages available).
We have identified these variants (price is from EBV home page for
128 MB RAM 256 MB Flash ?
256 MB RAM 512 MB Flash ?
512 MB RAM 512 MB Flash ?
128 MB RAM 0 Flash 13 EUR
256 MB RAM 0 Flash 23-37 EUR (there are different temperature ranges)
512 MB RAM 0 Flash 58 EUR
1024 MB RAM 0 Flash 126 EUR
for comparison what other projects use:
* GTA04A2 samples 256 MB RAM 256 MB Flash (~30€ but no longer available)
* Beagleboard 256 MB RAM 256 MB Flash
* BB-XM 512 MB RAM 0 Flash
* Pandaboard 1GB RAM 0 Flash (I have no idea how they can sell them at 179 USD without loosing much money)
* OpenPandora 256 MB RAM 256 MB Flash
The problem we have to solve is that we have not yet got a quotation
for the MC29C chips and nobody has them in stock. And they appear
to be available only in Asia or the US. I am working with AVNET
Europe since weeks to get through this. It is like wading through syrup...
The supply situation for the MT46H is better - but then we won't have
built in NAND flash which is good for permanently storing X-Loader,
U-Boot and the U-Boot environment.
From our experiences 256 MB RAM is good enough (BeagleBoard) but
512 MB would be better. 1GB is still too expensive.
So if you have experience to share or find other compatible solutions
or suppliers, please let us know.
All other components are quite easily available through DigiKey or
other sources, so we order them with low lead time.
2. PCB layout
We are working heavily on updating the PCB layout from the GTA04A2
samples towards the GTA04A3 version. This means fixing some nasty
bugs. We did have bugs in the component library which is a situation that
no integrated Design Rules Check can reveal. But we know from the
GTA04A2 samlpes what the most critical bugs are and let's hope that
we don't introduce new ones :)
Major changes from A2 -> A3 are:
* replace GTM501 by GTM601 incl. some driver logic (=> better UMTS performance,
cheaper, 1.8V logic compatibility, better availability since GTM501 will go out
* replace LDM303DLH (Accelerometer+Compass) by HMC5883L + BMA180
(LSM303 is not available, BMA180 has best ADC resolution we know of)
* redesign step-down converters for TPS65950 (we have problems during
power on and with higher battery levels - the system does a spurious
self-reset with voltage > 3.5 V and it appears that there is quite a bad
power conversion rate)
* fix some crossed over lines (I2C1, serial I/F for Bluetooth, reassignment of
some GPIOs to better match power-on states)
* adding two 60 pin B2B connector headers to allow to connect different
displays and peripherals
* AC charger power input added to RS232 connector (6 -> 8 pins)
I think we will need approx. 2 weeks to finalize this. And then, production
of the PCB needs approx. 4 weeks.
Our SMD production company is currently getting a new and bigger
pick&place machine so that they have the capacity to produce hundreds
of GTA04 units.
3. Which information expected in the Wiki?
I have set up a new wiki page:
which is thought to communicate the best information materials you need.
To structure this in advance, please add your wishes to the requested pages
4. Draft of the User Manual
We are also writing a user manual and please find attached an (early,
incomplete and sometimes wrong) draft.
So if you have ideas, suggestions, questions, please use this list for
BR and happy high-power-Freerunning :)
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